Maximal oxygen uptake (VO2max) is the best index of aerobic capacity and gold standard for cardio-respiratory fitness. However, it may not be achieved practically. Consequently, peak oxygen uptake (VO2peak) is used interchangeably to estimate VO2max. Airway obstruction and symptom perception may limit asthmatics to maximal exercise. The aim of our study is to evaluate the aerobic capacity to assess the cardio-respiratory fitness of adult asthmatics to perform physical activity.
Fifty-four stable asthmatics (34 males, 20 females) of mild to moderate severity were studied. The diagnosis was based on suggestive symptoms and significant reversibility to inhaled salbutamol (200 micrograms). Thirty-one, age and sex matched healthy subjects (20 males, 11 females) served as control group. All subjects underwent progressive treadmill exercise test (Sensormedics Vmax229 spectra machine) based on Modified Bruce Protocol and cardio-pulmonary responses to exercise were studied. Oxygen uptake (VO2) was analysed by non-dispersible infrared thermopile gas analyser and computed breath by breath as per the American Thoracic Society (ATS) guidelines. The differences in mean values between the two groups were tested by unpaired student ‘t’ test.
The mean VO2 peak in male asthmatics was 1.78 ± 0.41 L/min and in male controls 2.03 ± 0.46 L/min (p = 0.043). The mean VO2 peak in female asthmatics was 1.20 ± 0.26 L/min and in female controls 1.17 ± 0.15 L/min (p>0.05). The mean VO2/kg peak was comparable in patients and controls of both males (28.85 ± 6.32 ml/kg/min versus 31.37 ± 5.52 ml/kg/min, p>0.05) and females (22.16 ± 4.17 ml/kg/min versus 21.21 ± 2.25 ml/kg/min, p>0.05). Other cardio-pulmonary variables studied were not significantly different in study subjects.
Adult male and female asthmatics of mild to moderate severity have aerobic capacity (VO2/kg peak) comparable to controls.
Patients of bronchial asthma with mild to moderate severity need not restrict their physical activity.
R. Caroli, None.