Fig. 4. Ensemble averages of electromyographic (EMG) activity of the internal intercostal muscle. The patterns are similar for all dogs, indicating an expiratory function as well as a locomotor function. Samples are from four dogs (A—D), and the average across four dogs (E), with ventilatory (bold lines) and acceleration (thin lines) traces to reveal relationships to breath and stride (F). IF indicates ipsilateral forelimb support and CF contralateral forelimb support in the footfall bars at the bottom. All traces are on the same time scale. Exp., expiration; Insp., inspiration.