Impact Of Standardised Versus Non-standardised Athlete Presentation On Technical And Biological Error In Physique Assessment Methods

Abstract

Two compartment (2C) models of physique assessment contain assumptions that can be overcome by a three compartment (3C) model, where total body water (TBW) is measured rather than assumed, or a four compartment (4C) model, where both TBW and bone mineral content (BMC) are measured. However, as TBW is the most variable component of fat free mass (FFM) the impact of athlete presentation on measurement error in 2C models has not been established. PURPOSE: To evaluate the impact of standardised versus non-standardised athlete presentation on technical and biological error on 2C and 3C models of physique assessment compared with the reference 4C model, over thirty six hours. METHODS: Thirty two athletic males underwent five test sessions using dual energy x-ray absorptiometry (DXA), bioelectrical impedance spectroscopy (BIS) and air displacement plethysmography (BOD POD) to measure body composition, with combinations of these used to establish 3C and 4C models. Tests were conducted after an overnight fast (in duplicate) and ~7 hrs later after ad libitum food/fluid and physical activity, then repeated at 24 hrs replicating the initial test, and finally~15 min after ingestion of a standardised meal. Magnitudes of changes in the mean and typical errors of measurement were assessed by standardisation. RESULTS: Mean change scores for TBW assessment were trivial for standardised presentation tests (0.2%, -0.3%) and large for non-standardised test (~7 hrs post ad libitum) (3.4%). Standardised presentation mean change scores for fat mass (FM) were trivial for all models but substantially large for non-standardised tests (~7 hrs post ad libitum) in BIS, 3C, and 4C models (-15.1%,-6.9% and -6.7%) and post meal (9.8%, 5.7% and 5.2%). For FFM, mean change scores for standardised presentation tests were trivial for all models but non-standardised test (~7 hrs post ad libitum) produced large changes for BIS, 3C and 4C models (3.4%, 2.3% and 2.2%), small for DXA (1%) and trivial for BOD POD (0.9%). CONCLUSIONS: Models that included a measured TBW value from BIS (3C and 4C) were more sensitive to TBW changes in non-standardised conditions than 2C models in FM and FFM measurements. Biological error via acute hydration change in FFM is minimised in physique assessment models if athletes present in an overnight fasted state.