People who are prescribed physical exercise in primary care settings increase their levels of moderate to vigorous intensity activity by an average of 14 minutes a week, according to a new study.

A study published in The BMJ find in most countries physical activity programmes have been ineffective. Overall, one in four adults do not do enough physical exercise and there has been no improvement in participation rates over the past two decades. Previous studies of physical activity interventions delivered in primary care have reported mixed results and few have investigated their effect on increasing moderate to vigorous intensity physical activity (MVPA). The new study finds, however, that improvements can be delivered through primary care.

A team of UK researchers, led by Professor Amanda Daley, professor of behavioural medicine at Loughborough University, reviewed 51 trials involving more than 16,000 adults, comparing aerobic-based physical activity interventions delivered in primary care with usual care controls. MVPA was measured using self-report in 37 trials and using a device in 14 trials, while the length of trial follow-up ranged from one month to five years.

Overall, the researchers found that participants in the intervention groups increased MVPA by 14 minutes a week on average compared to controls and were also more likely than controls to meet guideline MVPA targets. Trials that measured physical activity with devices found no significant difference in MVPA between groups, while trials relying on self-reported activity showed an increase of 24 minutes a week in intervention groups.

Interventions involving five or more contacts with health professionals, longer follow-up, or those delivered by primary care plus other professionals, were associated with greater improvements. In trials that measured weight, intervention participants weighed 1kg less than controls at follow-up. Although the researchers point to some limitations, such as differences in the design and quality of the included trials, they say these were adjusted for in the analyses.

They write: “Physical activity interventions delivered by health professionals in primary care settings appear effective in increasing participation in physical activity as measured by self-report and reducing weight in adults. These data could help health professionals, policy makers, and healthcare commissioners make evidence based decisions about implementing physical activity interventions during consultations delivered in primary care.”