Figure 8.

Incidence of features in the signatures. Incidence of muscles in the muscle activation signatures from all participants over the pedalling (a) and walking (b) cycle. Each colour represents a muscle, as shown on the right of (a). The colour gradient represents the incidence of participants having that specific muscle as part of their signature at that point of the cycle, with lighter colours representing fewer participants and darker colours representing more participants. The maximal incidence (darkest colour, i.e. the colour used in the muscle legend) is set at N = 15. The figure provides a graphical overview of all the signatures from the testing group (baseline, day 1; N = 78) and highlights which phase of the cycles the muscles were part of the signatures of the tested participants. Areas coloured white indicate that no single participant had the specific muscle as part of their signature during that specific phase of the cycle. For pedalling, the figure shows that the timing of the signature features relative to the pedalling cycle varied significantly between muscles. For example, some muscles, such as VM and VL, were part of the signature only between the end of the upstroke and just past halfway through the downstroke, with the majority of incidence occurring during the first and final sections of this phase, as seen by the darker colours. Other muscles, such as RF or BF, were part of the signatures for a longer section of the cycle, starting halfway through the first part of the upstroke until the second part of the downstroke. This indicates that the variation in the phase of the cycle during which unique features occurred for this dataset varied more in RF and BF. For gait, the data are more spread out over all muscles except for SOL and TA, with no participants having unique features in their signature during the swing phase for SOL and no participants for TA during roughly 25–75% of the stance phase.