Fig. 7. Patterns of strain in the biceps (A) and vastus (C) during walking, trotting and galloping from three strides to show characteristic length-change trajectories during different gaits. Idealized strain trajectories are shown for the biceps (B) and vastus (D). In the biceps, strain trajectories can be divided into three discrete phases; in the vastus, four discrete phases are defined (described in more detail in the text). Dark gray shading represents the stance phase; light gray shading represents the swing phase.