Regardless of the goals of a resistance exercise program and the types of exercises prescribed and implemented, the exercises must not only be effective but safe. The therapist’s interpretation of the examination’s findings determine the exercise prescription. Awareness of precautions maximizes patient safety. General precautions for resistance training are summarized below.
General Precautions During Resistance Training
• Keep the ambient temperature of the exercise setting comfortable for vigorous exercise. Select clothing for exercise that facilitates heat dissipation and does not impede sweat evaporation.
• Caution the patient that pain should not occur during exercise.
• Do not initiate resistance training at a maximal level of resistance, particularly with eccentric exercise to minimize delayed-onset muscle soreness (DOMS). Use light to moderate exercise during the recovery period.
• Avoid use of heavy resistance during exercise for children, older adults, and patients with osteoporosis.
• Do not apply resistance across an unstable joint or distal to a fracture site that is not completely healed.
• Have the patient avoid breath-holding during resisted exercises to prevent the Valsalva maneuver; emphasize exhalation during exertion.
• Avoid uncontrolled, ballistic movements as they compromise safety and effectiveness.
• Prevent incorrect or substitute motions by adequate stabilization and an appropriate level of resistance.
• Avoid exercises that place excessive, unintended secondary stress on the back.
• Be aware of medications a patient is using that can alter acute and chronic responses to exercise.
• Avoid cumulative fatigue due to excessive frequency of exercise and the effects of overtraining or overwork by incorporating adequate rest intervals between exercise sessions to allow adequate time for recovery after exercise.
• Discontinue exercises if the patient experiences pain, dizziness, or unusual or precipitous shortness of breath.
Some of these precautions are found below. Special considerations and precautions for children and older adults who participate in weight-training programs are addressed on another chapter.
Valsalva Maneuver. The Valsalva maneuver (phenomenon), which is defined as an expiratory effort against a closed glottis, must be avoided during resistance exercise. The Valsalva maneuver is characterized by the following sequence. A deep inspiration is followed by closure of the glottis and contraction of the abdominal muscles. This increases intra-abdominal and intrathoracic pressures, which in turn forces blood from the heart, causing an abrupt, temporary increase in arterial blood pressure.
During exercise the Valsalva phenomenon occurs most often with high-effort isometric and dynamic muscle contractions. It has been shown that the rise in blood pressure induced by an isometric muscle contraction is proportional to the percentage of maximum voluntary force exerted. During isokinetic (concentric) testing, if a patient exerts maximum effort at increasing velocities, the rise in blood pressure appears to be the same at all velocities of movement despite the fact that the force output of the muscle decreases. Although occurrence of the Valsalva phenomenon more often is thought to be associated with isometric and eccentric resistance exercise, a recent study indicated that the rise in blood pressure appears to be based more on extent of effort – not strictly on the mode of muscle contraction.
The risk of complications from a rapid rise in blood pressure is particularly high in patients with a history of coronary artery disease, myocardial infarction, cerebrovascular disorders, or hypertension. Also at risk are patients who have had neurosurgery or eye surgery or who have intervertebral disc pathology. High-risk patients must be monitored closely.
Substitute Motions. If too much resistance is applied to a contracting muscle during exercise, substitute motions can occur. When muscles are weak because of fatigue, paralysis, or pain, a patient may attempt to carry out the desired movements that the weak muscles normally perform by any means possible. For example, if the deltoid or supraspinatus muscles are weak or abduction of the arm is painful, a patient elevates the scapula (shrugs the shoulder) and laterally flexes the trunk to the opposite side to elevate the arm. It may appear that the patient is abducting the arm, but in fact that is not the case. To avoid substitute motions during exercise, an appropriate amount of resistance must be applied, and correct stabilization must be used with manual contacts, equipment, or by means of muscular (internal) stabilization by the patient.
Overtraining and Overwork. Exercise programs in which heavy resistance is applied or exhaustive training is performed repeatedly must be progressed cautiously to avoid a problem known as overtraining or overwork. These terms refer to deterioration in muscle performance and physical capabilities (either temporary or permanent) that can occur in healthy individuals or in patients with certain neuromuscular disorders.
In most instances, the uncomfortable sensation associated with acute muscle fatigue induces an individual to cease exercising. This is not necessarily the case in highly motivated athletes who are said to be overreaching in their training program or in patients who may not adequately sense fatigue because of impaired sensation associated with a neuromuscular disorder.
The term overtraining is commonly used to describe a decline in physical performance in healthy individuals participating in high-intensity, high-volume strength and endurance training programs. The terms chronic fatigue, staleness, and burnout are also used to describe this phenomenon. When overtraining occurs, the individual progressively fatigues more quickly and requires more time to recover from strenuous exercise because of physiological and psychological factors.
