Well, yes, stress can add to movement difficulties. That’s discussed in an interesting way in Interactions of Task Demands, Performance, and Neurology. But I doubt that’s what the machine was measuring.

Imagine, for a moment, that you are running a great distance. By the time you get to the finish, you find yourself sweating and gasping for air.

Imagine further, that someone notices this. They then say, “Oh, you could move much greater distances, I bet, if we found something to suppress your sweating and panting.”

This would sound ridiculous, and be very dangerous for your body. Not being able to sweat is serious: I had that problem on some medications, and it greatly reduced my tolerance for heat (lower than it was already) and exercise. Panting is an attempt to get more air into your body more quickly, and trying to run on less air would not be useful.

But nonetheless, we have situations where they say “Your brain functions certain ways when you are depressed. Therefore these brain functions cause depression!” We don’t even know whether it’s the chicken or the egg, but they think they have the answer.

For another example, I saw an autism “expert” at a time in my life when I alternated between superficially good speech and either inability to speak or really bad speech, usually several times a day by that point. She told me that if she reduced anxiety, then I would not need to use a keyboard. While she picked up the fact that I was really stressed out around speaking, she didn’t pick up the fact that it was the act of speech that stressed me out, and that had stressed me out for my entire life, because of how difficult it was. She didn’t realize that a lot of the stress she saw was an attempt to use sheer momentum to keep speech going (or that this was a reason I talked so much when I did talk — if I stopped, I wasn’t always able to start easily again). Nor did she realize that a keyboard reduced my stress levels immensely in its own right. She just saw two things she thought were associated with each other, defined the causality on her own, and insisted she knew what to do about it and what the results would be.

Reducing stress is usually a good thing in its own right. (I say “usually” because sometimes, stress is a motivator that is indispensable to some people when doing certain things: there are times when if I don’t get enough adrenaline going into doing something, I’m not going to be able to do it. But I have to pay a price for that and so do most people, I have just paid a more obvious price than most, because losing speech is a tad more conspicuous than losing the ability to run really far for awhile.) But my strong suspicion is that this measured stress, for me, is a consequence of the effort of trying to move, not the cause of the difficulty moving.

I wonder why people so often get causality backwards on these things, and then seek to alleviate the result of a problem rather than the cause of it.