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Fig. 3. Expanded and averaged recordings of muscle length, force and
electromyographic (EMG) activity from the lateral gastrocnemius (LG, above)
and digital flexor-4 (DF-IV, below), normalized to a single stride. The
support phase of the stride is shaded in gray. Results are shown for bird 4,
running at 1.3 m s-1 on the level (left), and at 16° incline
(right). The traces of force and length are means ± S.D.
obtained from 10 strides, and a single EMG trace is shown for reference. The
error bars below the EMG traces indicate the mean ± S.D. for
the timing of EMG activity (onset, offset).