(A) Representative rectified and high pass filtered (>2Hz) EMG traces for extensors and flexors of each limb are shown during a treadmill trial, where MLR stimulation is applied at 20Hz, 30Hz, 40Hz, and 50Hz successively. (B) Traces showing stepping frequency and locomotor speed over time. (C) Relationship between stimulation frequency and stepping frequency. (D) Relationship between stimulation frequency and maximum locomotor speed. R: right, L: left, Tri: triceps, Brach: brachialis, TA: tibialis anterior, LG: lateral gastrocnemius, FL: forelimb, HL: hindlimb. A,B: modified with permission from Noga et al. [18].