NASA KNOWLEDGE!

[The True Adonis]

http://www.fasebj.org/cgi/content/full/13/9/1031

[The True Adonis]

Space travel causes rapid and pronounced skeletal muscle wasting in humans that reduces their long-term flight capabilities. To develop effective countermeasures, the basis of this atrophy needs to be better understood. Space travel may cause muscle atrophy indirectly by altering circulating levels of factors such as growth hormone, glucocorticoids, and anabolic steroids and/or by a direct effect on the muscle fibers themselves. To determine whether skeletal muscle cells are directly affected by space travel, tissue-cultured avian skeletal muscle cells were tissue engineered into bioartificial muscles and flown in perfusion bioreactors for 9 to 10 days aboard the Space Transportation System (STS, i.e., Space Shuttle). Significant muscle fiber atrophy occurred due to a decrease in protein synthesis rates without alterations in protein degradation. Return of the muscle cells to Earth stimulated protein synthesis rates of both muscle-specific and extracellular matrix proteins relative to ground controls. These results show for the first time that skeletal muscle fibers are directly responsive to space travel and should be a target for countermeasure development.—Vandenburgh, H., Chromiak, J., Shansky, J., Del Tatto, M., Lemaire, J. Space travel directly induces skeletal muscle atrophy.


Key Words: protein turnover • skeletal myofiber • spaceflight • TCA


    INTRODUCTION 
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
 
 
SPACE TRAVEL-INDUCED PHYSIOLOGICAL changes in skeletal muscle result in the loss of muscle mass and strength; the mechanism(s) that cause this loss are unknown. Skeletal muscle has evolved as a tissue whose primary function is to move objects against the force of gravity, and there is a close relationship between the size and metabolism of this tissue and gravitational force. When a heavy object is moved repeatedly, the muscle cells enlarge by hypertrophy, whereas a reduction in muscle tension or use, as occurs in bedridden patients and astronauts in space, leads to rapid skeletal muscle wasting (1,  2) . The mechanical forces that a muscle fiber generates to overcome gravity can be divided into two kinds: active and passive. Active muscle tension occurs during muscle contractions and results in the shortening of the myofiber's sarcomeres. Passive tension is tension applied to the muscle fibers by stretching and causes a decrease in the overlap of the sarcomeres. Both active and passive tensions are essential for normal muscle growth (3) ; they stimulate myofiber hypertrophy (4) and their loss leads to muscle atrophy (5) . Reduced generation of active and passive tensions in space most likely contributes to the muscle wasting process. Since extensive exercise programs during long-term space travel slow the rate of muscle atrophy but do not prevent it, other factors are also likely to influence the wasting process. For example, muscle atrophy during space travel may result from reduced levels of circulating hormones such as growth hormone (GH)2(6) or increased levels of the catabolic glucocorticoids (7) . Using a ground-based hind limb unloading rodent model for space travel-induced muscle atrophy, Grindeland et al. (8,  9) have shown a synergistic effect between GH and tension in attenuating muscle atrophy. The causes of muscle atrophy during space travel are therefore most likely multifaceted, with both local and systemic components.

Knowledge at the cellular and molecular level on how gravity/tension regulates muscle size by altering protein turnover rates has used tissue culture models to study these processes under defined in vitro conditions. These in vitro studies have shown significant interactions between muscle tension and exogenous growth factors. For example, increased muscle tension in avian myofibers increases their growth response to insulin-like growth factor-1 (10) and protects the muscle cells from the atrophying effects of the catabolic glucocorticoids (11) . Tissue-cultured myofibers therefore provide a unique model for studying the local vs. systemic interaction of these factors in the space environment and may assist in the future development of pharmacological agents to attenuate atrophy (12) . Studies with isolated cells in tissue culture offer a number of advantages over animal exercise physiology studies. It is easier in tissue culture to separate pure mechanical effects from other regulating factors present in vivo such as innervation, electrical activity, and levels of circulating hormones (13) . Tissue-cultured striated myofibers are uninnervated and can be maintained electrically quiescent in defined, serum-free medium (14,  15) . A potential disadvantage of tissue culture studies is that the skeletal myofibers are neonatal-like rather than adult fibers, based on morphology (14) and contractile protein isoform expression (16) . The cultured neonatal myofibers may therefore not respond to space travel in an identical manner to adult myofibers. With present technology, adult myofibers cannot be maintained in a healthy condition in vitro for more than several hours. Results obtained from tissue culture studies will complement those from in vivo studies (17,  18) to better understand gravity/tension regulation of skeletal muscle growth at the molecular level.

In the present study, tissue engineering techniques were used to form 3-dimensional skeletal muscle, organ-like structures containing several thousand well-aligned postmitotic myofibers capable of generating directed work (19) . These bioartificial muscles (BAMs) can be maintained without atrophy for over 30 days in vitro in perfusion bioreactor cartridges (20) and (as shown in this paper) successfully flown aboard the Space Shuttle in the mid-deck Space Tissue Loss (STL) Module hardware. BAMs were found to atrophy during 10–12 days of space travel in a similar manner to in vivo muscle and will thus provide a unique tool for studying the process of space travel-induced muscle atrophy and for countermeasure development.

[The True Adonis]

Gravity rules.

[The True Adonis]

Your training should be the most important factor.

[The True Adonis]

Why do Workouts Work?

By exploring how and why exercise causes muscles to grow, scientists hope to help astronauts avoid muscle atrophy.
 
 

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December 10, 2004: Most machines don't improve with use. Old pickup trucks don't gradually become Ferraris just by driving them fast, and a pocket calculator won't change into a supercomputer by crunching lots of numbers.

The human body is different. As weightlifters know, the more that people use their muscles, the stronger they become. And unused muscles do not remain preserved; neglect causes them to waste away, or atrophy.

Right: Heavy use doesn't wear muscles out; instead they grow bigger and stronger. Note: NASA astronauts don't need to be this buff.

It's a remarkable response, one that scientists don't fully understand. Somehow, muscle cells "sense" how they're being used and then remodel themselves to better fit the task. How does this happen? And what exactly is it about exercise that triggers the changes?

NASA needs to know the answers. Astronauts in space exercise furiously to keep fit. Even so, their muscles tend to weaken.



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"Normally, people's muscles do a lot of work that they're hardly aware of--lifting their bodies and maintaining posture against gravity. In space, that constant muscular work is removed. There's a danger of atrophy," explains Kenneth Baldwin, a professor in the Department of Physiology and Biophysics at the University of California, Irvine.

With NASA support, Baldwin is researching the inner workings of muscles and plumbing the fundamental mystery: Why do workouts work?

NASA has a special interest in isometric exercises--i.e., non-moving exercises where an astronaut pushes hard against a fixed surface. Motionless exercises allow for simple lightweight equipment less expensive to launch and less prone to break during a mission. But are they effective?

To find out, Baldwin's group gave laboratory rats a workout by activating the rodents' leg muscles with painless electrical stimulation. They tested three types of exercise: muscle contraction, muscle lengthening, and isometric, where the muscle exerts a force while remaining the same length. (Just think of doing push-ups: muscle contraction occurs in the "up" part of a push-up, muscle lengthening during the "down" part, and isometric while holding a push-up midway.)

Left: Prof. Kenneth Baldwin at work in his lab. [More]

After the sessions, the scientists performed tests to see how the rats' muscles responded. "What we found," says Baldwin, "was that after 12 sessions, all three types of workout tended to provide about the same amount of muscle growth," even the isometric exercises that involved no motion.

This was nothing new. Other scientists had come to the same conclusions before. But Baldwin's group took their analysis a step further:

In addition to measuring overall muscle mass--how "buff" were the rats?--they also measured the amount of contractile proteins within the muscle cells. Contractile proteins are what actually cause a muscle to contract. They are what give a muscle its strength.

To their surprise, Baldwin's team found that while isometric exercises did prevent leg muscles from withering, they did not stop a decline in the amount of contractile proteins in those muscles. The muscle was actually degrading on the molecular level.

Right: Each muscle cell contains many small bundles of contractile proteins, called myofibrils. These contractile proteins do the work of muscle contraction.

No one knows why this is so, but one thing seems clear: Isometric exercise might not be the best way to maintain astronaut muscles. Baldwin plans to investigate further with just-renewed funding from NASA.

A more unconventional possibility is that astronauts could stave off muscle atrophy by taking a pill. Anti-atrophy pills are only speculative right now, Baldwin says, but there are reasons to believe that they might be possible. That's because when atrophy sets in, the muscle isn't just withering away passively -- it's actively breaking itself down!

A complex network of enzymes within the muscle's cells disassembles muscle proteins molecule by molecule. "In order to chop those proteins up, you use a lot of energy," notes Baldwin. If scientists could pinpoint a key "lynchpin" enzyme in this network, they may be able to design a drug to block its action, thus slowing the breakdown of the muscle.

This active breakdown of muscle protein is going on all the time in everybody's muscles, as is the constant assembly of new proteins. Whether a muscle grows, shrinks, or stays the same size depends on the balance between these rates of destruction and construction, a bit like the water level in a bathtub that's both filling and draining at the same time.

Left: Astronaut Peggy Whitson works out onboard the International Space Station. [More]

Baldwin is taking a look at the mechanisms behind the "construction" half of this balance. In particular, his group is focusing on a hormone called Insulin-like Growth Factor 1 (IGF-1). Muscles produce IGF-1 in response to strenuous exercise, and this hormone in turn activates enzymes in the muscle cells that cause the cells to grow. Indeed, Baldwin found that levels of IGF-1 in the rats' muscles were higher just after exercising.

"Some people think that it's the mechanical stress that turns the gene (for IGF-1) on, but we really don't understand that process yet. What we do know is that IGF-1 triggers muscle growth," Baldwin explains.

