Minimum Duration of Exercise for Improving Aerobic Capacity in Middle-Aged and Elderly Female Patients With Coronary Heart Disease and/or Hypertension

To determine the minimum duration of exercise for improving the aerobic capacity of patients with coronary heart disease (CHD), 23 female patients with CHD and/or hypertension, aged 52.8±8.7 years, were studied. After pre-testing, all the patients were conditioned for 4 months in order to elicit improvements in their aerobic capacity and other healthrelated factors. Duration and contents of daily activities were recorded by each patient. After 4 months, oxygen uptake at lactate threshold (VO2LT) and VO2peak were increased significantly from 12.9±2.6 to 16.0±3.4ml/kg/min and from 18.5±4.2 to 22.3±5.6ml/kg/min, respectively. Duration of exercise conditioning for the 4 months averaged 23.8±12.2min per day, ranging from 4.6 to 49.7min. Correlational analyses were applied in order to determine the extent to which the improvement in aerobic capacity was associated with the individual mean duration of exercise conditioning. As a result, changes in VO2LT and VO2peak correlated significantly with the exercise duration (Pearson's r=0.51, Spearman's rho=0.47 for VO2LT; Spearman's rho=0.58 for VO2peak) . Both VO2LT and VO2peak tended to improve markedly when daliy exercise duration was 20 min or longer. Furthermore, it was shown that the improvement in aerobic capacity remained almost the same within a range of exercise duration of 20 to 60min. We suggest that the minimum exercise duration for improving the aerobic capacity of cardiac patients is 20 to 30min per day or 140min or more per week.