The outer limits of Walk
The general gist of this thought was covered in video lectures. However, I think this is an interesting diagrammatic distillation of the matter. So, on the extreme light side, you'd be getting someone who's almost "skipping along": no shortage of energy to "pop" out of the contacts, something not much different from the motion of a bouncing ball. Then on the other extreme, the majority of the motion is the labour of heaving one's weight through the contact segment; doubtless mainly two-legged contact, with fast "ups" to quickly plant the feet for the next swing-through.
And right through the middle, a Sine-like curve for good ol' Vanilla.
If only everything were so simple as a diagram suggests. But I think it holds up, I quite like it.
(What flavors are the other two walks? Maybe "skippy" is strawberry, and "hefty" is chocolate?)