Tag Archives: fatigue

Can reducing ammonia production during exercise improve performance?

Ammonia may be a central player in fatigue and exhaustion.  Exercise releases of ammonia into the blood stream.  Once in the blood stream it travels to the brain where it can accumulate if the pace of entry is faster than the body’s ability to metabolize it.   Athletes in studies who had the hardest time completing an intense exercise task also had the highest ammonia levels.(Nybo 2005).

The brain gets rid of extra ammonia by combining it with glutamate to produce glutamine.  If the brain is using glutamate to get rid of ammonia it is possible that glutamate levels decrease.    Decreased brain glutamate can impair function and may contribute to some of the wonky feelings of exhaustion.  Glutamate is an important neurotransmitter.  It is an excitatory neurotransmitter.  Glutamate makes it easier for nerves to fire and transmit information.  Without glutamate brain function may slow.  This is a very simplified picture.  However, it may help explain a bit of what is going on with fatigue.  Brain uptake of ammonia has been demonstrated in a number of studies.  One thing that has been noted is that there may be a lot of variation in the amount of ammonia produced.  This was found in a study of highly trained endurance athletes.  Athletes were:

  • young men
  • very similar weight
  • similar height
  • similar VO2max
  • living in Denmark (Nybo 2005).

Is it possible that variability in ammonia levels helps some people go longer or harder than others?  Is it less ammonia production or better brain clearance?  What causes it: genetics, diet, differences in training?

Reducing Ammonia:  Is it possible? Would it help for competition or training? Would it hurt?

There have been several studies that have looked at reducing blood ammonia levels.  Much of this comes from research on people with liver disease.  People with liver disease tend to produce a lot of ammonia.  They may also suffer a lot of muscle loss and brain dysfunction.  Their situation though is quite different from that of an athlete.

Is there any research on reducing ammonia levels during exercise?

Yes. Apparently glucose does.  Subjects (Nybo 2005) who were given glucose supplement had only about a third of the ammonia level as did subjects who did not.  A 2008 paper found that giving professional football players 100 mg per kg of glutamine prior to training reduced ammonia in blood.  Lastly, walnuts.  A study of walnut extracts showed less ammonia in blood of mice after they were subjected to a forced swim test.  Mice receiving walnut extract were able to swim quite a bit longer than those who did not (see reference for details.)  One of the things that was particularly interesting is that mice were subjected to several tests over several weeks.  Performance improved in the Walnut-Extract Mice from week 1 to week 2 to week 3 and then tapered off.  They never dropped to the level of No-Walnut mice.  Here is a link to the graph: Link.  The researchers suggested that Walnuts may reduce ammonia and fatigue through their anti-oxidant properties.

Should I eat walnuts, glucose and glutamine during training?

There is no evidence that walnuts, glucose or gluamine will improve your performance over the long term.  In fact, trying to lessen your ammonia production during training may hurt.  In the Nybo study the athletes with the highest levels of  ammonia in plasma and brain were the athletes who did not get glucose AND had the lowest VO2 max.  VO2 max is a marker of aerobic conditioning.  It is possible that the body gets more efficient in dealing with ammonia produced during exercise.  If that is the case, minimizing ammonia production might also minimize your ability to deal with it.  Its too early to know.

What about walnuts, glucose and/or glutamine for competition?

Hard to say too.  But . . . an ability to reduce ammonia might reduce fatigue and let you go longer or faster.  It might give a competitive edge.  Keep in mind some people may simply be better at metabolizing ammonia.  It might be genetic.  Or it might be from hard training.  For an overview of amino acid metabolism:

 

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Qiu J, Tsien C, Thapalaya S, Narayanan A, Weihl CC, Ching JK, Eghtesad B, Singh K, Fu X, Dubyak G, McDonald C, Almasan A, Hazen SL, Naga Prasad SV, & Dasarathy S (2012). Hyperammonemia-mediated autophagy in skeletal muscle contributes to sarcopenia of cirrhosis. American journal of physiology. Endocrinology and metabolism, 303 (8) PMID: 22895779

Nybo L, Dalsgaard MK, Steensberg A, Møller K, & Secher NH (2005). Cerebral ammonia uptake and accumulation during prolonged exercise in humans. The Journal of physiology, 563 (Pt 1), 285-90 PMID: 15611036

Snow RJ, Carey MF, Stathis CG, Febbraio MA, & Hargreaves M (2000). Effect of carbohydrate ingestion on ammonia metabolism during exercise in humans. Journal of applied physiology (Bethesda, Md. : 1985), 88 (5), 1576-80 PMID: 10797115

Bassini-Cameron, A., Monteiro, A., Gomes, A., Werneck-de-Castro, J., & Cameron, L. (2008). Glutamine protects against increases in blood ammonia in football players in an exercise intensity-dependent way British Journal of Sports Medicine, 42 (4), 260-266 DOI: 10.1136/bjsm.2007.040378

Breakthrough of the Year: Sleep cleanses the brain.

