Interpretation of dual energy X-ray absorptiometry-derived body composition change in athletes : a review and recommendations for best practice

Dual energy X-ray absorptiometry (DXA) is a medical imaging device which has become the method of choice for the measurement of body composition in athletes. The objectives of this review were to evaluate published longitudinal DXA body composition studies in athletic populations for interpretation of 'meaningful' change, and to propose a best practice measurement protocol. An online search of PubMed and CINAHL via EBSCO Host and Web of Science enabled the identification of studies published until November 2016. Those which met the inclusion criteria were reviewed independently by two authors according to their methodological quality and interpretation of body composition change. Twenty-five studies published between 1996 and November 2016 were reviewed (male athletes: 13, female athletes: 3, mixed: 9) and sample sizes ranged from n = 1 to 212. The same number of eligible studies were published between 2013 - 2016, as over the 16 years prior (1996 - 2012). Seven did not include precision error, and fewer than half provided athlete-specific precision error. There were shortfalls in the sample sizes on which precision estimates were based and inconsistencies in the level of pre-scan standardisation, with some reporting full standardisation protocols and others reporting only single (e.g. overnight fast) or no control measures. There is a need for standardised practice and reporting in athletic populations for the longitudinal measurement of body composition using DXA. Based on this review and that of others, plus the official position of the International Society for Clinical Densitometry, our recommendations and protocol are proposed as a guide to support best practice.