Now if you were on a bike, you could always figure out the truth – just stop pedaling and see if you slow down, coast along, or accelerate.

Digression – There are times I envy the cyclists passing me up as I run – how nice it must be to take a break now and then; set your tired legs in one spot and let yourself glide along, or keep on pedaling just enough to maintain your speed, breathing gently or chatting with a friend as the meters vanish almost by themselves.  But then I think of how hard it can be to get the body-machine back up to full power after a pause like that… As runners we have the burden of constant effort – there’s no coasting on feet – but that teaches us to seek out the ‘steady state,’ that level of exertion where inputs of nutrition and hydration are most nearly equal to the output of energy, so we can keep up that level of effort for quite a long time.   (Long is relative of course, at one stage in a runner’s development, ten or twenty minutes is a very long time; for others, it may be hours.  Whatever yardstick works for you, there is an immense satisfaction in looking back over a run and realizing, wow, I kept that up for that long? Hot Damn!).

And if that conditioning benefit isn’t enough to shoot down my cycle-envy, the hammer falls for sure as soon as I see a rider squatting on the shoulder repairing a flat, or when I hear a mountain-biker friend explaining over coffee that both of his (very expensive) bikes are out of service with mechanical problems, and he is looking to rent one for tomorrow’s ride.

But back to the issue – perception.  I’ve run plenty of events and training routes that start and finish at the same point and have established one firm conviction which flies in the face of Newton and Aristotle and everything we’re taught in science classes:  on any run that finishes at the same place it started – whether it’s an out-and-back, or a closed loop – there is always more uphill than downhill.

Maybe it has to do with the mechanics of converting the expansion and contraction of muscle fibers into a back and forth movement of the legs and arms, and then converting that into a solely-forward movement of the entire body – come to think of it, put that way, it’s no surprise that flat feels like uphill, heck it’s a bit of a miracle it works at all!

Then again, maybe some little gremlins have cranked up the jacks beneath the road, or moved the earth’s center of mass, just at the moment I switched directions…

Personally, I’ve given up trying to understand how this can be – and endeavor instead to take it as part of the challenge, the wonder, the endless variation and complexity of the world around us; up-hill feet and down-hill feet are not created equal.