King Grub
2010-03-11, 10:33
PURPOSE:: Determine if consuming isoenergetic (25 g) doses of carbohydrate (CHO) or protein (PRO) versus a non-caloric placebo (PLC) prior to conventional resistance training affected the myogenic expression of cell cycle-regulating genes as well as muscle [DNA] acutely following exercise.
METHODS:: Ten untrained men (mean +/- SD; 22 +/- 4 yrs; 77.8 +/- 8.3 kg; 17.8 +/- 4.0 % fat) participated in 3 resistance exercise sessions (3 sets of 10 repetitions at 80% 1RM for the bilateral hack squat, leg press, and leg extension exercises) in a cross-over fashion which were preceded by CHO, PRO, or PLC ingestion 30 min prior to training. Pre-supplement/exercise, 2-h, and 6-h post-exercise muscle biopsies were obtained during each session and analyzed for fold-changes in CDK4, CYCLIN D1, MGF, MYOD, P21, P27 mRNA expression using real-time RT-PCR as well as muscle ]DNA[ using cuvette-based fluorometric methods.
RESULTS:: Non-parametric statistics were completed and no conditions x time interaction effects were revealed. Several exercise-mediated responses were found to occur independent of condition: 1) muscle [DNA] increased at 6-h (+40%, p < 0.05), 2) CDK4 expression increased at 6-h (+86%, p < 0.05), 3) MYOD expression increased at 6-h (+98%, p < 0.05), 4) P27 expression decreased at 2-h (-35%, p < 0.05) and 6-h (-59%, p < 0.001), and 5) P21 expression substantially increased 2-h and 6-h post-exercise by (+1,250% and +4,670%, respectively, p < 0.001).
CONCLUSIONS:: The tandem DNA and cell cycle regulator gene expression analyses provides preliminary evidence to suggest that satellite cell activation and proliferation may be occurring at early post-exercise time points following a conventional resistance exercise bout; a phenomenon which may seemingly be independent of pre-exercise macronutrient ingestion.
Med Sci Sports Exerc. 2010 Mar 8. Effects of Pre-Exercise Feeding On Markers of Satellite Cell Activation.
METHODS:: Ten untrained men (mean +/- SD; 22 +/- 4 yrs; 77.8 +/- 8.3 kg; 17.8 +/- 4.0 % fat) participated in 3 resistance exercise sessions (3 sets of 10 repetitions at 80% 1RM for the bilateral hack squat, leg press, and leg extension exercises) in a cross-over fashion which were preceded by CHO, PRO, or PLC ingestion 30 min prior to training. Pre-supplement/exercise, 2-h, and 6-h post-exercise muscle biopsies were obtained during each session and analyzed for fold-changes in CDK4, CYCLIN D1, MGF, MYOD, P21, P27 mRNA expression using real-time RT-PCR as well as muscle ]DNA[ using cuvette-based fluorometric methods.
RESULTS:: Non-parametric statistics were completed and no conditions x time interaction effects were revealed. Several exercise-mediated responses were found to occur independent of condition: 1) muscle [DNA] increased at 6-h (+40%, p < 0.05), 2) CDK4 expression increased at 6-h (+86%, p < 0.05), 3) MYOD expression increased at 6-h (+98%, p < 0.05), 4) P27 expression decreased at 2-h (-35%, p < 0.05) and 6-h (-59%, p < 0.001), and 5) P21 expression substantially increased 2-h and 6-h post-exercise by (+1,250% and +4,670%, respectively, p < 0.001).
CONCLUSIONS:: The tandem DNA and cell cycle regulator gene expression analyses provides preliminary evidence to suggest that satellite cell activation and proliferation may be occurring at early post-exercise time points following a conventional resistance exercise bout; a phenomenon which may seemingly be independent of pre-exercise macronutrient ingestion.
Med Sci Sports Exerc. 2010 Mar 8. Effects of Pre-Exercise Feeding On Markers of Satellite Cell Activation.