The Effects Of Obesity On Exercise Ventilatory Response In Elderlies: Role Of Operational Lung Volumes

PURPOSE: Obesity causes a decrease in operational lung volumes increasing the risk of developing mechanical ventilatory constraints (MVC), which could influence the ventilatory response to exercise. While the effect of obesity on respiratory mechanics has been studied in younger adults, the effect in older adults is unclear. Given that aging also has the potential to increase MVC, we hypothesized that the exercise ventilatory response could be blunted in older adults with obesity. Method: We evaluated 37 older adults with (BMI ≥ 30) and without obesity (BMI < 30). All participants underwent pulmonary function testing, body composition scans (DEXA), and an incremental cycling test. Operational lung volumes (i.e., end expiratory lung volume [EELV] & end inspiratory lung volume [EILV]), expiratory flow limitation (EFL), exercise ventilatory response (V̇E & V̇E/V̇CO2-slope), and peak exercise capacity (V̇O2) were measured. Data were analyzed by independent T-test. RESULTS: Forced vital capacity and total lung capacity (TLC) were reduced in the adults with obesity (Table 1). At peak exercise, EELV was lower in those with obesity (p < 0.05), while EILV was similar between groups. However, EQ \O(V,•)E was significantly lower (p = 0.05) when the adults with obesity reached their peak EILV. As a result, the V̇E/V̇CO2-slope was highly blunted during heavy exercise contributing to an elevated PETCO2 in the older adults with obesity (p = 0.003). EILV was moderately related to V̇E/V̇CO2 slope only in the adults with obesity (r2 = 0.5, p = 0.002). EFL and peak V̇O2 were not different between the groups. CONCLUSION: The ventilatory response to heavy exercise is blunted in older adults with obesity due to the limits set by operational lung volumes, especially the upper limit of EILV. Clinically, older adults with obesity could present with a normal exercise capacity while ventilatory response, gas exchange, and respiratory mechanisms could be significantly altered. Supported by: AG070262