Bodybuilding workouts, 30-45 second sets followed by 1-2 min rest,
are primarily glycolytic.
So, if you're training in a carb depleted state, your workouts would figure to be sluggish, as you're relying on a slower burning fuel, fat, which is more appropriate for less intense training like jogging at 9-10 minute mile pace.
Of course, if you're dieting for a show, you might be willing to sacrifice the intensity for the increase in fat burning.
