Implications of face mask use on body composition assessment by air-displacement plethysmography

The BOD POD (COSMED USA Inc., Concord, CA) is a common instrument used to assess body composition by employing air displacement plethysmography and whole-body densitometry to determine body volume. This instrument requires isothermal conditions during testing; therefore, the introduction of outside isothermal air can impact testing results. With the COVID-19 pandemic introducing face mask mandates, it is unknown whether the use of a face mask during BOD POD testing may lead to erroneous measurement by introducing isothermal air. Thus, the purpose of this cross-sectional study was to investigate the impact of wearing a surgical face mask compared to not wearing a surgical face mask on body composition assessment among adults.

During testing, female subjects were required to wear a swimsuit or form-fitting lycra shorts and a sports bra and male subjects were required to wear form-fitting lycra shorts. American Society for Testing and Materials (ASTM) level one surgical face masks (bacterial and particulate filtration efficiency of 95%) and standard swim caps were provided by researchers. Variables of interest included percent body fat, body fat, percent lean body mass, and lean body mass. Participants (n = 33) completed one test wearing a mask and one test without a mask back-to-back with conditions held constant. Dependent-sample sign tests, Bland-Altman Plots, and Passing-Bablok regression analyses were used to test mask-on versus mask-off differences and agreement between variables of interest.

There were no significant median differences in any body composition results between face mask use and non-face mask use using dependent-sample sign tests. Bland-Altman Plots demonstrated acceptable agreement between mask usage and non-mask usage. No significant differences were seen in the slopes of the variables using Passing-Bablok regression.

Results suggest that wearing a face mask does not appreciably impact body composition results. Therefore, ASTM level 1 disposable surgical face mask does not introduce a significant amount of isothermal air during BOD POD testing.