Might supplements of IGF-1 be used to ensure that construction of muscle proteins keeps pace with protein destruction in astronauts? Baldwin says they're entertaining the idea and are already discussing ways in which that might be done.

If they're successful, it will be good news for more than just astronauts. After all, we're all owners of that incredible, self-adapting machine called the human body.

 

[The True Adonis]

Google boy here knows all.

Of course I know all.  IT`s my job.

[The True Adonis]

Gravity hurts: you can feel it hoisting a loaded backpack or pushing a bike up a hill. But lack of gravity hurts, too: when astronauts return from long-term stints in space, they sometimes need to be carried away in stretchers.

Gravity is not just a force. It's also a signal -- a signal that tells the body how to act. For one thing, it tells muscles and bones how strong they must be. In zero-G, muscles atrophy quickly, because the body perceives it does not need them. The muscles used to fight gravity --like those in the calves and spine, which maintain posture-- can lose around 20 percent of their mass if you don't use them. Muscle mass can vanish at a rate as high as 5 percent a week.

For bones, the loss can be even more extreme. Bones in space atrophy at a rate of about 1 percent a month, and models suggest that the total loss could reach 40 to 60 percent.

Why astronauts look puffy in space

Blood feels gravity, too. On Earth, blood pools in the feet. When people stand, the blood pressure in their feet can be high -- about 200 mmHg (millimeters of mercury). In the brain, though, it's only 60 to 80 mmHg. In space, where the familiar pull of gravity is missing, the head-to-toe gradient vanishes. Blood pressure equalizes and becomes about 100 mmHg throughout the body. That's why astronauts can look odd: their faces, filled with fluid, puff up, and their legs, which can lose about a liter of fluid each, thin out.

But that shift in blood pressure also sends a signal. Our bodies expect a blood pressure gradient. Higher blood pressure in the head raises an alarm: The body has too much blood! Within two to three days of weightlessness, astronauts can lose as much as 22 percent of their blood volume as a result of that errant message. This change affects the heart, too. "If you have less blood," explains Dr. Victor Schneider, research medical officer for NASA headquarters, "then your heart doesn't need to pump as hard. It's going to atrophy."

The question is, do such losses matter?

Thirsty returnees

Perhaps not if you plan to stay in space forever. But eventually astronauts return to Earth -- and the human body has to readjust to the relentless pull of gravity. Most space adaptations appear to be reversible, but the rebuilding process is not necessarily an easy one.

"Each of the parameters have their own normal recovery time," says Schneider. Blood volume, for example, is typically restored within a few days. "Astronauts get thirsty when they come back," Schneider explains, "because their body says, you don't have enough blood in your blood vessels, and that causes the messengers to say, drink more. [Also, the body doesn't] urinate as much."

Muscle, too, can be recouped. Most comes back "within a month or so, "although it might take longer to recover completely. "We normally say that it takes a day [of recovery on Earth] for each day that somebody's in space," says Schneider.

Bone stubborn

Bone recovery, though, has proven problematic. For a three to six month space flight, says Schneider, it might require two to three years to regain lost bone -- if it's going to come back, and some studies have suggested that it doesn't. "You really have to exercise a lot," says Schneider. "You really have to work at it."

According to Dr. Alan Hargens, recently of NASA Ames and now a professor of orthopedics at the University of California San Diego medical school, it is important to keep astronauts in good physical condition. "You want the crew members to function normally when they come back to Earth ... and not have to lie around for long periods of rehabilitation," he says.

And Earth isn't the only planet that astronauts might visit. One day humans will journey to Mars -- a six-month trip in zero-G before they disembark on a planet with 38 percent of Earth's gravity. "[We'll have to maintain] those astronauts at a fairly high level of fitness," explains Hargens. "When they get to Mars, there won't be anyone to help them if they get into trouble." They will need to be able to handle everything themselves.

Bungee cords and vacuums

Exercise is the key. But exercising in space differs from exercising on Earth. Here, gravity's pull automatically provides a resistive force that maintains muscles and bones. "[In space] even if you do the same amount of work that you were doing down here on Earth, you miss that gravity component," says Schneider.

Various devices have been developed to mimic the help that gravity provides. One Russian experiment provides resistance by strapping jogging cosmonauts to a treadmill with bungee cords. But that particular combination has not yet proven effective in preventing bone loss -- perhaps because it cannot provide sufficient loads. "The straps are so uncomfortable that the cosmonauts can only exercise at 60 to 70 per cent of their body weight," says Hargens.

There's also IRED, a NASA-developed Interim Resistive Exercise Device. IRED consists of canisters that can provide more than 300 pounds of resistance for a variety of exercises. IRED's effectiveness is still being monitored, says Schneider.

Yet another promising device attempts to mimic gravity even more closely. Hargens and his colleagues are developing a Lower Body Negative Pressure (LBNP) device, a chamber that contains a treadmill, and that relies, says Hargens, on the suction of an ordinary vacuum cleaner. "We've found," he says "that we can provide body weight by applying negative pressure over the lower body."

The device, explains Hargens, prevents much of the loss of cardiovascular function and of muscle. It also seems to be effective in reducing some indices of bone loss. One reason is that the LBNP allows astronauts to exercise with an effective body weight between 100 percent and 120 percent of what they would feel on Earth. Another is that -- unlike any previous exercise device -- it restores the blood pressure gradient, increasing blood pressure to the legs.

There's growing evidence, Hargens says, that the body's systems interact with each other. For example, "you can't just put high loads on the bone and then expect it to recover if you're not taking care of the blood flow to that bone as well."

The daily struggle with gravity

Scientists aren't yet sure how gravity "signals" the body to keep bones and muscles strong. "We know that, somehow, gravity is converted from a mechanical signal to a chemical signal -- and we know a lot about these chemical signals," says Schneider. The mechanical signals, though, remain a mystery.

Solving these problems, says Schneider, could lead to better therapies for people who aren't using gravity properly here on Earth. Aging is the perfect example. Zero-G living mimics closely the effects of old age. Like astronauts, the elderly fight gravity less. They're more sedentary, which triggers the loop of muscle atrophy, bone atrophy, and lower blood volume.

If researchers can identify the signals that generate strong muscles and bones, it might be possible "to get new pills and do exercises" that would trigger those signals here on Earth.

"We've just begun to do research ... looking at the changes that can happen to humans," says Schneider. "There are so many wonderful questions."

And the answers? They're waiting for us ... up there in space, where the absence of weight reminds us that gravitation isn't all bad. Sometimes it's a struggle, our daily contest with gravity, but now we know the struggle is good!

[Palpatine Q]

So when their is no stress on a muscle, even one as benign as gravity, the muscle atrophies.

Whoopdie-fvckin-dooo. is there a point to all of this neverending bullshit?

[bigmc]

you need to get out more TA

[nycbull]

Glad to see NASA is using tissues cultures instead of live animals. Finally getting with the times. Too late for the poor chimps they experimented on that died "due to psychological stress"..basically they were so scared they died. imagine that?

Edit: the lab tests on the rats are ridiculous, in fact the NYTimes did a study and reported that animal experiments are the least reliable of all scientific experiments and should be taken with a grain of salt.  Its a great public relations ploy to make it look like their doing a lot with our tax money but its a huge waste and a fraud on the American public. Dont fall for it.

[The True Adonis]

Glad to see NASA is using tissues cultures instead of live animals. Finally getting with the times. Too late for the poor chimps they experimented on that died "due to psychological stress"..basically they were so scared they died. imagine that?

Correct!

[The True Adonis]

BIOMEDICAL RESULTS OF APOLLO
SECTION III

CHAPTER 6
NUTRITIONAL STUDIES

by

Paul C. Rambaut, Sc.D.

Malcolm C. Smith, Jr., D.V.M.
Harry O. Wheeler, Ph.D.

Lyndon B. Johnson Space Center


Introduction
The importance of nutrition in the adaptation of man to weightlessness was recognized long before the first Apollo flight. Nutrition remained a primary concern despite the fact that early projections of difficulties in swallowing, defecating, and urinating in weightlessness had proved unfounded. By the conclusion of the Gemini Program, space life scientists had noted several subtle changes with possible nutritional etiology.

Changes in musculoskeletal function appeared to be significant among these findings (Rambaut et al., 1973; Vogel et al., 1974). Prior to the first manned space flight, it had been suspected that the musculoskeletal system would be particularly susceptible to prolonged withdrawal of gravitational stress. Astronauts were subjected to a nullified gravitational field while they were confined in a vehicle in which mobility and physical activity were restricted. These conditions singly, or in combination, were expected to cause deterioration of bones and muscles.

The control studies by Deitrick, Whedon, and Shorr (1948) of the immobilization of four young, healthy men for as long as seven weeks clearly demonstrated that immobilization in body casts led to marked increases in urinary calcium. These levels more than doubled in five weeks and were accompanied by negative calcium balances as well as by related changes in nitrogen and phosphorus metabolism. In addition, a decrease in the mass and strength of the muscles of the lower extremities occurred, and deterioration in circulatory reflexes to gravity resulted within one week.

Other studies with immobilized subjects indicated that the clinical disorders most likely to be encountered during prolonged space flight are primarily a consequence of an imbalance between bone formation and resorption. As a result of these conditions, there is a loss of skeletal mass, which could eventually lead to hypercalcemia, hypercalciuria, osteoporosis, and possibly nephrolithiasis (Issekutz et al., 1966).

Since the most meticulous work has disclosed that the greatest loss of calcium during bed rest is a result of increased urinary excretion, studies in which only urine calcium was measured are pertinent. The total evidence indicates that a one to two percent per month loss of body calcium is a reasonable prediction for persons in a weightless environment (Hattner & McMillan, 1968).

