Recuperation Aided by Placebo: How?

I just skimmed a long and detailed explanation of the biochemstry of reacting to beliefs about recovery caused by taking fake treatments. The claim is that when we’re seriously ill or injured, we’re either in a resting mode or a fight/flight mode. If we’re still fighting whatever injured us, our body doesn’t budget for healing; it suppresses the pain. If we accept that our role is to be laid up and cared for until we recover, then we budget for it (and feel psychologically unable to exert ourselves hard). A placebo treatment definitely makes it seem like our tribe expects us to rest and recuperate - that we’ll be protected, that it’s safe to make ourselves sluggish and disabled in a way that can’t be immediately reversed.

I’ve noticed the tension between fighting and recuperating, subjectively, in my mild soccer injuries. Initially, I’m not sure about the severity, but for a few seconds at least, I’m unwilling to move at all, until I can take stock. Later, if I decide to keep competing, it takes a while to overcome the resistance to voluntary movement that the pain signals gave me (I doubt my muscles are so functionally disabled by a kick in the shin). Of course, later, when the match is over, I feel more impaired than when I was fighting, and I doubt it’s only because of swelling setting in.

This hypothesis also explains why I’ve had extremely poor results whenever I lifted weights or otherwise exercised extremely hard when in the beginning or middle of a cold/fever, and perhaps how I’ve escaped full symptoms by allowing extra sleep when I feel tired after the scratchy-inflamed-throat beginnings of a cold.

I wish I knew when it was okay to treat symptoms directly (without that suppression of symptoms suppressing necessary responses to the underlying cause). For example, hospitals that medicate to lower fevers of under 104F kill more of their patients than they save.