Chapter objectives
- •
Differentiate between rehabilitation and physical conditioning.
- •
List the general goals of rehabilitation.
- •
Define and explain the general phases of rehabilitation and the objectives for each phase.
- •
Explain the influence and importance of the neurologic system in rehabilitation.
- •
List and describe the types of therapeutic exercise.
- •
List and summarize the methods of progressive resistive exercise.
- •
Discuss the differences between and implications for using open versus closed chain exercises.
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Discuss strategies of physical conditioning during rehabilitation.
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Explain the parameters of conditioning and rehabilitation.
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Explain the importance of function-based rehabilitation.
This chapter provides an overview of the rehabilitation process and reviews key concepts that need attention during the development of athletic rehabilitation programs. The first part of the chapter begins with a broad definition of rehabilitation and a discussion of the various stages of rehabilitation. Next, key concepts pertaining to the neuromuscular system and motor learning are reviewed. This is followed by an account of the different types of exercise used in the rehabilitation process and considerations for their incorporation into rehabilitation programs. Finally, physical conditioning during rehabilitation and the various parameters pertinent to program progression are discussed. Many of the concepts are explained briefly, and the reader is referred to other specified sources, some located within this text.
Rehabilitation, from the Medieval Latin root word rehabilitare , literally means “to restore to a rank.” From the aforementioned definition, rehabilitation is a broad conceptual term used to describe restoration of physical function. Physical rehabilitation reverses various physical conditions associated with injury or dysfunction.
Rehabilitation is similar to other types of physical conditioning. Essentially, body systems respond to physical stress by undergoing adaptations that ultimately improve their functioning (see the section on conditioning later in this chapter). Rehabilitation is the process of applying stress to healing tissue in accordance with specific stresses that the tissue will face on return to a particular activity. Thus, rehabilitation involves reconditioning injured tissue. When the healing tissue is mature, the emphasis moves to more aggressive conditioning in preparation for the athlete returning to his or her sport.
The physical rehabilitation process often involves many health care professionals, each with their specific role to help the athlete progress through recovery ( Box 4-1 ). Sometimes professional responsibilities overlap, but each plays an active role in the rehabilitation process while working together to meet the many needs of an athlete undergoing physical rehabilitation.
Physician
Athletic trainer
Physical therapist
Nutritionist
Registered nurse
Strength and conditioning specialist
Coach
Clergy
Psychologist
Before implementing a rehabilitation program, the rehabilitation specialist should perform and be familiar with the findings of a thorough physical examination. The physical examination should rule out other pathologic conditions and reveal problems inherent in the athlete’s current physical condition. Clinical decisions regarding the course of rehabilitation depend on adequate information derived from a comprehensive clinical examination. The physical examination should address joint range of motion, muscle flexibility, muscle strength, proprioception, posture, and ambulation and gait patterning, in addition to other specific criteria. Thus, depending on the findings, the rehabilitation program may address multiple problem areas. Box 4-2 lists the key components of a physical examination.
Effective rehabilitation occurs when health professionals coordinate their efforts based on written and verbal communication and documentation. As appropriate, research the medical records to obtain the most accurate picture of an athlete’s condition. Next, make sure to document the athlete’s condition on your examination and frequently record changes in status. This helps other health care providers who may need information at a point later in the rehabilitation process.
- 1.
History (subjective)
- 2.
Examination of specific systems (objective)
- a.
Neurologic: sensation via dermatome assessment, gross strength via myotome assessment, and reflexes
- b.
Musculoskeletal: range of motion/flexibility, strength, coordination, agility, special tests, and functional performance tests
- c.
Cardiopulmonary: respiratory rate, heart rate, and blood pressure
- d.
Integumentary: skin condition, color, and temperature
- a.
- 3.
Assessment
- a.
Problem list, short-term goals (1 to 2 weeks), long-term goals (functional goals), and rehabilitation potential
- b.
Summarizing the evaluation
- a.
- 4.
Plan
- a.
Specifying interventions and the frequency and duration of treatment
- a.
Rehabilitation programs, whether conservative or occurring after invasive procedures, are specifically tailored to an injury or surgical intervention. No matter how specific the rehabilitation is to a particular condition, general physiologic events that occur in response to trauma must be considered (see Chapters 2 and 7 ). Remember that the effectiveness of rehabilitation during the recovery period usually determines the degree and success of future athletic competition. Thus, it is the clinician’s role to optimize the healing environment of the injured tissue and return the athlete to competition as soon as possible without compromising the healing process. At least two foundational goals are applicable to any rehabilitation program: (1) reverse or deter the adverse sequelae resulting from immobility or disuse and (2) facilitate tissue healing and avoid excessive stress on immature tissue. The generic goals of any rehabilitation program are listed in Box 4-3 .