From the Editors at Science:
Science 20 December 2013:
Vol. 342 no. 6165 pp. 1440-1441
DOI: 10.1126/science.342.6165.1440-a
  • NEWS

To Sleep, Perchance to Clean

In work that Science‘s editors named a runner-up for Breakthrough of the Year, researchers studying mice have found experimental evidence that sleep helps to restore and repair the brain.

 Why do we sleep?

Questions of biology don’t get much more fundamental than that. This year, neuroscientists took what looks like a major stride toward an answer.

Most researchers agree that sleep serves many purposes, such as bolstering the immune system and consolidating memories, but they have long sought a “core” function common to species that sleep. By tracking colored dye through the brains of sleeping mice, scientists got what they think is a direct view of sleep’s basic purpose: cleaning the brain. When mice slumber, they found, a network of transport channels through the brain expands by 60%, increasing the flow of cerebral spinal fluid. The surge of fluid clears away metabolic waste products such as β amyloid proteins, which can plaster neurons with plaques and are associated with Alzheimer’s disease.

Until this discovery, researchers thought the brain’s only way to dispose of cellular trash was to break it down and recycle it inside cells. If future research finds that many other species undergo this cerebral housekeeping, it would suggest that cleaning is indeed a core function of sleep. The new findings also suggest that sleep deprivation may play a role in the development of neurological diseases. But with a causal role far from certain, it’s too early for anyone to stay awake worrying.

References and Web Sites

E. Underwood, “Sleep: The Brain’s Housekeeper?” Science 342, 6156 (18 October 2013).

L. Xie et al., “Sleep Drives Metabolite Clearance From the Adult Brain,”Science 342, 6156 (18 October 2013).

Physiology of Fatigue: What are we fighting when we try to push through a challenging workout?

Why are workouts so hard?

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We are fighting a lot when we push ourselves through workouts that are challenging. There are times we may be fighting a bad attitude, discouragement, lack of confidence, drive or our own personalities, but we are, at times, also fighting a very complex regulatory system designed to protect us from severe self-induced damage.

Fatigue and Temperature

Fatigue can be defined as reaching a point where the body seeks to slow down or stop. Exhaustion is that point where a person (or animal) is unable to continue. The most important factor driving suppression of motor activity is believed to be brain temperature. In an untrained person, exhaustion may occur when core body temperature reaches 100 to 102F(~38 to 39C) while a highly trained person may not reach exhaustion until body temperature has reached 104F (~40C).

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Interestingly, it’s not only humans who are stopped at these temperatures. Internal temperatures of ~104 oF will stop other animals whether sprinters (Cheetahs) or the generally more placid and possibly endurance-oriented (Goats) (Taylor and Rowntree 1973). And yes, I’m sure you’re wondering: temperatures were measured rectally, and the animals ran on a treadmill while wearing masks so oxygen and carbon dioxide levels could be assessed. The research team also cranked the heat up. Cheetahs ran for shorter periods when the room was hot. The authors of this paper concluded that the duration of a Cheetah’s sprint is limited by core temperature, which is influenced by air temperature. Keep this in mind when you are working out in the summer with no air-conditioning. There are other factors that are also thought to play roles in regulation of intense physical output. Working muscles send feedback to the brain, and in most of us, they are not yelling “Go! Go! Go!” At first they are saying things like “we need more oxygen over here” and “pump the heart faster.” Unfortunately you maximum output can only go on for as long as you have the necessary materials to keep the system running. Your maximum obtainable heart rate will matter. That may be one you cannot make “just do it.” although you can improve your ability to pump blood with training.

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Blood concentrations of important factors or metabolites, and depletion of working materials, are also monitored by the brain. Changes in concentrations and availability of neurotransmitters, endorphins, cytokines, along with a build-up of ammonia in the brain, occur during continued intense exercise. Cerebral energy use increases requiring more oxygen, while blood flow will decrease by about 20% due to constriction of brain arterioles. Low oxygen, loss of neurotransmitters, and accumulation of waste products can cause a problem that is truly “all in your head” but a real problem none the less. An increased need for oxygen and fuel in the brain may be part of what causes someone to want to slow down or stop.

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Another strong woman shirt for strong women. Be fit and wear an awesome shirt. For strong women who love art, irony and kettlebells

Practice improves physiology and performance.

Increasing oxygen intake may improve performance not necessarily by providing muscles with additional oxygen, but in providing the brain with what it needs to keep the system running. Depletion of brain glycogen and excessive use of lactate as an alternative brain fuel may also signal fatigue. This may happen faster in untrained athletes. Physical training is, after all, about much more than simple strength and endurance. It includes getting all systems, including subtler aspects of physiology like the ability to dissipate heat, produce lactate, carry oxygen and oxygenate the brain, to work as efficiently as possible. We can reach our limits, but our brains rarely stupid enough to allow us to go beyond them and recklessly run our bodies off the edge of a cliff. The brain also likes to know what’s going on and practice (going through the motions) and rehearsal are important to performance. Rehearsing movements before a WOD may be as important as traditional warming up. It preps your system for what it is about to do and lets it know what is coming. Even imagining movements may help improve strength output and performance (Jeukendrup et al. 1996).

