Fig. 5. Ensemble averages of electromyographic (EMG) activity of the parasternal portion of the internal intercostal muscle. The bursting pattern is consistent in uncoupled breath averages, indicating a clear inspiratory function for this muscle. The bursting is much more variable in uncoupled stride averages and almost undetectable in the average across all dogs (E), indicating a variable or sporadic locomotor function that may be different in each dog. 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.