Determinants of change in blood pressure during S.W.E.A.T.: the sedentary women exercise adherence trial

1. In a long-term study of the optimal approach to initiating and maintaining a regular exercise programme in previously sedentary older women (40-65 years), we have assessed determinants of change in resting blood pressure (BP) after 6 and 12 months. 2. Women (n = 126) were randomly assigned to either a centre-based or home-based exercise programme for an initial 6 months. The centre-based group attended supervised sessions three times per week, while the home-based group exercised unsupervised at home three times per week. Both groups were home-based during a second 6 months. Within each arm, subjects were further randomized to either exercise at moderate intensity (40-55% heart rate reserve; HRres) or at vigorous intensity (65-80% HRres). A nonintervention comparison group of 30 women was followed throughout. 3. At 6 months there was a fall in BP with moderate, but not vigorous intensity exercise (-2.7 mmHg; P = 0.025), an effect no longer significant at 12 months. 4. Change in BP was unrelated to improvements in fitness (VO2max), increases in lean tissue mass, number of exercise sessions completed or a composite measure of the total number of exercise sessions completed multiplied by the mean exercise intensity expressed as a percentage of heart rate reserve (%HRres). 5. Continuing participation in any regular exercise was a consistent predictor of change in BP, with those subjects still exercising in the 2 weeks before BP measurement having 1.9 mmHg lower BP at 6 months (P = 0.038) and 3.8 mmHg lower BP at 12 months (P = 0.016). 6. We conclude that the small effects of exercise on resting BP in these older women are predominantly related to continuing participation in lower intensity exercise, rather than to improvements in fitness or body composition.