According to Michael Boyle, author of “Advances in Functional Training,” most injuries in sports seem to be caused by very common muscle imbalances. Injuries tend to occur when stabilizing muscles are weak and fail to neutralize the stress placed on a joint and its structures. Moreover, whenever there is an imbalance between opposing muscle groups, the body tends to recruit other muscles in an attempt to stabilize the forces in the particular region. The problem is that those muscles were not designed for this function and won’t be able to do a good job, which allows some of the stress to be placed on joints, tendons and ligaments. As this abnormal muscle activation becomes frequent, it alters the relationship between the opposing muscles, affecting posture, body alignment, and movement patterns.
Muscle imbalances often happen because most people tend to emphasize certain body parts and overlook others when exercising. It is very common among athletes and recreational exercisers to over-develop the muscles of the chest, quads (front part of the thighs), and superficial abdomen (the “six-pack” muscle), while ignoring upper-back, hamstrings (back part of the thighs), glutes, and deep abdominal muscles. These disparities put a considerable amount of stress on the shoulders, knees, and lower-back regions, which sooner or later will become a painful condition.
Low-back Pain
It is estimated that nearly 80% of the adult population suffers from low-back pain, and that 6% to 15% of athletes experience low-back pain at some point in their career. Low-back pain is usually caused by weakness of the deep abdominal muscles (transverse abdominals and internal obliques). The problem is that when people think of training the abdominals, they often think of performing an infinite number of crunches. While crunches can develop the “six-pack” muscle, they are not functional exercises and won’t target the deep stabilizer muscles. To strengthen the deep abdominals, you must use them as they were designed for: as stabilizers. Great exercises for this purpose are body-weight squats and planks.
Knee Injuries
Knee injuries account for more than 50% of injuries among high school and college athletes; the knee is one of the most commonly injured regions of the body. Interestingly, 70% to 75% of these injuries occur during noncontact events. This means that muscle imbalances are the real culprit. Generally, knee problems are due to weak hip stabilizers, i.e., gluteus medius, hip adductors, quadratus lumborum, and hip external rotators. When the hip stabilizers are not strong enough to counteract the action of their antagonists (muscles that work in opposition with them), misalignments occur, altering static posture, joint function, and mobility. Stress is placed on the knee joint, which can contribute to ligament tears and overuse of the knee cartilage or menisci. To prevent injuries, it is important to incorporate in your routine exercises to strengthen the lower back (quadratus lumborum), inner thighs (hip adductors) and outer thighs (gluteus medius and external rotators of the hips).
Shoulder Issues
Approximately 21% of the general population complains of shoulder pain. Shoulder impingement (compression of the structures in the shoulder joint) is the most prevalent diagnosis. Shoulder impingement is an issue involving the rotator cuff group, small muscles attached to the head of the humerus (upper arm bone) that are responsible for stabilizing the shoulder joint. The problem is that those are tiny muscles that depend on the superficial larger muscles to do their job. Whenever there is an imbalance between the muscles of the front and back part of the shoulders, the rotator cuff muscles are placed under stress. The most common imbalance happens when the upper chest and front shoulder muscles are stronger than the upper back muscles (shoulder retractors), pulling the shoulders forward. Weakness of the scapula retractors (muscles that pull the shoulder blades close together) alters the joint movement pattern, decreasing the activation of the rotator cuff muscles, which reduces stabilization and leads to muscle impingement. Preventive exercises that strengthen these muscles include horizontal rows and chest stretches.
References
Boyle, M. Advances in Functional Training. Santa Cruz, CA: On Target Publications. 2010.
Clark, M. et al. NASM Essentials of Corrective Exercise Training. Baltimore, MD: Lippinicott Williams & Wilkins. 2011.