A Preliminary study of Ventilatory Responses during Maximal Exercise in Healthy Thais

Abstract

Background and objectives: Cardiopulmonary exercise testing (CPET) evaluates the ability of cardiovascular and respiratory systems in maximal exercise. It is used for the diagnosis and prognosis of cardiovascular and pulmonary disease patients. Assessment of the breathing pattern at maximal exercise in patients is limited because the range of ventilatory responses at maximal exercise in healthy Thai is unknown. This study aimed to evaluate the ventilatory response to maximal exercise and to compare the differences in these responses between genders.

Methods: The maximal cardiopulmonary responses were performed in 30 healthy Thai subjects (15 males; aged 27±5 years and 15 females; aged 27±3 years) who underwent the CPET using a ramp protocol until reaching symptom limitation.

Results: All subjects had normal ranges of clinical characteristics except that weight and height in males were higher than in females (p<0.001). Maximal work rate (WRmax), maximal voluntary ventilation (MVV), maximal expired total ventilation ( max) and maximal tidal volume (VTmax) in males were significantly higher than in females (205 vs 111 W, 149.5 vs 107.2 L/min, 96.1 vs 54.8 L/min; p<0.001 and 2.0 vs 1.3 L; p<0.01). In addition, respiratory frequency (Rf), VT were  increased as a function of WR in both genders (p<0.001). Nevertheless, the breathing reserve was not significantly different between genders.

Conclusions: The present study provides primarily data on ventilatory responses to maximal exercise using the CPET in healthy Thais. We also demonstrated that males have ventilatory responses at an anaerobic threshold (AT) and at maximal exercise higher than those of females.