UP-REGULATION OF ANTIOXIDANT ENZYME ACTIVITY FOLLOWING UNILATERAL RESISTANCE EXERCISE TRAINING IN OLDER ADULTS

Abstract

A prominent theory for aging, the free radical theory, states that reactive oxygen species (ROS), formed as a by-product of normal energy metabolism, may cause cellular damage ultimately lead to a loss of cell function. Resistance exercise training leads to many benefits for the older adults, however, exercise has also been shown to induce oxidative stress. Whether resistance exercise augments or attenuates oxidative stress in older adults remains unknown. PURPOSE To examine the effects of resistance exercise training on markers of oxidative stress, antioxidant enzymes, and mitochondrial enzymes in older adults. METHODS Elderly men (n=12) were recruited to take part in a 10 week unilateral resistance exercise training protocol. Muscle biopsies were taken from the vastus lateralis of the training leg (T) and the non-training (NT) leg before and 48hrs following the last exercise bout. RESULTS Muscle protein carbonyls did not change significantly in the T or NT leg. There was no increase in mitochondrial enzymes (citrate synthase, complex II+III, complex IV) in either the T or NT leg. Catalase activity increased significantly in the trained leg (Pre-8.19 ±2.3, Post-14.88 ±7.6, P=0.02), and did not change in the NT leg. There was a trend towards an increase in Total Superoxide dismutase (SOD) following training (P=0.13), whereas there was no change in Total SOD in the NT leg. CuZn SOD (cytosolic) increased significantly in the T leg (Pre-7.2 ±2.7, Post-12.6 ±5.5, P=0.002), and remained unchanged in the NT leg, and MnSOD (mitochondrial) did not change in either leg. CONCLUSION These results suggest that, in older adults, resistance exercise training does not lead to an increase in oxidative stress, potentially due to significant increases in, predominantly cytosolic, antioxidant enzyme activity. Furthermore, 10 weeks of resistance training in older adults does not induce adaptations at the mitochondrial level. This work was supported by NSERC.