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Brain-Body Chemistry

By April 16, 2015July 27th, 2020Lifestyle & Stress

Excerpt: Chapter 28

Building a Better Athletic Brain in “The Big Book of Endurance Training and Racing”
by Dr. Phil Maffetone

Physical activity is intricately related to ongoing brain development. This process begins at the earliest age when a child’s first movements stimulate brain growth, and continues throughout life unless one stops being active.

This activity increases levels of a family of natural protein-based chemicals in the brain called neurotrophins. Perhaps the most researched chemical includes brain-derived neurotrophic factor (BDNF), which promotes cellular growth and repair in the brain and body. BDNF improves brain function by helping cell-to-cell communication, important for learning, memory, and overall cognition. BDNF also stimulates the production of new brain cells—a process called neurogenesis—and protects cells from degeneration, associated with a decline in brain function with age. Physical activity also stimulates BDNF to help mobilize gene expression, switching on many of the genetic benefits programmed within the body while turning off the bad genetic profiles. Even an easy workout can benefit the brain in another way, by promoting plasticity—the ability to improve overall brain function at any age. Those individuals with depression, Alzheimer’s disease, and other brain disorders often have low levels of BDNF. Even those with high body fat, diabetes, and other conditions are low in BDNF.

BDNF also affects our muscles by helping them function more effectively through improving contraction and fat burning for energy production throughout the body. And BDNF is considered a key chemical for overall human survival—something we don’t think much about these days, but a long endurance event is just that: a test of survival that relies heavily on optimal brain and muscle function.

Which workouts are best for brain health? The answer is any training that promotes overall health, especially those that are aerobic. This can even include an easy walk, regardless of one’s level of fitness.

For endurance athletes, the brain’s most important job is to preserve the body’s delicate physiological mechanisms to prevent injury, ill health, and possible death in the extreme circumstances of tough endurance races. Even during competition, when one’s more rational thoughts sometimes get lost in the heat of the battle, the brain will pick up the slack. If you consciously decide, for example, to keep up with the lead pack in a cycling event, despite a usual finish in the middle of the pack, your brain will prevent that attempted high level of effort— subconsciously slowing you down by reducing muscle power. This natural decrease is ultimately for your benefit.

Another common way the brain protects athletes is through its ability to help the body physically compensate for problems such as muscle imbalance. Our eyes play a key role in this physical balance. (The brain also relies on the inner ear’s delicate nerve endings to control balance by sensing body motion and adjusting muscle activity.)

Our eyes, which are part of the brain controlled from within, can influence the muscles throughout our body and even change our running, cycling, or swimming form for better or worse. Here’s an example. Normally, vision is very high up on the brain’s list of priorities; the brain dedicates a significant amount of neurons and energy to visual activity.
Through visual input, the brain will maintain body balance even at the expense of muscles in the neck, shoulder, lower back, and legs. Here’s why. It’s important that the normal position of both eyes resides in a horizontal plane for optimal function. If muscle imbalance in the neck causes the head to tilt, the eyes may not maintain their normal horizontal position. This is because muscle imbalance can cause the head to tilt slightly to one side, causing the eyes to lose their normal horizontal balance. When this happens, the brain must immediately compensate in the easiest and best way to bring the two eyes back to balance. If the problem muscles in the neck can’t be corrected by the brain, other types of compensation are attempted. The brain can do this by creating an opposite imbalance in other muscles, slightly tilting the spine and pelvis to accomplish this task. While this restores the eyes to their normal position, it’s done at the expense of other muscles, which now don’t function as well. Some of these muscles may be key to the process of running or biking, reducing our effectiveness and altering our form. In addition to slowing us down, it also increases the risk of additional secondary muscle problems and increases stress on joints and other mechanical areas such as ligaments and bones.

This example is very common; just watch marathoners approaching the finish line and you’ll see some who are literally physically twisted—wounded by the brain’s compensation. But if the brain didn’t act accordingly, the athlete may not have ever completed the race.

By remaining fit and healthy, one can usually prevent the original imbalance in the neck, which caused the eyes to become stressed, thereby eliminating the need for the brain to make such dramatic compensations.

