Usain Bolt’s rocketship explosiveness has made sprints wildly popular, but what about Bolt’s contemporaries in the longer races — athletes who can run a 26 mile marathon in just over 2 hours? That’s less than 5 minutes per mile — a mind-boggling feat, considering that the fastest single mile ever was run in just under 4 minutes.
How is this humanly possible? Though running seven, ten, or even twelve miles a day is of course critical, most athletes don’t realize that the development of endurance is largely influenced by — you guessed it — the brain.
Classical Theories of Endurance
Theories of endurance traditionally focus on cardiovascular, respiratory, metabolic, and muscular mechanisms. That is, endurance is typically viewed as a factor of physiological characteristics such as pulmonary ventilation, cardiac output, and lactate threshold.
Of course, genetics and environment play a large role in how these physiological traits develop. For example, Kenyans and Ethiopians have come to dominate middle-and long-distance Olympic events, and the fastest marathon ever was run in 2:02:57 by Dennis Kimetto of Kenya.
The reason? Kenyans and Ethiopians possess a unique blend of genetics that provides favorable adaptations for an endurance lifestyle. Beyond genetics, Kenyans and Ethiopians also run and walk extensively at an early age, so their bodies become heavily conditioned for endurance. In addition, they usually train at high altitudes, in places such as the Aberdare Range of Kenya and the Ethiopian Highlands of Ethiopia.The Aberdare Range has an average elevation of 11,480 feet, and the Ethiopian Highlands can reach heights of up to 14,928 feet.
According to research from the Athlete Performance Laboratory of the United States Olympic Committee, this unique blend of nature and nurture has led both cultures to develop adaptive characteristics enabling survival in highly-elevated environments, such as a high maximal oxygen uptake, high hemoglobin levels, and favorable skeletal-muscle-fiber composition.
Although environment and genetics largely dictate the endurance profile of an athlete, the real key to success in endurance sports is training. Take Galen Rupp, for example, a 30 year old Portland, OR native who practiced endurance training tirelessly for over 14 years and won the 2016 American Olympic trials with a 2:11:11 marathon, in his first marathon ever. Rupp does not possess the genetic makeup or environmental background of a runner like Kimetto (though it’s possible he shares some of the same genetic polymorphisms), but he’s still managed to develop highly competitive levels of endurance through years of focused endurance training.
The fact that both Rupp and Kimetto are competitive endurance athletes negates the possibility that endurance is completely due to favorable physical characteristics invoked by genetics or environment. That’s why a purely physical understanding of endurance is incomplete. There is something more fundamental that Rupp and Kimetto both have the ability to train, and that is: the brain.
The brain is a critical common denominator across elite endurance athletes of all backgrounds, so all athletes can benefit equally from training this fascinating organ.
The Brain’s Role in Endurance
Many athletes don’t realize that the brain plays a big role in endurance. Scientists, however, have long known that the brain plays a role in fatigue and exercise tolerance. As early as 1890, Italian scientist Angelo Mosso published a book providing preliminary evidence regarding the effects of cognitive activity on fatigue. According to Mosso, two of his fellow physiology professors experienced reduced muscular endurance after giving a series of lectures and oral exams to students.
More recently, a 2009 study published in the Journal of Applied Physiology found that cognitive fatigue limits athletic performance — individuals who performed heavy cognitive tasks before a time-to-exhaustion cycling task could only cycle for an average of 640 seconds, while individuals who did not perform cognitive tasks were able to cycle for an average of 754 seconds.
Despite its role in endurance, the brain has been overlooked in endurance training, primarily because endurance is measured by physiological changes such as heart rate, stroke volume, and oxygen transport. Coaches typically focus on cardiovascular and respiratory components of training in order to optimize these qualities. However, because of the brain’s prominent role in exercise tolerance, it makes sense that a more deliberate and focused training of the brain could allow endurance athletes to take long-distance sports to an entirely new level.
In order to unlock the secrets of brain training as it relates to endurance, let’s first build an understanding around the neurological mechanism that regulates fatigue.
Two Types of Fatigue Influence Endurance
According to Mosby’s Medical Dictionary, athletic endurance is defined as “the ability to continue an activity despite increasing physical or psychological stress, as in the effort to perform additional numbers of muscle contractions before the onset of fatigue”.
In a nutshell, this definition states that endurance is essentially the ability to fend off fatigue.
There are two distinct types of fatigue: peripheral and central. Peripheral fatigue is the type of fatigue targeted through traditional endurance training. Central fatigue has hardly been recognized in athletics, although athletes naturally address central fatigue during classical endurance training without realizing it. Although both types of fatigue result in decreased performance capacity of the muscles, they follow different mechanisms.
