Abstract

Objective : The effects of regular exercise training on the expression of heat shock protein (HSP) in skeletal muscle of senescent animals are unknown. Therefore, the purpose of this study was to investigate the effects of long-term exercise on skeletal muscle HSP expression in both young and old rats. Materials and Methods : Young adult (12 weeks old) and old (100 weeks old) female Fisher 344 rats were assigned to either a sedentary control or an endurance exercise training group (n= 6/group). Rats in both training groups completed a treadmill exercise program (75-80 % Vo2max, 60 min/day, 5 days /wk) for 10 weeks. After 72 hours of completing the training program, the soleus (SOL) and extensor digitorum longus (EDL) muscles were excised and the levels of HSP72 were determined by Western blot. Results : No differences (p>0.05) existed in the basal levels of skeletal muscle HSP72 between young and old sedentary control animals. Compared to age-matched sedentary controls, exercise training resulted in increased (p<0.05) levels of HSP72 in skeletal muscles in both young (SOL+22%, EDL+200%) and old animals (SOL+15%, EDL+115%). Conclusions : Endurance training increases the expression of HSP72 in skeletal muscle in young and old animals. However, the response to endurance training in fast skeletal muscle (EDL) becomes moderate with age.