At four months , in the subgroup of participants with a baseline comfortable walking speed of > 0.4 m/s , treadmill training produced an extra distance of 72m ( 95 % CI 23 to 121 ) and an increased comfortable speed of 0.16 m/s ( 95 % CI 0.00 to 0.32 ) , compared with the subgroup with a speed of 0.4 m/s .