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Mental Fatigue Can Affect Physical Endurance
February 24, 2009When participants performed a mentally fatiguing task prior to a difficult exercise test, they reached exhaustion more quickly than when they did the same exercise when mentally rested, a new study finds.
The study also found that mental fatigue did not cause the heart or muscles to perform any differently. Instead, our "perceived effort" determines when we reach exhaustion. The researchers said the next step is to look at the brain to find out exactly why people with mental fatigue perceive exercise to be more difficult.
Samuele M. Marcora, Walter Staiano and Victoria Manning of Bangor University, Wales, the United Kingdom, did the study, "Mental fatigue impairs physical performance in humans." The study will appear in the March print edition of the Journal of Applied Physiology. The American Physiological Society published the study.
The study
The 16 participants rode a stationary bicycle to exhaustion under two conditions: once when they were mentally fatigued and once when they were mentally rested. The trials took place in the laboratory on different days. The participants got the same amount of sleep, drank the same amount and had the same meal before each of the sessions.
The mental fatigue sessions began with a challenging 90-minute mental task that required close attention, memory, quick reaction and an ability to inhibit a response. After undergoing this session, participants reported being tired and lacking energy. The control session consisted of watching neutral documentaries for 90 minutes and was not mentally fatiguing.
After each of the 90-minute sessions - mentally fatiguing or non-fatiguing - the participants did an intense bout of exercise on a stationary bicycle. They rode until exhaustion, defined as the point when they could not maintain a cadence of at least 60 revolutions per minute for more than five seconds.
Throughout both exercise sessions, the researchers tracked a variety of physiological measures, such as oxygen consumption, heart rate, cardiac output, blood pressure, ventilation, and blood lactate levels. The participants completed surveys to measure their motivation and perceived effort. The researchers offered monetary prizes for the best performance on the exercise and mental tasks as a way to keep motivation high.
Results
* The participants stopped exercising 15% earlier, on average, when they were mentally fatigued.
* The participants stopped at the same perceived effort level in both the fatigued and non-fatigued trial. However, mentally fatigued participants started at a higher level of perceived effort and reached the endpoint sooner.
* The cardio-respiratory and musculo-energetic measurements did not vary between the two trials when compared at specific points in time. However, because the non-fatigued trials went longer, heart rate and blood lactate levels were higher at the end of those trials.
* Motivation was the same in both trials and was not a factor.
The researchers speculate that the perception of effort occurs in the brain. Dr. Marcora said his team is considering two possibilities:
* mental fatigue lowers the brain's inhibition against quitting, or
* mentally fatigue affects dopamine, a brain chemical that plays a role in motivation and effort
One interesting note is that demanding mental tasks activate the anterior cingulate cortex of the brain. Previous research has shown that rats with a lesion in the anterior cingulate cortex would not work as hard for a reward compared to rats with no lesion. This area of the brain may be where perception of effort originates, Dr. Marcora said.
Applying the results
This research could provide a way to study chronic fatigue syndrome, Dr. Marcora said. People with chronic fatigue report they lack energy and experience "brain fog," just like the mentally fatigued participants in this study. In addition, as in this study, people with chronic fatigue perceive exercise to be more difficult despite physiological responses considered normal during exercise.
The research model may also be helpful for military personnel. They do physically demanding tasks after long period of vigilance. Vigilance produces mental fatigue.
Finally, the study suggests that people doing high intensity training, such as competitive athletes, should do their training while mentally rested. However, people who exercise after work should continue doing so, even if mentally fatigued. Most people work out at a moderate intensity, which still gives plenty of physiological and psychological benefit, including relief from stress and improved mental performance.
The American Physiological Society
The study
The 16 participants rode a stationary bicycle to exhaustion under two conditions: once when they were mentally fatigued and once when they were mentally rested. The trials took place in the laboratory on different days. The participants got the same amount of sleep, drank the same amount and had the same meal before each of the sessions.
The mental fatigue sessions began with a challenging 90-minute mental task that required close attention, memory, quick reaction and an ability to inhibit a response. After undergoing this session, participants reported being tired and lacking energy. The control session consisted of watching neutral documentaries for 90 minutes and was not mentally fatiguing.
After each of the 90-minute sessions - mentally fatiguing or non-fatiguing - the participants did an intense bout of exercise on a stationary bicycle. They rode until exhaustion, defined as the point when they could not maintain a cadence of at least 60 revolutions per minute for more than five seconds.
Throughout both exercise sessions, the researchers tracked a variety of physiological measures, such as oxygen consumption, heart rate, cardiac output, blood pressure, ventilation, and blood lactate levels. The participants completed surveys to measure their motivation and perceived effort. The researchers offered monetary prizes for the best performance on the exercise and mental tasks as a way to keep motivation high.
Results
* The participants stopped exercising 15% earlier, on average, when they were mentally fatigued.
* The participants stopped at the same perceived effort level in both the fatigued and non-fatigued trial. However, mentally fatigued participants started at a higher level of perceived effort and reached the endpoint sooner.
* The cardio-respiratory and musculo-energetic measurements did not vary between the two trials when compared at specific points in time. However, because the non-fatigued trials went longer, heart rate and blood lactate levels were higher at the end of those trials.
* Motivation was the same in both trials and was not a factor.
The researchers speculate that the perception of effort occurs in the brain. Dr. Marcora said his team is considering two possibilities:
* mental fatigue lowers the brain's inhibition against quitting, or
* mentally fatigue affects dopamine, a brain chemical that plays a role in motivation and effort
One interesting note is that demanding mental tasks activate the anterior cingulate cortex of the brain. Previous research has shown that rats with a lesion in the anterior cingulate cortex would not work as hard for a reward compared to rats with no lesion. This area of the brain may be where perception of effort originates, Dr. Marcora said.
