Associations Between Ventilatory Efficiency During Exercise And Body Composition Metrics Among Young Adults

Cardiovascular disease (CVD) is the leading cause of death worldwide. Higher CVD risk can be predicted by a higher minute ventilation/rate of carbon dioxide production slope (V̇E/V̇CO2) during exercise. A higher V̇E/V̇CO2 has been reported among adults with obesity (body mass index [BMI] >30 kg/m2) and various comorbidities. However, it is unknown whether obesity is associated with V̇E/V̇CO2 in the absence of comorbidities. PURPOSE: This study tested the hypothesis that a higher BMI is associated with V̇E/V̇CO2 in young, otherwise healthy adults with and without obesity. METHODS: We enrolled adults 20-39 years old with a BMI <40 kg/m2 and no cardiometabolic/pulmonary diseases, uncontrolled hypertension, or recent nicotine use. We measured body composition using anthropometrics and dual x-ray absorptiometry (DXA). Participants completed a cardiopulmonary exercise test on a cycle ergometer starting with 3 min at 20 W and progressive increases in workload (males: 20 W/min, females: 15 W/min) until task failure. We calculated V̇E/V̇CO2 (i.e., ventilatory efficiency) using data at 20 W until the ventilatory threshold. We employed Spearman's correlations (ρ) and present data as median [IQR]. RESULTS: The sample (n = 31) characteristics were: 24[6] years old; 45% female; 10% Asian, 16% Black, 74% White; 29% Latinx; relative peak V̇O2 35.5[10.4] mL O2/kg/min (absolute: 3.03[1.52] L O2/min). V̇E/V̇CO2 (33.1[4.7]) was not correlated with BMI (31.6[9.4] kg/m2; ρ = 0.01, P = 0.96). V̇E/V̇CO2 was also not correlated with DXA body fat (26.0[21.0]%; ρ = 0.22, P = 0.24) or visceral adipose tissue (539[562] g; ρ = -0.14, P = 0.47). Additionally, V̇E/V̇CO2 was not correlated with waist circumference (89.0[22.9] cm; ρ = -0.05, P = 0.79) or waist-to-hip ratio (0.82[0.06]; ρ = -0.10, P = 0.59). Finally, we did not find a correlation between V̇E/V̇CO2 and any body composition metric when we repeated analyses after covariate adjustment for age, sex, race, ethnicity, and absolute peak V̇O2 (ρ ≤ |0.19|, P ≥ 0.39). CONCLUSION: These preliminary data suggest that V̇E/V̇CO2 is not meaningfully correlated with any body composition metric. These results suggest that obesity-related comorbidities (e.g., cardiometabolic diseases), rather than body composition itself, may influence ventilatory efficiency during exercise among young adults. Supported by: Florida State University Graduate School Legacy Fellowship (CD), National Institutes of Health K01HL160772 (JCW), and American Heart Association 23CDA1037938 (JCW).