Mediation analysis suggested that dog walking partially mediated the association between exposure to greenspace and change in physical activity (Table 5). For overall physical activity, 22.6% of the total effect is mediated, accounting for baseline activity, age, sex, BMI, social class and marital status. The mediated percentage increased to 28.1% for recreational physical activity and 50.0% for outdoor physical activity.Table 5Total, direct, and indirect effect, via the mediator of dog walking, of exposure to green space on change in physical activity.Table 5.95% CIEffect (on PA change) Ref=least green quartileCoef.LowerUpperSt. errorPOverall physical activity (n=10573)aTotal effect8.331.9014.773.280.011Direct effect6.450.0112.893.280.050Indirect effect (through dog walking)1.881.252.780.35<0.001 Recreational physical activity (n=10446)bTotal effect6.202.0610.342.110.003Direct effect4.460.338.582.110.034Indirect effect (through dog walking)1.741.222.350.27<0.001 Outdoor physical activity (n=10616)cTotal effect4.161.087.241.570.008Direct effect2.08-0.975.140.280.182Indirect effect (through dog walking)2.081.502.740.28<0.001Least green quartile versus all other quartiles of home neighbourhoods. Coefficients with 95% confidence intervals (bias corrected for indirect effects) and significance values (P). All models are adjusted for baseline physical activity, age, sex, BMI, social class and marital status.aPercent mediated 22.6%.bPercent mediated 28.1%.cPercent mediated 50.0%.