Overtraining is brought on by inadequate rest intervals between exercise sessions, too rapid progression of exercises, and inadequate diet and fluid intake. Fortunately, in healthy individuals, overtraining is a preventable, reversible phenomenon that can be resolved by tapering the training program for a period of time by periodically decreasing the volume and frequency of exercise (periodization).
The term overwork, sometimes called overwork weakness, refers to progressive deterioration of strength in muscles already weakened by nonprogressive neuromuscular disease. This phenomenon was first observed more than 50 years ago in patients recovering from polio who were actively involved in rehabilitation. In many instances the decrement in strength that was noted was permanent or prolonged. More recently, overwork weakness has been reported in patients with other nonprogressive neuromuscular diseases, such as Guillain-Barre syndrome. Postpolio syndrome is also thought to be related to long-term overuse of weak muscles.
Overwork weakness has been produced in laboratory animals, which provides some insight to its cause. When strenuous exercise was initiated soon after a peripheral nerve lesion, the return of functional motor strength was retarded. It was suggested that this could be caused by excessive protein breakdown in the denervated muscle.
Prevention is the key to dealing with overwork weakness. Patients in resistance exercise programs who have impaired neuromuscular function or a systemic, metabolic, or inflammatory disease that increases susceptibility to muscle fatigue must be monitored closely, progressed slowly and cautiously, and re-evaluated frequently to determine their response to resistance training. These patients should not exercise to exhaustion and should be given longer and more frequent rest intervals during and between exercise sessions.
Exercise-Induced Muscle Soreness. Almost every individual unaccustomed to exercise who begins a resistance training program, particularly one that includes eccentric exercise, experiences muscle soreness. Exercise-induced muscle soreness falls into two categories: acute and delayed onset.
1. Acute Muscle Soreness. Acute muscle soreness develops during or directly after strenuous exercise performed to the point of muscle exhaustion. This response occurs as a muscle becomes fatigued during acute exercise because of the lack of adequate blood flow and oxygen (ischemia) and a temporary buildup of metabolites, such as lactic acid and potassium, in the exercised muscle. The sensation is characterized as a feeling of burning or aching in the muscle. It is thought that the noxious metabolic waste products may stimulate free nerve endings and cause pain. The muscle pain experienced during intense exercise is transient and subsides quickly after exercise when adequate blood flow and oxygen are restored to the muscle. An appropriate cool-down period of low-intensity exercise (active recovery) can facilitate this process.
2. Delayed-Onset Muscle Soreness. After vigorous and unaccustomed resistance training or any form of muscular overexertion, delayed-onset muscle soreness (DOMS), which is noticeable in the muscle belly or at the myotendinous junction, begins to develop approximately 12 to 24 hours after the cessation of exercise. As was already pointed out in the discussion of concentric and eccentric exercise in this chapter, high-intensity eccentric muscle contractions consistently cause the most severe DOMS symptoms. Below is a list of the signs and symptoms over the time course of DOMS. The DOMS sensation usually intensifies and peaks 24 to 48 hours after exercise. Although the time course varies, the signs and symptoms, which can last up to 10 to 14 days, gradually dissipate.
Pathological Fracture. When a patient with known (or at high risk for) osteoporosis or osteopenia participates in a resistance exercise program, the risk of pathological fracture must be addressed. Osteoporosis is a systemic skeletal disease characterized by reduced mineralized bone mass that is associated with an imbalance between bone resorption and bone formation, leading to fragility of bones. In addition to the loss of bone mass, there is also narrowing of the bone shaft and widening of the medullary canal.
The changes in bone associated with osteoporosis make the bone less able to withstand physical stress. Consequently, bones become highly susceptible to pathological fracture. A pathological fracture (fragility fracture) is a fracture of bone already weakened by disease that occurs as the result of minor stress to the skeletal system. Pathological fractures most commonly occur in the vertebrae, hips, wrists, and ribs. Therefore, to design and implement a safe exercise program, a therapist needs to know if a patient has a history of osteoporosis and, as such, an increased risk of pathological fracture. If there is no known history of osteoporosis, the therapist must be able to recognize those factors that place a patient at risk for osteoporosis. Postmenopausal women, for example, are at high risk for primary (type I) osteoporosis. Secondary (type II) osteoporosis is associated with prolonged immobilization or disuse, restricted weight bearing, or extended use of certain medications, such as systemic corticosteroids or immunosuppressants.
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