The implications of undertaking DXA scans using best practice protocols (subjects fasted and rested) or a less precise but more practical protocol in assessing chronic changes in body composition following training and a specialized recovery technique were investigated.
Twenty-one male cyclists completed an overload training program, in which they were randomized to four sessions per week of either cold water immersion therapy or control groups. Whole-body DXA scans were undertaken with best practice protocol (Best) or random activity protocol (Random) at baseline, after 3 weeks of overload training, and after a 2-week taper. Magnitudes of changes in total, lean and fat mass from baseline-overload, overload-taper and baseline-taper were assessed by standardization (Δmean/SD).
The standard deviations of change scores for total and fat-free soft tissue mass (FFST) from Random scans (2–3%) were approximately double those observed in the Best (1–2%), owing to extra random errors associated with Random scans at baseline. There was little difference in change scores for fat mass. The effect of cold water immersion therapy on baseline-taper changes in FFST was possibly harmful (-0.7%; 90% confidence limits ±1.2%) with Best scans but unclear with Random scans (0.9%; ±2.0%). Both protocols gave similar possibly harmful effects of cold water immersion therapy on changes in fat mass (6.9%; ±13.5% and 5.5%; ±14.3%, respectively).
An interesting effect of cold water immersion therapy on training-induced changes in body composition might have been missed with a less precise scanning protocol. DXA scans should be undertaken with Best.
Nana and Burke are with the AIS Sports Nutrition, Australian Institute of Sport, Canberra, ACT, Australia. Slater is with the School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, Queensland, Australia. Hopkins is with the Sport and Recreation, Auckland University of Technology, Auckland, New Zealand. Halson is with the AIS Performance Recovery, Australian Institute of Sport, Canberra, Australia. Martin is with the AIS Physiology, Australian Institute of Sport, Canberra, Australia. West is with the Microbiology and Immunology Research Group, Griffith University, Nathan, Queensland, Australia.