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Managing Muscle Fatigue, Part 2: Build a faster, fatigue-resistant body and brain

By May 1, 2015August 18th, 2020Exercise

Read Part 1

Almost everyone feels muscle fatigue. Normally, it can be noticed during a race, hard training session, or a long workout. But if pushed too much we feel the consequence of excess fatigue as more severe soreness or pain, muscle imbalance producing a joint that hurts, or the inability to properly recover.

The real feeling of muscle fatigue may come from various levels of pain more than any other single sensation or movement. The brain interprets pain in an area called the limbic system—the emotional center. The idea of pain as an emotion is not new, and the symptom of excess fatigue is usually quite real. Our awareness of the problem in the brain allows our neurons to compensate for normal fatigue by improving fitness, or excessive fatigue by correcting related problems.

The brain can also teach our sometimes stubborn conscious mind to avoid unhealthy training and racing, take adequate time to recover, and other healthy habits that help build fitness. This is referred to as intuition or instinct.

In a race, the brain uses the feeling of fatigue as a key regulator to insure that the event is completed as fast and successfully as possible, and without excessively damaging the body.

So the primary factor controlling muscle fatigue is the brain. All other features discussed in Part 1, from cardiovascular function and oxygen, to lactate and energy, are secondary.

Dr. Timothy Noakes, in his writings about the importance of the athletic brain, states that, “the ultimate control of exercise performance resides in the brain’s ability to vary the work rate and metabolic demand by altering the number of skeletal muscle motor units recruited during exercise.” For many years, Noakes has discussed the physiological and emotional mechanisms, both unconscious and conscious, of muscle fatigue.

Training the Brain

If the brain is this important in sports performance, which it is, how can we train it? All athletes can improve the brain for better performance by stimulating the full spectrum of aerobic muscle fibers—the bulk of muscle in the human body. A unique feature of these muscles is that they are fatigue-resistant. They can function at very high levels for hours, or if necessary, all day long and even well into the night.

In addition, almost all endurance race energy comes from the aerobic system, which is under the guidance of the brain. These muscle fibers also support the physical body to correct and prevent injury, help antioxidant function to maintain better immunity and speed recovery, improve circulation, and significantly increase the amount of fat burned for fuel, reducing stored body fat.

But even more important, training the entire aerobic system has a powerful therapeutic affect on the brain. It is an incredible physiological cycle, and those who maintain it well come closer to their athletic potential.

The Neuromuscular Mechanism

Every step you take starts with the brain sending messages to specific muscle fibers throughout the body to either contract or relax. In turn, and almost immediately, messages from each muscle fiber are sent to the brain with information about its status. In addition to the creation of physical movement and other aerobic benefits, this mechanism increases the brain’s blood circulation (brining in oxygen and other nutrients), stimulates the growth of new neurons (brain cells), and improves communication between cells. New neurological pathways between the brain and body are produced. The result is that you can build a better brain that takes care of your athletic body more effectively. And it does not take much: Just a slow jog with proper warm up and cool down can do this, and actually increase the size of the brain.

In addition to making movements more efficient, including improved balance and a better gait, the brain can benefit in more amazing ways. These include improvement of those areas associated with memory, cognition, social function, speech, hearing, behavior, and learning.

In order to train the full spectrum of aerobic muscle fibers, and its counterpart in the brain, an effective warm up and cool down, as described in “The Big Book of Endurance Training and Racing,” is vital. This might mean spending a bit of time walking at the onset of a workout, and at the very end of it, to stimulate those muscles that move the body easily—otherwise, the full spectrum of aerobic fibers may not be trained. I recommend this routine regardless of the level of ones fitness.

It also means being serious and disciplined—and honest—about following a heart rate that helps keep the workout truly aerobic (see The MAF 180 Formula). In addition, rather than guessing your aerobic system is being properly trained, the MAF test is an important monthly evaluation that more objectively measures these changes.

