Determine the correct treatment plan for muscles and tissues exposed to unusual stress levels
The structure of muscles and connective tissues is such that they respond and adapt to the usual amount of stress exposure. Damage occurs when the muscle or connective tissue is exposed to higher than usual stress levels. This can be a single, sudden excessive stress, or the result of repetitive stress to the muscle or ligament. In either case, DCs must determine how the damage occurred, and then make appropriate recommendations to help the body heal the injury and to prevent a recurrence.
Problems can also develop when these tissues are not exposed to sufficient regular stress to maintain functional health. It is important to recognize that there is a continuum or spectrum of usual stress to the tissues in the body, and that categorizing a patient’s level of use helps in the planning of treatment and rehabilitation programs.
Within Range
What we usually consider to be normal use is in the mid-range of the use continuum.
Paralysis. At one far end is paralysis, when the skeletal muscles and ligaments are completely unused. When the muscles and ligaments are not used, their functional properties rapidly diminish. The combination of muscle atrophy and ligament stiffening produces joints that do not function smoothly or easily. In some cases, the complete lack of use causes calcium to infiltrate into the soft tissues, resulting in heterotopic ossification.3
Immobilization. Close to paralysis is immobilization, such as in a cast or with bedrest. The difference is that paralysis lacks a neurological stimulus, called tone, which is present in immobilized (yet still neurologically intact) muscles and skeletal ligaments.1
When a joint or extremity has been immobilized, atrophy sets in rapidly. The muscles shrink and the ligaments get stiffer and weaker. Within a month, an immobilized muscle will lose up to one half its normal size.4 After just 1 week of immobilization, there is a 20% decline in muscle strength.5 Ligaments that have been immobilized for 2 months are found to have only about half of their functional strength and resistance to stretch and injury.6
Sedentarism. Next is sedentarism, which is when the ligaments and muscles are used only minimally. Unfortunately, this condition is becoming more common among all age groups because of many labor-saving devices.2 In today’s society, we are able to avoid most physical efforts that were previously necessary to put food on the table and keep our homes warm. Most of our patients no longer have to perform any significant physical labor, which results in several problems: overweight, deconditioning, hypertension, and poor fitness.
One in three Americans is clinically obese (defined as 20% or more above normal weight), and more than half are overweight.7 This new reality causes problems for chiropractors who attempt to return patients to all capabilities; they find that many of their patients are too out of shape to maintain normal spinal function. Among other terms, this condition has very appropriately been called the disuse syndrome.8
Normal use. Normal use can vary widely, but requires the intermittent and regular exercise and use of all muscles and ligaments. Throughout most of our existence, humans have needed to perform a variety of physical activities every day. Some strength was needed, as was a certain amount of flexibility and endurance. This began to change when the Industrial Revolution required certain repetitive movements, and now has been modified by our labor-saving inventions over the past century.
Strenuous use. Those who are employed in active (usually blue collar) jobs and people who engage in regular, active recreational pursuits fall into the strenuous use category.
By exercising regularly and participating in recreational sports, some patients work their connective tissues and muscles harder than most. Some occupations place more than the usual stress on the feet, legs, and spine of some patients. This is beneficial, as long as the use does not exceed the body’s response to the stress. However, these are the patients who are susceptible to repetitive injuries, due to ongoing, stressful use, which eventually overcomes the ability to strengthen muscle and ligaments.
Progressive overload. Then there are athletes, who are always trying to improve and push their limits by specifically building and strengthening their muscular and skeletal ligament tissues. They are at the far end of the continuum, demonstrating the body’s response to progressive overload.
Athletes who push their bodies to continuously improve their performance take advantage of our innate ability to respond to stress by building strength. In response to gradually increasing loads, the muscles and ligaments strengthen and improve their function.9 Many factors, such as reps, sets, daily/weekly training frequency, and competition schedule, must be considered when designing and implementing these types of programs, so that injury can be avoided.10
Less Is More
The muscles and ligaments in any of the categories can be overused and damaged. Less stress is needed to cause injury to tissues in the less-active end of the continuum. After several days of immobilization, or when someone has been on bedrest or is a couch potato, even mildly strenuous effort can be too much. Fitness protects from some injuries, especially overuse conditions of the spine. Athletes who regularly push their muscles and ligaments most likely end up with either overuse or acute injuries. There are two major categories of excessive stress to ligaments and muscles—repetitive use (chronic, over time), and sudden injury (strain or sprain) with tissue tearing.
