Harber, M., Suer, M., Wolff, C., & Konopka, A. (2014). Influence of age and gender on factors regulating skeletal muscle size with aerobic exercise training. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 2222.

The purpose of this investigation was to examine the influence of age and gender on factors regulating skeletal muscle size before and after aerobic exercise training. Older women (N = 9; ~70 years), older men (N = 6; ~74years), and young men (N = 7; ~20years) underwent 12 weeks of aerobic exercise training on a cycle ergometer. Skeletal muscle biopsies from the vastus lateralis were obtained prior to and 48 hours following training.

Whole muscle size and function at baseline were influenced by age and gender (young men were greater than older men who were greater than older women) while training-induced changes were more pronounced in older women. Despite the drastic differences in total work performed during the training protocol (older women were less than older men who were less than young men), absolute increases in whole muscle size were similar between groups. Baseline myostatin was similar between groups and was reduced after aerobic exercise training independent of age and gender. Baseline and the exercise-induced reduction of phosphorylated-CDK2(Tyr15) were more pronounced in older women (gender effect). Furthermore, CDK2 activation status increased in response to training. Acetylated-to-total-p53 had a tendency to be higher in older women at baseline however, it did not change with training in any group. Elevated levels of phosphorylated-SAPK/JNK in older individuals of both genders after training may indicate that age-specific pathways were activated with aerobic exercise training.

Implication. Aerobic exercise training appears to be an effective tool in older individuals regardless of gender. Aerobic exercise training-induced skeletal muscle hypertrophy appears likely to be related to myostatin signaling.

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