Racing through the Brain’s “Eyes”

Poets have often written about how the eyes are the windows to the soul. For endurance athletes, the eyes are also a portal to the brain’s inner workings. Using the example of a ten-mile running road race, let’s take a journey through the eyes of a competitor’s brain. The challenge for our fictional runner is to finish the race in just under eighty minutes, a decision based on his MAF Test results (data), course terrain (data), past race experience (memory), and overall general feelings (emotional).

Throughout the race, the brain will monitor the body’s activity through messages sent by nerves informing the brain about muscle balance (physical capability), terrain (up and down hills), fat and sugar burning (energy availability), body temperature (a reflection of metabolism), foot stress (influence of shoes and road conditions), pain (emotion), and many other factors such as heart and breathing rate. These factors provide the brain with sufficient information to create a highly effective race strategy.

Even before the gun sounds, our runner’s body and brain are continuously sending messages back and forth in preparation for the event. If he goes out too fast, his brain will make the appropriate changes to slow down, both consciously, when he hears the first mile split, and subconsciously (by reducing muscle power to slow him down).
After the second mile, the brain slows the pace because it has determined that the current speed is too difficult to maintain. As the gravitational stresses fluctuate with the uphills and downhills, continuous adjustments are made with pace, muscle function, and energy needs. Perhaps he is checking splits with a watch, consciously and subconsciously estimating a finishing time.

By mile five, the halfway mark, the brain assesses where he is in relation to the finish line and what it will take to maintain current pace. This includes reserving the energy and physical capability. But subtle muscle imbalance that previously existed is now worsening with the physical and metabolic stresses of the first five miles. The brain has been noticing these changes, and now knows it must make take action. It sends messages from the motor cortex down through the spinal cord to create the most effective compensation for the reduced power output of certain muscles by providing more contraction to other muscle fibers. This is accompanied by adjustments in fuel use, attempting more fat burning to conserve sugar. The result of these neurological adjustments is that the pace is slightly reduced.

By mile seven, the body’s fuel gauges indicate a problem—there is still too little energy coming from fat and too much from sugar. This imbalance has caused a slight reduction in blood sugar with too much glycogen use. This complication resulted from trying to keep pace with nearby runners up a hill in mile six—an emotional situation the brain must now adapt to. Because of these metabolic changes, the mile seven pace must be adjusted downward. Also, dehydration has caused too much of an increase in body temperature and water must be consumed; our runner also pours water on his head for added cooling. As a result of these effective adjustments, he recovers and runs mile eight at a slightly quicker pace.

Now that the finish line is mentally within his reach, adjustments are made near mile nine. These include making conscious decisions to continue quenching thirst (which prevents too much dehydration and controls rising temperatures), factoring in pain tolerance (accepting the discomfort knowing the race will soon end), adjustment of breathing (a bit deeper), and slightly shortening stride length to cut down on physical stress. All this takes place while the brain continues adapting from moment to moment to all the other physical, chemical, and mental requirements, including muscle balance, energy production, and stress control.

During the last mile, if his brain and body coordination was successful throughout the race, he has an increased pace and finds himself crossing the finish in reasonably good shape, perhaps with a stronger kick at the end. If not, he becomes a wounded warrior, limping erratically through the final painful mile. Or worse, he collapses before the finish line because his brain has shut the body down to prevent serious damage. Consider Julie Moss in the February 1982 Hawaii Ironman race—she was forced to crawl those last few feet.

This continuous back-and-forth communication between the brain and body during the race comes with another interesting feature: trial and error. This is due to the brain’s periods of “uncertainty” where it must make a particular physiological adjustment during a race, then wait to gauge the result. For instance, if, during mile seven the brain determines that the blood sugar levels are dropping too low, some physical adjustments are made—perhaps reducing muscle contraction to conserve sugar, which slows the pace, or converting more glycogen to glucose. Then the brain may have to wait again to see if these changes improved blood sugar; if not, it considers what other changes may be necessary, such as further slowing or even stopping at the water station. But while the brain is preoccupied with such activities, all this compensation can take away from better performance by using up more energy, ultimately slowing one’s finishing time. Over the years, I have noticed that experienced athletes who are healthier physically, chemically, and mentally can maintain better pacing through a long event with less of the brain’s trial and error periods, which can also increase wear and tear, contribute to injury, and slow recovery.

Stay tuned for more excerpts from “The Big Book of Endurance Training and Racing” by Dr. Phil Maffetone