Including EMG signals and historical information in the real-time control system resulted in significantly lower classification error ( mean , 7.9 % [ 95 % CI , 6.1 % -9.7 % ] ) across a mean of 683 steps ( range , 640-756 steps ) compared with using mechanical sensor data only ( mean , 14.1 % [ 95 % CI , 9.3 % -18.9 % ] ) across a mean of 692 steps ( range , 631-775 steps ) , with a mean difference between groups of 6.2 % ( 95 % CI , 2.7 % -9.7 % ] ( P = .01 ) .