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dc.contributor.advisorBlack, Katherine
dc.contributor.authorMcIntosh, Nicholas Dean
dc.identifier.citationMcIntosh, N. D. (2015). 11 week Beta-Hydroxy beta-Methylbutyric acid (HMB) supplementation: Effects on body composition and exercise performance in trained athletes. (Thesis, Bachelor of Medical Science with Honours). University of Otago. Retrieved from
dc.description.abstractBackground: Originally used in the farming industry to ‘bulk up’ cattle, interest in the leucine metabolite, beta-hydroxy beta-methylbutyrate (HMB), has been growing following a clinical trial which demonstrated significant improvements in strength and body composition in humans. Subsequent trials reaffirmed that previously untrained individuals benefitted from supplementation. However, trials involving athletes have demonstrated mixed results with short (<6 week) trials showing no benefit and one study indicating that a longer supplementation period is required. Thus this study aimed to determine whether HMB supplementation was beneficial for athletes with regard to body composition and/or exercise performance Design: During this double-blind, parallel study, 27 elite male rugby union players were randomly assigned to consume either 3g Ca-HMB or placebo (cornflour) per day for 11 weeks. Body composition (body mass and sum of eight skin folds) and exercise performance (1RM bench press, squat, clean, weighted pull up and a multistage aerobic fitness test as per New Zealand Rugby Union guidelines) were measured at baseline and week 11. Participants followed a standardised strength training programme developed by their strength and conditioning trainer with weekly volume and intensity increments. Participants brought their dosing containers to each training session to measure compliance. Additionally, participants completed a three day weighed food record and diet questionnaire during weeks one and nine to assess dietary confounding. Outcomes: Body mass increased in HMB group (+0.6kg ± 2.6kg) but decreased in placebo (-1.39kg ± 2.0kg) (p=0.029). Aerobic fitness decreased in the HMB group (-80m ± 119m) and increased in placebo (+160m ± 111m) (p=0.003). There were no statistically significant differences in any of the four strength tests between groups (all p>0.05), nor was there a statistically significant difference with respect to skin fold measurements (p>0.05). Conclusion: The increase in body mass found in this study is consistent with other long term (>6 week) HMB supplementation studies. These gains in body mass may have influenced running performance as a larger mass is required to be moved. As no significant differences in body composition or strength were seen, the findings of this study suggest caution needs to be taken when supplementing with HMB as negative performance effects may occur. Therefore close attention to the type of activities required by the athlete needs to be considered prior to supplementation.
dc.publisherUniversity of Otago
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dc.subjectBeta hydroxy beta methylbutyrate
dc.subjectBody composition
dc.subjectExercise performance
dc.title11 week Beta-Hydroxy beta-Methylbutyric acid (HMB) supplementation: Effects on body composition and exercise performance in trained athletes.
dc.language.rfc3066en of Medicine and Department of Human Nutrition of Medical Science with Honours of Otago
otago.openaccessAbstract Only
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