With the advent of space flight, additional studies have been performed on the effects of simulated weightlessness on skeletal metabolism. Graybiel and co-workers (1961) found there was no increase in urinary calcium excretion after one week of almost continuous water immersion. Negative balances of small magnitude and changes in bone density of the calcaneus during bed rest are indicated by Vogt and co-workers (1965).

The role of simulated altitude in modifying the metabolic effect of bed rest has been investigated (Lynch et al., 1967). In a study of 22 healthy men, four weeks of bed rest at ground-level atmospheric pressure conditions resulted in expected increases in urinary and fecal calcium and in urinary nitrogen, phosphorus, sodium, and chloride. In similar metabolic studies performed with another 22 subjects at bed rest at simulated altitudes of 3000 and 3700 meters, urinary calcium losses were significantly less as the altitude increased (Lynch et al., 1967). Urinary losses of phosphorus, nitrogen, sodium, and chloride were less at a simulated altitude of 3700 meters than they were during bed rest studies at ground level. Results of these studies indicate that diminished atmospheric pressure, or perhaps a decreased partial pressure of oxygen or a change in pH, may have a preventive effect on mineral loss from the skeleton. Limited data available from inflight studies tend to support the use of immobilization as a terrestrial model to simulate alterations in calcium metabolism during space flight. During the 14-day Gemini 7 flight, loss of calcium occurred in one of the two astronauts, and the changes in phosphorus and nitrogen balance also indicated a loss of muscle mass (Lutwak et al., 1969; Reid et al., 1968).

As evidenced from bed rest studies lasting from 30 to 36 weeks, mineral losses are likely to continue unabated during prolonged space flight. In balance studies (Vogel & Friedman, 1970; Donaldson et al., 1970), calcium losses from the skeleton during bed rest averaged 0.5 percent of the total body calcium per month. In the same subjects, tenfold greater rates of localized loss from the central portion of the calcaneus were detected by gamma-ray-transmission scanning.

Inflight weight losses were experienced throughout Project Mercury, Gemini, and the Apollo missions. Such weight losses were attributed, in part, to losses in body water. Since weight was not regained completely in the 24-hour period immediately postflight, it was probable that tissue had also been lost. What part of these losses was brought about by insufficient caloric intakes was unknown.

Speculation on the theoretical energy requirements of man during space flight began before the United States Project Mercury and the Soviet Vostok flights. At one time, it had seemed logical to assume that activity in a weightless environment would require less energy than at one because work associated with counteracting the force of gravity would be eliminated. However, caloric requirements are affected by numerous variables including age, physical and mental activity, stress, body size and composition, together with relative humidity, radiation, pressure, and environmental temperature. During the Apollo missions, therefore, the question of inflight caloric requirements was explored in much greater depth.

Metabolic changes in addition to those associated with an inadequate intake of energy were also elucidated during the Gemini Program. The possibility remained that space flight conditions would exert exaggerated demands on the micronutrients and would thus lead to some marginal deficiency state. It is believed that Soviet nutritionists provided their crewmen with elevated quantities of water-soluble vitamins, and that they had observed increased destruction of the B vitamins under conditions of prolonged low frequency vibration of test subjects. These observations were not confirmed during the Gemini Program. However, because alterations were seen in red cell mass and plasma volume, the vitamin E content of the diet in the presence of the hyperoxic Gemini spacecraft atmosphere was questioned (Fischer et al., 1969).

The development of future space food systems necessitated an accurate knowledge of inflight human nutrition requirements. Food systems having minimum weight and minimum volume are required for space flight (Heidelbaugh et al., 1973). For this reason, the Apollo foods were generally dehydrated and formulated to occupy little volume. The nutritional consequence of these measures was a matter of continuing interest in the Apollo Program.

__________

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Approach

Food Analysis
With very few exceptions, all foods used during the Apollo Program were analyzed for nitrogen, fat, carbohydrate, crude fiber, calcium, phosphorus, iron, sodium, potassium, and magnesium content. Some composite Apollo menus were analyzed for water- and fat-soluble vitamins. It was not always feasible to analyze the same lot of food that was actually used during the mission, and the variation in analytical values from one lot to another and from one item to another must be considered when the intake data are reviewed.


Dietetics
The menus used by the Apollo astronauts were formulated from flight-qualified Apollo foods in combinations that complied with the personal preferences of the crewmen and that met the Recommended Daily Dietary Allowances (NAS, NRC, 1968). The menus were primarily composed of dehydrated foods that could be reconstituted before eating. The foods were consumed in a prearranged sequence but could be supplemented by a variety of additional items that were packaged in an individually accessible form.


Nutrient Intake Measurements
The quantity of individual nutrients consumed during all Apollo missions is presented in table 1 as a composite estimate derived from numerous measurements. The crewmen were provided with prepackaged meals that were normally consumed in a numbered sequence. Foods omitted or incompletely consumed were logged. During the Apollo 16 and 17 missions only, these deviations from programmed menus were reported to flight controllers in real time. Snack items consumed that were not in the programmed prepackaged menus were also recorded in the flight logs. On all Apollo flights, most food residue and unopened food packages were returned; the residue was weighed only to provide more precise information on inflight food consumption and to verify inflight logging procedures. For the Apollo 16 and 17 missions, nutrient intake information was obtained for 72 hours before flight and for approximately 48 hours after flight.

For the Apollo 17 mission, a five-day metabolic balance study was performed approximately two months before the mission by using the flight menus and collecting urine and fecal wastes. Low residue diets were generally used commencing three days before each Apollo flight in order to reduce fecal mass and frequency during the first few days of flight.

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Fecal Measurements
Fecal samples were returned from all Apollo flights and analyzed for a variety of constituents either by nuclear activation analysis or by wet chemistry techniques.


Metabolic Balance
Analysis of blood obtained postflight on early Apollo missions, together with certain endocrinological and electrocardiographic changes in Apollo 15, made it desirable to measure urine volume and bring back samples of urine on Apollo 16. During this mission, it was also possible to continue to return fecal samples and to continue to measure nutrient intake. Sufficient data were therefore available to conduct a partial metabolic study.

For a more detailed metabolic balance study in conjunction with Apollo 17, accurate measurements of fluid intake and output were performed approximately two months before the mission. A five-day food compatibility/metabolic study was performed in which the three Apollo 17 prime and backup crewmembers consumed their flight foods, and metabolic collections were performed. The study was designed to obtain baseline data on the excretory levels of electrolytes and nitrogen in response to the Apollo 17 flight menus. The crewmembers consumed the flight menu foods for five complete days. During the last three days of this test, complete urine and fecal collections were made.

Beginning 64 hours before Apollo 17 lift-off and continuing throughout the mission until 44 hours following recovery, all food and fluid intake was measured. For the Lunar Module Pilot, these collections continued until suit donning; for the Commander and the Command Module Pilot, collection continued until approximately 12 hours before lift-off. All urine was collected, measured, sampled, and returned for analysis. Urine was collected before and after flight in 12-hour pools. Complete stool collections were performed.

All deviations from programmed food intake were logged and reported. All foods were consumed according to preset menus arranged in four-day cycles. Every food item used during the flight was derived from a lot of food that had been analyzed for the constituents to be measured. Inflight water consumption was measured by use of the Skylab beverage dispenser. During the preflight and postflight periods, conventional meals were prepared in duplicate for each astronaut. One duplicate of each meal was analyzed in addition to the residue from the other duplicates to measure intake and output.

Apollo 17 inflight urine samples were collected by means of a biomedical urine sampling system (BUSS). Each BUSS consisted of a large pooling bag, which could accommodate as much as four liters of urine collected during a day, and a sampling bag, which could accommodate as much as 120 cc. The BUSS was charged with 30 mg of lithium chloride. The lithium chloride concentration in the sample bag was used as a means of determining total urine volume. Each BUSS also contained boric acid to effect stabilization of certain organic constituents.

The inflight urine collection periods began with suit doffing at approximately 00:07:00 ground elapsed time (GET). The collection periods were the times between scheduled effluent dumps and were approximately 24 hours each. During undocked flight of the Command Module, urine was collected only from the Command Module Pilot. During periods in which the crewmen were suited, urine was collected in the urine collection and transfer assembly and subsequently dumped overboard without sampling. However, urine collected in the Commander and Command Module Pilot assemblies during the Command Module extravehicular activities (255:00:00 to 260:00:00 GET) was also returned. For the Apollo 17 mission, the periods during which urine was not collected are as follows:


Commander and Command Module Pilot - lift-off to suit doffing (00:00:00 to 00:07:00 GET)

Command Module Pilot - Lunar Module activation and lunar descent (108:00:00 to 114:30:00 GET)

Command Module Pilot - rendezvous (187:00:00 to 195:00:00 GET)

Commander and Lunar Module Pilot - Lunar Module activation, lunar descent, lunar surface operations and rendezvous (107:00:00 to 208:00:00 GET)
Urine collected from the Commander and the Command Module Pilot from rendezvous to the beginning of the first collection period after rendezvous (approximately 197:00:00 to 208:00:00 GET) was also dumped directly overboard.

Each BUSS was marked with the name of the crewmember and the ground elapsed time of collection. Following each collection period, the urine pool was thoroughly mixed before a sample was taken. The urine samples represented a 24-hour void and were subsequently analyzed for electrolytes, nitrogen, and creatine.

All fecal samples collected from each crewmember for the following periods were returned: beginning 64 hours before lift-off, during the mission, and for 44 hours after the flight. Inflight fecal samples were chemically preserved for storage in the spacecraft.


Body Volume Measurements
For the Apollo 16 crewmembers, a measurement of body volume was made by stereophotogrammetry, using a special computer program, three times before the flight and three times after the flight (Peterson & Herron, 1971). Body density was calculated from body volume and weight. Density was used to calculate the percentage of fat by means of the following formula.