Decrease pain
Decrease the inflammatory response to trauma
Return to full active and pain-free range of motion
Decrease effusion
Return to full muscular strength, power, and endurance
Return to full asymptomatic functional activities at the preinjury level
Incomplete rehabilitation and premature sports re-entry predispose the athlete to reinjury. Figure 4-1 illustrates the body’s response to injury and the result of inadequate rehabilitation.
The cardinal rule of rehabilitation is to avoid exacerbating the athlete’s present condition. The athlete’s pain and tissue responses dictate progression through the various stages of rehabilitation.
General rehabilitation considerations
Specific problems associated with injury include swelling, pain, and muscle spasm. On a positive note, pain and swelling serve to alert the rehabilitation specialist and athlete that tissue damage is present, which facilitates clinical decision making and proper determination of exercise progression. However, the presence of these injury by-products may hinder early therapeutic exercise because of pain and muscle inhibition.
Peripheral Receptor Afferent Activity
Pain is something directly unseen by clinicians, yet we must rely on the patient’s subjective complaint and interpret it according to the nature and time frame of the injury. Pain may be acute, chronic, or persistent. Acute pain occurs soon after the injury and is typically of short duration (matter of days). Acute pain is often a protective response that alerts us that something is wrong. Chronic pain is present for at least 6 months, frequently recurs, and resists alleviation with intervention. It may continue long after the original injury has healed as a result of factors such as altered biomechanics or learned habits of guarding. In a person with chronic pain, the pain may become a dysfunction in itself. Persistent pain, unlike chronic pain, generally occurs with a condition that responds to treatment over a period of time, which is variable according to the condition and the individual’s interpretation of pain (pain threshold). The latter type of pain may have a cognitive-behavioral component that may require counseling or other psychologic intervention.
Controlling existing edema (present in soft tissue outside a joint) and prevention of further effusion (excess fluid inside a joint) are critical in the rehabilitation process for several reasons. Edema increases localized pressure, which compresses sensory nerve endings and contributes to the sensation of pain. Joint effusion increases intraarticular pressure and afferent activity, which contributes to muscle inhibition. In fact, even small increases in fluid in a joint (as little as 10 mL) can produce a 50% to 60% decrease in maximal voluntary contractions of the quadriceps. (See the section on arthrogenic inhibition later in this chapter and in Chapter 2 .)
Rehabilitation adjuncts, such as electrophysical modalities (see Chapter 8 ), are instrumental in controlling and reducing these responses and allowing the athlete to begin early range-of-motion and strengthening exercises. The modality itself, however, is almost never considered the only course of treatment of most athletic injuries. Therapeutic modalities assist the body’s response to inflammation, but most do little to stress healing tissue. An exception is low-intensity ultrasound, which can facilitate the healing process when applied during the granulation phase of healing. Only with therapeutic exercise can the injured body part or parts be restored to their preinjury level through the adaptation process associated with physical activity when prescribed in the correct dosage. Therefore, the injury cycle may continue if therapeutic exercise is not included—or if improperly instituted—within a rehabilitation program.
Furthermore, exercise in the early rehabilitation phases diminishes the adverse effects of disuse or immobility. Athletes can improve their physical condition by training, yet those training responses readily reverse when activity ceases or diminishes, with ill effects becoming evident in as short a time as a few days. Unfortunately, the rate of reversal is much faster than the rate of improvement. For example, untrained individuals can improve their cardiovascular conditioning by 1% per day of training, but the rate of reversal can be as high as 3% to 7% if they suddenly become totally inactive ( Box 4-4 ). Therefore, the longer an athlete is inactive, the longer it takes to return to preinjury fitness levels.
Remove or diminish the presence of pain, edema, and joint effusion as soon as possible. These sources of afferent activity result in reflex inhibition of associated musculature, which delays the rehabilitation process.
- 1.
Muscle
- a.
Cross-sectional area: atrophy rates of 0.5% to 1% per day of inactivity for the quadriceps
- b.
Strength: decreases 0.5% to 2% per day of inactivity for the plantar flexors and quadriceps
- a.
- 2.
General deconditioning (reduced strength production and endurance capacity)
- 3.
Structural changes in articular capsule connective tissue causing decreased range of motion
- 4.
Degeneration of articular cartilage
- 5.
Cardiovascular deconditioning
- 6.
