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The effects of phosphatidylserine (PS) supplementation on performance during and recovery following prolonged intermittent exercise. / Daniel Peter Wadsworth
Swansea University Author: Daniel Peter Wadsworth
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Prolonged intermittent exercise, in the guise of simulated soccer match play, has the potential to elevate the production of reactive oxygen species and leave participants susceptible to oxidative stress, subsequent muscle damage (Thompson et al, 2001) and muscle soreness (Wadsworth et al, 2004). Su...
|Degree level:||Master of Philosophy|
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Prolonged intermittent exercise, in the guise of simulated soccer match play, has the potential to elevate the production of reactive oxygen species and leave participants susceptible to oxidative stress, subsequent muscle damage (Thompson et al, 2001) and muscle soreness (Wadsworth et al, 2004). Supplementation with phosphatidylserine (PS), a primary constituent of the inner membranes of neurones, has been shown to enhance cognitive function in the elderly (Pepu et al, 1996; Blokland et al, 1999) and inhibit the exercise-induced release of stress hormones (Monteleone et al, 1990; Monteleone et al, 1992; Fahey and Pearl, 1998). In addition to a myriad of membrane functions, in-vitro studies have demonstrated that PS has the potential to act as an antioxidant (Latorraca et al, 1993; Dacaranhe and Terao, 2001). Consequently, it is plausible that exogenous supplementation with PS may provide additional defence against the oxidative stress caused by exercise; however this action has yet to be explored. Therefore, the aim of the current study was to investigate the effect of chronic soybean-derived PS (S-PS) supplementation on muscle damage, delayed onset muscle soreness, and the body's response to prolonged intermittent exercise. Sixteen familiarised male subjects were administered with either 750 mg-day[-1] of S-PS or a glucose placebo, in a double-blind randomised fashion, for 10 days prior to a prolonged intermittent exercise protocol. The protocol was based on the Loughborough intermittent shuttle test (LIST) (Nicholas et al, 2000), but was adapted to specifically simulate soccer match play. Subjects' response to exercise was assessed by measuring heart rate (HR) throughout exercise, while blood lactate and glucose concentrations, and rate of perceived exertion (RPE) were measured prior to exercise, at half time, and immediately post-exercise. Moreover, perceived muscle soreness and blood concentrations of cortisol, creatine kinase (CK), lipid hydroperoxide (HPO), vitamin C, and vitamin E were measured prior to exercise and after 20 min, 24 hr, and 48 hr of recovery. The prolonged intermittent exercise protocol used in this study led to exercise- induced stress, as demonstrated by the significant elevation of blood cortisol concentrations during exercise (P<0.001). Moreover, the exercise protocol was shown to significantly elevate markers of muscle damage (P<0.001), delayed onset muscle soreness (DOMS) (P<0.001), and oxidative stress (P<0.001). These variables were affected to an equal extent in placebo and S-PS groups, and had returned to pre-exercise levels within 48 hours of recovery. However, those supplemented with S-PS did demonstrate a trend towards enhanced performance (P=0.082). It is plausible that the trend of improved performance of the S-PS group, and consequent elevation in blood cortisol concentration and oxidative stress markers, may have negated any benefits that S-PS supplementation had on these markers. Therefore, future research should attempt to clarify the potential ergogenic effect of S-PS supplementation, and ascertain if such supplementation has any effect on the elevation of blood cortisol and oxidative stress associated with prolonged intermittent exercise.
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