Effects of training and detraining on the distribution of cholesterol, triglyceride, and nitrogen in tissues of albino rats.

The effects of standardized exercise training and detraining on the content of cholesterol, triglyceride, and nitrogen in blood, myocardium, skeletal muscle, and epididymal fat of rats were studied. Forty-eight 90-day-old male rats were randomly assigned to four groups (two control groups, one trained group, and one trained and detrained group). Trained rats were subjected to 8 weeks of moderate running in motor-driven wheels; detraining was effected by discontinuing the running program for 8 weeks. Rats were provided a standard diet and water ad libitum. Trained rats displayed lower body weights and resting bradycardia. Training lowered (P<0.01) serum cholesterol, serum triglyceride, and adipose triglyceride levels but had no effect on these lipids in heart or skeletal muscle. These lowered lipid levels persisted after 8 weeks of detraining even though body weight was regained rapidly. Total nitrogen content was higher (P<0 .01) in myocardial and triceps muscles of both trained and trained-detrained rats. Heart cholesterol and triglyceride levels were unchanged by detraining, but skeletal muscle cholesterol content was lowered. The results indicate that the changes in lipid content associated with training and detraining are tissue specific: reduction occurred in some tissues (serum and adipose tissue), although the lipid content of others (skeletal and heart muscle) was independent of training status, body weight, or circulating lipid levels.