(495/ body density) - 450 = percent fat
Changes in calculated lean body mass and total body fat were converted into caloric equivalents by means of standard values of 37.6 kJ/gm [where 1 Joule = .239 calorie] for fat and 16.7 kJ/gm for protein.

Total body water was measured by means of potassium-42 dilution (Johnson et al., 1974). Lean body mass was calculated as follows.


LBM = total body water/0.73
body weight - LBM = total body fat

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Findings
The nutritional composition of the typical Apollo inflight diet is given in table 2. This diet, which is characteristically high in protein and carbohydrate and low in residue and fat, was not necessarily consumed by all astronauts in its entirety.

A typical Apollo diet was analyzed for vitamins, and results were compared with Recommended Daily Dietary Allowances (NAS, NRC, 1968). The data indicate the Apollo diet provided an excess of some vitamins (A, E, C, B12, B6, and riboflavin) and marginal amounts of others (nicotinate, pantothenate, thiamine, and folic acid).

The average intake of protein, fat, and carbohydrate for the Apollo 7 through 17 crewmen is given in table 3. Fiber intake measurements are given for the Apollo 12, 15, 16, and 17 missions.

The quantity of energy supplied by dehydrated food for the Apollo 15 to 17 missions is given in table 4. The average energy intake of each Apollo crewmember is given in table 5. These energy values were calculated from the composition of the food consumed. Average energy intakes expressed on the basis of body weight are given in table 6. For comparison, the average energy intake of selected Apollo crewmembers during a mission and on the ground is given in table 7.

The average intakes of calcium, phosphorus, sodium, and potassium for each Apollo crewman are given in table 8. Diets for the Apollo 16 and 17 missions were fortified with potassium gluconate. The contribution of supplementary potassium gluconate to the total intake for the Apollo 15, 16, and 17 crewmen is given in table 9.

Inflight fecal samples were analyzed for inorganic constituents using nuclear activation analyses and wet chemistry techniques. The findings were summarized by Brodzinsky and co-workers (1971). Inflight fecal samples were also analyzed for total fat, fatty acids, and conjugated and unconjugated bile acids (table 10 and table11). Data on fat absorption in flight (Apollo 16 and 17) are given in table 12.


Apollo 16 Metabolic Study
The input and output of various elements, particularly potassium, were carefully examined in the Apollo 16 balance study and a detailed assessment of energy metabolism was made (Johnson et at., 1974). The average daily inflight potassium intake for the Commander was 113.6 milliequivalents. During the mission, potassium was lost by the fecal route at a rate of approximately 6.4 mEq/day, whereas approximately 18.8 mEq/day were lost before the flight and 20.5 mEq/day after the flight. During the mission, absorbed potassium levels were 107.2 mEq, whereas preflight and postflight levels were 94.8 and 77.6 mEq, respectively. During the extravehicular and lunar surface periods, the Commander consumed a maximum of 152.4 mEq daily.

The average daily inflight potassium intake for the Lunar Module Pilot was 114.7 mEq, compared with an average daily preflight intake of 110.5 mEq and an average daily postflight intake of 97.5 mEq. During the preflight, inflight, and postflight phases, the average daily fecal losses were 33.5, 11.1, and 31.0 mEq, respectively. The absorbed daily potassium levels for preflight, inflight, and postflight phases were 77.0, 103.6, and 66.5 mEq, respectively. Although these levels were less than the recommended levels of 150 mEq per day, they were adequate for ground-based requirements. A peak level of 148 mEq per day was consumed by the Lunar Module Pilot during lunar surface activities.

For the Command Module Pilot, average daily preflight, inflight, and postflight dietary potassium intakes were 94.3, 79.9, and 82.4 mEq, respectively. Fecal samples for the same periods indicated that potassium levels were 27.6, 6.3, and 26.2 mEq, respectively. Available daily preflight, inflight, and postflight potassium levels were, therefore, 66.7, 73.6, and 56.2 mEq, respectively.

Input and output data on sodium, chloride, and calcium levels for the Apollo 16 crewmembers are summarized in table 13A, table 13B, table 13C, table 13D, and table 13E.

In the analysis of the balance study performed for the Apollo 17 mission, inflight metabolic data were compared with those obtained during the five-day control study conducted approximately two months prior to flight. Rigorous intake and output measurements were accomplished immediately before the flight and after the flight to detect gross changes; however, the duration of these periods was not sufficient to establish reliable metabolic baselines.

For the Apollo 17 Command Module Pilot, water consumption from all sources was considerably lower during the flight than during the control balance study (table 14). Inflight urine outputs were also proportionately lower for all three crewmembers than those established during the control study. When the conditions of temperature and humidity that prevailed during the flight are considered, it is estimated that in insensible water loss of 900 to 1200 cc/day occurred. This loss was equivalent to the preflight loss. Total body water measurements also did not support the tendency toward negative water balance (see Section III, Chapter 2, Clinical Biochemistry).

Based on numbers adjusted for equilibrium during the control phase and insensible losses, all three crewmembers were in negative calcium balance during the inflight period (table 14). The negative balance was particularly pronounced for the Command Module Pilot. For two of the crewmembers, the negative calcium balance persisted after the flight. All crewmembers had exhibited a pronounced positive balance during the five-day control period study possibly because the flight diets contained a higher calcium level than did the customary daily intake of these crewmembers (table 14). As can be expected from the negative calcium balance, phosphorus balance was generally negative during the flight.

All three crewmembers demonstrated a sustained negative nitrogen balance during the flight (table 14). Occasional negative nitrogen balances of small magnitude were also detected before the flight. Diminished nitrogen retention is supportive evidence for the general musculoskeletal deterioration note on previous flights and during ground-based hypokinetic simulations of flight-type conditions.

Sodium intakes during the flight were all less than 250 mEq/day. Intake and output measurements for sodium indicated positive balances for this element during the flight for all three crewmembers (table 14). However, sodium output in sweat was not measured and this route of excretion could have accounted for all the apparent "positive balance" and even have resulted in a slight negative balance for sodium. Sodium balance was positive during the flight for all three crewmembers (table 15) if insensible losses are neglected.

In compliance with previous recommendations based on observed inflight potassium deficits, inflight potassium intakes were maintained above normal ground-based intakes (73 to 97 mEq/day) (table 15). Potassium retention during the flight was significantly less than that established during the control study. A summary of overall metabolic balance for Apollo 17 crewmembers with all numbers adjusted to reflect equilibrium during the control period is presented in table 15.


Anthropometric Measurements
A summary of body weight changes based on the mean of the weights on 30, 15, and 5 days before lift-off compared to those obtained immediately after recovery is presented in table 16. The weight changes during the 24-hour period immediately following recovery are also given.

Body volume was measured before and after the Apollo 16 mission by stereophotogrammetry. An analysis of densitometric data is presented in table 17.


Discussion
Most of the Apollo crewmembers did not eat all the food available. Among the reasons for reduced appetite were decreased hunger, a feeling of fullness in the abdomen, nausea (Berry & Homick, 1973), and preoccupation with the critical mission tasks. Dislike of the food and inadequate rest during the mission were minor problems (Berry, 1970). The evidence suggests that either weightlessness or some other aspect of the mission environment caused the crewmen to restrict their food intake below quantities available and below quantities necessary to maintain body weight.

A reasonable estimate of the energy requirement during a flight can be obtained by correlating careful measurements of food intake with losses or gains in body tissue. The data reveal a mean energy intake of 7854 ± 1735 kJ/day for astronauts during the Apollo missions. If this intake is compared to the NAS, NBC Recommended Daily Dietary Allowance of about 12 000 kJ/day, it is apparent that an average energy deficit was incurred by each Apollo astronaut.

To quantitate the metabolic energy demands throughout the mission and to help define body composition changes, efforts were made during the Apollo 16 mission to control nutrient intake at a constant level throughout the preflight, inflight, and postflight periods. It was believed that stabilizing dietary intake would afford maximum opportunity for detecting body composition changes caused by adaptation to weightlessness.

The mean loss in body weight between the day of the preflight total body water determination and the day of recovery was 3.9 kg. Measurements of total body water loss by tritiated water dilution indicated a mean decrease of 1.77 liters.

When body water loss was converted into lean body mass lost, it was determined that the three crewmembers lost fat in addition to lean body mass because the lean body mass loss does not equal the recorded weight loss. The daily caloric expenditure of the Apollo 16 crewmen can be calculated from the known caloric value of metabolized fat (37.6 kJ/gm and of lean body mass (16.7 kJ/gm). For the three crewmembers, the mean daily caloric expenditure was 17 347 kJ.

Changes in total body potassium measured both by radioactive (potassium 42) dilution and by balance techniques did not reveal a significant loss of lean body mass, an indication that a fat and fluid loss occurred rather than a lean body mass loss. If only body fat were lost, the energy requirement for the three Apollo 16 crewmen would 21 556, 12 043, and 14 291 kJ/day, with a mean of 15 963 kJ (Johnson et al., 1970).

In an alternate method of summarizing the data, each crewman’s body mass loss was calculated from the differences between his mean body weight obtained 30, 15, and 5 days before flight and his weight immediately after flight.

Total body water lost was defined as the mass regained by each astronaut during the 24-hour period following recovery. In this instance, it was assumed that the mean weight loss that was not due to either water or protein loss was due to loss of fat. By this method, a larger loss in body fat was calculated to have occurred in all crewmembers.

Because of difficulties in controlling the respiratory cycle during body volume measurement (Peterson & Herron, 1971), the calculated changes in body composition included the effect of respiration as a random variable; thus, the data have too large a variance for calculation of individual changes in body fat.

