Walking Reduces Hypertension Risk in Men

Moderate exercise, such as walking, is a recommended part of the treatment for hypertension, but does it reduce the risk for hypertension?

We know from previous Bandolier reports that walking, or other moderate exercise, reduces the risk of heart disease and other causes of death (Bandolier 50 and 68 ). Can we add the prevention of hypertension as another reason to take just a little exercise?

Message

This study showed that regular exercise can prevent hypertension in men. And just as importantly it showed that the exercise doesn't have to be every day, once a week is just as beneficial. This is an important message since many people believe that exercise has to be taken several times a week to be of any benefit and because the commitment is too great, do none. Once a week is less formidable, more achievable and equally beneficial.

Study

As part of the Osaka Health Survey, this study looked at the association of physical activity (duration of the walk to work and leisure time exercise) with the risk of hypertension between 1981-1997. Taking part were a group of 6,017 Japanese men, with sedentary occupations, aged between 35-60 years, with systolic blood pressure less than 140 mmHg, diastolic blood pressure less than 90 mmHg, normal glucose levels and no history of hypertension or diabetes at the start of the study. They were followed for 16 years.

Every two years, nurses carried out thorough clinical examinations (including blood pressure, fasting plasma glucose levels, body mass index). Hypertension was diagnosed by physicians using the criteria of systolic blood pressure > or equal to 160 mmHg, diastolic blood pressure > or equal to 95 mmHg, or both, or use of anti-hypertensive medication. Detailed questions were also asked concerning health behaviours (eg. exercise, smoking, alcohol consumption), leisure time exercise (exercising long enough to sweat, for 30 minutes or more) and duration of the walk to work. Exercise was classified in two ways: (i) broadly into less than once a week and at least once a week; (ii) more sensitively into less than once a week, once a week, and twice or more a week.

Results

Out of 6,017 men, 626 men developed hypertension. Adjustments were made for age, body mass index, alcohol consumption, smoking status, leisure-time exercise (or duration of the walk to work), blood pressure and fasting plasma glucose level.

Duration of Walking

Risk for hypertension decreased as the duration of the walk to work increased (Figure 1). Men whose walk lasted 20 minutes or more reduced their risk by 29% (relative risk 0.71, 95% confidence interval 0.52 to 0.97) compared with men whose walk lasted 10 minutes or less. Increasing the walk by just 10 minutes reduced the risk for hypertension by 12% (relative risk 0.88, 95% confidence interval 0.79 to 0.98).

Taking the results of 4,410 men over 10 years (with 375 cases of hypertension) it was calculated that for every 26 men who walk 20 minutes or more (compared with those walking 10 minutes or less), one case of hypertension will be prevented. For men who walked 11-20 minutes the number needed to walk increased to 111 (compared with men walking 10 minutes or less).

Exercise Less than Once Weekly versus Once Weekly

Men who exercised at least once a week reduced their risk by 30% compared with men who exercised less than once a week (relative risk 0.70, 95% confidence interval 0.59 to 0.84).

The comparison was also made after 4 years since the men's leisure time exercise could change over the study (16 years). After 4 years the men who exercised at least once a week reduced their risk by 39% compared with those who exercised less than once a week (relative risk 0.61, 95% confidence interval 0.47 to 0.80).

Exercise Less than Once Weekly, Once Weekly, Twice or More Weekly

In this case more is not necessarily better (Figure 2). Men reduced their risk by 35% when they exercised once a week and by 28% when they exercised at least twice a week, compared with men exercising less than once a week (relative risk 0.65, 95% confidence interval 0.47 to 0.90 and relative risk 0.72, 95% confidence interval 0.59 to 0.88, respectively).

Comment

This large, long term study gives us another good reason to walk or take moderate amounts of regular exercise. A daily walk lasting 20 minutes or more significantly reduces the risk of hypertension in men. For every 26 men who walk 20 minutes or more, one case of hypertension will be prevented. Alternatively, as little as 30 minutes vigorous exercise just once a week will also significantly reduce the risk. Furthermore, a key message from this study is that exercising more than once a week will not necessarily reduce the risk any further.

The reason why the duration of the walk reduced the risk for hypertension was not identified, but it was not the case that participants with a longer walk to work had more active lifestyles (only 33% of men with the longest walk exercised at least once a week and adjustments were made for leisure-time exercise in the analyses).

Reference

T Hayashi et al. Walking to work and the risk for hypertension in men: The Osaka Health Survey. Annals of Internal Medicine1999 131: 21-26.