Protein synthesis and the expression of growth-related genes are altered by running in human vastus lateralis and soleus muscles

Human Performance Laboratory, Ball State University, Muncie Indiana Submitted 7 November 2008 ; accepted in final form 30 December 2008 Recent evidence suggests aerobic exercise may help preserve soleus muscle mass during unloading. The purpose of this investigation was to examine the muscle-specific metabolic response to running as it relates to muscle growth. Mixed-muscle protein synthesis [fractional synthetic rate (FSR)] and gene expression (GE) were examined in the vastus lateralis (VL) and soleus (SOL) muscles from eight men (26 ± 2 yr; O 2max 63 ± 2 ml·kg –1 ·min –1 ) before and after a 45-min level-grade treadmill run at 77 ± 1% intensity. Muscle glycogen utilization was similar between muscles. Resting FSR was similar between the VL (0.080 ± 0.007 %/h) and SOL (0.086 ± 0.008 %/h) and was higher ( P < 0.05) 24 h postexercise compared with rest for both muscles. The absolute change in FSR was not different between muscles (0.030 ± 0.007 vs. 0.037 ± 0.012 %/h for VL and SOL). At baseline, myostatin GE was approximately twofold higher ( P < 0.05) in SOL compared with VL, while no other muscle-specific differences in GE were present. After running, myostatin GE was suppressed ( P < 0.05) in both muscles at 4 h and was higher ( P < 0.05) than baseline at 24 h for VL only. Muscle regulatory factor 4 mRNA was elevated ( P < 0.05) at 4 h in both SOL and VL; MyoD and peroxisome-proliferator-activated receptor-gamma coactivator-1 (PGC-1 ) were higher ( P < 0.05) at 4 h, and forkhead box [FOXO]3A was higher at 24 h in SOL only, while muscle-RING-finger protein-1 (MuRF-1) was higher ( P < 0.05) at 4 h in VL only. Myogenin and atrogin-1 GE were unaltered. The similar increases between muscles in FSR support running as part of the exercise countermeasure to preserve soleus mass during unloading. The subtle differences in GE suggest a potential mechanism for muscle-specific adaptations to chronic run training. fractional synthesis rate; myogenic; proteolytic; exercise; myostatin Address for reprint requests and other correspondence: M. Harber, Human Performance Laboratory, Ball State Univ., Muncie, IN 47306 (e-mail: mharber{at}bsu.edu )