EXAMINING THE EFFECTS OF THORACIC LUNG VOLUME MANIPULATION ON BODY COMPOSITION BY AIR DISPLACEMENT PLETHYSMOGRAPHY
M. Murillo, M. Grogan, K. Son, M. Lockard
Willamette University, Salem, OR
Air displacement plethysmography (ADP) is commonly used to determine body composition (%BF), as an assessment of health and fitness among athletes and non-athletes alike. Using Boyle’s law, by manipulating the volume of the ADP chamber and measuring the resulting changes in pressure, the volume and density of the subject can be determined. ADP relies upon the assumed compressibility of air surrounding the test subject (adiabatic air), as well as thoracic gas volume (isothermal air). During normal breathing thoracic gas volume is predicted by height, sex, and age. PURPOSE: To analyze changes in %BF results when violating the assumption of thoracic gas volume. METHODS: 20 healthy college students were recruited from Willamette University. %BF was determined via ADP under five randomly ordered conditions: normal breathing/normal seating position, expanded chest/normal seating position, depressed chest/normal seating position, expanded chest/arched back, and depressed chest/arched back. Differences within subjects across all conditions were assessed by repeated-measures ANOVA with pairwise post hoc analyses and Bonferroni correction. RESULTS: %BF measures increased when comparing normal breathing/normal seating condition ( X¯=22.450±10.717) to both the depressed chest/ normal seating position (X¯=24.475±10.012, p<0.001) and depressed chest/arched back position (X¯=24.785±10.291, p< 0.0001). Expanded chest/normal seating (X¯=21.430±10.317) and expanded chest/arched back (X¯=22.195±10.692) were lower than normal breathing/normal seating position at non-significant levels. The expanded chest/normal seating position resulted in significantly lower %BF than the depressed chest/normal seating (p<0.002) and the depressed chest/arched back (p<0.001). Similar differences were noted when comparing the expanded chest/arched back to the depressed chest/normal seating (p<0.007) and the depressed chest/arched back position (p<0.012). CONCLUSION: Results of this study indicate that changes in breathing during ADP may alter body fat % readings, likely due to changes in the volume of isothermal air present. Accurate results when using ADP require clear instructions that emphasize normal breathing throughout testing.
Murillo, M; Grogan, M; Son, K; and Lockard, M
"EXAMINING THE EFFECTS OF THORACIC LUNG VOLUME MANIPULATION ON BODY COMPOSITION BY AIR DISPLACEMENT PLETHYSMOGRAPHY,"
International Journal of Exercise Science: Conference Proceedings: Vol. 8:
8, Article 68.
Available at: https://digitalcommons.wku.edu/ijesab/vol8/iss8/68