A meta-analysis 1 http://hyper.ahajournals.org/cgi/content/full/46/4/667 involved randomized controlled trials studying endurance-type training and designed to increase endurance performance. The study populations had to consist of normotensive or hypertensive adults who were otherwise healthy (antihypertensive medication was allowed). The duration of training had to be at least 4 weeks. After a systematic literature search, 72 trials comprising 105 study groups and 3936 participants were included in the meta-analysis. The quality of the included studies was not assessed.
Study duration varied from 4 to 52 weeks (median 16). Training frequency ranged from 1 to 7 days per week (median 3). Intensity was between 30% and 87.5% of heart rate reserve (Hrres; median 65). Each training session lasted from 15 to 63 minutes (median 40). Training involved mainly walking, jogging, running, or cycling. Median age of the participants was 47 years, baseline weight approximately 76 kg and body mass index approximately 26. In the groups including hypertensives, the average age and body weight was somewhat higher than in other groups.
Baseline resting blood pressure was 128/82 mmHg (median). The overall weighted net effect on systolic blood pressure was -3.0 mmHg (95% confidence interval [CI] -4.0 to -2.0) and on diastolic blood pressure -2.4 mmHg (95% CI -3.1 to -1.7). This net difference was calculated by subtracting the change in the mean blood pressure in the control groups (no training) during the intervention from the respective change in the training groups and weighting the result by the number of participants in each group.
The net change in blood pressure was -2.4/-1.6 mmHg in normotensives (n=599) and -1.7/-1.7 mmHg in prehypertensives (with blood pressure values around the upper limit of the normal range; n=1087). In hypertensives (n=492), the net change was greater than in the other two groups (-6.9/-4.9 mmHg). All these net changes were calculated by weighting the result from each trial by the number of participants in the training group.
Weight reduction was 1.2 kg (95% CI -1.5 to -0.9) and reduction in body fat (measured in different ways) was 1.4 percentage units (95% CI -1.8 to -1.0) greater in the training groups as compared to the controls. Maximal oxygen uptake (VO2max, determined with different methods) increased 4.0 ml/min/kg (95% CI 3.5 to 4.5) more in the training groups as compared to the controls. The effect of factors associated with the training or of other factors (e.g. age, body composition) on the change in the blood pressure was analyzed with metaregression. The only (positive) association was found between the change in VO2max and the blood pressure change.
Comment: In conclusion, the effect of training on resting blood pressure appeared to be greater in hypertensives than in normotensives. The meta-analysis also considered the effects of training on the changes in blood lipids and in glucose-insulin-metabolism. In addition, the haemodynamic and hormonal factors were considered, which may explain changes in the blood pressures.
A meta-analysis 1 included 29 randomized, controlled studies from the years 1980-95 (altogether 1 533 subjects). Approximately one third of the subjects had elevated blood pressure (no medication). 1 031 persons were randomised to training groups and 839 served as non-training controls. Three studies used muscle resistance training at a gym, while in other studies the exercise was endurance training (in most cases combinations of various forms of exercise). Five studies had a cross-over design while others had a parallel group design. Three studies used ambulatory blood pressure measurement while other studies used auscultatory BP measurement.
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