Anthropometry and the response to dietary supplementation in exercise: Review of the anthropometric methods employed to evaluate the effectiveness of popular dietary supplements to alter body composition

Abstract

A high proportion of athletes consume dietary supplements in the belief that they will enhance performance or alter body composition. Therefore, research into dietary supplements should accurately evaluate alterations in body composition, specifically muscle and fat mass (FM). A number of factors need to be considered in the selection of anthropometric methodologies to evaluate body composition changes due to dietary supplementation. These factors include measurement details (reliability, validity, accuracy and sensitivity), ethical factors such as invasiveness, statistical effect size and practical considerations such as time, cost and equipment availability. Researchers should first consider the statistical effect size of the supplement under study. Does previous research indicate a marked effect of the supplement on body composition? If so, then a less sensitive methodology can be utilised. Where previous research indicates only a small or negligible effect on body composition, the more sensitive anthropometric methodologies should be employed. The validity and reliability of the anthropometric technique is important. However, there is a lack of research into the reliability and validity of various anthropometric methodologies when assessed in conjunction with dietary supplementation. Examination of recent research into the most popular dietary supplements including creatine monohydrate, β-hydroxy- β-methyl butyrate (HMB), chromium picolinate, Tribulus Terrestris, ephedrine and l -carnitine, reveals utilisation of a wide variety of anthropometric methodologies with no particular methodology associated with detecting significant effects on body composition. Ephedrine, when combined with caffeine, and creatine are amongst the few dietary supplements consistently reported to alter body composition. Changes in hydration status can lead to confounding errors when assessing body composition and researchers should aim to minimise or control alterations in hydration status. Future research is needed in the area of anthropometry and dietary supplementation, particularly investigating the validity and reliability of various anthropometric techniques to detect change in body composition as a result of dietary supplementation. A greater availability of this information would assist researchers to choose appropriate anthropometric methodology to assess the effects of dietary supplements on muscle and FM.