The work in the British Medical Journal (BMJ) looked at hundreds of trials involving nearly 340,000 patients to assess the merits of exercise and drugs in preventing death.
Physical activity rivaled some heart drugs and outperformed stroke medicine.
The findings suggest exercise should be added to prescriptions, say the researchers.
Experts stressed that patients should not ditch their drugs for exercise – rather, they should use both in tandem. Prescriptions rise
Too few adults currently get enough exercise. Only a third of people in England do the recommended 2.5 hours or more of moderate-intensity activity, such as cycling or fast walking, every week.
In contrast, prescription drug rates continue to rise.
There were an average of 17.7 prescriptions for every person in England in 2010, compared with 11.2 in 2000.
For the study, scientists based at the London School of Economics, Harvard Pilgrim Health Care Institute at Harvard Medical School and Stanford University School of Medicine trawled medical literature to find any research that compared exercise with pills as a therapy.
They identified 305 trials to include in their analysis. These trials looked at managing conditions such as existing heart disease, stroke rehabilitation, heart failure and pre-diabetes.
When they studied the data as a whole, they found exercise and drugs were comparable in terms of death rates.
But there were two exceptions.
Drugs called diuretics were the clear winner for heart failure patients, while exercise was best for stroke patients in terms of life expectancy.