With repetitive overwhelming, the physical stress occurs so frequently that this process is overcome, resulting in damage. For example, runners who quickly increase their mileage, workers placed in a new position requiring repetitive movement or bending, and athletes throwing to the point that they injure their shoulders. Even someone taking up walking after years of standing on rigid flooring can quickly overwhelm the foot’s ability to strengthen, developing plastic deformation of the plantar fascia with arch collapse.
Trauma to a ligament or muscle is a single episode of stress that causes damage. When a muscle or ligament is torn, there is immediate pain, followed by swelling and loss of function. Around the spine, this is often a complex injury, since it is inevitable that several layers of both muscles and connective tissues are damaged (a strain/sprain injury). Understanding of the healing response is necessary for good management of acute injuries to muscles and ligaments, wherever their location.
Healing Response
Whether damaged by repetitive overuse or by acute injury, muscles and ligaments will heal rapidly and completely when they are treated properly. A brief period of relative rest is important; the amount depending on the extent of injury. This may require 1 to 4 days of immobilization of the damaged region, followed by gradual reintroduction of movement and activity.11 Then, rehabilitation is necessary, which usually requires specific exercise instruction and expert guidance. The patient should be encouraged to return to the level of pre-injury, and then advised on preventing further injury, either by providing additional response time or by improving muscle strength and balance (or both). Occasionally, ligaments become damaged and deformed to the point that full repair is not possible. In these cases modification of stress may be necessary, either through changes in activities or the use of supports, such as knee braces or custom orthotics.
It is vitally important to understand the status of a patient’s muscle and con nective tissues prior to injury. It is also necessary to realize how these tissues became overwhelmed: Was it an acute injury, or can a history of repetitive insult be elicited? Once the doctor of chiropractic has the information for the start point and an understanding of the method of stress damage, the treatment can proceed rapidly. CP
Kim D. Christensen, DC, CCSP, DACRB, CSCS, founded the SportsMedicine & Rehab Clinics of Washington. He is a team physician to high school and university athletic programs, a postgraduate faculty member at numerous chiropractic colleges, president of the ACA Rehab Council, and a lecturer and the author of many musculoskeletal rehabilitation and nutrition texts. He can be reached via email: kimdchristensen@hotmail.com.
References
1. Resnick D, Niwayama G. Diagnosis of Bone and Joint Disorders. 2nd ed. Philadelphia: WB Saunders; 1988:3127.
2. Schafer RC. Clinical Biomechanics: Musculoskeletal Action and Reactions. 2nd ed. Baltimore: Williams & Wilkins; 1987:163.
3. Guyton AC. Textbook of Medical Physiology. 5th ed. Philadelphia: WB Saunders; 1976:145.
4. Noonan TJ, Garrett WE. Muscle strain injury: diagnosis and treatment. J Am Acad Orthop Surg. 1999;7:262–269.
5. Noyes FR. Functional properties of knee ligaments and alterations induced by immobilization. Clin Ortho Rel Res. 1977;123:210–242.
6. Tudor-Locke CE, Myers AM. Challenges and opportunities for measuring physical activity in sedentary adults. Sports Med. 2001;31(2):91–100.
7. Update: prevalence of overweight among children, adolescents, and adults—United States, 1988-1994. MMWR Morbid Mortal Weekly Report. 1997;46:199–202.
8. Bortz WM II. The disuse syndrome. West J Med. 1984;141:69–-694.
9. Frank C, Amiel D, Woo SL, Akeson W. Normal ligament properties and ligament healing. Clin Orthop. 1985;196:15–25.
10. Baechle TR. Essentials of Strength Training and Conditioning. Champaign, Ill: Human Kinetics; 1994.
11. Jarvinen MJ, Lehto MUK. The effects of early mobilisation and immobilisation on the healing process following muscle injuries. Sports Med. 1993;15:78-89.
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