Rapid onset and offset of circulatory adaptations to exercise training in men

Abstract

Chronic aerobic exercise lowers blood pressure (BP), peripheral resistance and cardiac work, and is used widely in antihypertensive and cardiac rehabilitation programmes. In this study, we tested the hypothesis that the cardiovascular benefits of training would occur progressively over several weeks and would diminish over a similar time course on termination of training. In all, 17 young, healthy men undertook a 4-week programme of cycle ergometry (30 min at 60% VO_2peak 3–4 times/week) and 13 subjects matched for age, body mass index and fitness acted as controls. Resting BP and rate-pressure product (RPP) had fallen significantly after only 1 week's training and reached a nadir after 2 weeks training. At this time, BP had fallen from 121±7/66±6 to 110±5/57±7 mmHg and resting RPP had fallen from 85±10 to 71±9 (mmHg (beats min⁻¹))⁻² (P<0.001 each). In parallel, resting forearm conductance had risen from 0.026±0.010 to 0.052±0.029 (ml min⁻¹) 100 ml⁻¹ mmHg⁻¹ and peak reactive hyperaemia following 3 min brachial artery occlusion was increased from 0.105±0.031 to 0.209±0.041 (ml min⁻¹) 100 ml⁻¹ mmHg⁻¹ (P<0.001 each). No significant further circulatory changes occurred over weeks 3–4 of training. On cessation of training, all values returned to pretraining levels within between 1 (SBP, RPP, vascular conductance) and 2 (DBP, MAP, heart rate, reactive hyperaemia) weeks. The results indicate that the optimal cardiovascular benefits of moderate exercise occur rapidly. At least with short training programmes, the benefits regress once training stops just as quickly as they appeared.