Effects of high-intensity intermittent swimming on PGC-1α protein expression in rat skeletal muscle

Aim: The aim of the present investigation was to elucidate the effects of exercise intensity on exercise-induced expression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1 alpha) protein in rat skeletal muscle. Methods: We measured PGC-1 alpha content in the skeletal muscles of male Sprague-Dawley rats (age: 5-6 weeks old; body weight: 150-170 g) after a single session of high-intensity intermittent exercise (HIE) or low-intensity prolonged swimming exercise (LIE). During HIE, the rats swam for fourteen 20-s periods carrying a weight (14% of body weight), and the periods of swimming were separated by a 10-s pause. LIE rats swam with no load for 6 h in two 3-h sessions, separated by 45 min of rest. Results: After HIE, the PGC-1 alpha protein content in rat epitrochlearis muscle had increased by 126, 140 and 126% at 2, 6 and 18 h, respectively, compared with that of the age-matched sedentary control rats' muscle. Immediately, 6 and 18-h after LIE, the PGC-1 alpha protein content in the muscle was significantly elevated by 84, 95 and 67% respectively. The PGC-1 alpha protein content observed 6 h after HIE tended to be higher than that observed after LIE. However, there was no statistically significant difference between the two values (P = 0.12). Conclusion: The present investigation suggests that irrespective of the intensity of the exercise, PGC-1 alpha protein content in rat skeletal muscle increases to a comparable level when stimuli induced by different protocols are saturated. Further, HIE is a potent stimulus for enhancing the expression of PGC-1 alpha protein, which may induce mitochondrial biogenesis in exercise-activated skeletal muscle.