The BodPod® (COSMED, Concord, CA) uses predicted (pTGV) or measured thoracic gas volume (mTGV) during estimations of percentage body fat (%BF). In young adults, there is inconsistent evidence on the variation between pTGV and mTGV, and the effect of sex as a potential covariate on this relationship is unknown. This study examined the difference between TGV assessments and its effect on %BF and potential sex differences that may impact this relationship. A retrospective analysis of BodPod® pTGV and mTGV for 95 men and 86 women ages 18–30 years was performed. Predicted TGV was lower than mTGV for men (−0.49 ± 0.7 L; p < .0001). For men, %BF derived by pTGV was lower than that by mTGV (−1.3 ± 1.8%; p < .0001). For women, no differences were found between pTGV and mTGV (−0.08 ± 0.6 L; p > .05) or %BF (−0.03 ± 0.2%; p > .05). The two-predictor model of sex and height was able to account for 57.9% of the variance in mTGV, F(2, 178) = 122.5, p < .0001. Sex corrected for the effect of height was a significant predictor of mTGV (β = 0.483 L, p < .0001). There is bias for pTGV to underestimate mTGV in individuals with a large mTGV, which can lead to significant underestimations of %BF in young adults; this was especially evident for men in this study. Sex is an important covariate that should be considered when deciding to use pTGV. The results indicate that TGV should be measured whenever possible for both men and women ages 18–30 years.

BodPod®（COSMED，Concord，CA）在估算体脂百分比 (%BF) 期间使用预测的 (pTGV) 或测量的胸腔气体体积 (mTGV)。在年轻人中，关于 pTGV 和 mTGV 之间差异的证据不一致，并且性别作为潜在协变量对这种关系的影响尚不清楚。本研究检查了 TGV 评估之间的差异及其对 %BF 的影响以及可能影响这种关系的潜在性别差异。对年龄在 18-30 岁的 95 名男性和 86 名女性进行了 BodPod® pTGV 和 mTGV 的回顾性分析。预测的 TGV 低于男性的 mTGV (-0.49 ± 0.7 L; p  < .0001)。对于男性，pTGV 得出的 %BF 低于 mTGV（-1.3 ± 1.8%；p  < .0001）。对于女性，pTGV 和 mTGV 之间没有发现差异（-0.08 ± 0.6 L；p  > .05) 或 %BF (-0.03 ± 0.2%; p  > .05)。性别和身高的双预测模型能够解释 mTGV 方差的 57.9%，F (2, 178) = 122.5, p  < .0001。针对身高影响校正的性别是 mTGV 的重要预测因子 (β = 0.483 L, p  < .0001)。在 mTGV 较大的个体中，pTGV 存在低估 mTGV 的偏差，这可能导致年轻人显着低估 %BF；在这项研究中，这对男性来说尤其明显。性别是决定使用 pTGV 时应考虑的重要协变量。结果表明，应尽可能测量 18-30 岁男性和女性的 TGV。