John Cleese’s classic “silly walk” burns more calories than a normal gait

Efficiency seems like a bad target, I'd rather aim for minimum damage.

Food is cheap, we've got fridges and don't need to store much of our own energy as fat, and many of us no longer do enough physical labor to experience significant fatigue.

Plus, athletic performance is no longer a matter of everyday practicality.

The biggest concerns, as I see it, become whatever mechanism causes health issues from being sedentary, and damage to joints by wear and tear.

It's interesting to think if what tradeoff walking in the current normal natural gain has, and what possibilities there are now that most of us don't need efficiency.

Most exercise programs and movement training skills talk about efficiency and performance, what would an exercise program look like that was entirely optimized for preventing disease and injury rather than maximizing capability look like?

If tennis is said to be the best sport for lifespan, can we design a new sport with new equipment that shares as many of the properties as possible with less impact injuries?

In the extreme case, maybe you could even have a sport where you wear some kind of damping brace that prevents certain unsafe movements, so that there is no advantage for the team willing to do them, or just with rules that heavily favor the healthiest movements.