During the Apollo 17 mission, a complete collection of urine and feces samples was added to a record of dietary intake so that metabolic balance measurements could be made. By using the results of this study, the energy balance of each crewmember during the Apollo 17 mission was estimated. Each crewmember decreased his intramission energy intake. During the mission, this intake decreased from a mean of 141.3 kJ/kg body weight to 109.1 kJ/kg and represented a 23 percent decrease in the caloric intake of the crewmen. This decrease would result in a net mean deficit in caloric intake of 30 129 kJ throughout the mission (Johnson et al., 1974).

The mean weight loss of the Apollo 17 crewmen was 3.3 kg. Nitrogen balance data reveal a loss of approximately 1 kg of protein, and the remaining loss can be attributed to fat. A mean caloric deficit of approximately 104 500 kJ is, therefore, assumed to have occurred (Johnson et al., 1974; Leach et al., 1974).

Body tissue losses were first calculated for each astronaut by averaging successive body weights obtained before the mission and subtracting the body weights measured 24 hours after recovery (Rambaut et al., 1973). It had been assumed that any decrease in body mass between the preflight weight and the weight recorded 24 hours after recovery represented water lost. An average of 1.5 kg weight was not renamed during this 24-hour period. If this loss was composed entirely of fat, it would represent an additional inflight expenditure of approximately 5643 kJ/day. Commencing with Apollo 16, food and fluid intake, urinary and fecal output, and total body water were measured for each crewman before, during and after the flight. From these measurements were derived estimates of protein loss, lean body mass, and total body fat. Body volume was estimated by stereophotogrammetry, and body density was calculated. From all these data, it became apparent that crewmembers had lost fat in addition to losing lean body mass.

Losses of musculoskeletal constituents (Rambaut et al., 1973; Vogel et al., 1974) and a variety of fluid and electrolyte anomalies have been detected by biochemical investigations associated with the Gemini, Apollo, Voskhod, and Soyuz flights. The electrolyte anomalies were particularly pronounced during the Apollo 15 mission and may have been associated with inflight cardiac arrhythmias and postflight changes in exercise performance and cardiovascular responses.

Certain therapeutic measures including the elevation of dietary potassium intake were partly responsible for the lack of significant metabolic disturbances following the Apollo 16 mission. Similar elevations in dietary potassium were effected for the Apollo 17 crewmembers.

The negative nitrogen and potassium balances that were observed during the Apollo 17 mission are indicative of a loss in the body mass.

[The True Adonis]

Summary
Apollo nutrient intakes have been characteristically hypocaloric. Estimates of body composition changes from metabolic balance data, from preflight and postflight weights and volumes, and from total body water and potassium provide no evidence for diminished caloric requirements during a flight.

As observed during the Gemini Program and during periods of bed rest, measurements of bone density and metabolic balance confirm a tendency toward loss of skeletal tissue in weightlessness.

No evidence exists that any inflight metabolic anomaly, including hypokalemia, was induced by marginal or deficient nutrient intakes. In general, the Apollo crewmen were well nourished and exhibited normal gastroenterological functions, although appetite was somewhat diminished and the organoleptic response to food was somewhat modified during flight.

[The True Adonis]

BIOMEDICAL RESULTS OF APOLLO
SECTION VI

CHAPTER 1
APOLLO FOOD TECHNOLOGY

by

Malcolm C. Smith, D.V.M.
N.D. Heidelbaugh, V.M.D.
Paul C. Rambaut, Sc.D.
R.M. Rapp
Harry O. Wheeler, Ph.D.

Lyndon B. Johnson Space Center

C.S. Huber, Ph.D.
C.T. Bourland, Ph.D.

Technology, Inc.


Introduction
Before man ventured into space for the first time, there was concerned that he might choke while attempting to swallow food in zero gravity. Foreign body pneumonia from aspiration of food particles and droplets was feared by some. The ability of man to digest and absorb food in a weightless environment was also seriously debated. These concerns for man’s physiological well-being during weightlessness were augmented by fears that the unfamiliar and austere limitations imposed by the space vehicle and flight plans might place unacceptable constraints on the food system. Some food technologists doubted that edible foods could be prepared to withstand conditions of temperature, pressure, and vibration which were characteristic of unmanned space flight vehicles. Limitations on allowable weight and volume would also have direct impact on the food system.

Despite early concerns, restrictions, and technological hurdles surrounding space food development, adequate and acceptable diets were formulated and made available in sufficient time to accommodate the needs of man in space. The earliest food systems used in the Project Mercury flights and the short duration Gemini Program flights resembled military survival rations. For the first long term flight, the two-week Gemini 7 mission, nutritional criteria became important considerations and began to constrain food system designers. Adequate provisions for energy and nutrient, had to be made within an exceedingly small weight and volume envelope. This food system envelope, about .77 kg per man per day (1.7 pounds) and 1802 cm3 per man per day (110 cubic inches), also had to allow for all packaging materials needed to protect foods.

Because water produced as a by-product of fuel cell operation in the Gemini Spacecraft could be made available, it became highly attractive from a food acceptance and weight savings standpoint to use dehydrated foods that could be reconstituted in flight. This was the departure point for the development of the Apollo food system, and systematic improvements were subsequently made as technology became available and the application was feasible. The results of these efforts are described in this chapter.


The Apollo Food System
The overall objective of the Apollo food system development program was to provide adequate and safe nutrition for man during the most ambitious space explorations ever attempted. This objective had to be achieved within many critical biological, operational, and engineering constraints. Considerations from which specific constraints were developed are listed in table 1. Details concerning the constraints are described in the Apollo Experience Report — Food Systems (NASA TN D-7720, July 1974).

Apollo food system technology evolved over a considerable period of time, with the aid of efforts from the U.S. Air Force Manned Orbiting Laboratory Program, the U.S. Army Natick Laboratories, industry, and universities. The earliest "space foods" were bite-sized foods suitable for eating with one’s fingers, and pureed foods, squeezed directly into the mouth from flexible metal toothpaste-type tubes. Extensive modifications in food and food packaging were made throughout Project Mercury and the Gemini and Apollo Programs. Modifications of the food system were especially necessary during the Apollo Program for the following reasons.


Inflight food consumption proved inadequate to maintain nutritional balance and body weight.

Inflight nausea, anorexia, and undesirable physiological responses experienced by some crewmen were believed to be partly attributable to the foods.

Meal preparation and consumption required too much crew time and effort.

Water for reconstitution of dehydrated foods was unpalatable initially and contained undesirable amounts of dissolved gases.

Functional failures occurred in the rehydratable food packages in the early Apollo flights.
Stepwise modifications of food system technology improved system capability to deliver adequate nutrients in a form that enhanced food acceptance and convenient use. This general trend of increased acceptance was reported by each successive Apollo flight crew.

An overall impression of the evolution of the Apollo food system can be gained by comparing the flight menus for the Apollo 7, 11, and 17 missions (table 2a, 2b, 2c, 3a, 3b, 3c, 3d, 3e, 4a, 4b, 4c, 4d, 4e, and 4f). The similarity of the menus for each Apollo 7 astronaut should be compared with the high degree of individuality, achieved for each Apollo 17 astronaut. This difference resulted from increased personal selection of food items by the astronauts as the program progressed. Table 4 also indicates the greatly increased variety of foods available for Apollo 17 crewmen.

Increased variety of foods was important, but more important was the improvement in quality of individual foods. Improved food quality is not apparent from the listing of foods. For example, fruit cocktail was reformulated because the original product became crushed by the effects of atmospheric pressure on the package and it was then difficult to rehydrate.

Details of the evolution in space food science and technology, from the first days of planning for manned space flight to the end of the Apollo Program, can be traced in reports cited in the chronological bibliography at the end of this chapter.

Each mission in the Apollo series had different objectives and requirements, and the scope of the Apollo food system was modified to fit the needs of each. The primary mission phases, from the vantage point of food provision, included times during which the crewmen occupied the Command Module (CM) and the Lunar Module (LM), and times when they were being transported in various vehicles from the recovery site to the NASA Lyndon B. Johnson Space Center in Houston, Texas. A contingency food system also was provided to be used if emergency decompression of the space vehicle occurred. For the Apollo 11 through 14 missions, a postflight quarantine period required a food system for use in the Mobile Quarantine Facility (MQF) and the Lunar Receiving Laboratory (LRL). Each of these environments presented a different set of constraints and requirements for the food system. Inflight metabolic balance studies were conducted on the Apollo 16 and 17 missions. These studies imposed unique requirements on the food system for preflight, inflight, and postflight measurements and control of dietary intake.

Before an Apollo launch, each prime and backup crewmember evaluated available flight foods and selected the food items he preferred. Then the foods were assembled into nutritionally balanced menus which were reviewed by crewmembers and nutritionists for maximum acceptability within nutritional constraints. Finally, the astronauts were briefed on spacecraft food stowage, preparation, and waste disposal.

The initial Apollo inflight food system consisted of two basic food types: (1) light weight, shelf-stable, dehydrated foods that required rehydration prior to consumption, and (2) ready-to-eat, dehydrated bite-sized foods. Dehydrated foods were selected because of shelf life and because weight was critical in the Apollo vehicle. Approximately 80 percent of the weight of fresh food is water; therefore, the removal of water resulted in a substantial reduction of food system weight. As was previously noted, water for rehydration available as a by-product of fuel cell operation, wherein hydrogen is combined with oxygen to release electrical energy.

[The True Adonis]

Freeze Dehydrated Foods
The optimal method of dehydrating food is freeze dehydration, a technique preferred because of the remarkable preservation of quality in the resulting product. Color, texture, flavor, nutrient content, and reconstitution of foods which are properly freeze-dried closely approximate the original food. However, as with any other method of preservation, the food which is preserved cannot be of higher quality than the original.

