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      Effects of β-alanine supplementation on exercise performance: a meta-analysis

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          Abstract

          Due to the well-defined role of β-alanine as a substrate of carnosine (a major contributor to H + buffering during high-intensity exercise), β-alanine is fast becoming a popular ergogenic aid to sports performance. There have been several recent qualitative review articles published on the topic, and here we present a preliminary quantitative review of the literature through a meta-analysis. A comprehensive search of the literature was employed to identify all studies suitable for inclusion in the analysis; strict exclusion criteria were also applied. Fifteen published manuscripts were included in the analysis, which reported the results of 57 measures within 23 exercise tests, using 18 supplementation regimes and a total of 360 participants [174, β-alanine supplementation group (BA) and 186, placebo supplementation group (Pla)]. BA improved ( P = 0.002) the outcome of exercise measures to a greater extent than Pla [median effect size (IQR): BA 0.374 (0.140–0.747), Pla 0.108 (−0.019 to 0.487)]. Some of that effect might be explained by the improvement ( P = 0.013) in exercise capacity with BA compared to Pla; no improvement was seen for exercise performance ( P = 0.204). In line with the purported mechanisms for an ergogenic effect of β-alanine supplementation, exercise lasting 60–240 s was improved ( P = 0.001) in BA compared to Pla, as was exercise of >240 s ( P = 0.046). In contrast, there was no benefit of β-alanine on exercise lasting <60 s ( P = 0.312). The median effect of β-alanine supplementation is a 2.85% (−0.37 to 10.49%) improvement in the outcome of an exercise measure, when a median total of 179 g of β-alanine is supplemented.

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          Distribution Theory for Glass's Estimator of Effect Size and Related Estimators

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            Free radicals and muscle fatigue: Of ROS, canaries, and the IOC.

            Skeletal muscle fibers continually generate reactive oxygen species (ROS) at a slow rate that increases during muscle contraction. This activity-dependent increase in ROS production contributes to fatigue of skeletal muscle during strenuous exercise. Existing data suggest that muscle-derived ROS primarily act on myofibrillar proteins to inhibit calcium sensitivity and depress force. Decrements in calcium sensitivity and force are acutely reversible by dithiothreitol, a thiol-selective reducing agent. These observations suggest that thiol modifications on one or more regulatory proteins are responsible for oxidant-induced losses during fatigue. More intense ROS exposure leads to losses in calcium regulation that mimic pathologic changes and are not reversible. Studies in humans, quadrupeds, and isolated muscle preparations indicate that antioxidant pretreatment can delay muscle fatigue. In humans, this phenomenon is best defined for N-acetylcysteine (NAC), a reduced thiol donor that supports glutathione resynthesis. NAC has been shown to inhibit fatigue in healthy adults during electrical muscle activation, inspiratory resistive loading, handgrip exercise, and intense cycling. These findings identify ROS as endogenous mediators of muscle fatigue and highlight the importance of future research to (a) define the cellular mechanism of ROS action and (b) develop antioxidants as novel therapeutic interventions for treating fatigue.
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              The time course of phosphorylcreatine resynthesis during recovery of the quadriceps muscle in man.

              The time course of phosphorylcreatine (PC) resynthesis in the human m. quadriceps femoris was studied during recovery from exhaustive dynamic exercise and from isometric contraction sustained to fatigue. The immediate postexercise muscle PC content after either form of exercise was 15-16% of the resting muscle content. The time course of PC resynthesis during recovery was biphasic exhibiting a fast and slow recovery component. The half-time for the fast component was 21-22s but this accounted for a smaller fraction of the total PC restored during recovery from the isometric contraction than after the dynamic exercise. The half-time for the slow component was in each case more than 170 s. After 2 and 4 min recovery the total amount of PC resynthesized after the isometric exercise were significantly lower than from the dynamic exercise. Occlusion of the circulation of the quadriceps completely abolished the resynthesis of PC. Restoration of resynthesis occurred only after release of occlusion.
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                Author and article information

                Contributors
                +44-115-8483505 , +44-115-8486616 , craig.sale@ntu.ac.uk
                Journal
                Amino Acids
                Amino Acids
                Amino Acids
                Springer Vienna (Vienna )
                0939-4451
                1438-2199
                24 January 2012
                24 January 2012
                July 2012
                : 43
                : 1
                : 25-37
                Affiliations
                [1 ]Biomedical, Life and Health Sciences Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS UK
                [2 ]Junipa Ltd, Newmarket, Suffolk, UK
                Article
                1200
                10.1007/s00726-011-1200-z
                3374095
                22270875
                0bae9744-6b02-49a1-8dac-26f306887c03
                © The Author(s) 2012
                History
                : 21 October 2011
                : 9 December 2011
                Categories
                Original Article
                Custom metadata
                © Springer-Verlag 2012

                Genetics
                exercise test and duration,meta-analysis,β-alanine supplementation
                Genetics
                exercise test and duration, meta-analysis, β-alanine supplementation

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