Background: 

Aging is characterized by a progressive loss of muscle mass and strength (sarcopenia), particularly in fast muscles. One of the possible causes of this decline in muscle performance is the abnormal accumulation of reactive oxygen species (ROS), negatively impacting the regenerative ability.

Aim: 

This study was designed to determine the effect of a short-term endurance training on the antioxidant capacity and on the myogenesis pathway in aged rat skeletal muscles.

Methods: 

12 young (5 months) and 12 aged (22 months) male Wistar rats were exercised for 3 weeks following an aerobic training.

Results: 

Xanthine oxidase activity (+44%, p<0.05) and catalase protein content (+63%, p<0.01) were markedly increased in gastrocnemius muscle with aging. Carbonylated proteins content of gastrocnemius muscle from the aged group was higher as compared with that of young rats (+76%, p<0.001). Endurance training did not change oxidative stress markers in the gastrocnemius of aged rats. Myogenin protein content increased with aging in gastrocnemius (+42%, p<0.01) whereas no change in MyoD and Myf5 protein content were noticed. No modifications of myogenic regulator factors (MRF) protein content were observed with endurance training in aged rats.

Conclusion: 

Cellular redox potential of skeletal muscle becomes progressively more oxidized with aging, but short term endurance training failed to reduce it. Increase of myogenin protein content with aging demonstrates a compensatory mechanism to limit muscle wasting. This up-regulation occurring with aging could explain the incapacity of aged skeletal muscle to increase further MRFs with endurance training.

The authors' work was supported by grants BFU2007-65 803/BFI, 35/UPB20/08 and ISCIII2006-RED13-027.