Perception of effort, not muscle fatigue, limits endurance performance

Mar 19, 2010

(PhysOrg.com) -- The physiological theory that underpins all endurance training and coaching for the last 100 years has just been disproved.

As recently as 2008, scientific research papers were citing the theory that endurance performance is limited by the capacity of the skeletal muscles, heart and lungs and that exhaustion occurs when the active muscles are unable to produce the force or power required by prolonged exercise.

Dr Sam Marcora, an exercise physiologist at Bangor University, has now disproved this for the first time and proposed an alternative - that it is your of effort that limits your endurance performance, not the actual capability of your muscles. He showed that the muscles were still able to achieve the power output required by endurance exercise even when the point of perceived exhaustion had been reached.

This will inevitably lead to new training and coaching techniques, based on this new understanding of the role of perceived effort in endurance performance.

What Marcora has found is that athletes give up endurance exercise, feeling that they are , before reaching their absolute physiological limit. In fact, immediately after exhaustion, the leg muscles are capable of producing three times the power output required by high-intensity cycling exercise.

Like other , perception of effort is a powerful feeling that is there for a reason. The perception that we have reached exhaustion prevents us from injuring ourselves by exercising too much. Marcora uses the analogy of pain- if you twist your ankle you might still be able to undertake the mechanics of walking, but the pain prevents you- and so prevents you from causing further injury- so it is with perceived exhaustion, he argues.

The question for sports scientists, coaches and athletes has to be how far can athletes go beyond that perceived exhaustion to improve performance still further?

"We are already developing and testing new training techniques based on the neurobiology of perceived effort that will help endurance athletes improve their performance," says Marcora.

The original theory led to the development of countless training developments, such as heart rate monitors, eating carbohydrates to replenish glycogen in the tired muscles and even blood doping, so that the haemoglobin carries more oxygen to the active muscles.

"These techniques have been proved to be effective- and are still effective," says Sam Marcora, "but we now have a new theoretical model of endurance performance and this in turn will lead to further techniques and coaching strategies to help endurance athletes to improve their performance."

Explore further: Experts call for higher exam pass marks to close performance gap between international and UK medical graduates

More information: The limit to exercise tolerance in humans: mind over muscle? Samuele Maria Marcora, Walter Staiano, European Journal of Applied Physiology, DOI:10.1007/s00421-010-1418-6 published online March 11 2010.

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User comments : 12

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ISEEE
1 / 5 (4) Mar 19, 2010
Have you ever noticed on the cop chase shows that a person gets super tired with a short run. There is more fatigue in someone who is being chased than the person doing the chasing. This explains why people get caught in the horror movies and basically jog away from the chaser. This new theory may allow people to outrun police dogs
fourthrocker
4.6 / 5 (5) Mar 19, 2010
I guess the people doing this study never went to boot camp or watched a strength trainer. Both seem to be aware of this principle...GIMME TEN MORE MAGGOT
Squirrel
3.8 / 5 (5) Mar 19, 2010
This idea is hardly new. The Nobel Prize winner Archibald Hill proposed the idea of a central control over endurance in 1924. More recently the idea was proposed by Tim Noakes in 1997 in terms of a "central governor". The Wikipedia article "central governor" provides a good introduction.
Digi
5 / 5 (5) Mar 19, 2010
Next time I am at the gym I will take solace that I have as much endurance as the next guy.. its just my super heightened perception of effort dragging me down...
googleplex
4.8 / 5 (4) Mar 19, 2010
I agree that this is common sense.
The point is that the pain is there for a reason. I am sure some damage is done to the cells if you enter into physiological exhaustion (as opposed to perceived exhaustion).
Personally, if I extremely over exert (sprint up a mountain) then I can hear my heart rate in my ear. I know that I can push it further but At this point I ease off. My reasoning is that I am close to a point where I could do damage from execessive blood pressure/heart rate. Not sure if others experience this and if my arbitrary reasoning is sound?
MorituriMax
1 / 5 (1) Mar 19, 2010
"What Marcora has found is that athletes give up endurance exercise, feeling that they are exhausted, before reaching their absolute physiological limit. In fact, immediately after exhaustion, the leg muscles are capable of producing three times the power output required by high-intensity cycling exercise."

In 100 years, nobody else noticed this triple power output??
Samueleuk
3 / 5 (2) Mar 19, 2010
A. V. Hill, in his book Muscular Activity (332), adopted the view subsequently accepted widely by exercise physiologists. Athletes were best for studies of the limits of voluntary performance because "with young athletic people one may be sure that they really have gone `all out,' moderately certain of not killing them, and practically certain that their stoppage is due to oxygen-want and to lactic acid in their muscles (from: http://physrev.ph...725#T1). In other words, it has been thought for more than 100 years that exhaustion during endurance exercise is caused by muscle fatigue (also see this: http://physrev.ph...287/F9). I suggest reading the papers at the provided links before making rubbish comments.
wiserd
5 / 5 (1) Mar 20, 2010
Trained athletes don't seem to benefit that much from carbo-loading, according to the studies I've seen.
bmcghie
5 / 5 (2) Mar 20, 2010
Trained athletes don't seem to benefit that much from carbo-loading, according to the studies I've seen.


It's true. Once you've got your glycogen stores full in the liver and muscles... you've got roughly 5 hours of high output endurance capability, regardless of whether or not your stomach has food in it. Lactic acid levels go higher, yes, but performance remains the same. It just hurts more. :) This has been my experience, and every other serious athlete I've ever trained with, and all my physiology professors.
Digi
not rated yet Mar 20, 2010
Yes, just look at Eddie Izzard. A 47 year old, he just ran 43 marathons in 51 days with minimal training - very inspring. We are all genetically adapted for endurance, we just don't appreciate it.
dan42day
3 / 5 (2) Mar 21, 2010
That's what Morpheus kept telling Neo.

More seriously though, it is also probably related to the stories of people exhibiting superhuman strength in emergencies and why it's so hard to subdue a meth-head.
axemaster
not rated yet Mar 21, 2010
"Like other bodily sensations, perception of effort is a powerful feeling that is there for a reason. The perception that we have reached exhaustion prevents us from injuring ourselves by exercising too much."

Yes, I can't wait for the stories about all the Olympic athletes dying or being injured because they went beyond their limits. These mental boundaries exist for a reason.

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