How Muscle Fatigue Originates in the Head

[bananas]

http://www.sciencedaily.com/releases/2011/12/111205081643.htm

How Muscle Fatigue Originates in the Head

ScienceDaily (Dec. 5, 2011) — Researchers from the University of Zurich have now studied in detail what sportsmen and women know from experience: The head plays a key role in tiring endurance performances. They have discovered a mechanism in the brain that triggers a reduction in muscle performance during tiring activities and ensures that one's own physiological limits are not exceeded. For the first time, the study demonstrates empirically that muscle fatigue and changes in the interaction between neuronal structures are linked.

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[Javaman]

1. Radiolab did a great story on this a while back...

the summation was that the body holds about 10% of a persons total energy ability in reserve. That's why we always here about these incredible athletes about to "dig down deep" for that extra humph to win.

In reality they are tapping into that 10%.

It's really fascinating stuff.

[bananas]

2. Is this the episode?

http://www.runblogger.com/2010/05/radiolab-limits-fantastic-podcast.html

"Jad and Robert talk to two Ironman competitors, Julie Moss and Wendy Ingraham to find out how they do what they do. Physiologist Dr. David Jones tells us how to trick the voice in your head that tells you you're exhausted. Then we follow two men, Patrick Autissier and Jure Robic, as they bike across the country as fast as they can in a crazy race called The Ride Across America. Producer Lulu Miller brings us their story and New York Times writer Daniel Coyle walks us through the process of physical and mental breakdown RAAM competitors face."

[Javaman]

3. Maybe, it was on about 3 or 4 months ago and featured a world class woman

triathlete.

[TheMadMonk]

6. And sometimes send themselves into total muscular meltdown.

Learning to overide our "natural limits" at will, as opposed to dire need, is the reason why a country footballer can play well into his fifties, whilst someone competing on the national stage is all too often a broken wreck by his early thirties.

There is nothing laudible in a 9 second 100m dash for a ribbon, chunk of metal or wad of cash. There is, in knocking a kid from in front of a car, without ever knowing how the fuck you did it.

But yet the first is a 100m dollar advertising cashcow. The second a 5 minute wonder.

[Ready4Change]

4. Sounds like they are seeing feedback mechanisms?

Brains tells muscles to move, muscles report they are moving, brain sees the report and decides muscles are getting tired. Question is: Are the muscles actually reaching the point of tiredness yet? What is their level of reserves? Can you push further, or are you about to start damaging yourself?

Sounds to me very much like strategies for managing an electric vehicles batteries. Those can handle discharging a small amount (10-30%) very easily. But they can be damaged if drained deeply (90%+). So, does a cars control system shut it down before it reaches deep discharge levels?

Am I gathering correctly from the linked story that muscles just report "I'm working" and leave it up to the brain to determine reserves?

[ProfessorGAC]

5. You May Be Onto Something

As an MS patient, i've looked into these sort of things. There is a proposed mechanism for people with the cerebellar form of MS (like me) who get pain and fatigue in the legs, even though there is no physiological dysfunction in the legs.

What they propose is that since the lesions in the brain can form in the pain centers near the brain stem, the brain TELLS the legs they hurt and the system reacts by "protecting" the muscles by tightening up. There is limited proof of this, but the statistics indicate that they may be right. About 80% of cerebellar MS patients experience pain or burning in the leg that also involve cramping and heaviness that feel very much like one has just run 10 miles or something. Very few of such people have any actual physiological dysfunction. I'm in that group.

My legs wear down too easily for someone my age, especially since i only weigh 150 pounds. That's only 12 pounds more than when i graduated from college in 1976. So, i'm not carrying a lot of extra weight, and i'm pretty active, yet there are times i walk 400 yards, and feel like i won't make it back home. Yet, i always CAN make it home. Just very heavy-legged and worn down.

There are times my legs feel like a couple of 200 pound bags of wet sand. But, there is nothing actually wrong with my legs.

This is an important finding to me personally. May lead to a better understanding of the mechanism.