Acute Resistance Exercise Augments Cumulative Myofibrillar, But Not Mixed Muscle Protein Synthesis: 791: June 3 1:45 PM - 2:00 PM : Medicine & Science in Sports & Exercise

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D-16 Free Communication/Slide - Protein Metabolism I: JUNE 3, 2010 1: 00 PM - 3: 00 PM: ROOM: 331

Acute Resistance Exercise Augments Cumulative Myofibrillar, But Not Mixed Muscle Protein Synthesis

791

June 3 1:45 PM - 2:00 PM

Gasier, Heath G.1; Fluckey, James D.2; Wiggs, Michael P.; Lee, Chang-Woock2; Previs, Stephen F.3; Reichman, Steven E.2

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Medicine & Science in Sports & Exercise 42(5):p 63-64, May 2010. | DOI: 10.1249/01.MSS.0000385212.10161.2e
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Resistance exercise (RE), in the post-absorptive state, stimulates mixed muscle and myofibrillar protein synthesis from 1-72 h following the session. However, the published data mostly refer to short-term stable isotopic measurements under controlled conditions, and studies have not considered whether these short-term responses are descriptive of cumulative daily muscle anabolism.

PURPOSE: To determine whether an acute bout of high-intensity resistance exercise, in the fed state, would augment cumulative (over 24 h) mixed muscle and myofibrillar fractional rates of protein synthesis (FSR) when total macronutrient intake was controlled.

METHODS: Twelve, recreationally active, healthy young men were studied over 24 h (all meals provided), and performed an acute bout of exhaustive unilateral leg-press and knee-extension exercise (5 sets of each exercise performed until failure at 85% of their 1 repetition maximum); such that one leg was exercised (Ex) and the other served as an internal control (NoEx). 2H2O (70%) was provided (4 time points, 75 ml per dose) to measure mixed muscle and myofibrillar FSR (expressed as % · h-1) over 24 h, and muscle biopsies (vastus lateralis) were collected from the Ex and NoEx legs 16 h following the RE session.

RESULTS: The 2H-labeling of body water over the course of the experiment was 0.32±0.01 mole percent excess. Interestingly, cumulative mixed muscle FSR was similar between the Ex (0.69±0.06%) and NoEx (0.76±0.81%) legs; however, upon determination of myofibrillar FSR, there was an RE effect (Ex, 0.94±0.08% vs. NoEx, 0.78±0.03%, P<0.05).

CONCLUSION: High intensity RE without prior training impacts specific subfractions of the total muscle protein pool, perhaps without altering total cumulative responses.

Supported by the Gatorade Sports Science Institute, the U.S. Egg and Poultry Association, NIH MMPC and the Sydney and J.L. Huffines Institute for Sports Medicine and Human Performance.

© 2010 American College of Sports Medicine