Featured Research

from universities, journals, and other organizations

How muscle fatigue originates in the head

Date:
December 5, 2011
Source:
University of Zurich
Summary:
Researchers 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.

Test on the bicycle ergometer with the measurement of brain activity.
Credit: University of Zurich

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.

Related Articles


The extent to which we are able to activate our muscles voluntarily depends on motivation and will power or the physical condition and level of fatigue of the muscles, for instance. The latter particularly leads to noticeable and measurable performance impairments. For a long time, the research on muscle fatigue was largely confined to changes in the muscle itself. Now, a joint research project between the University of Zurich and ETH Zurich has shifted the focus to brain research. Headed by neuro-psychologist Kai Lutz from the University of Zurich in collaboration with Urs Boutellier from the Institute of Human Movement Sciences and Sport at ETH Zurich, the researchers discovered neuronal processes for the first time that are responsible for reducing muscle activity during muscle-fatiguing exercise. The third and final part of this series of experiments, which was conducted by Lea Hilty as part of her doctoral thesis, has now been published in the "European Journal of Neuroscience."

Muscle's nerve impulses inhibit motoric area in the brain

In the initial study, the researchers showed that nerve impulses from the muscle -- much like pain information -- inhibit the primary motoric area during a tiring, energy-demanding exercise. They were able to prove this using measurements in which study participants repeated thigh contractions until they could no longer attain the force required. If the same exercise was conducted under narcotization of the spinal chord (spinal anesthesia), thus interrupting the response from the muscle to the primary motoric area, the corresponding fatigue-related inhibition processes became significantly weaker than when the muscle information was intact.

In a second step, using functional magnetic resonance imaging, the researchers were able to localize the brain regions that exhibit an increase in activity shortly before the interruption of a tiring, energy-demanding activity and are thus involved in signalizing the interruption: the thalamus and the insular cortex -- both areas which analyze information that indicates a threat to the organism, such as pain or hunger.

Neuronal system has regulating effect on muscle performance

The third study has now shown that the inhibitory influences on motoric activity are actually mediated via the insular cortex: In tests using a bicycle ergometer, the researchers determined that the communication between the insular cortex and the primary motoric area became more intensive as the fatigue progressed. "This can be regarded as evidence that the neuronal system found not only informs the brain, but also actually has a regulating effect on motoric activity," says Lea Hilty, summing up the current result. And Kai Lutz points to the new research field that now opens up with these results: "The findings are an important step in discovering the role the brain plays in muscle fatigue. Based on these studies, it won't just be possible to develop strategies to optimize muscular performance, but also specifically investigate reasons for reduced muscular performance in various diseases." Prolonged reduced physical performance is a symptom that is frequently observed in daily clinical practice. It can also appear as a side effect of certain medication. However, so-called chronic fatigue syndrome is often diagnosed without any apparent cause.


Story Source:

The above story is based on materials provided by University of Zurich. Note: Materials may be edited for content and length.


Journal References:

  1. Lea Hilty, Lutz Jäncke, Roger Luechinger, Urs Boutellier, Kai Lutz. Limitation of physical performance in a muscle fatiguing handgrip exercise is mediated by thalamo-insular activity. Human Brain Mapping, 2011; 32 (12): 2151 DOI: 10.1002/hbm.21177
  2. Lea Hilty, Kai Lutz, Konrad Maurer, Tobias Rodenkirch, Christina M. Spengler, Urs Boutellier, Lutz Jäncke, Markus Amann. Spinal opioid receptor-sensitive muscle afferents contribute to the fatigue-induced increase in intracortical inhibition in healthy humans. Experimental Physiology, 2011; DOI: 10.1113/expphysiol.2010.056226
  3. Lea Hilty, Nicolas Langer, Roberto Pascual-Marqui, Urs Boutellier, Kai Lutz. Fatigue-induced increase in intracortical communication between mid/anterior insular and motor cortex during cycling exercise. European Journal of Neuroscience, 2011; DOI: 10.1111/j.1460-9568.2011.07909.x

Cite This Page:

University of Zurich. "How muscle fatigue originates in the head." ScienceDaily. ScienceDaily, 5 December 2011. <www.sciencedaily.com/releases/2011/12/111205081643.htm>.
University of Zurich. (2011, December 5). How muscle fatigue originates in the head. ScienceDaily. Retrieved November 27, 2014 from www.sciencedaily.com/releases/2011/12/111205081643.htm
University of Zurich. "How muscle fatigue originates in the head." ScienceDaily. www.sciencedaily.com/releases/2011/12/111205081643.htm (accessed November 27, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Thursday, November 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Experimental Ebola Vaccine Shows Promise In Human Trial

Experimental Ebola Vaccine Shows Promise In Human Trial

Newsy (Nov. 27, 2014) — A recent test of a prototype Ebola vaccine generated an immune response to the disease in subjects. Video provided by Newsy
Powered by NewsLook.com
Pet Dogs to Be Used in Anti-Ageing Trial

Pet Dogs to Be Used in Anti-Ageing Trial

Reuters - Innovations Video Online (Nov. 26, 2014) — Researchers in the United States are preparing to discover whether a drug commonly used in human organ transplants can extend the lifespan and health quality of pet dogs. Video provided by Reuters
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) — Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com
From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) — The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins