by Erik Dalton Ph.D.

Sports activities have become a regular way of life for many today and involve people from all age groups. From those with an avid interest, to those who just wish to keep fit… from elite professionals, to casual participants, all are at risk for cumulative trauma disorders.

Many injuries such as tennis elbow, piriformis syndrome, and ‘pulled’ hamstrings result from overuse, i.e. playing too hard and too often, not warming up properly beforehand or warming down after exercise (Fig. 1). Overuse injuries, otherwise known as cumulative trauma disorders, are described as tissue damage that results from repetitive demand over the course of time. The term refers to a vast array of diagnoses, including occupational, recreational, and habitual activities. The pathophysiology of overuse injuries is based on the idea that tissues adapt to the stresses placed on them over time as fully discussed in “Human Silly Putty”.

These stresses include shear, torsion, compression, impingement, vibration, and contraction. Mechanical fatigue within tendons, ligaments, nerves, and other soft tissues results in characteristic changes depending on their individual properties. This fatigue leads to adaptations and compensations throughout the body.

Sports Injury
Ischemic Nerve Damage

Reduced joint flexibility will affect the degree of performance and may result in injury if the player is unaware that they cannot perform to the same level as they used to. Such examples include the golfer who cannot turn at the waist as well as before or the enthusiastic, yet aging, football player whose knees do not bend as well as they once did.

As the tissues attempt to adapt to the demands placed on them, they can incur injury unless they have appropriate time to heal. The rate of injury simply exceeds the rate of adaptation and healing in the tissue. Evidence also suggests that chemical mediators are involved in the initiation and propagation of overuse injuries. For example: In disorders such as piriformis and thoracic outlet syndromes, nerve tissues are at particular risk for ischemic injury (Fig 2). Compression, nerve entrapment and eventual loss of blood supply leads to characteristic changes in the nerve itself. The length of time a tissue can survive oxygen deprivation varies, but eventually, all ischemic tissue becomes necrotic (Fig. 3). Restoration of blood supply should minimize the damage, but not always. The timeline generally begins with subperineurial edema, followed by thickening of the perineurium, thickening of the internal and external epineurium, thinning of the peripheral myelin, and, eventually, as the nerve breaks down… axonal degeneration.

Brachial layered

Overuse injuries in runners are a good example of the athlete’s strenuous interaction with the environment. Problems can arise from either the environment (extrinsic factors) or the individual’s biomechanics (intrinsic factors). Immediate treatment will include modifications of training and improvements in muscle balance – stretching of tight muscles and strengthening of weakened areas. For long-term improvement, biomechanical alignment problems will need to be addressed. Failure to recognize these intrinsic complicating factors will result in a client/patient with recurring pain and compensation. A comprehensive approach to rehabilitation of injuries provides the best hope for many years of recreational enjoyment.

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Erik Dalton, Ph.D., shares his broad therapeutic background in massage, Rolfing and osteopathy through innovative pain-management workshops, books and videos. Developer of the Myoskeletal Alignment Techniques and fbunder of the Freedom From Pain Institute, Dalton is dedicated to research and treatment of chronic pain conditions. Freedom From Pain Institute workshops and home-study courses are approved by the National Certification Board for Therapeutic Massage and Bodywork, the Florida Board of Health and most state certifiing agencies. Visit to subscribe to free monthly pain-management newsletters.