Check this out, found it while researching. Crazy workout from hell -
Tyson in his youth didnt use weights at all but his 'bulk' came from being naturally big (200lb at age 15), eating high protein diets (steak, pasta and fruit juices were his ONLY diet up until firing Rooney in 1988).
Well i digress, his regimen in the olden days was this:
5am: get up and go for a 3 mile jog
6am: come back home shower and go back to bed (great workout for those huge legs of his)
10am wake up: eat oatmeal
12pm: do ring work (10 rounds of sparring)
2pm: have another meal (steak and pasta with fruit juice drink)
4pm: more ring work and 60 mins on the exercise bike (again working those legs for endurance and power)
5pm: floor exercises: 2000 sit ups; 500-800 'dips'; 500 press ups and 500 shrugs with a 30kg barbell and 10 mins of neck exercises (working the biceps, triceps, chest, abs and shoulders)
7pm: steak and pasta meal again with fruit juice (orange i think it was).
8pm: another 30 minutes on the exercise bike
9:30 watch TV and then go to bed.
I heard this on an interview with Tyson saying it himself to Ian Darke (Sky commentator). Contrary to belief, Tyson wasnt always in the ring sparring for hours and hours, but he did his roadwork and kept his body in shape, with 10 rounds of sparring a day he virtually eliminated his ring rust and could work on the power punches which came from natural exercices (the press ups etc) and those big powerful legs. It's this discipline that made Tyson so great up until firing Kevin Rooney.
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there is a link on the BBC website somewhere in which Tyson tells Ian Darke his whole workout regime. This was taken from 1988 when Tyson went to England to watch a Frank Bruno match.
http://www.saddoboxing.com/boxing_forum/index.php/topic,11886.0.html