The Effect of Body Mass Index on Ventilatory Parameters During Exercise

Abstract

PURPOSE: Obesity causes lung restriction and often results in exertional dyspnea. Exercise capacity is reduced in obese subjects, possibly due to impairment in ventilation during exercise. Body Mass Index (BMI) affects exercise capacity (VO2max). Whether BMI affects ventilatory parameters during exercise, thereby contributing to dyspnea has not been studied. The objective of this study was to determine the impact of BMI on ventilatory parameters-maximal voluntary ventilation (MVV), ventilation at maximal exercise (VEmax), Breathing reserve (BR), Respiratory rate (RR) and Tidal volume (VT) at peak exercise during Cardiopulmonary Exercise Testing (CPExT). METHODS: Patients who underwent CPExT for evaluation of dyspnea in our institution over the last 2 years were studied. The following parameters were obtained from their records: age, gender, BMI, VO2max, MVV, RR, VT, VEmax, and BR during CPExT. Correlation between BMI and respectively MVV, VEmax, RR, VT and BR was determined by using Pearson's test for linear correlation. p < 0.05 was deemed statistically significant. RESULTS: Of 84 patients, who underwent CPExT, 58% were females; mean age was 56AE 15 years. Mean BMI was: 28.3AE5.6 kg/sqm; 33% were obese with BMI > 30. Mean values of studied parameters: VO2 max ¼ 71AE5.6 percent predicted (%); MVV ¼ 85 AE23%; VEmax¼65AE17.6 %; BR ¼ 30AE17 percent; RR ¼ 32AE 8 breaths/minute; VT ¼ 3AE12.4L. The correlation between BMI and respective studied parameters and their statistical significance were as follows: