Fig. 3. Mean normalized EMGs from six dogs trotting uphill and downhill on an incline of 14° to the horizontal (i.e. fore-aft force manipulation). For each muscle, the black line represents the average EMG when the dogs trotted on the level (control) and the grey line represents the average EMG when the dogs trotted on the incline. For each dog, the trotting speed was the same during the control and incline trials. The error bars are the s.e.m. for each sampling bin.