"Swimming, walking or lifting weights in the gym 'treats high blood pressure as well as drugs'," reports the Mail Online.
High blood pressure (also called hypertension) is common among older people and can increase the risk of heart attacks and strokes. Many people take one or more medicines to keep blood pressure under control.
Researchers carried out a review of 391 studies and trials which had looked into the effects of either blood pressure medicines or exercise programmes on blood pressure. When they compared the effects of the 2 different interventions, they found exercise produced similar results to medicines for people with high blood pressure.
The study adds to evidence that exercise is a good way to keep blood pressure under control. However, the researchers found no studies that directly compared medicines with exercise programmes, meaning the results rely on indirect comparisons between groups of people that may have been quite different. This makes it harder to rely on the results.
As the Mail Online rightly points out, you should never stop taking a prescribed medicine for high blood pressure without first seeking advice from a health professional. But increasing your activity levels could help enhance the protective effects of any medication.
Find out more about recommended exercise levels for adults.
Where did the story come from?
The researchers who carried out the study were from the London School of Economics and Political Science, University of Bristol and University of Oxford in the UK, University of Bern in Switzerland, University of Pennsylvania and Stanford University School of Medicine in the US. The researchers had funding from the Higher Educational Funding Council for England, the Medical Research Council (UK) and the Swiss National Science Foundation.
The UK media's reporting of the study was reasonably accurate and balanced. Most reports included warnings from the researchers that people should not stop taking blood pressure medicines.
However, not all reports made it clear that the trials involving exercise were smaller, and often included people who did not have high blood pressure. Both these factors make the results less reliable.
What kind of research was this?
This was a network meta-analysis of randomised controlled trials (RCTs).
A meta-analysis pools results of trials, usually looking at the same intervention and outcome. A network meta-analysis is a way of comparing results of trials of different interventions, in this case exercise and medicines, when they have not been compared directly in trials.
What did the research involve?
Researchers searched for the most up to date meta-analyses of trials of blood pressure medicines, and of exercise programmes that measured effect on systolic blood pressure. (Systolic pressure is the pressure of blood as it is pumped out of the heart and through the blood vessels). They also looked for additional RCTs of exercise programmes, published since the most recent meta-analyses.
They didn't look for more recent RCTs of blood pressure medicines, as the meta-analyses were considered up to date and no new drugs had come onto the market since the meta-analyses were carried out, so it was unlikely there would be new evidence.
The researchers divided the medicines group into 5 types of drug: ACE inhibitors, angiotensin-2 receptor blockers, beta blockers, calcium channel blockers and diuretics, and into high or low doses.
They divided exercise into endurance (aerobic exercise such as walking, jogging and swimming), resistance (strength training such as using weights) or a combination of both. They also categorised exercise as high, moderate or low intensity.
For each study, the researchers looked at the difference between systolic blood pressure at the start and at the end of the study, for people who'd had the intervention (exercise or medicine) compared to the control group (no exercise or placebo). They used this figure to calculate the average change in blood pressure that could be attributed to the intervention.
They then compared the average change in blood pressure across the different groups (exercise, different types of exercise, medicines, different types of medicines).
Many people in the exercise studies did not have high blood pressure, or had only slightly raised blood pressure. All the people in the medicine studies had high blood pressure.
Because of this, the researchers looked separately at the effects of exercise on people with high blood pressure only (140mmHg or over).
What were the basic results?
The researchers included 197 studies looking at exercise (with 10,461 participants) and 194 studies looking at medicines (with 29,281 participants). None of the studies directly compared exercise with medicines. Only 56 of the exercise studies (with 3,508 participants) included people with high blood pressure.
Taking all the participants together:
- average drop in blood pressure attributable to exercise was -4.83mmHg (95% confidence interval (CI) -5.55 to -4.13)
- average drop in blood pressure attributable to drugs was -8.80mmHg (95% CI -9.58 to -8.02)
However, looking just at people with high blood pressure:
- average drop in blood pressure attributable to exercise was 8.96mmHg (95% CI -10.27 to -7.64 )
This indicated there was no difference in effectiveness of exercise and medicines in this group.
All types of exercise and all types of medication worked better than the control groups to lower blood pressure. Programmes which combined endurance and resistance exercise seemed to have the biggest effect.
Studies involving exercise were more likely to be subject to bias, however, because of a lack of blinding (people in the groups knew whether they were the exercise or control groups).
How did the researchers interpret the results?
The researchers said their study showed evidence of "modest but consistent reductions in systolic blood pressure across diverse populations and settings" which "appear similar to that of commonly used antihypertensive medications" among people with high blood pressure.
This summary of research adds to evidence that exercise can be a powerful tool to reduce and control blood pressure. It should encourage everyone to do enough physical activity to keep blood pressure at healthy levels.
The results do not mean, however, that people should ditch their blood pressure medication. Lowering blood pressure by exercise takes time and may require more sustained exercise than many people are used to. Anyone taking blood pressure medicines who wants to try to control blood pressure by exercise should talk to their GP first, so they can plan this properly.
The review has a number of limitations. Most importantly, the included studies don't compare exercise and medicines directly, which makes it hard to rely on the indirect comparison between the 2 interventions. Participants in the exercise and medicine studies were quite different from each other – for example, people in the medicine studies had higher blood pressure and were older – so we don't know how well the results translate from one group to another.
As the researchers point out, many people currently taking blood pressure medication are on several medicines and have a number of illnesses. This makes it hard to know what sort of exercise, what intensity and duration, they could routinely do to help control their blood pressure. The review also found problems of bias in many of the exercise studies.
None of the drawbacks detract from the conclusion that exercise helps to reduce blood pressure, and people should include physical activity in their daily routine.
Find out more about recommended exercise levels for adults.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Sun, 19 December 2018
Mail Online, 19 December 2018
ITV News, 19 December 2018
The Daily Telegraph, 18 December 2018
The Times (subscription required), 19 December 2018
Links to the science
British Journal of Sports Medicine. Published online December 18 2018