Notice the differences in running (top) vs sprinting (bottom) activation patterns?
This picture (along with the MIchaud muscular firing pattern ones) are becoming some of my favorite ones to talk about. I just stare at them and look for differences and similarities.
Check out that the abs do not seem to fire in running (in this study at least), but do in sprinting. Note also that most muscles fire longer (and we wil assume harder) during sprinting. Also check out the peroneals, which fire just as the foot touches down in sprinting, probably to make up for the instrinsics not firing, and assist in creating a rigid lever for push off.
from: Mann et al 1986