Effect of exercise on protein degradation: 3-methylhistidine and creatinine excretion.

The effect of 1 hr of intensive exercise per day on protein breakdown was studied in a group of young male volunteers (20-25 years old) who were on a meat-free diet during the entire period of the study. Urinary 3-methylhistidine and creatinine were estimated as index of protein degradation. When studied over a period of 24 hr at different time points, the mean rates of 3-methylhistidine excretion were 2.4 and 2.9 nmole/min/kg for the day of exercise and nonexercise, respectively. Immediately following the exercise period, 3-methylhistidine and creatinine excretion rates decreased significantly.