Zurich studies suggest muscle fatigue signals, like disordered pain signals, start in brain

Us ME/CFS sufferers love good science. Not the decide-the-results-beforehand type of science that seems to pervade the world of ME research in the west; no, we like the kind of real work-out-what’s-happening science that actually investigates what’s going on! We appreciate real science. Unfortunately, due to the rapid deteriation of our brains (like glasses in a coffee-shop in January, they fog up pretty fast), it’s hard to read scientific articles and take in what they are saying. So, as an aid to myself as much as anyone else, I want to `translate’ some papers/medical articles etc. into a semi-readable form. Here goes!

This is a less confusing version of http://www.prohealth.com/library/showarticle.cfm?libid=16687: Zurich studies suggest muscle fatigue signals, like disordered pain signals, start in brain

So: They break down the ability to use your muscles into 3 areas: how much you want to use them, how tired they actually are, and how tired your brain thinks they are. In the past they have just been looking at the actual fatigue of the muscle, and not what the brain thinks is going on – but this study looks at what the brain thinks is going on instead.

First study:
In order for your brain to control your muscles, it needs to send signals to them and also receive signals from them, so it knows what is going on. The first study they did showed that when your muscles get physically tired, they send signals to your brain to tell it this. These signals are telling your brain that it shouldn’t be doing so much work. They then anaethitised the spinal cord (ie: put it to sleep/massive painkillers), and found that this interrupted some of the signals; so your brain doesn’t realise how tired your muslces are getting when it’s under the effect of a strong pain-killer.

Second study:
They used super-fancy equipment to take photos of the brain (basically an MRI which shows what parts of the brain are active). They took the images of the brain when the body had been doing enough strenuous exercise that the brain was about to tell it to stop. The active areas at that point should be the parts that are going to tell it to stop. It turns out that these parts are quite `basic’ ones which analyse threatening situations.

Third study:
They looked at how much communication was going on between these parts of the brain to work out what parts control what’s going on. They discovered that one part (‘insular cortex’) gets a lot more active the more fatigue messages are sent from the muscles to the brain. It gets active by communicating with the part of the brain which controls movement of the muscles. So, this shows that the insular cortex is controlling (to some extent) whether the brain thinks you are too fatigued or not.

Overall results:
The brain has a huge influence on muscle fatigue, in that it has to deal with the signals coming from the muscles and whether the muscles are too fatigued to do more work. This will hopefully help them to discover two things: 1) new ways to improve performance of muscles and 2) why muscles are perceived to be so fatigued with certain illnesses, when they can’t find much physical reason for it.


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