Practical Issues in Evidence-Based Use of Performance Supplements: Supplement Interactions, Repeated Use and Individual Responses

Sports Medicine, Mar 2017

Current sports nutrition guidelines recommend that athletes only take supplements following an evidence-based analysis of their value in supporting training outcomes or competition performance in their specific event. While there is sound evidence to support the use of a few performance supplements under specific scenarios (creatine, beta-alanine, bicarbonate, caffeine, nitrate/beetroot juice and, perhaps, phosphate), there is a lack of information around several issues needed to guide the practical use of these products in competitive sport. First, there is limited knowledge around the strategy of combining the intake of several products in events in which performance benefits are seen with each product in isolation. The range in findings from studies involving combined use of different combinations of two supplements makes it difficult to derive a general conclusion, with both the limitations of individual studies and the type of sporting event to which the supplements are applied influencing the potential for additive, neutral or counteractive outcomes. The repeated use of the same supplement in sports involving two or more events within a 24-h period is of additional interest, but has received even less attention. Finally, the potential for individual athletes to respond differently, in direction and magnitude, to the use of a supplement seems real, but is hard to distinguish from normal day to day variability in performance. Strategies that can be used in research or practice to identify whether individual differences are robust include repeat trials, and the collection of data on physiological or genetic mechanisms underpinning outcomes.

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Practical Issues in Evidence-Based Use of Performance Supplements: Supplement Interactions, Repeated Use and Individual Responses

Sports Med Practical Issues in Evidence-Based Use of Performance Supplements: Supplement Interactions, Repeated Use and Individual Responses Louise M. Burke 0 1 2 0 Mary MacKillop Institute for Health Research, Australian Catholic University , Melbourne, VIC , Australia 1 Sports Nutrition, Australian Institute of Sport , PO Box 176, Belconnen, ACT 2616 , Australia 2 Real-life Uses of Performance Supplements Current sports nutrition guidelines recommend that athletes only take supplements following an evidencebased analysis of their value in supporting training outcomes or competition performance in their specific event. While there is sound evidence to support the use of a few performance supplements under specific scenarios (creatine, beta-alanine, bicarbonate, caffeine, nitrate/beetroot juice and, perhaps, phosphate), there is a lack of information around several issues needed to guide the practical use of these products in competitive sport. First, there is limited knowledge around the strategy of combining the intake of several products in events in which performance benefits are seen with each product in isolation. The range in findings from studies involving combined use of different combinations of two supplements makes it difficult to derive a general conclusion, with both the limitations of individual studies and the type of sporting event to which the supplements are applied influencing the potential for additive, neutral or counteractive outcomes. The repeated use of the same supplement in sports involving two or more events within a 24-h period is of additional interest, but has received even less attention. Finally, the potential for individual athletes to respond differently, in direction and magnitude, to the use of a supplement seems real, but is hard to distinguish from normal day to day variability in performance. Strategies that can be used in research or practice to identify whether individual differences are robust include repeat trials, and the collection of data on physiological or genetic mechanisms underpinning outcomes. 1 Introduction According to surveys and the experience of most sports nutrition professionals, there is a high prevalence of use of sports foods and supplements among competitive athletes [1]. While there are some concerns associated with such observations, particularly around the indiscriminate use of performance supplements [2], many expert groups now take a pragmatic approach to the use of products and protocols which have passed a risk:benefit analysis of being safe, effective, and legal, while also being appropriate to the athlete?s age and maturation in their sport [2, 3]. Indeed, a number of supplements have received plentiful and insightful attention from sports scientists to produce robust evidence of the scenarios in which they can enhance sports performance. These include caffeine [4, 5], creatine monohydrate [6, 7], bicarbonate [8, 9], beta-alanine [10, 11], and beetroot juice/nitrate [12, 13]. While the evidence-base for the use of these products is generally sound, it typically produces a recommended protocol that is generic and isolated from other performance strategies that the athlete may also be implementing. Indeed, the laboratory situations in which most supplement studies are conducted often fail to include many of the important features associated with competitive sport. Earlier work identified a range of characteristics which should be included in investigations of strategies to enhance sports performance to allow them to be more easily applied to competitive athletes [14, 15]. These included using highly trained participants to whom the results are intended to apply, choosing performance protocols which mimic reallife sport, and incorporating other nutritional strategies or features according to the way they should be practiced in the targeted sport or event. Such features have been integrated into many recent investigations, including a number of field studies in which the effect of a performance supplement has been observed during simulated [16, 17] or actual [18] sporting events. Despite these advances, there are several real-life issues related to the use of performance supplements that remain relatively ignored. Poor interrogation of such issues makes it difficult for athletes to undertake a thorough risk:benefit analysis of their potential use of a supplement or to implement a scenario-specific protocol for their product use that is truly evidence-based. These issues included the additive and interactive effects of combining the use of several performance supplements for a single event, considerations regarding the repeated use of a performance supplement within a relatively brief period, and the notion of individual responsiveness to supplement use. The aim of this review is to examine our current state of knowledge around these issues. It will focus on the performance supplements which were previously identified as enjoying str (...truncated)


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Louise M. Burke. Practical Issues in Evidence-Based Use of Performance Supplements: Supplement Interactions, Repeated Use and Individual Responses, Sports Medicine, 2017, pp. 79-100, Volume 47, Issue 1, DOI: 10.1007/s40279-017-0687-1