Effects of clothing on accuracy and reliability of air displacement plethysmography

Purpose: The purpose of this investigation was to quantify the effects of different attire on the accuracy and reliability of estimating percent body fat (%fat) by using air displacement plethysmography (ADP). Methods: Fifteen adults were tested four times on four separate occasions. Each session consisted of estimating %fat with ADP wearing a swimsuit (ADP_SS), a hospital gown (ADP_HG), and in the nude (ADP_N), plus assessment by hydrostatic weighing (HW). Results: An ANOVA revealed no significant differences within any of the four methods over the 4 days. Intraclass correlation coefficients revealed a strong relationship for repeated measures in ADP_SS (r = 0.981), ADP_HG (r = 0.993), ADP_N (r = 0.989), and HW (r = 0.976). Mean data for each condition indicated a significant underestimation (P < 0.05) of %fat while wearing a hospital gown (13.8 ± 7.7%) compared with ADP_SS (22.0 ± 7.8%), ADP_N (23.5 ± 7.5%), and HW (22.6 ± 6.8%). Conclusion: Reliability of ADP does not appear to be compromised by clothing; however, wearing a hospital gown significantly affects accuracy, reducing %fat estimations by approximately 9% compared with the recommended swimsuit. Measurement in the nude does not provide more reliable or accurate measures than wearing a swimsuit.