It does not take long for these changes in the brain to occur—in fact, they begin during your very first high quality workout. And as the months pass the many physical changes that occur in the brain—and they can be significant—continue with each training session.

Performance and the Brain

Effective racing involves pacing. I don’t mean the mental strategy that involves our competitors, but rather, how the brain budgets muscle energy in our own body on a moment-to-moment basis. This helps create the ideal performance.

The sum total of all our physical experiences is recorded in the brain—a mechanism referred to as muscle memory. So not just any workout will do. Efficient training helps build a better brain leading to optimal performance. One of the best lessons about the athlete’s brain can be found in a quote by Green Bay Packers’ legendary coach Vince Lombardi: “Practice does not make perfect. Only perfect practice makes perfect.” Optimal training is perfect practice, and it teaches the brain how best to perform.

Performance is a combination of many factors, which when not working well can cause excess muscle fatigue. Only when muscle fatigue is managed well can performance improve consistently and for a longer time. Training, nutrition, and stress are three key lifestyle factors that could either help the brain effectively manage fatigue, or not. Let’s look at each topic.

1. Training is obviously a key factor for optimal performance, and is associated with how the muscles are treated during physical activity. Minimizing fatigue is important, whether we are training for endurance, or strengthening bones and muscles. Yet, without stressing the body sufficiently, no training effect will occur. It is a question of balancing the quality of the workout or race, and the ability to recover from it. My traditional training equation is one that athletes should post in a prominent place where it can be seen everyday: Training = workout + recovery.

By far the most common mistake by athletes is too much training (intensity and or duration), too little recovery (rest), or both. This results in excess muscle fatigue and brain function that is below par.

2. Nutrition is another key factor for optimal muscle, brain and race performance. This means eating the optimal diet for your needs. It starts by avoiding all junk food, including refined carbohydrates, fast food and other harmful items.

Muscles are continuously replacing old parts, so to speak, especially between workouts as part of the repair and recovery process. The building materials needed these activities come from our diet. Along with all the vitamins and minerals, protein is particularly important to improve training and racing tolerance in muscles.

Oxidative stress is associated with muscle fatigue, both at rest, and during physical activity. The aerobic muscle fibers utilize anti-oxidant nutrients for optimal function, including prevention of excess fatigue. Essentially, almost any nutrient is important for our anti-oxidant system, not just vitamins C and E, and others touted in ads. The best source of these substances is a healthy diet that includes 10 servings of fresh vegetables and fruits. Some of the more powerful foods include blueberries, blackberries, apples, and beets, spinach and kale. However, supplements of antioxidants may not only be ineffective, but can worsen oxidative stress.

Healthy fats are important too. In addition to the brain being 60 percent fat, this macronutrient regulates the body’s inflammatory mechanisms, which can dramatically increase muscle fatigue.

Another factor associated with muscle fatigue is the increased levels of the brain’s neurotransmitter serotonin. This chemical rises with the intake of high carbohydrate foods, and is reduced with the consumption of more complete protein.

3. Stress regulation is another key aspect of great performance in the brain and body. It’s simple: too much stress can increase muscle fatigue. The most obvious example is overtraining, which leads to poor muscle recovery, excess fatigue, and reduced performance.

Stress can be external, such as a bad job or relationship, overtraining, or poor diet, or internal, such as blood sugar impairments, mental or emotional strain, or poor training and racing strategies. In all stress situations, it’s the brain that must deal with it. When successful, stress won’t defeat us. But if not, our brain sends messages to the pituitary gland, and the adrenal glands, to try adapting. Muscle fatigue and other impairments, electrolyte imbalance (sodium deficiency), poor water regulation, and other problems result. In particular, the rise in the stress hormone cortisol reduces other hormones such as testosterone, which increases muscle fatigue. (Long training session greater than two hours can also reduce testosterone levels.)

With balanced training, diet and stress control, increased aerobic function, and a better brain, not only is muscle fatigue significantly reduced, but performance improves.

In Part 3 of this series, I will have a checklist to further help you manage muscle fatigue.