Reduced stimulus for bone mineral deposition, possibly contributing to diminished bone density
Rehabilitation concepts
Healing Constraints
The most important factors to consider when designing a rehabilitation program are the physiologic constraints to healing. Generally, across different tissue types, tissue strength decreases after injury, but as time elapses and healing occurs, tissue strength increases ( Table 4-1 ). The athlete’s age, health, and nutritional status and the magnitude of injury are the primary factors influencing the rate of physiologic healing, and the rehabilitation program must be structured around these constraints (see Chapters 2, 3, and 7 ). New medicinal advances, however, may facilitate the healing process, such as autologous platelet-rich plasma technologies (see Chapter 2 ) and matrix metalloproteinase inhibitors.
| Tissue | Time to Return to Approximately Normal Strength |
|---|---|
| Bone | 12 weeks |
| Ligament | 40-50 weeks |
| Muscle | 6 weeks up to 6 months |
| Tendon | 40-50 weeks |
Connective tissue, present in some form or another in almost all tissue, accommodates force—or stress—in a manner described by Hooke’s law and the stress-strain curve (see Box 4-5 for definitions of force terms). The specific composition and fiber arrangement of connective tissue determine the tissue’s relative reaction to stress. For example, ligaments stretch relatively farther than tendons with the same magnitude of tensile force. Ligaments stretch farther because of the more irregular or multidirectional arrangement of their collagen fibers in comparison to those of tendons, which are more specialized to resist tensile force.
Force: something that causes or tends to cause a change in the motion or shape of tissue
Stress: generally synonymous with force; types include compression, tension, torsion, and shear
Compression: pushing or squeezing tissue together
Tension: pulling tissue apart
Torsion: twisting tissue
Shear: tearing across tissue
Strain: deformation of tissue
Elasticity: ability of tissue to accommodate strain and return to its original length
Plasticity: permanent change in tissue structure resulting from strain beyond the elastic region
Failure: tissue disruption resulting from strain beyond the plastic region
The aforementioned stress-strain curve graphically depicts how stress affects connective tissue. It is described as a sinusoidal curve with specific areas that include the toe, elastic region, plastic region, and point of failure ( Fig. 4-2 ). The toe area is the elongation of connective tissue up to its point of stretch (e.g., taking up the slack in the tissue). The elastic point begins when the tissue stretches beyond approximately 2% of its resting length. Within the elastic region, tissue returns to its prestretch length. Permanent elongation occurs to a degree when the tissue surpasses its resting length by approximately 4%, known as the plastic region. Permanent elongation results from actual disruption of a few but not all collagen fibers present within the connective tissue. Finally, the failure point of connective tissue results from stretch beyond 6% to 10% of the tissue’s resting length. Thus, excessive stress applied to tissue may result in failure of that tissue. Rehabilitation must accommodate the fragility of healing tissue because its ability to withstand tensile stress is compromised early in rehabilitation.
Stages of Rehabilitation
“Time waits for no one” and “timing is everything” are clichés that describe how dependent we are on time. Just as in everything else, timing is crucial during recovery from injury and rehabilitation. It has already been mentioned that proper intervention by the rehabilitation expert may include the use of therapeutic modalities or therapeutic exercises. However, certain intensities of therapeutic exercise and certain forms of therapeutic modalities may damage immature tissue in the early phases of rehabilitation. Damage to immature tissue incites further inflammation and prolongs the recovery process.
Rehabilitation phases are time frames that consider general healing constraints and assist the rehabilitation specialist in planning rehabilitative interventions. However, it is important to recognize that there is no absolute transition from one rehabilitation phase to the next. In fact, the phases may overlap. Furthermore, there is interindividual variability within these time constraints. Therefore, these stages or phases should not dictate progression of rehabilitation but should serve as a guide for the clinician because the experience of the rehabilitation specialist is important in maneuvering through the sometimes murky waters of rehabilitation and recovery.
Overall, the phases are progressive in nature; that is, they should build on one another like building blocks. When tasks that are relatively basic are accomplished, such as range of motion, the athlete may progress to strengthening within the newly acquired range of motion. As healing occurs and newly formed connective tissue matures, tolerance of increased exercise intensity improves.
Phases of rehabilitation include the acute, subacute (intermediate), and chronic or return-to-sport phases. Other authors describe a fourth phase, the advanced strengthening phase, that follows the subacute (intermediate) phase and precedes the return-to-sport phase.
Acute Phase
The acute phase occurs from the moment that tissue sustains injury until the time that inflammation becomes controlled. Generally, the acute phase of soft tissue healing lasts 4 to 6 days after injury. The goals of the acute phase of rehabilitation are to diminish pain, control inflammation, and begin the restoration of joint range of motion, muscle flexibility and strength, and proprioception in a pain-free fashion.
