Compared to controls , participants randomized to the intervention increased their 6-minute walk distance from baseline to 12-month follow-up , ( from 355.4 to 381.9 m in the intervention versus 353.1 to 345.6 m in the control group ; mean difference = +34.1 m ; 95 % confidence interval [ CI ] = +14.6 , +53.5 ; P < 0.001 ) and their Walking Impairment Questionnaire ( WIQ ) speed score ( from 36.1 to 46.5 in the intervention group versus 34.9 to 36.5 in the control group ; mean difference = +8.8 ; 95 % CI = +1.6 , +16.1 ; P = 0.018 ) .