Examination of the efficacy of acute L-alanyl-L-glutamine ingestion during hydration stress in endurance exercise

Abstract

BackgroundThe effect of acute L-alanyl-L-glutamine (AG; Sustamine™) ingestion on performance changes and markers of fluid regulation, immune, inflammatory, oxidative stress, and recovery was examined in response to exhaustive endurance exercise, during and in the absence of dehydration.MethodsTen physically active males (20.8 ± 0.6 y; 176.8 ± 7.2 cm; 77.4 ± 10.5 kg; 12.3 ± 4.6% body fat) volunteered to participate in this study. During the first visit (T1) subjects reported to the laboratory in a euhydrated state to provide a baseline (BL) blood draw and perform a maximal exercise test. In the four subsequent randomly ordered trials, subjects dehydrated to -2.5% of their baseline body mass. For T2, subjects achieved their goal weight and were not rehydrated. During T3 - T5, subjects reached their goal weight and then rehydrated to 1.5% of their baseline body mass by drinking either water (T3) or two different doses (T4 and T5) of the AG supplement (0.05 g·kg-1 and 0.2 g·kg-1, respectively). Subjects then exercised at a workload that elicited 75% of their VO2 max on a cycle ergometer. During T2 - T5 blood draws occurred once goal body mass was achieved (DHY), immediately prior to the exercise stress (RHY), and immediately following the exercise protocol (IP). Resting 24 hour (24P) blood samples were also obtained. Blood samples were analyzed for glutamine, potassium, sodium, aldosterone, arginine vasopressin (AVP), C-reactive protein (CRP), interleukin-6 (IL-6), malondialdehyde (MDA), testosterone, cortisol, ACTH, growth hormone and creatine kinase. Statistical evaluation of performance, hormonal and biochemical changes was accomplished using a repeated measures analysis of variance.ResultsGlutamine concentrations for T5 were significantly higher at RHY and IP than T2 - T4. When examining performance changes (difference between T2 - T5 and T1), significantly greater times to exhaustion occurred during T4 (130.2 ± 340.2 sec) and T5 (157.4 ± 263.1 sec) compared to T2 (455.6 ± 245.0 sec). Plasma sodium concentrations were greater (p < 0.05) at RHY and IP for T2 than all other trials. Aldosterone concentrations at RHY and IP were significantly lower than that at BL and DHY. AVP was significantly elevated at DHY, RHY and IP compared to BL measures. No significant differences were observed between trials in CRP, IL-6, MDA, or in any of the other hormonal or biochemical measures.ConclusionResults demonstrate that AG supplementation provided a significant ergogenic benefit by increasing time to exhaustion during a mild hydration stress. This ergogenic effect was likely mediated by an enhanced fluid and electrolyte uptake.

Effects ofl-Alanyl-l-Glutamine Ingestion on One-Hour Run Performance

“…Participants were also required to cycle to exhaustion at 75% of VO 2max . The investigators reported significantly greater times to exhaustion in participants who were provided the dipeptide compared to a no-fluid trial [16]. Time to exhaustion was not significantly different between the no-fluid trial and water-only trial.…”

“…Glutamine is a nonessential amino acid and is involved in many physiologic functions, including cellular proliferation, acid-base balance, transport of ammonia between tissues, and antioxidant synthesis [15]. It has been used in both medical and athletic settings to try to enhance fluid absorption [16][17][18][19]. During prolonged starvation, sepsis, and long-duration physical activity, glutamine concentrations may become deficient [20].…”

“…Additionally, alanine is considered the most gluconeogenic amino acid [23] and has been identified as a major gluconeogenic precursor in prolonged exercise [24]. Hoffman and colleagues [16] examined the efficacy of the alanine-glutamine dipeptide in participants who were dehydrated to ¡2.5% of their body weight and then rehydrated to ¡1.5% with the dipeptide. Participants were also required to cycle to exhaustion at 75% of VO 2max .…”

Glutamine Supplementation and Basketball Players Power Performance Changes

“…There is glutamine in many physiologic functions including cellular proliferation, acid-base balance, transport of ammonia between tissues, and antioxidant synthesis [1][2][3]. Glutamine supplementation stimulates an increase in protein synthesis in the muscle, improves glycogen re-synthesis and can lead to an improvement in performance [4,5]. Glutamine has been shown to increase fluid and electrolyte absorption in both animal and human models [6].…”

“…Glutamine has been shown to increase fluid and electrolyte absorption in both animal and human models [6]. Recently, consumption of an alanine-glutamine dipeptide was reported to enhance fluid uptake and reduce the magnitude of performance decrement during exercise to exhaustion under hypohydrated conditions [5]. Furthermore, the alanine-glutamine dipeptide was shown to be significantly more effective than water alone.…”