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Fig. 2. Mean normalized EMGs from six dogs trotting with 12% of body mass carried
in a backpack located over their pectoral girdle (i.e. anterior-trunk loading
manipulation). For each muscle, the black line represents the average EMG when
the dogs trotted on the level without added mass (control) and the grey line
represents the average EMG when the dogs carried the added mass. For each dog,
the trotting speed was the same during the control and added mass trials. The
error bars are the s.e.m. for each sampling bin.