Let's say you are already walking at a maximally efficient combination of pace and stride (or $\omega$ and $X_0$ I guess) but you need to reach your destination faster. Should you increase/decrease your pace and/or stride to achieve this goal (assuming that any adjustment will result in a net increase in speed)? How can I interpret this question as a question about kinetic energy of oscillators?
I have tried solving the equation $KE'=0$ to find a minimum $KE$ but this seems like the wrong approach, for all that seems to tell me is the if you do not walk (ie $w$ or $X_0$ is $0$) then yes, of course you have kept your kinetic energy at a minimum. Where does this idea about "efficiency" come into play?
Edit: Pace is the frequency of steps, stride is the length of steps, and average speed is the product of pace and stride.