Twelve studies (n=295,177) met the inclusion criteria: one randomised controlled trial (RCT) and 11 prospective cohort studies. Sample sizes ranged from 196 to 73,743. Follow-up ranged from two to 16 years. There were 7,094 cases of coronary heart disease at follow-up.
Risk of developing coronary heart disease was reduced when walking intensity was increased by 8 MET per hour per week, equivalent to an increase of approximately 30 minutes of normal walking a day for five days a week (19%, 95% CI 14% to 23%, I2=37%; eight studies). Risk of developing coronary heart disease was also reduced when walking pace was increased by 2km per hour (21%, 95% CI 15% to 27%, I2=0%; eight studies) and when normal walking time was increased by 3.5 hours per week (32%, 95% CI 11% to 48%, I2=16%; eight studies).
There was no evidence of heterogeneity or publication bias (p=0.39) for any of these analyses. Results were similar for sensitivity and subgroup analyses.