Glutathione in Athletic Performance, Endurance and Sports Nutrition

The effect of whey protein supplementation with and without creatine monohydrate combined with resistance training on lean tissue mass and muscle strength
Burke DG, Chilibeck PD, Davidson KS, Candow DG, Farthing J, Smith-Palmer T. Department of Human Kinetics, St. Francis Xavier University, Antigonish, Nova Scotia, B2G 2W5, Canada. [1: Int J Sport Nutr Exerc Metab 2001 Sep;11(3):349-64] Males that supplemented with whey protein while resistance training demonstrated greater improvement in knee extension peak torque and lean tissue mass than males engaged in training alone. Males that supplemented with a combination of whey protein and creatine had greater increases in lean tissue mass and bench press than those who supplemented with only whey protein or placebo.

  

Physical exercise intensity can be related to plasma glutathione levels
Gambelunghe C, Rossi R, Micheletti A, Mariucci G, Rufini S. [J Physiol Biochem 2001 Mar;57(2):9-14] The aim of the present study was to examine the effect of different kinds of physical exercise on plasma glutathione levels. Our results suggest that GSH plays a central antioxidant role in blood during intensive physical exercise and that its modifications are closely related to exercise intensity.

Oxidants, antioxidant nutrients and the athlete
Packer L. [Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.] Strenuous physical exercise induces oxidative stress. Severe or prolonged exercise can overwhelm antioxidant defences, which include vitamins E and C and thiol antioxidants, which are interlinked in an antioxidant network, as well as antioxidant enzymes. Evidence for oxidative stress and damage during exercise comes from direct measurement of free radicals, from measurement of damage to lipids and DNA, and from measurement of antioxidant redox status, especially glutathione. There is little evidence that antioxidant supplementation can improve performance, but a large body of work suggests that bolstering antioxidant defences may ameliorate exercise-induced damage, suggesting that the benefits of antioxidant intervention may be for the long term rather than the short term.

Antioxidants and physical performance
Clarkson PM. Department of Exercise Science, University of Massachusetts, Amherst 01003, USA.[Crit Rev Food Sci Nutr 1995 Jan;35(1-2):131-41] Performance of strenuous physical activity can increase oxygen consumption by 10- to 15-fold over rest to meet energy demands. The resulting elevated oxygen consumption produces an "oxidative stress" that leads to the generation of free radicals and lipid peroxidation. A defense system of free radical scavengers minimizes these dangerous radicals. Changes in antioxidant scavengers and associated enzymes (e.g., glutathione, tocopherol, glutathione peroxidase) also provide clues about demands on the defense system. Physical training has been shown to result in an augmented antioxidant system and a reduction in lipid peroxidation. Supplementation with antioxidants appears to reduce lipid peroxidation but has not been shown to enhance exercise performance. The "weekend athlete" may not have the augmented antioxidant defense system produced through continued training. This may make them more susceptible to oxidative stress. Whether athletes or recreational exercisers should take antioxidant supplements remains controversial. However, it is important that those who exercise regularly or occasionally ingest foods rich in antioxidants.

Mitochondria changes in human muscle after prolonged exercise, endurance training and selenium supplementation
Zamora AJ, Tessier F, Marconnet P, Margaritis I, Marini JF. [Eur J Appl Physiol 1995;71(6):505-11] The functional and structural responses to acute exercise (E) and training, (T) with or without selenium supplementation (Sel), were investigated in a double-blind study on 24 young male subjects. The results in Sel would seem to suggest a dampening effect of the selenium on the mitochondria changes, both in chronic and acute exercise. The mechanism of this action on mitochondrial turnover is uncertain, but might be related to a higher efficiency of the selenium-dependent enzyme glutathione peroxidase.

  

Reductions in blood glutamine concentration following intense exercise may contribute to immune suppression in overtrained athletes

  

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