Previous meta-analyses of randomized controlled trials on the effects of chronic dynamic aerobic endurance training on blood pressure reported on resting blood pressure only. Our aim was to perform a comprehensive meta-analysis including resting and ambulatory blood pressure, blood pressure-regulating mechanisms, and concomitant cardiovascular risk factors. Inclusion criteria of studies were: random allocation to intervention and control; endurance training as the sole intervention; inclusion of healthy sedentary normotensive or hypertensive adults; intervention duration of > or =4 weeks; availability of systolic or diastolic blood pressure; and publication in a peer-reviewed journal up to December 2003. The meta-analysis involved 72 trials, 105 study groups, and 3936 participants. After weighting for the number of trained participants and using a random-effects model, training induced significant net reductions of resting and daytime ambulatory blood pressure of, respectively, 3.0/2.4 mm Hg (P<0.001) and 3.3/3.5 mm Hg (P<0.01). The reduction of resting blood pressure was more pronounced in the 30 hypertensive study groups (-6.9/-4.9) than in the others (-1.9/-1.6; P<0.001 for all). Systemic vascular resistance decreased by 7.1% (P<0.05), plasma norepinephrine by 29% (P<0.001), and plasma renin activity by 20% (P<0.05). Body weight decreased by 1.2 kg (P<0.001), waist circumference by 2.8 cm (P<0.001), percent body fat by 1.4% (P<0.001), and the homeostasis model assessment index of insulin resistance by 0.31 U (P<0.01); HDL cholesterol increased by 0.032 mmol/L(-1) (P<0.05). In conclusion, aerobic endurance training decreases blood pressure through a reduction of vascular resistance, in which the sympathetic nervous system and the renin-angiotensin system appear to be involved, and favorably affects concomitant cardiovascular risk factors.