The high quality of freeze-dried food derives largely from the technique of removing the water by sublimation directly from ice to vapor with minimum exposure of the food to heat. The food is frozen rapidly in circulating air at a temperature of approximately 233° K (-40° C). The frozen food is then placed in a vacuum chamber, where the pressure is reduced to less than 270 N/m2 (~2 mm Hg). Energy in the form of heat is applied by means of heating plates maintained at temperatures of 298° to 303° K (-25° to 30° C), depending on the product. Under vacuum, this heat source provides the energy required to sublime the ice while the temperature of the food is maintained below the eutectic point. The heat input is carefully controlled to provide optimum removal of water vapor, which is collected on condensers within the vacuum chamber. The core of ice in the food completely disappears when the food reaches a moisture content of approximately two percent. This residual moisture remains bound to the food, and the energy level required to free it is greater than that of sublimation.

Critical relationships exist between pressure and temperature during the drying process, and criteria were developed for each food employed in the system. These criteria were developed to assure the most rapid method of processing while maintaining organoleptic quality and preventing destruction of nutrients.


Bite-Sized Foods
Bite-sized, ready-to-eat foods supplemented rehydratable foods for the first Apollo manned flight. These bite-sized foods were either dehydrated (moisture less than two percent) or prepared so that water in the product would be bound and, therefore, not available for microbial growth. The latter category is generally referred to as intermediate-moisture food to differentiate it from fresh foods at one extreme and dehydrated food at the other. The intermediate-moisture foods (moisture less than 40 percent) are highly acceptable since they closely approximate the texture of fresh foods and are ready to eat without reconstitution. Even with this combination of foods, however, the range of texture and tastes was fairly limited for early Apollo astronauts, a situation that was gradually rectified throughout the program.


Packaging
Packaging, like food items themselves, underwent substantial modification during the Apollo Program. Flexible packaging protected each individual portion of food and made handling, and consumption easier. A series of redesign cycles finally resulted in a rehydratable food package that had (1) an improved, transparent barrier-film of laminated polyethylene-fluorohalocarbon-polyester-polyethylene; (2) a water injection port consisting of a one-way, spring-loaded valve; and (3) an improved opening that permitted food consumption in weightlessness with a conventional tablespoon.

Cold [~283° K (10° C)] and hot [~333° K (60° C)] water were available for food preparation. Following water injection with the Apollo water dispenser, the food package was kneaded to rehydrate the food and then opened for consumption. Early packages shown in figure 1, were fitted with plastic tubes through which rehydrated food was extruded into the mouth. This configuration was changed by the introduction of a spoon-bowl package, pictured in figure 2 and described in greater detail in the following sections.

Bite-sized, ready-to-eat foods were contained in packets made from the same plastic laminate material used for packaging rehydratable foods. These packets were opened simply by cutting with scissors (figure 3). The food was eaten directly from the package or by use of the fingers.

[Big N]

you need to get out more TA

lol

[The True Adonis]

Evolution in Apollo Food Technology
Improvement in the food system were aimed at maintaining astronauts in the best possible physiological condition and with a high level of morale. Modifications to improve ease of consumption, stowage weight, and nutrient intake were reviewed and implemented as dictated by changes in mission objectives, new activities, and medical operational, and experimental requirements.


Apollo 7
The food system for the first manned Apollo mission was basically that provided in the Gemini Program but featured a wider variety of foods. However, while the availability of 96 food items for the Apollo 7 flight contributed to better acceptance and increased consumption relative to Gemini foods, the time and trouble required for meal preparation was increased.


Apollo 8
The first departure from heavy reliance on rehydratable foods occurred during the Apollo 8 flight. On Christmas day, 1968, during the first lunar orbital mission, the Apollo 8 astronauts opened packages of thermostabilized turkey and gravy and ate with spoons. This turkey entree required no water for rehydration because the normal water content (67 percent) had been retained. The thermally stabilized, ready-to-eat meal in a flexible can became known as a "wetpack," a term used to differentiate this package from the dehydrated space foods that required the addition of water before consumption. The flexible packs were made from a laminate of polyester, aluminum foil, and polyolefin.

Wet-type foods had not been used previously because of the disadvantages associated with high moisture content, particular]y the requirement for sterility and the weight penalty associated with this type of food. The improved crew acceptance of the product justified the weight increase. Technology for heat sterilization in flexible packages was sufficiently advanced by the time of Apollo 8 to assure a high quality product with minimal chance for failure.

The Apollo 8 crew also used a conventional teaspoon to eat some foods. and found that this mode of food consumption in weightlessness was quite satisfactory. This finding led to food package redesign which made the use of spoons much more convenient.


Apollo 9
Beginning with the Apollo 9 mission, more wetpack items were added to the food system. The variety of foods provided for this flight made crew diets more typical of those consumed on Earth. The extensive use of wetpack containers without difficulty during this mission confirmed the potential for eating a substantial portion of food from open containers. The Apollo 9 crewmen experimented further by cutting open a rehydratable food package and eating its contents with a spoon; the experiment was successful.

During Apollo 9, the Lunar Module Pilot experienced nausea and vomiting. Menu manipulation in flight to reduce the tendency for nausea represented the first use of real-time food selection for countering undesirable physiological responses to vestibular stimuli. The Apollo 9 mission also included the first use of the Lunar Module food System.


Apollo 10
Evolution of the Apollo food system was continued with the Apollo 10 flight, during which the spoon-bowl package (see figure 2) was introduced. The spoon-bowl package permitted convenient use of a spoon for consuming rehydrated foods. This modified package had a water inlet valve at one end and a large plastic-zippered opening on the other, which provided access to the rehydrated food with a spoon. Large pieces of dehydrated meat and vegetables could now be included to provide a more familiar and acceptable texture. As a result of this modification, some Apollo crewmen expressed a preference for selected foods in rehydratable form over the wetpack equivalent.

The feasibility of eating from open containers with spoons in weightlessness was first tested in aircraft flight and subsequently, verified during the flight of Apollo 8 and Apollo 9. Using jet aircraft flying parabolic patterns, numerous foods, packages, and utensils were tested. While these flights produced only brief periods of near-weightless conditions, the results indicated that spacecraft application of the spoon-bowl concept could be made successfully without dispersal of food particles throughout the vehicle.

Apollo 10 also marked the first successful use of conventional slices of fresh bread and sandwich spreads. This bread had a shelf life at Apollo vehicle temperatures for at least four weeks when packaged in a nitrogen atmosphere (figure 4). Provision of the bread allowed crewmen to make sandwiches using meat salad spreads provided in separate containers. The sandwich spreads were preserved by thermal processing and final package closing in a hyperbaric chamber. The process enhances preservation of natural flavor and texture by reducing thermal processing time and temperature.

An additional modification for the Apollo 10 mission was the introduction of the pantry concept. Locker space was reserved for an assembly of food to provide ad libitum selection of meal components. This method allowed for some versatility in menu planning and for inflight dietary modification. In all subsequent Apollo flights, pantry-stocked foods augmented prepackaged meals. Even though most astronauts expressed a desire prior to flight for real-time food selection, they typically reported that this often proved to be more trouble than it was worth.

The Apollo 10 crewmen reported some discomfort from a feeling of fullness and gastric awareness immediately after eating. This was troublesome to individual astronauts throughout the Apollo Program. Many causes for this condition have been suggested. Among these are (1) aerophagia; (2) undissolved gases (oxygen and hydrogen); (3) reduced atmospheric pressure; (4) changes in gastrointestinal motility; and (5) shifts in intestinal microflora. Moreover, removal of water during the process of food dehydration is a complex phenomenon that causes many physical-chemical shifts at the cellular level. It is conceivable that, during the rehydration process, continued occurrence of microscopic phenomena could cause osmotic displacements sensed by the cells of the gastric or intestinal mucosa.


Apollo 11
New food items for the Apollo 11 flight included thermostabilized cheddar cheese spread and thermostabilized frankfurthers. Sandwich spreads were packaged in "401&quo; aluminum cans, which featured a pull-tab for easy removal of the entire top of the can. This can proved successful and eventually became the nucleus for the development of the open-dish eating concept implemented in the Skylab Program.

Command Module food for the first five days of the Apollo 11 mission was assembled in nominal meal packages (figure 5). Forty-two man-meals (starting with day 1, meal B), an oral hygiene kit, and spoons were contained in a Command Module food locker. Command Module menus for each Apollo 11 astronaut are presented in table 3(A) and table 3(B). Because the wetpack food items included did not require reconstitution in flight, the menu was planned for consumption of wetpack foods during the midday meal when crew activity was highest. The wetpack foods were stowed separately from nominal meal packages.

A six-day supply of food and accessory items were stowed in pantry fashion (figure 6) to permit some food selection based on real-time preference and appetite and to supplement the meal packages if more food was desired by an individual. The foods included beverages, salads, soups, meals, breakfast items, desserts, and bite-sized foods [see table 3(D) for listing]. Primary food packages were placed in nonflammable overwraps, which served to keep food groups together and to partition the spacecraft food container for ease of retrieval in flight. Germicide tablets were provided for stabilization of any food residue remaining in the primary food packages.

Four lunar surface meal periods were scheduled. The Apollo 11 Lunar Module menu is outlined in table 3(C). Foods for the four nominal meals (two each of meals A and B), spoons, wetpack food, extra beverages, and tubed ham sandwich spread were stowed in the Lunar Module food box. The remaining items (bread, candy, and dried fruit) were stowed in the utility-light compartment of the flight data file.

Another major component of the Apollo 11 food system was the system employed on the prime recovery ship in the Mobile Quarantine Facility (MQF) and, subsequently, at the Lunar Receiving Laboratory (LRL) at Johnson Space Center. A typical MQF menu is shown in table 5. The MQF foods were used from time of splashdown until the crewmen entered the LRL. The menu contained primarily precooked, frozen entrees, which were reconstituted in a microwave oven in the MQF. The LRL system used the same type of entrees with the addition of a wider variety of frozen vegetables, salads, and snacks. The LRL food system also included a "first class" restaurant service, complete with table linens, china, and silverware which was available to the flight crew, their support team, and the lunar quarantine staff of approximately 20 scientists and technicians.


