Exercise may be just as effective as drugs at treating common diseases, according to a new study.
The research, on more than 339,000 people, found being active was just as good as medicine for those with existing heart disease and in the prevention of diabetes.
It also appeared to be a more effective treatment than drugs for people who had a stroke.
Experts at the London School of Economics, Harvard Medical School and Stanford University School of Medicine in the United States examined the findings of 305 trials on four conditions: pre-diabetes, heart disease, stroke and heart failure.
Of the studies, 57 looked specifically at the effect of exercise and included 14,716 people.
More than 200 trials examined drug treatment for the conditions, such as the effects of statins, beta blockers and antiplatelet therapy on preventing significant illness in those with heart disease.
The results showed that exercise was just as effective as drugs in treating people with heart disease and whose blood sugar control suggested they were at high risk of diabetes.
The results on heart failure were more unclear, with diuretic drugs being found to be more effective than exercise and all other types of drug treatment.
The findings were most impressive for stroke, with exercise found to be more beneficial than drug treatment.
Writing online in the 'British Medical Journal' (BMJ), the team concluded: "Our analysis suggests that exercise potentially had similar effectiveness to drug interventions with two exceptions.
"In the case of stroke rehabilitation, exercise seemed to be more effective than drug interventions."