Peripheral fatigue is defined as a transient decrease in a muscle group’s capacity for exercise. This can be caused by a number of factors, including reduced pulmonary ventilation, metabolite depletion, or reduced cardiac output. To put it into context, peripheral fatigue is what causes runners to start gasping for breath at the end of a long-distance run, and is responsible for “the burn” felt by cyclists at the the top of a hill.
Unlike peripheral fatigue, central fatigue involves changes in intracortical excitability that cause decreased neural drive from the motor cortex to the muscles. In other words, the longer the workout, the weaker the signal becomes from the brain to the muscles. A 2000 study completed by Tergau and colleagues at the University of Göttingen in Germany confirmed its role in exhaustive exercise, finding that the number of pull-ups completed during an exhaustive task is strongly correlated with a reduction in excitatory brain activity.
Excitation vs. Inhibition
If the reduction of excitatory brain activity is the neural mechanism of central fatigue, the maintenance of excitatory brain activity becomes the neural mechanism of endurance. Neuroscientists have identified a precise neural circuit that explains an athlete’s ability to fend off central fatigue. There are two distinct phases of this circuit, inhibition and facilitation.
The inhibition phase is as follows:
- Sensory inputs from the peripheral system sends an inhibitory signal up the spinal cord to the primary motor cortex.
- The primary motor cortex reduces motor output via increased activity of inhibitory GABA receptors. It alerts other brain areas to follow suit, which cumulatively signals the body to reduce motor activity. Brain regions involved in this circuit constitute the inhibition system.
Let’s walk through these steps in plain terms. The first step is essentially the body letting the brain know that it feels tired. We can think of this as perceived exertion. This could come in the form of heavy breathing, muscle cramps, “the burn,” etc.
The second step is when the brain gets the signal that the body is tired, which gives the body the green light to slow down. If the athlete slows down, the heart rate will decline, the breath will slow, and movement will weaken. However, if the athlete still has enough energy to keep going, the inhibition signals can be minimized. To do this, an athlete invokes the second part of the circuit, the facilitation (i.e. excitation) phase.
The facilitation phase is as follows:
- Cortical inputs send an excitatory signal to the primary motor cortex.
- The motor cortex increases motor output to the peripheral system in order to counteract the inhibitory signal. This allows motor activity to be maintained at the same level instead of dropping off due to fatigue. Brain regions involved in this circuit constitute the facilitation system.
Again, in plain terms, the first step is the athlete’s ability to continue exercising.
The second step is when this ability gets translated into action, i.e. the brain signals the body to keep the muscles moving, the heart rate up, and the breath heavy so that the athlete can keep going.
While the facilitation system does an excellent job of fending off central fatigue, an athlete can only exercise for so long. After long periods of exhaustive exercise, eventually the body uses up all available resources and reaches its true exertion potential, at which point the athlete must terminate activity.
Research Points to the Benefits of Neurological Training
By repetitively practicing long-distance exercises, athletes naturally train their brains to fend off fatigue, which steadily builds endurance over time. However, there are more gains to be had than those achieved through endurance training alone. Even while running marathons at near sprinting pace for mere mortals, endurance athletes are only activating a small fraction of their brain’s excitatory capacity with traditional long-distance training methods.
The good news is that scientists have found that training the brain through neurostimulation can significantly increase the body’s capacity for endurance. In this way, endurance athletes can push their perceived exertion potential closer to their true exertion potential.
A number of academic articles have confirmed brain stimulation as an effective method to increase endurance. By inducting plasticity in the brain, neurostimulation trains the brain to maximize excitatory signals and minimize inhibitory signals in order to help athletes maintain the same level of exertion for longer periods of time.
For example, a recent study from a group of Italian scientists at the Universitá di Milano found that transcranial direct current stimulation (tDCS) over the motor cortex increases both cortical excitability and time to exhaustion in an isometric elbow flexion exercise. Another study conducted by a group of Brazilian neuroscientists found that tDCS over the motor cortex significantly increased time to exhaustion in an exhaustive cycling task.
Halo Sport: A Training Tool for Endurance Athletes
Recognizing the potential of brain stimulation on endurance sports, Halo Neuroscience developed neurotechnology that allows athletes to tap into the brain’s full exertion potential.
Halo Sport applies tDCS over the motor cortex in order to send stronger excitatory brain signals from the brain to the muscles. The device places the brain in temporary state of hyperplasticity, and when combined with active training, athletes can learn to better manage and stave off central fatigue. Athletes can then push their perceived maximal exertion closer to their true maximal exertion for a longer period of time.
With Halo Sport, endurance athletes can stay closer to their maximal endurance potential for longer, which allows them to exercise longer, faster, and harder.
Curious about taking the next step towards improving your endurance? Try Halo Sport risk free with our 30 day money back guarantee. Order yours here.
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