Muscle Imbalance As a Cause of Fatigue

Another cause of fatigue is muscle imbalance, which usually occurs from the brain-muscle connections rather than from exercise-related issues of power and strength. To understand this better, let’s differentiate between normal and abnormal muscle tensions. In the course of normal activity, muscles become tight as they contract, and more loose when relaxed. When there is an imbalance, muscles become too tight (almost like a spasm) and abnormally loose (often called “weak”). This state of abnormal tightness and weakness is termed muscle imbalance. But it has nothing to do with muscle power, as even a very strong muscle can be out of balance.

Once created, muscle imbalance can persist for weeks, months, or years. The cause may have been an injury from a fall, trauma directly to the muscle, over-stretching, or overuse. But in many cases an athlete may not recall any event that would have caused a problem because it was subtle. And, the severity of the original injury is often not related to level of disability. Therefore, serious chronic pain could be due to a relatively minor muscle imbalance caused by some seemingly minor trauma.

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The most common cause of muscle imbalance is for a muscle to become weak, while another muscle, or muscles, becomes tight. This pattern of weak and tight can occur anywhere in the body, on the front and back of the arm, thigh, leg, foot, or other areas. The result is reduced and abnormal body movements reducing overall function, especially in the joints. Despite little or no sensation of muscle imbalance in its early stages, the problem often leads to pain and disability. Muscle imbalance can contribute to significant physical stress such as increased wear and tear on joints, ligaments, and other muscles, and reduces efficiency of physical movement.

Other causes of muscle imbalance include the excess wear and tear of training and competition, inadequate recovery (lack of proper rest), and trauma. Poorly fitting sports shoes can also cause muscle imbalance due to micro-trauma as discussed in detail later. And, muscle imbalance itself can predispose an athlete to further muscle problems and injury.

The brain compensates for muscle imbalance to prevent further damage by increasing the workload of other muscles. So a variety of imbalances can cause many muscles to work much harder than when the muscles are balanced. All of this requires extra energy, which is taken away from performance efforts. The end result is slower physical activity, reduced efficiency of movement (especially important for sports requiring eye-hand coordination), and increased risk for further injury. Because of the added stress on joints, muscles, and other areas, the brain receives more messages regarding body stress, adding to reduced activity and fatigue.

In other words, simple muscle imbalance can cause the body to use more energy to accomplish the same or less work—so without the muscle imbalance more energy would be available for performance. This can be significant in running, cycling, swimming, and activities that require long and sustained movements.

Another way to look at the problems muscle imbalance causes is to consider the cost in terms of oxygen use and heart rate. A hip problem (most are due to muscle imbalance), for example, which can have significant compensation from other large muscles, can dramatically increase oxygen needs—the oxygen cost (the energy required to perform) for activity is directly related to the extent of the athlete’s muscle imbalance. In addition, the heart rate can rise substantially with muscle imbalance, with some studies showing almost a twenty-beat increase! The end result is inefficient movement, a higher cost of energy, and reduced performance.

Another example is a knee problem, also commonly associated with muscle imbalance. In most athletes, these problems are usually not associated with an isolated muscle imbalance around the knee. Instead, there are often various other muscle imbalances directly or indirectly related to knee mechanics, often taking place in the foot. The sum total of all muscle imbalances requires an increased effort by the athlete, which can reduce overall performance significantly.

While muscle imbalance is often asymptomatic—the athlete does not always feel the problem—observation of movement (gait) and standing posture will often reveal irregularities caused by muscle imbalance. Throughout my career I traveled to many different sporting events with athletes, with the goal of balancing muscles to help finely tune their neuromuscular system to reduce or eliminate muscle imbalance. This can be accomplished quickly and easily using various methods of manual biofeedback discussed later. Once competition starts, the athlete is biomechanically very balanced and efficient.

In most instances muscle imbalance is self-correcting, just like we heal a cut finger, a bruise, or other common problem. A healthier athlete will correct more of the problems because the body’s various systems function better. However, if the body is unable to correct muscle imbalance, due to insufficient rest or less than adequate health, for example, the imbalance can become chronic.

In addition to a poorly developed aerobic system and muscle imbalance, there are other possible causes of fatigue during training and competition, including illness, such as allergy or asthma, anemia, or dietary insufficiencies.

Many endurance athletes focus too much on training the physical muscles and less on the energy they generate or the hormones or foods that influence them. If a muscle’s physical attribute was the primary element in endurance, then weight lifting would provide more success than any other training technique, but this is not the case. In a sense, the muscle’s physical attributes are just pawns in the endurance game. They are the workhorses, controlled by the brain and dependant on the metabolism that generates energy in the muscle for its action, and other factors, such as hormones that make up our overall metabolism.