title: Effect of supplementation with a cysteine donor on muscular performance.
abstract: Oxidative stress contributes to muscular fatigue. GSH is the major intracellular antioxidant, the biosynthesis of which is dependent on cysteine availability. We hypothesized that supplementation with a whey-based cysteine donor [Immunocal (HMS90)] designed to augment intracellular GSH would enhance performance. Twenty healthy young adults (10 men, 10 women) were studied presupplementation and 3 mo postsupplementation with either Immunocal (20 g/day) or casein placebo. Muscular performance was assessed by whole leg isokinetic cycle testing, measuring peak power and 30-s work capacity. Lymphocyte GSH was used as a marker of tissue GSH. There were no baseline differences (age, ht, wt, %ideal wt, peak power, 30-s work capacity). Follow-up data on 18 subjects (9 Immunocal, 9 placebo) were analyzed. Both peak power [13 +/- 3.5 (SE) %, P < 0.02] and 30-s work capacity (13 +/- 3.7%, P < 0.03) increased significantly in the Immunocal group, with no change (2 +/- 9.0 and 1 +/- 9.3%) in the placebo group. Lymphocyte GSH also increased significantly in the Immunocal group (35.5 +/- 11.04%, P < 0.02), with no change in the placebo group (-0.9 +/- 9.6%). This is the first study to demonstrate that prolonged supplementation with a product designed to augment antioxidant defenses resulted in improved volitional performance.
authors.affiliation: Division of Respiratory Medicine, McGill University Health Centre-Montreal Children's Hospital, Montreal, Quebec, Canada H3H 1P3. larry.lands@muhc.mcgill.ca
authors.forename: L C
authors.initials: LC
authors.lastname: Lands
authors.forename: V L
authors.initials: VL
authors.lastname: Grey
authors.forename: A A
authors.initials: AA
authors.lastname: Smountas
mesh_terms: D000328:Adult; D001642:Bicycling; D003545:Cysteine / Q000494:pharmacology*; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D008894:Milk Proteins / Q000494:pharmacology*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D010807:Physical Endurance; D000067816:Whey Proteins
chemical_list: D008894:Milk Proteins; D000067816:Whey Proteins; D005978:Glutathione; D003545:Cysteine