Applying the results
This research could provide a way to study chronic fatigue syndrome, Dr. Marcora said. People with chronic fatigue report they lack energy and experience "brain fog," just like the mentally fatigued participants in this study. In addition, as in this study, people with chronic fatigue perceive exercise to be more difficult despite physiological responses considered normal during exercise.
The research model may also be helpful for military personnel. They do physically demanding tasks after long period of vigilance. Vigilance produces mental fatigue.
Finally, the study suggests that people doing high intensity training, such as competitive athletes, should do their training while mentally rested. However, people who exercise after work should continue doing so, even if mentally fatigued. Most people work out at a moderate intensity, which still gives plenty of physiological and psychological benefit, including relief from stress and improved mental performance.
The American Physiological Society
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Low motivation means failure
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Interruptions at work have multiple effects
Interruptions make people speed up their work pace, while maintaining the required quality of work. However, interruptions do have negative impact on emotion and well-being, and lead to an increase in effort, leaving workers tired.
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Mental Fatigue During Continuous Exercise of a Single Function by Thomas Russell Garth (Author) | |
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The Men Starring: Marlon Brando, Cliff Clark, Virginia Farmer, John Hamilton, Nita Hunter Also With: Robert de Grasse (Cinematographer), Dimitri Tiomkin (Composer) Marlon Brando set the mark for a brilliant career in Stanley Kramer's THE MEN, his motion picture debut. As a war veteran paralyzed in combat, he returns home to face the torturous ordeal of rehabilitation. The courage and strength of the soldier are betrayed by the fear and insecurity of the man when he learns he will never walk again. Embittered by his condition, he refuses to see his fiancee and sinks into a solitary world of hatred and hostility. Fighting the wishes of her parents, the coldness of a guilt-ridden society and her own self-doubts, it is she who must force him to confront the reality of his condition and break his physical and emotional confinement. When feeling starts to return to his legs, it could be his last hope...or his final downfall. |
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PhytoCaps Ginkgo Leaf 60C by Gaia Herbs Supports Healthy Oxygen Flow to the Brain and the Micro-Vascular System Provides Plant Derived Antioxidant Protection Ultimate Support to Improve Memory |
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EuroPharma Anti-Fatigue Remedy Tablets, 60-Count Boxes (Pack of 2) by EuroPharma For physical fatigue, mental fatigue. Anti-Fatigue Remedy is manufactured under homeopathic principles. Product of France. |
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Herbalife Liftoff - Lemon-Cola Kick (Box of 10 Tablets) by Herbalife Herbalife proudly introduces a new kind of energy! Liftoff is an effervescent energy drink tablet that does more than give you your body a boostitll shift your mind into high gear! With an exclusive energy blend of taurine, guarana, caffeine, Panax ginseng and Ginkgo biloba, Liftoff fights fatigue and improves mental performance. Liftoff also contains 100% of your daily supply of antioxidant Vitamin C and more than 100% of your Vitamins B6 and B12 for enhanced energy production. Try both refreshing flavors, Ignite-Me Orange and Lemon-Lime Blast, today. |
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Roll-on Relief -Mental Energizer Lotion by Amrita Aromatherapy This blend will increase your mental performances like: memory, concentration and alertness. * Organic Peppermint to create alertness * Organic Lemon and Lime to stimulate brain function * Organic Ginger to energize the mind |
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Invigorating Body Oil by Amrita Aromatherapy With a stimulating and reviving blend of Basil and Rosemary essential oils. This body oil will boost your energy and melt your fatigue away. Ideal for times of increased physical and mental demands and for use before exercising. Ingredients: Holy Basil and Rosemary Essential Oils Base: Apricot Kernel, Almond, Hazelnut Oils and Vitamin E |
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Washington Homeopathic Products Combination Remedy for Mental Fatigue (#68) by Washington Homeopathic Products About Washington Homeopathics (WHP) Washington Homeopathic Pharmacy (WHP) is the world leader in homeopathic and began in 1873 in Washington, DC. In 1991, Joe and Linda Lillard bought the pharmacy. In less than 20 years Washington Homeopathic Products has grown from a storefront pharmacy to one that is now serving over 65,000 customers in more than twenty countries. Today, WHP is the oldest full line homeopathic manufacturer in the nation offering a selection of over 1700 homeopathic medicines. They strive to make just about every product they offer. All plant materials used to manufacture homeopathic medicine must be organically grown. Over 50 species of plants used to process remedies are grown on the Lillards West Virginia farm. Sourcing local botanical materials... |
![Studies of Mental Fatigue in Relation to the Daily School Program [ 1914 ]](http://ecx.images-amazon.com/images/I/31fUAWtvaTL._SL160_.jpg) |
Studies of Mental Fatigue in Relation to the Daily School Program [ 1914 ] by William Harry Heck (Author) Originally published in 1914. This volume from the Cornell University Library's print collections was scanned on an APT BookScan and converted to JPG 2000 format by Kirtas Technologies. All titles scanned cover to cover and pages may include marks notations and other marginalia present in the original volume. |
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Mental Fatigue During Continuous Exercise of a Single Function by Thomas Russell Garth (Author) This volume is produced from digital images created through the University of Michigan University Library's preservation reformatting program. The Library seeks to preserve the intellectual content of items in a manner that facilitates and promotes a variety of uses. The digital reformatting process results in an electronic version of the text that can both be accessed online and used to create new print copies. This book and thousands of others can be found in the digital collections of the University of Michigan Library. The University Library also understands and values the utility of print, and makes reprints available through its Scholarly Publishing Office. |
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