Background: 

Guidelines of the European Society of Cardiology advise physical activity as a first line treatment regime for hypertensives. The aim of this recommendation is to reduce blood pressure, to reduce the dosis of anti-hypertensive drugs, and to reduce other risk factors. In the development of pharmacological treatment protocols data are used from a plenty of animal experiments supporting the concept of drug treatment. However, in case of the effect of physical activity on hypertensives there are only few data available with small number of animals. Unfortunately, such studies do not result in a clear picture.

The aim of this study is to use a meta-analysis of animal experiments published already to decide whether general aspects of the effect of physical activity of hypertensives can be drawn from animal experiments.

Methods: 

Using a Med-Line Analysis 19 studies were identified from 2002–2008 in that exercise effects on spontaneously hypertensive rats (SHR) were investigated.

Results: 

214 trained versus non-trained SHR were analyzed in total. In 16 out of 19 studies a moderate exercise protocol was used (treadmill). In 2 studies the animals had free access to running wheels. In one study rats were exposed to swim training. The mean age of the animals under investigation was 4.4 months (1–16 months) at the start of the exercise program. The mean exercise duration was 5 months (1.5–16 months). Although expected otherwise a clear reduction of blood pressure was not obviously (-11.221.5%, n.s. from 194 to 184 mmHg). Such an effect was only being seen in rats which started to be trained before the onset of hypertension or in the very early period of hypertension. In none of the study groups that were exposed to exercise at a stage of advanced hypertension such a reduction was observed. In all studies, however, a reduction of resting heart rate was observed (-35.913.9%, p<0.001) from 442 to 406 bpm. In two studies with old SHR (15–16 months) an improved survival was observed in one group with a moderate exercise program but not in a group with free excess to running wheels. In the latter group a significant increase in myocardial hypertrophy was observed.

Conclusion: 

Based on animal studies a reduction in blood pressure cannot be expected. However, an uncontrolled exercise activity of hypertensives leads to an augmentation of myocardial hypertrophy and an increase in risk. Therefore, there are no experimental findings that support a general recommendation of physical activity to hypertensives.