L-Glutamine supplementation: effects on endurance, power and recovery

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Date: February-May 2013
From: Current Topics in Nutraceutical Research(Vol. 11, Issue 1-2)
Publisher: New Century Health Publishers, LLC
Document Type: Article
Length: 4,735 words
Lexile Measure: 1350L

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ABSTRACT: The purpose was to examine the influence of L-Glutamine on endurance and power. Cardio-respiratory capacity (V[O.sub.2peak]) was determined in 12 men using a cycle ergometer. After 2 days, subjects performed 3 Wingate tests to assess total revolutions (TR), peak (PP) and mean Power (MP); and a time trial to exhaustion (TTE). Two Wingates were conducted before and immediately after the TTE, the third after 24hrs. Subjects were then randomized to either L-glutamine (GLU) or placebo (CON) for 6 days. After 6 days all tests, except the V[O.sub.2peak], were repeated. There were no group differences for V[O.sub.2peak], power indices, and TTE before supplementation. Both groups showed a similar drop in power (TR:-22%; PP:-27%; MP:-27%, p<0.001) immediately after the TTE, with incomplete recovery at 24hrs. After 6 days, GLU improved TTE by 3.16[+ or -]0.75min (p<0.05) compared to no change in CON. Delta values (Post-Pre supplementation) revealed group differences for TR (GLU: [DELTA]1.83[+ or -]4.79; CON: [DELTA]-5.33[+ or -]4.13; p=0.02), PP (GLU: [DELTA]-58.59[+ or -]50.52; CON:-[DELTA]113.67[+ or -]63.35, p=0.12), and MP (GLU: [DELTA]28.93[+ or -]75.02; CON: [DELTA]-72.25[+ or -]62.14, p=0.02). No effects were noted immediately and 24hrs after the TTE. These findings suggest 6 days of glutamine supplementation does not affect acute recovery from exhaustive exercise; but does increase endurance and restores and/or improves power indices.

KEY WORDS: L-Glutamine; Power; Recovery; Time to Exhaustion

INTRODUCTION

The suggested reasons for glutamine supplements (i.e. support for immune system, increased glycogen synthesis, anti-catabolic effect, and enhanced fluid and electrolyte uptake) have received some support from well-controlled scientific studies (Gleeson, 2008). In fact, in a recent study physical performance (defined as time to exhaustion) was increased during a mild hydration stress, and in a subsequent study the same investigators found that rehydration with glutamine resulted in the ability to maintain performance during a basketball game (Hoffman et al. 2010, Hoffman et al. 2012). Closer examination of available literature reveals a possible role for glutamine in stimulating anabolic processes, including muscle glycogen and protein synthesis, and to some extent in situations of recovery from hydration stress [Gleeson, 2008, Walsh et al. 1998). These findings suggest that in addition to an effect on acute performance, Glutamine may be important during recovery from acute exercise. Given many individuals are challenged to produce high level performances separated by short recovery times, accelerated recovery is critical.

Typically, high intensity exercise, results in significant stress to the human body, with evidence of damage to skeletal muscle (Powers et al. 2011). As a consequence performance typically declines, and remains depressed on subsequent bouts, when an individual is challenged to perform within a narrow window of recovery. Exercise induced muscle damage to muscle fibers results in an inflammatory response, during which time the consumption of glutamine in immunologic tissues and cells increases (Newsholme, 2001). Increase in consumption, coupled with enhanced utilization by other tissues, results in a demand for glutamine that may outstrip the supply (Newsholme, 2001). Thus it could be hypothesized that the role of exogenous supplementation of glutamine may be to...

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Gale Document Number: GALE|A462796996