Dual energy x-ray absorptiometry (DXA) is widely used for determining body composition because it is quick, atraumatic and involves minimal radiation exposure. However, this method yields lower body fat values in lean individuals when compared with the criterion four compartment model. But the ability of DXA to detect longitudinal body composition changes in lean athletic cohorts is yet to be established.
PURPOSE: To compare DXA and the four compartment model for the detection of body composition changes in lean individuals.
METHODS: Eight physically active lean males (mean ± SD: 23.5 ± 4.7 yr, 74.29 ± 9.58 kg, 180.4 ± 5.0 cm) had body composition determined prior to and following a 3 wk detraining intervention. Four compartment body composition estimates were established by measuring body density, total body water and bone mineral mass via hydrodensitometry, deuterium dilution and DXA, respectively. DXA (DPX-L scanner, 1.3Z software, Lunar Corporation, Madison, WI, USA) body composition estimates were determined at the same time as the other measurements.
RESULTS: The body composition results (mean ± SD) are summarized below:
While the four compartment percent body fat (%BF) and fat free mass (FFM) estimates revealed statistically significant changes pre to post intervention, the smaller changes identified via DXA did not reach significance.
CONCLUSIONS: DXA may be unable to accurately track longitudinal body composition changes in lean individuals.