Abstract
Accurate assessment of pulmonary function is critical for diagnosing respiratory pathology and monitoring chronic disease. PURPOSE: To evaluate the test-retest reliability of a portable spirometry device and to investigate the anthropometric determinants of Forced Vital Capacity (FVC) in a Hispanic adult cohort. METHODS: A cross-sectional analysis was conducted on 94 adults (34 males, 60 females; mean Age = 51.9 ± 7.8 yrs). Subjects underwent sequential spirometry testing during two separate visits within a 10-day period. The primary maneuver assessed was FVC, which consisted of three relaxed tidal breaths followed by a maximal inhalation and a subsequent maximal forced exhalation. Participants performed familiarization trials, followed by three maximal efforts with 1 to 2 minutes of rest between attempts. Body composition was assessed via Dual-Energy X-ray Absorptiometry. To examine test-retest reliability, the coefficient of variation (CV) was calculated between the highest FVC values achieved on each visit. Secondary metrics analyzed included Forced Expiratory Volume in 1 second (FEV1), Peak Expiratory Flow (PEF), and the Tiffeneau-Pinelli index (TIFF, FEV1/FVC). Hierarchical stepwise multiple regression was utilized to identify the best predictors for FVC, using variance inflation factors (VIF) to examine multicollinearity. RESULTS: Paired t-tests revealed no significant differences in FVC, FEV1, PEF, and TIFF within males or females. In order, the average CV% for each test was 2.56 ± 2.34%, 3.53 ± 3.38%, 13.01 ± 11.92%, and 4.20 ± 4.27%, respectively. Stepwise multiple regression identified fat-free mass (FFM) as the single strongest predictor of FVC, explaining 67.4% of the variance (adjusted R² = 0.677, p < 0.001). A compiled model [F(3,90) = 87.462, p < 0.001] including FFM, BMI, and Age increased the predictive power to 74.5% (adjusted R² = 0.745). Notably, when Sex was forced into the model, it failed to achieve statistical significance (p = 0.175), while FFM remained highly significant (p < 0.001). Collinearity diagnostics revealed substantial covariance between Sex and FFM (VIF = 3.60 and 4.65, respectively). CONCLUSION: The robust agreement between testing sessions demonstrates that valid and reliable lung function data can be obtained from a single visit, provided that protocols for maximal effort and technique are strictly followed. Physiologically, regression analysis suggests that the variance in lung capacity typically attributed to biological sex is largely mediated by differences in muscle mass. These findings challenge the reliance on sex-based correction factors alone and advocate for the inclusion of body composition metrics, specifically FFM, to improve the precision of predicted lung function values among Hispanic clinical populations.
Recommended Citation
Gamboa, Marianna; Cantu, Nicole; Guadiana, Camila; Martinez, Samantha; and Moris, Jose M.
(2026)
"Fat-Free Mass Mediates Sex Differences in Lung Capacity: A Validation and Regression Analysis of Spirometry Indices in a Hispanic Cohort,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
18, Article 87.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss18/87