Apollo 12
The food system for Apollo 12 was quite similar to that which had proven successful for Apollo 11. Freeze dehydrated scrambled eggs were introduced and were well accepted by the crew. Other changes in the menu were directed toward meeting individual crewmember nutrient requirements.


Apollo 13
The Apollo 13 inflight explosion and loss of fuel cell systems tested the food system in an emergency situation in which fluid and electrolyte intakes were critical for life support. After the accident, crew nutrient consumption was limited by the amount of available water. Beverage bags proved to be extremely useful as an emergency means of storing water that was rapidly being depleted. The use of these packages and the availability of wetpack foods for providing fluids for the Apollo 13 crewmen has been largely credited with maintaining the health of the astronauts throughout the emergency.

The beverage packages found other uses during Apollo missions and proved to be versatile, durable, and reliable. They were used in experiments on the separation of gas from liquids in weightlessness and also served as head supports on the couch during reentry of the Command Module in at least one mission.

The Apollo 13 food system included the first dehydrated natural orange juice. Orange juice had not been employed in space food systems previously because the dehydration methods available failed to prevent fusion of natural sugars with the formation of an insoluble mass. The provision of fruit juices further improved the quality and nutritional value of the food system.


Apollo 14
The Apollo 14 flight marked the first time space crewmen returned to Earth without a significant change in body weight. The Commander and the Lunar Module Pilot had consumed essentially, all of their programmed food supply.

The Apollo 14 food system included an in-suit drinking device. This allowed the astronauts to better maintain fluid balance during extensive lunar surface operations.

The food safety regimen throughout the Apollo Program included the production and final packaging of all food items in a Class 100 000 filtered-air cleanroom to maintain low microbiological counts of Apollo foods. Foods were also examined for the presence of heavy metals. The only deviation from perfect performance in the food safety area was a failure in the early detection of mercury contamination in the Apollo 14 tuna fish salad. The mercury content ways in excess of maximum limits established by the U.S. Food and Drug Administration. The tuna fish was removed from the food system shortly prior to launch, and a nutritionally equivalent substitute from the pantry was used to supplement the menu.


Apollo 15
Apollo 15 crewmen consumed solid food while working on the lunar surface. High nutrient density food bars were installed inside the full pressure suit (figure 7). Figure 8 shows a view of the neck ring area of the Apollo lunar surface pressure suit with the in-suit food bar and the in-suit drink device installed. The in-suit drink device was designed to provide water or fruit flavored beverages. This crew was the first to consume all of the mission food provided. Negligible weight losses, after equilibration for fluid losses, reaffirmed that the diet provided adequately for the crew’s energy requirements. The typical Apollo menu ultimately provided energy equivalent to 155 ± 117 kJ/kg (37 ± 4 kcal/kg) of body weight. Sliced fresh bread that had been pasteurized by exposure to 50 000 rads of cobalt-60 gamma irradiation was first used for the Apollo 15 flight.


Apollo 16
Electrocardiographic recordings for Apollo 15 crewmen indicated occasional arrhythmias believed to be possibly linked to a potassium deficit. In an effort to prevent recurrence of a similar situation in the Apollo 16 crew, a requirement was levied to provide 140 ± 5 milliequivalents of potassium in the Apollo 16 diets daily during flight and for 72 hours both before and after flight. In addition, nutrient intake and absorption for each Apollo 16 crewman was monitored during the entire period, beginning 72 hours before flight and ending 72 hours after flight. This control of nutrient intake afforded maximum opportunity to detect physiological changes accompanying transition to and from the weightless state.

The requirement for 140 ± 5 mEq of potassium could not be met by menu manipulations using unmodified flight-qualified Apollo foods. Therefore, potassium fortification of qualified inflight foods was investigated, and the development of modified preflight and postflight foods was undertaken. It was found that Apollo 16 beverages and soups could be modified by the addition of 10 mEq per serving of potassium in the form of potassium gluconate (2.35 gm per serving).

The physiological safety of potassium gluconate for food fortification and supplementation was verified by a search of the literature concerning its use and effects and by three studies involving human volunteers. The compatibility of this level of potassium with individual flight crewmembers was tested by providing each individual with fortified foods for consumption and evaluation.

Apollo 16 grape drink, orange drink, pineapple-orange drink, pineapple-grapefruit drink, grapefruit with sugar, and cocoa were fortified with potassium gluconate, for an average daily inflight potassium intake of approximately 100 mEq. Real-time adjustments in nutrition were applied by menu rearrangements to counteract the gastrointestinal awareness reported by one crewmember and believed to be associated with dietary potassium intake.


Apollo 17
In addition to a liberal usage of previously described improved foods, the Apollo 17 system was modified by the inclusion of shelf-stable ham steak that had been sterilized by exposure to cobalt-60 gamma irradiation (3.7 megarads). The Apollo 17 food system also incorporated a fruit cake that provided complete nutrition in shelf-stable, intermediate-moisture, ready-to-eat form. Both proved to be highly acceptable to the crewmen. This type of intermediate-moisture food was included in the Skylab contingency food system and is being evaluated for rise in the Space Shuttle food program.


Conclusions
Large improvements and advances in space food systems were achieved during the Apollo food program. Nevertheless, the majority of Apollo astronauts did not consume sufficient nutrients. Loss of body weight, fluids, and electrolytes was the rule, with few exceptions. The Apollo food program showed that man and his eating habits are not easily changed. Adequate nutrition begins with appropriate food presented to the consumer in familiar form.

A space food system must fulfill program requirements and provide proper nutrition to maintain physiological well-being during the specific environments and stresses imposed by the mission. Such a system must ultimately rely on nutritious foods that are easy to prepare, that have familiar flavor and texture, and that provide diversion, relaxation, security, and satiety.

Modifications of the Apollo food system were directed primarily toward improving delivery of adequate nutrition to the astronaut. Individual food items and flight menus were modified as nutritional countermeasures to the effects of weightlessness. Unique food items were developed, including some that provided nutritional completeness, high acceptability, and ready-to-eat, shelf-stable convenience. Specialized food packages were also developed.

The Apollo Program experience clearly showed that future space food systems will require well-directed efforts to achieve the optimum potential of food systems in support of the physiological and psychological well-being of astronauts and crews. The accomplishments of the Apollo food program provide a significant beginning.

[king]

Of course I know all.  IT`s my job.

hey adonis what is ur job?


honest to god question

[ToxicAvenger]

hey adonis what is ur job?


honest to god question

he installs cable! 

[ToxicAvenger]

and umm after reading all adonis has said..

do ya still think we went to the moon when and how we say we did?

[The True Adonis]

Pumping Iron in Microgravity
Spaceflight weakens astronauts, but new exercise regimens promise to change that - and deliver important benefits on Earth as well.


January 22, 2004 : Video feeds from the International Space Station (ISS) invariably show crew- members exercising in the background. Exercise is serious business on the ISS because microgravity causes skeletal muscles to lose power and stamina. Workouts help astronauts fight back.
Yet despite rigorous workouts, astronauts return to Earth shockingly weaker than when they left. Only 11 days in microgravity may atrophy (shrink) muscle fibers as much as 30 percent and cause soreness as damaged muscles tear while readjusting to Earth's gravity.

 

Above : The presence or absence of gravity affects skeletal muscle tissues, as shown in these two electron micrographs of human soleus muscle cells before and after 17 days in microgravity. Preflight, gravitational load stimulates the production of proteins that keep muscle fibers strong and symmetrical (A). After 17 days in microgravity (B), greatly reduced load on skeletal muscle has slowed protein production in the individual muscle cells, and they have grown more irregular and fragile as they atrophy. The prevalence of white lipid droplets (L) indicates that in microgravity, muscles build fat stores instead of using them for energy. Credit: Danny Riley and James Bain, Medical College of Wisconsin . Source: OBPR Space Research Newsletter, Winter 2003 (Vol. 3, No. 1) .

Earthly implications

Fortunately, muscles recover rapidly after weeks in microgravity. But what might happen during a years-long mission like a trip to Mars? How long would muscles atrophy during spaceflight, and what levels of muscle strength would the astronauts have when equilibrium is reached? Could more vigorous aerobic workouts prevent wasting, or would other types of exercise be more effective? Such questions intrigue Robert H. Fitts, professor of biology at Marquette University in Milwaukee, Wisconsin. He has been examining astronauts' muscle tissue before and after ISS missions to project how longer spaceflights would answer these and other questions.

Fitts, an expert on exercise physiology and a serious runner, says that his ISS research will help develop workouts for astronauts to minimize or even prevent atrophy. Any success would also deliver benefits on Earth, where similar exercises could help the elderly stay strong and speed the rehabilitation of certain patients after lengthy illnesses.

Pumping iron

Muscle atrophy involves many subtle chemical as well as physical interactions, but the basic principle is simple. Muscles, explains Fitts, are adaptable tissues. Increase the load on them by lifting weights or other types of exertion, and they grow larger and stronger. Reduce the load by lying in bed or living in microgravity, and they grow smaller and weaker.

"When you load a muscle," Fitts continues, "its fibers begin a series of intracellular signaling steps. Genes within the cell nucleus make RNA [ribonucleic acid], which synthesizes proteins that make up muscle fiber. Pumping iron activates the expression of these proteins, which accumulate and enlarge the muscle fibers."

Microgravity has the opposite effect. It reduces the load that gravity naturally places on muscles, interrupting protein synthesis so that fibers begin to atrophy. This loss of muscle mass contributes to reduced skeletal muscle strength when astronauts return to Earth.

