Low-intensity Resistance Exercise Stimulates Mitochondria Protein Synthesis And PGC-1α mRNA Expression: 948: June 2 3:30 PM - 3:45 PM : Medicine & Science in Sports & Exercise

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D-61 Free Communication/Slide - Protein and Amino Acid Metabolism: JUNE 2, 2011 3: 15 PM - 5: 15 PM: ROOM: 402

Low-intensity Resistance Exercise Stimulates Mitochondria Protein Synthesis And PGC-1α mRNA Expression


June 2 3:30 PM - 3:45 PM

Burd, Nicholas A.; West, Daniel W.D.; Little, Jonathan P.; Gibala, Martin J.; Baker, Steven K.; Phillips, Stuart M. FACSM

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Medicine & Science in Sports & Exercise 43(5):p 135, May 2011. | DOI: 10.1249/01.MSS.0000403078.39646.85
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Limited data exists on the acute effects of resistance exercise on rates of mitochondria protein synthesis and mRNA expression of peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α, a key regulator of mitochondrial biogenesis, during post-exercise recovery.

PURPOSE: To determine if changes in mitochondrial protein synthesis and PGC-1α mRNA expression after low-intensity resistance exercise are influenced by the time the muscle is under tension (TUT).

METHODS: Eight men (23±1 y, BMI= 26.5±1.0 kg·m-2) received a primed, constant infusion of L-[ring-13C6]phenylalanine and biopsies of the vastus lateralis were obtained in the fed (i.e., 20g whey protein) and fasted-states at rest (FAST), 5hFED, 24hFAST, 29hFED post-exercise. Subjects performed 3 sets of unilateral knee extension exercise at 30% 1RM performed at a slow (SLOW) TUT (6-s concentric, 1-s hold, 6-s eccentric) or an external work-matched standard TUT control (1-s concentric, 0-s hold, 1-s eccentric; CTL).

RESULTS: Exercise at SLOW and CTL were identical in the number of contractions performed for set 1 (12±1), set 2 (7±0.5), and set 3 (6±0.4). TUT was greater (P<0.05) for all 3 sets in SLOW (set 1: 3.3min; set 2: 2min; set 3: 1.5min) as compared to CTL (set 1: 0.4min; set 2: 0.2min, set 3: 0.2min). Exercise-induced rates of mitochondrial protein synthesis were elevated by 114% above fasted rates at 5hFED only after the SLOW condition; however, at 29hFED both CTL (126%) and SLOW (175%) conditions were elevated above FAST (all P<0.05). PGC-1α mRNA expression was significantly increased above FAST at 5hFED in SLOW (3.1-fold) and CTL (2.7-fold) conditions

CONCLUSIONS: TUT affects the acute amplitude (1-5h) of rates of mitochondrial synthesis; however, a carryover effect of resistance exercise, regardless of TUT, exists on mitochondria protein synthesis 24-29h later. Further, PGC-1α may, in part, mediate the response at further time points after resistance exercise.

Supported by NSERC

© 2011 American College of Sports Medicine