To review the evidence for the effect of exercise training on the lowering of blood-pressure, particularly in patients with hypertension.

Sources searched were not stated in the publication, although in a personal communication, the author stated that MEDLINE was searched, reference lists of papers and bibliographies were checked, and unpublished studies were identified through personal contacts and from presentations at international meetings. No search strategy was given.

Study designs of evaluations included in the review

Randomised controlled trials (RCTs) and controlled studies of physical training in which the actual blood-pressures for the training and control groups or periods, or the pressure changes, were reported.

Specific interventions included in the review

Physical training. The included studies mainly involved walking, jogging, running or cycling. The duration of training ranged from 4 to 68 weeks (median 16) with a frequency of 1 to 7 sessions per week (median 3). The average training intensity in the various groups ranged from 50 to 85% of maximum exercise capacity.

Participants included in the review

Normotensive and hypertensive people with no identifiable cardiovascular diseases. Most of the participants included in the studies were male, and of 16 to 72 years in age.

Outcomes assessed in the review

Systolic and diastolic blood-pressure, heart rate, weight and physical work capacity were assessed.

How were decisions on the relevance of primary studies made?

The author does not state how the papers were selected for the review, or how many of the reviewers performed the selection.

The author does not state that they assessed validity.

The author does not state how the data were extracted for the review, or how many of the reviewers performed the data extraction.

How were the studies combined?

The mean changes in systolic and diastolic blood-pressure, heart rate, weight and physical work capacity were adjusted for control group data and weighted for the number of trained participants. The weighted average of the adjusted means was calculated.

How were differences between studies investigated?

The impact of differences in the average pre-training blood-pressure levels was assessed by grouping the studies into three categories: normotensive, definite hypertensive and borderline. The response of blood-pressure to training was more pronounced among hypertensive participants.

Weighted, single regression analysis was used to investigate whether different effects might be associated with variations in participants' age, sex, race or changes in body weight. These demographic and anthropometric characteristics did not appear to have any effect.

Weighted, single regression analysis was used to investigate whether differences in the total duration of the training programme, and the intensity, duration and frequency of exercise might explain interstudy variation. None of these factors contributed significantly to interstudy variation.

Increases in exercise capacity and fitness were associated with greater decreases in diastolic blood-pressure. Studies in which allocation to experimental and control groups was randomised, and those in which the control groups were followed or contacted regularly, showed the smallest decrease in blood-pressure, i.e. greater scientific rigour was associated with smaller effect sizes.

There were 36 published papers, of which 21 were RCTs and 15 were controlled trials. A total of 48 training groups or programmes were available for analysis. The total number of participants was not stated and could not be ascertained from this paper.

Net weighted mean changes associated with exercise training were:

for systolic blood-pressure, -5.3 mmHg (95% confidence interval, CI: -7.2, -3.4);

diastolic blood-pressure, -4.7 mmHg (95% CI: -6.2, -3.4);

heart rate, -6.1 beats per minute (95% CI: -7.3, -4.8);

weight, -0.84 kg (95% CI: -1.16, -0.53); and

physical work capacity, +15.1% (95% CI: +13.4, +16.9).

Blood-pressure changes varied between studies and were greater in those with a higher initial blood-pressure. Blood-pressure change (systolic/diastolic) in normotensive people was -3/-3 mmHg, and in hypertensive people was -10/-8 mmHg. Greater blood pressure changes were also seen in studies in which participants demonstrated a larger gain in exercise capacity.

The findings on the relationship between fitness and blood-pressure led to a consensus statement by the World Hypertension League. This recommended dynamic exercise (e.g. walking, running, cycling, swimming, cross country ski-ing, callisthenics), at a frequency, duration and intensity tailored to the needs of the individual patient.

The search strategy and methods of execution of this review are unclear. Studies may have been missed and decision making may have been flawed. [A: Strict internal protocol was followed.]

The author also presents data relating to the impact of antihypertensive drugs on exercise capacity, but since the origins of this data are unclear it is not reported in this review. [A: more detailed information on the training studies can be found in the publications listed below.] Practical recommendations are made at the end of the paper. Not all of these are directly derived from the review findings: they represent the views of a consensus panel.

1. Fagard RH, Tipton CM. Physical activity, fitness and hypertension. In: Bouchard, editor. Physical activity, fitness and health consensus statement. Campaign (IL): Human Kinetics Publishers; 1994. p. 633-55.

2. Fagard RH, The role of exercise in blood pressure control: supportive evidence. J Hypertens 1995;13:1223-7.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.