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  • Author: Melissa J. Crowe x
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Melissa J. Crowe, Donna M. O’Connor and Joann E. Lukins

This study aimed to investigate the effects of 6 wk oral supplementation of ß-hydroxy- ß-methylbutyrate (HMB) and HMB combined with creatine monohy-drate (HMBCr) on indices of health in highly trained athletes. Elite, male rugby league players (n = 28) were allocated to 1 of 3 groups: a control group (n = 6), a HMB group (3 g/d; n = 11), or a HMBCr group (3 g/day HMB, 3 g/d Cr; n = 11). Testing prior to, and immediately following, supplementation included a full blood count, plasma testosterone and cortisol, blood electrolytes, lipids, urea and glucose, sperm count and motility, and assessment of psychological state. A 3 X 2 factorial ANOVA revealed no effect of HMB or HMBCr on any of the measured parameters except minor changes in blood bicarbonate and blood monocyte and lymphocyte counts. Blood bicarbonate was significantly decreased in the HMB post-supplementation sample compared to the control and HMBCr groups. Blood monocyte and lymphocyte counts showed no within-group changes for HMB or HMBCr supplementation but were significantly different from the control. However, the majority of these readings remained within normal range. HMB and HMBCr were concluded to have no adverse effects on the parameters evaluated in this study when taken orally by highly trained male athletes over a 6-wk period.

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Melissa J. Crowe, Anthony S. Leicht and Warwick L. Spinks

This study investigated the effects of caffeine on repeated, anaerobic exercise using a double-blind, randomized, crossover design. Seventeen subjects (five female) underwent cognitive (reaction time, number recall) and blood (glucose, potassium, catecholamines, lactate) testing before and after consuming caffeine (6 mg/kg), placebo, or nothing (control). An exercise test (two 60 s maximal cycling bouts) was conducted 90 min after caffeine/placebo consumption. Plasma caffeine concentrations significantly increased after caffeine ingestion, however, there were no positive effects on cognitive or blood parameters except a significant decrease in plasma potassium concentrations at rest. Potentially negative effects of caffeine included significantly higher blood lactate compared to control and significantly slower time to peak power in exercise bout 2 compared to control and placebo. Caffeine had no significant effect on peak power, work output, RPE, or peak heart rate. In conclusion, caffeine had no ergogenic effect on repeated, maximal cycling bouts and may be detrimental to anaerobic performance.