Fig. 8. Principal component loading scores for PCI and PCII from the plantaris (green), soleus (red) and medial gastrocnemius (blue) muscles during each locomotor condition. Each point shows the mean ± s.e.m. pooled from each muscle from six subjects. There are 20 points on each graph, which represent the 20 time windows within each stride. ^*Time points corresponding to 0% stride duration; ^time points corresponding to 100% stride duration. Points for the soleus and plantaris always track in a clockwise direction, whereas points for the medial gastrocnemius follow an anti-clockwise loop, except during the incline conditions 20° and 25° where a figure-of-eight configuration occurs. PCI loading score values are indicators of the level of muscle activity, with higher values indicating a greater level of activity. A scale bar is shown on the right.