Effects of acute resistance exercise on proteolytic and myogenic markers in skeletal muscles of former weightlifters and age-matched sedentary controls.

Background: Former athletes who continue a regular, performance-oriented training throughout life provide a unique model for studying successful aging. With this in mind, the current study aimed to compare the effects of an acute resistance exercise on proteolytic and myogenic markers in older weightlifters and untrained participants.
Methods: Sixteen older men (8 former weightlifters, 8 age-matched untrained controls) with an age of 61.2±8.2 years volunteered to participate in the study. Two days after assessing 1-RM, an acute exercise protocol (3 sets, 70-75% of one-repetition maximum until voluntary fatigue) was applied unilaterally on the dominant leg while the other leg served as control. Three hours after termination of the exercise, skeletal muscle tissue was obtained from m. vastus lateralis of both legs.
Results: Acute resistance exercise led to an up-regulation (>1.5-fold) of 14 genes in controls and of 13 genes in weightlifters. The transcription factors FOS and early growth response 1 (EGR1), as well as the E3 protein ligase TRIM63 comprised the most responsive genes to resistance exercise (EGR1:15.7-fold increase, P=0.003, FOS: 36.3-fold increase, P<0.001; TRIM63: 2.9-fold increase, P<0.001). In addition, myostatin levels were decreased in the exercised leg (0.6-fold, P<0.001). FOXO3 gene expression was significantly higher in weightlifters than in untrained controls (1.5-fold, P=0.042).
Conclusions: Trained and untrained older adults respond to an acute bout of resistance exercise in a very similar way irrespective of training status, although some differences exist in FOXO3, potentially reflecting the superior capacity of trained persons in regulating cellular homeostasis.