Request for Clarification: Pitchford et al. suggest that the supplements used by McIntosh et al. (3) contained no beta-Hydroxy beta-Methylbutyrate (HMB) leading to the null hypothesis on strength measures, the significant negative effect on YoYo running performance, and increase in body mass. However, it should be noted that the product tested by Pitchford et al. "Maximum HMB" (Reactiv Supplements) is not the same product as used by McIntosh et al. who used Ca-HMB (Reactiv Supplements, Auckland, New Zealand). Reactiv Supplements supplied a certificate of analysis for their Ca-HMB capsules, stating 84% of HMB content. Furthermore, the original source of maximum HMB differs to that of Ca-HMB; therefore, it is difficult to infer the analysis by Pitchford et al. to the McIntosh et al. (3) findings. Although independent testing of a commercially available supplement would be the gold-standard procedure, this is often beyond the means of athletes, sports teams, and many research articles. If as suggested 2 placebo trials were provided, this could explain only the strength measures and not the body mass nor the decreased aerobic performance results. A recent meta-analysis in well-trained and competitive athletes showed HMB supplementation resulted in no significant effects on muscle strength (6) in line with McIntosh et al. (3). Studies investigating aerobic capacity/performance with HMB supplementation have mainly recruited untrained or recreationally trained participants, and it seems that the effects of HMB on untrained and highly trained participants are different (2,4). Beta-Hydroxy beta-Methylbutyrate was shown to improve cycling performance in elite rowers (1) and trained cyclists (8); however, differences in responses to HMB may be between endurance athletes and those engaged in more resistance training (5). The one other study in highly trained rugby players, using a running protocol showed no beneficial effect of HMB on aerobic performance (5). It is possible that the increased body mass seen in the study by McIntosh et al. (3) resulted in a decrement in running performance. Four of the 6 participants on HMB saw a reduction in YoYo performance compared with an improvement by all the placebo groups. Overall, it seems that the findings of McIntosh et al. (3) are supported by the previous research (5,6) suggesting HMB supplementation is not beneficial to elite rugby players. However, it highlights a key issue for athletes that despite due diligence in supplement procurement, they still may not be obtaining the supplement they believe, adding support to the food first approach advocated by many sports nutritionists.
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