STRESS, PHYSICAL-ACTIVITY AND CORONARY HEART-DISEASE

Recent years have witnessed an increasing popularity of corporate fitness programmes. Regular physical activity and, in particular, high aerobic fitness are associated with a lower risk of coronary heart disease. Apart from its beneficial effects on resting levels of blood pressure and cholesterol, fitness is believed to reduce the impact of psychological stress. This hypothesis has been put to the test in 33 studies examining the physiological stress response of groups selected to differ in their fitness level. Although some evidence was found for a reduced response to stress in high fit subjects, the effects were not very strong. During 54 confrontations with a stressful task, significantly lower heart rate reactions in high fit subjects were seen in only nine tasks (17%). With nine out of 36 stressors (28%), fit subjects showed a lower diastolic blood pressure response. However, in combination with a frequently found reduction in basal levels, the high fit showed a consistently favourable cardiovascular profile under stress. This adaptation may reflect the benefits of regular exercise over a more sedentary lifestyle, but a combined influence of genetic make-up on cardiovascular reactivity and fitness cannot be ruled out.