The influence of exercise intensity on cardiorespiratory function in the sedentary elderly with coronary heart disease

Objective To observe the influence of exercise intensity on cardiorespiratory function in the elderly with coronary heart disease using simplified 24-action Taijiquan and jogging. Methods A total of 115 sedentary elderly patients with heart disease were randomly divided into a control group ( no exercise), a low-intensity exercise group, a medium-intensity exercise group (whose exercise was simplified 24-action Taijiquan at 40-60% of their individual maximum oxygen consumption (VO2max) for 90 to 200 minutes per week) and a high-intensity exercise group ( whose exercise was jogging on a treadmill at ＞ 70% of their maximum oxygen consumption for 200 minutes per week). The regime was maintained for 6 months. All patients accepted a treadmill exercise test before and after the 6 months of exercise to evaluate the changes in VO2max, maximum heart rate ( HRmax), VO2max/HRmax and exercise time (t). Results ( 1 ) After 6 months of exercise, VO2max, HRmax, VO2/HRmax and t had increased sisnificantly in all three exercise groups. Work capacity had increased 18.6% , 33% and 34.4% and HRmax had increased 9.3% , 13.8%, 19.1%. There was no difference between before and after in the control group. (2) Compared with the control group the average VO2max, HRmax and t of all three exercise groups had increased significantly. VO2 max was 9.4% , 26% and 23. 1% better; HRmax was 6.7% , 8.8% and 12% better; t was 3.5,4 and 4.9 minutes longer. (3) Compared with the low-intensity exercise group, VO2max, HRmax and t in the medium- and high-intensity groups increased significantly more. VO2max increased 16.6% and 13.7% more; HRmax increased 2.1% and 3.2% more and average t was 0.5 and 1.4 minutes longer. (4) There was no significant difference between the medium- and high-intensity exercise groups in terms of VO2max. (5) The incidence of self-reported adverse responses to exercise such as dizziness, chest stuffiness and fatigue in the high-intensity exercise group increased significantly compared with the other 3 groups. Conclusions Exercise can gradually improve cardiorespiratory function in the sedentary elderly with heart disease. The effects of medium-intensity exercise are similar to those of high-intensity exercise, but medium intensity is safer. Key words: Taijiquan; Elderly; Coronary disease; Cardiorespiratory function; Exercise prescriptions