Influence of subject presentation on interpretation of body composition change after 6 months of self-selected training and diet in athletic males
High precision body composition assessment methods accurately monitor physique traits in athletes. The acute impact of subject presentation (ad libitum food and fluid intake plus physical activity) on body composition estimation using field and laboratory methods has been quantified, but the impact on interpretation of longitudinal change is unknown. This study evaluated the impact of athlete presentation (standardised versus non-standardised) on interpretation of change in physique traits over time. Thirty athletic males (31.2 ± 7.5 years; 182.2 ± 6.5 cm; 91.7 ± 10.3 kg; 27.6 ± 2.6 kg/m2) underwent two testing sessions on 1 day including surface anthropometry, dual-energy X-ray absorptiometry (DXA), bioelectrical impedance spectroscopy (BIS) and air displacement plethysmography (via the BOD POD), with combinations of these used to establish three-compartment (3C) and four-compartment (4C) models.
Tests were conducted after an overnight fast (BASEam) and ~ 7 h later after ad libitum food/fluid and physical activity (BASEpm). This procedure was repeated 6 months later (POSTam and POSTpm). Magnitude of changes in the mean was assessed by standardisation.
After 6 months of self-selected training and diet, standardised presentation testing (BASEam to POSTam) identified trivial changes from the smallest worthwhile effect (SWE) in fat-free mass (FFM) and fat mass (FM) for all methods except for BIS (FM) where there was a large change (7.2%) from the SWE. Non-standardised follow-up testing (BASEam to POSTpm) showed trivial changes from the SWE except for small changes in FFM (BOD POD) of 1.1%, and in FM (3C and 4C models) of 6.4 and 3.5%. Large changes from the SWE were found in FFM (BIS, 3C and 4C models) of 2.2, 1.8 and 1.8% and in FM (BIS) of 6.4%. Non-standardised presentation testing (BASEpm to POSTpm) identified trivial changes from the SWE in FFM except for BIS which was small (1.1%). A moderate change from the SWE was found for BOD POD (3.3%) and large for BIS (9.4%) in FM estimations.
Changes in body composition utilising non-standardised presentation were more substantial and often in the opposite direction to those identified using standardised presentation, causing misinterpretation of change in physique traits. Standardised presentation prior to body composition assessment for athletic populations should be advocated to enhance interpretation of true change.
KeywordsBody composition Air-displacement plethysmography Dual-energy X-ray absorptiometry Bioelectrical impedance spectroscopy Surface anthropometry
- 2C model
- 3C model
- 4C model
Baseline morning testing session, standardised presentation
Baseline afternoon testing session, non-standardised presentation
Bioelectrical impedance spectroscopy
Body mass index
Bone mineral content
- BOD POD
Air displacement plethysmography
Coefficient of variation
Dual-energy X-ray absorptiometry
National Health and Nutrition Examination Survey
Post 6 months morning testing session, standardised presentation
Post 6 months afternoon testing session, non-standardised presentation
Smallest worthwhile effect
Total body water
Technical error of measurement
Percentage of body fat
Volume of thoracic gas
The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation.
The authors’ responsibilities were as follows—AK and GJS: study concept and design; AK: acquisition of data; AK and GJS: analysis and interpretation of data; AK: draft of manuscript; AK, GJS and NB: critical revision of the manuscript for important intellectual content; AK: statistical analysis; and GJS: study supervision. AK had full access to all of the data in the study and takes responsibility for the integrity and the accuracy of the data analysis.
Compliance with ethical standards
Conflict of interest
The authors have no financial or personal conflicts of interest to declare.
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