Fig. 4. Mean values (± S.E.M.) of kinematic and electromyographic (EMG) duty factors (A), maximum (L_max) and (L_min) minimum muscle strain (B), net muscle strain (L_net) (C) and average muscle shortening velocity (D) versus speed. All values of strain are given as a percentage of resting muscle length (L₀). Mean values were calculated for the total number of strides pooled across three (A) or four (B–D) individuals. W/R, walk–run transition; L, resting length of the caudofemoralis muscle.