Walking endurance was measured using a 6-Minute Walk Distance. Participants were asked to walk back and forth on a measured path marked clearly at both ends for turning purposes, while being told when each minute has passed, and receiving verbal encouragement every 60 seconds. Total distance was measured in meters with higher distances equating to higher walking endurance. Each individual participant distance from Baseline was subtracted from Month 6 to represent change over the length of the study. Higher positive values represent more improvement in walking distance. In addition to the primary analysis (unadjusted baseline to 6 month comparison), statistical contracts were evaluated to determine if there was significant between-group differences in the change from baseline to 3 months and additional analysis of covariance were performed to adjust for baseline values and covariates that differed across groups at baseline.