Not all muscles atrophy at the same rate in microgravity. Back and leg muscles that work against Earth's gravity to maintain an erect posture waste fastest in microgravity. Yet even among these muscles, there are differences. In microgravity, astronauts naturally assume a modified fetal position, with legs bent at the knees and feet extended downward. This posture shortens the calf muscles in the back of the lower leg, removing tension and speeding atrophy. It also lengthens the shin muscles in the front of the leg, creating enough tension to impede atrophy.

Fast and slow

Microgravity also has a profound effect on fast- and slow-twitch muscle fibers. As the name suggests, slow-twitch fibers contract gradually and generate little power but have high aerobic capacity and resist fatigue. Fast-twitch fibers contract more quickly and generate more power but tire quickly.

"Slow-twitch muscle fibers dominate in running marathons and fast-twitch muscle fibers in the 100-yard dash," says Fitts. Analysis of rats exposed to microgravity initially led researchers to believe that spaceflight degraded slow-twitch fibers more rapidly than fast-twitch fibers, but more recent human studies indicate that both types of muscle fibers undergo significant atrophy.

Surprisingly, spaceflight alters the balance of fast- and slow-twitch fibers. "Not only is there a change in the amount of protein synthesized but also the type synthesized," says Fitts. "During extended flights, about 15 to 20 percent of slow-twitch muscle fibers become fast-twitch fibers." Muscle conversion is likely caused by changes in the type of muscle proteins synthesized by the body, he explains. Changes in fiber type may also be responsible for muscle tears when astronauts return home. "Our theory is that microgravity may suppress expression of proteins that anchor contractile filaments to the muscle fiber surface," he says.

Regimen change?

Any microgravity exercise routine must maintain not only muscle mass but also the right mix of proteins to balance fast-twitch muscle power with slow-twitch muscle endurance while firmly anchoring contractile filaments. This sounds like a tall order, but Fitts believes that preserving muscle mass will automatically balance protein synthesis as well.

Muscle atrophy during spaceflight has always been tough to avoid. Historically, U.S. and Russian astronauts have relied on aerobic exercises, primarily pedaling a cycle ergometer (an exercise bike) and running while tethered to a treadmill. Unfortunately, aerobic exercises are designed to condition the cardiovascular system rather than apply loads systematically to a wide range of muscles, Fitts explains. Cycling, for example, applies a good load to the upper leg but not the lower leg or back, he says. "It does not preserve muscle."

"At this point," Fitts says, "we know we're losing muscle mass and not getting the proper muscle activation with aerobics." Although the ideal microgravity exercise program remains undefined, Fitts believes it will include more strength training.

Strength training, says Fitts, involves two different types of resistance exercises: high-intensity isotonics, which shortens and lengthens muscles (for example, lifting and lowering a dumbbell), and isometrics, which fully contracts muscles without movement (for example, pushing against a doorway). Both types of exercise could potentially reduce muscle atrophy in microgravity. Fitts' experiments with rats, however, suggest that isometrics may protect slow fibers better than isotonics because slow fibers develop very little force during relatively fast isotonic motions.

It is easy to develop a strength training program that combines isometrics and isotonics on Earth. In microgravity, where a dumbbell "weighs" no more than a feather, it is difficult — but NASA may have a solution. Studies are under way to evaluate the efficacy in microgravity of the interim resistive exercise device, which was installed aboard the ISS in April 2001. The device generates up to 300 pounds of resistance for various exercises. (NASA licensed the technology to Schwinn, which now sells it as the RiPP Pro unit.)

 

Above : NASA has long understood the importance of exercise in battling muscle atrophy in microgravity. Here, astronaut Robert F. Overmyer works out on a treadmill aboard Spacelab in 1985 (left). Sixteen years later, European Space Agency astronaut Umberto Guidoni works out on a cycle ergometer aboard Space Shuttle Endeavour (right). Although these aerobic exercises work the muscles of the upper leg, Fitts believes they may not provide the right types of loads to prevent muscle wasting in microgravity. Credit: NASA . Source: OBPR Space Research Newsletter, Winter 2003 (Vol. 3, No. 1) .

Fitts says several research groups are working to develop similar units that could provide adequate loads to protect skeletal muscle while living in microgravity. The challenge, he says, is designing compact, reliable devices that can generate consistent, measurable loads for the various skeletal muscle groups located throughout the body.

Testing

After determining the best kind of exercise for astronauts, the next question is, how much exercise is enough? "If you're pumping iron on Earth, two or three times weekly is enough to build muscle," says Fitts. "In [microgravity], you'll have to do it maybe one or two times per day" — and that's only to maintain muscle strength, not increase it.

The operative word here is "maybe," because the effects of prolonged microgravity on muscle fibers remain largely uncharacterized. Without fully understanding how each type of muscle fiber changes over time, any proposed countermeasures are educated guesses at best. Yet Fitts' guesses are more educated than most. He led a team that characterized human limb muscle fibers for the 17-day STS-78 flight in 1996. Now he has begun to run similar tests on astronauts before launch and immediately after they return from extended ISS missions.

Fitts is studying the two major muscles of the calf: the outermost gastrocnemius, which contains both fast- and slow-twitch muscle fibers, and the soleus underneath, which contains mostly slow-twitch fibers. Instead of measuring gross muscle performance, he is assessing individual muscle fibers from small tissue samples taken from the calf muscles of astronauts before and after spaceflight.

Fitts chemically activates the muscle fibers to cause them to contract so he can measure force, velocity, and power. When the force they generate reaches its peak, he stretches the fibers 10 percent — equivalent to the stretching that occurs during walking or climbing stairs — and measures their peak force again. Muscle fibers from people who exercise on Earth typically show little change in strength after five stretches; Fitts expects postflight muscle fibers to show significant damage after only one or two stretches. Fitts then determines where tears occur in the fibers by examining them with an electron microscope. He also uses antibodies that react with specific proteins in the fibers to identify protein changes. Together, the information helps him precisely characterize variations in muscle fiber size, peak force, power, speed, and tear resistance.

On Mars and Earth

Fitts will use the data obtained from his experiments on single muscle fibers to try to predict changes that may occur in muscles during such prolonged space missions as a voyage to Mars. His measurements will also provide important baseline data for evaluating future microgravity exercise programs.

Some of Fitts' discoveries may have an immediate impact on Earth. People steadily lose muscle mass and aerobic power after age 55. Until recently, physiologists have typically recommended aerobic exercise to counter this effect. "The problem with walking or bicycling is that many elderly are too weak to get out of a chair," says Fitts. "Until very recently, most fitness programs for the elderly didn't emphasize muscle mass. Therapists are just starting to get the word that the elderly need resistance exercises, too."

The challenge, says Fitts, is choosing the right exercises. That's where space research comes in. "Spaceflight acts like accelerated aging," he explains. "It causes rapid loss of muscle mass. If we can learn how to prevent muscles from wasting during spaceflight, that information can help people on Earth stay strong as they age." The same insights could help patients with serious burns, who are often confined to bed for months and treated with steroids that break down muscle. "Optimal exercise could reduce rehabilitation time in many clinical settings," Fitts explains.

By honing today's best approaches in the demanding microgravity environment, NASA researchers may learn how to keep muscles strong and healthy in microgravity as well as on Earth.

[The True Adonis]

CAPE CANAVERAL, Fla. (AP) -- Before doing their heavy lifting in space, the astronauts on the shuttle Atlantis did lots of heavy lifting back on Earth.

 

Weight training is essential to help them counter the effects of zero gravity while taking on a herculean construction job -- expanding the international space station.

 

“Most of us have spent a lot of time in the gym, doing weights, to build up the forearm strength, to build up upper body strength,'' said astronaut Heidemarie Stefanyshyn-Piper.

 

She's one of four astronauts who will take a six-hour spacewalk over the next few days. She and Joe Tanner go on their outing Tuesday when they try to connect a 17 1/2-ton addition to the orbiting outpost.

 

Training an astronaut for a spacewalk in zero gravity is not all that different from preparing an athlete for competition, said Jamie Chauvin, a trainer at Johnson Space Center who helped the Atlantis crew prepare for the 11-day mission.

 

But look at it this way: “Just imagine lying in bed for 11 days,'' said Chauvin. That's the best way to describe the effect weightlessness has on the body. Astronauts can experience muscle loss and loss of coordination.

 

Of course, the effects are much worse for the full-time inhabitants of the space station, who live there for six months. Once back home, it can take 45 days of physical rehabilitation for the astronauts and cosmonauts to regain their bone and muscle mass and balance skills. After their mission, the space station crew usually works on rebuilding strength in the spine, pelvis and hips.

 

To train for the Atlantis mission, the spacewalking astronauts concentrated on building muscle and cardiovascular endurance. Spacewalks can last more than six hours, involve repetitive motions and require astronauts to be attached by foot tethers for long periods of time.

 

Typically, the astronauts do some cardiovascular work at least four times a week and hit the weight room two or three times a week before their going into space.

 

The workout routine often starts with stretching and then moves on to at least two leg exercises that emphasize large muscle groups and body stabilization. Astronauts usually do chest, back, shoulder, abdominal and lower back exercises before working on certain muscle groups specific to mission tasks. For spacewalkers, that means hand and shoulder muscles.

 

“In the spacesuit, it's hard to open and close your hands due to the pressurization of the suit,'' Chauvin said. “Also, good shoulder strength is necessary to do tasks.''

 

Like all Earth-bound mortals, the astronauts have likes and dislikes.

 

Astronaut Dan Burbank, who will participate in the mission's second spacewalk on Thursday, loves running -- usually logging 40 miles a week -- and hates weights.

 

“I have a weightlifting routine I go through where my goal is to get in and out and finish that just as soon as I can.''