CrossFit training, rational mental toughness.

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We can improve performance intelligently rather than fight what we imagine to be a lack of mental toughness, or allow ourselves be discouraged. We can keep cool and well-hydrated. We can be patient enough to recognize that our physiological and biochemical systems are becoming more efficient as we train, even if our speed or strength has plateaued, and not give up on long-term goals. Finally, encouragement and cheers can help people achieve their maximal level of oxygen consumption (Nybo & Secher 2004) and maximum performance. This may be especially true if they are new to Crossfit and have type A personalities. New Crossfitters may be putting superhuman efforts into their workouts and should be congratulated and admired for these as much as our seasoned champions.

Taylor CR, & Rowntree VJ (1973). Temperature regulation and heat balance in running cheetahs: a strategy for sprinters? The American journal of physiology, 224 (4), 848-51 PMID: 4698801

JEUKENDRUP, A., SARIS, W., BROUNS, F., & KESTER, A. (1996). A new validated endurance performance test Medicine & Science in Sports & Exercise, 28 (2), 266-270 DOI: 10.1097/00005768-199602000-00017

Nybo, L., & Secher, N. (2004). Cerebral perturbations provoked by prolonged exercise Progress in Neurobiology, 72 (4), 223-261 DOI: 10.1016/j.pneurobio.2004.03.005

Taylor CR, & Rowntree VJ (1973). Temperature regulation and heat balance in running cheetahs: a strategy for sprinters? The American journal of physiology, 224 (4), 848-51 PMID: 4698801 Nybo, L., & Secher, N. (2004). Cerebral perturbations provoked by prolonged exercise Progress in Neurobiology, 72 (4), 223-261 DOI: 10.1016/j.pneurobio.2004.03.005ResearchBlogging.org

What causes fatigue? Why is it different in CrossFit?

What causes fatigue? And why is it sometimes so hard to push through it?

Few people enjoy the sensations of fatigue and pain that accompany intense exercise.  While endurance athletes may get a “runners’ high” that feeling of elation is not common during a CrossFit WOD or in other forms of intense physical output.  The runners high is thought to be caused by feel-good chemicals produced by the brain that blunt pain and allow people (and animals) to run for long distances.  You can read up on these chemicals (endocannabinoids) here.  Without them you will feel very differently.  There are several thoughts on what causes fatigue.  Possibilities are:

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  • Build-up of metabolic by-products
  • Signals produced by the brain that try to tell you “that’s enough”
  • Production of inflammatory cytokines
  • Signals from the body that enter the brain to tell it “stop.”

Is buildup of Ammonia a factor in Fatigue?

It may be.  Ammonia builds up in blood just a little during moderate intensity exercise.  But it increases rapidly when levels of effort are heavily ramped up.  And it increases during prolonged (over an hour) sub-maximal efforts.  The buildup of ammonia may be caused by the breakdown of Branched Chain Amino Acids (BCAA’s).  When ammonia builds up in the blood it can enter the brain and cause problems.  Including stupor.  Maybe this is part of what happens to marathon runners.

Caffeine, Amino Acids and Escaping Fatigue

Caffeine has been shown to reduce fatigue and improve athletic performance.  Caffeine also changes the manner in which amino acids (and BCAA’s) are metabolized during exercise.  Perhaps one of the ways caffeine helps workouts is by reducing the amount of ammonia build up.   Meanwhile, it seems that supplementation with glutamine suppresses fatigue and ammonia build-up.  Glutamin is considered a non-essential amino acid, but there is growing evidence that it might be particularly important under intense exercise.  Good sources of glutamine include beef, chicken etc. as well as wheat.  This is not the same thing as MSG (mono-sodium glutamate) which can trigger nasty headaches in many people.  Supplementation with branched-chain amino acids may also suppress build-up of ammonia as well.  We’ll see what comes up in the next few years.

 

Bassini A, Magalhães-Neto AM, Sweet E, Bottino A, Veiga C, Tozzi MB, Pickard MB, & Cameron LC (2013). Caffeine Decreases Systemic Urea in Elite Soccer Players during Intermittent Exercise. Medicine and science in sports and exercise, 45 (4), 683-690 PMID: 23135367
Wilkinson DJ, Smeeton NJ, & Watt PW (2010). Ammonia metabolism, the brain and fatigue; revisiting the link. Progress in neurobiology, 91 (3), 200-19 PMID: 20138956

Bassini-Cameron, A., Monteiro, A., Gomes, A., Werneck-de-Castro, J., & Cameron, L. (2008). Glutamine protects against increases in blood ammonia in football players in an exercise intensity-dependent way British Journal of Sports Medicine, 42 (4), 260-266 DOI: 10.1136/bjsm.2007.040378