Rest, ice, compression, and elevation are necessary to combat pain and swelling in the acute injury state. Rest is paramount to manage inflammation during the first 24 hours after injury. Therapeutic modalities, especially cryotherapy and electrophysical agents, play a crucial role in controlling the inflammation process and the athlete’s pain early in rehabilitation. Cryotherapy helps prevent secondary hypoxic injury and aids in controlling hemorrhage and edema. Application of external pressure to the injury site assists in limiting the amount of soft tissue edema. Compression wraps are applied from a distal to proximal direction, with a decreasing pressure gradient as the wrap moves proximally. Stockinettes are excellent for compression and can be applied and removed easily by the athlete. Elevation assists the lymphatic system in moving any extracellular tissue fluid away from the injury site. Passive and active assisted movements, when indicated, are beneficial in assisting proper healing of soft tissue. Motion stresses immature collagen, which assists in alignment of its fiber along lines of stress while preventing excessive development of adhesions. Table 4-2 summarizes treatment considerations during the acute stage of soft tissue healing.
| Goals | Treatment |
|---|---|
| Control inflammation | Rest and protection of the injured area, cryotherapy, compression, elevation, gentle (grade I) pain-free mobilization of the affected joint |
| Minimize deleterious effects of immobilization | Passive motion within limits of pain, isometric muscle setting, electrical stimulation, axial loading for early proprioception |
| Reduce joint effusion | Pain-free active range of motion as tolerated, medical intervention (joint aspiration) if necessary |
| Maintain condition of noninjured areas | Activity of nonaffected extremities as tolerated |
Advancement from the acute stage to the intermediate phase begins when the effects of cryotherapy have plateaued, as manifested by the stabilization of edema, relative restoration of pain-free range of motion, and removal of hyperemia. Another way to view the criteria for progression to the subacute or intermediate phase is the relative reduction of inflammation, which is evidenced by diminution of its five classic indicators: redness (rubor), heat (calor), pain (dolor), swelling (tumor), and loss of function (functio laesa). When the pain and inflammation are under control, emphasis shifts to restoring function because diminished pain does not imply that restoration of function has occurred.
Subacute (Intermediate) Phase
As mentioned earlier, the subacute phase of soft tissue resolution begins as the effects of inflammation decrease. In this phase the healing connective tissue is still immature and relatively fragile; therefore, therapeutic exercises used during this phase should be gentle and cause no pain. This phase is transitional to active movement. However, tissue may revert back to the acute stage if it is overstressed and inflammation recurs. Nonetheless, an appropriate amount of stress is necessary in this phase to avoid understressing tissue. Inadequate stress applied to soft tissue diminishes its mobility, which not only delays restoration of range of motion but also potentially results in more severe consequences, such as the formation of adhesions.
Joint range of motion should dramatically improve in the subacute stage and allow the rehabilitation specialist to advance the rehabilitation program to flexibility training and strengthening exercises. Joint range of motion forms the basis for physical performance, and its improvement is paramount for successful rehabilitation. To improve joint range of motion, specific joint motion must occur progressively and be in the form of accessory or physiologic movements (see the section on therapeutic exercise later in this chapter and in Chapter 6 ). Strengthening should also be increased progressively in a rehabilitation program during the subacute stage. A few methods that progressively increase strength training include the low-resistance, high-repetition method, the DeLorme and Watkins regimen, the Oxford technique, and daily adjustable progressive resistive exercise philosophies (see the section on progressive resistive exercise later in this chapter). As range of motion and strength improve, coordination and agility activities begin to increase as rehabilitation progresses.
Coordination and agility are important for normal functioning, whether it be functional activities or performance-specific actions of a particular sport. Normal movement requires complex neuromuscular coordination between similar or opposing muscle groups (or both). Movement patterns are smoother and more fluidlike when the action of muscle groups is coordinated. The subacute (intermediate) stage plays a role in reestablishing neuromuscular control via progression of proprioceptive exercises (see Chapter 24 ).
The ultimate goal of the subacute stage is to prepare the athlete for the more complex activities that occur in the return-to-sport phase. Table 4-3 summarizes treatment considerations during the subacute stage of soft tissue healing.
| Goals | Treatment |
|---|---|
| Continue to control inflammation | Protect the area with prophylactic devices, if necessary; gradually increase the amount of joint movement; and continuously monitor tissue response to progression of exercise and adjust the intensity/duration accordingly. |
| Progressively increase mobility | Progress from passive to more active ROM; gradually increase the intensity of tissue stretch for tight structures. |
| Progressively strengthen muscles | Progress from isometric to active ROM without resistance and gradually increase the amount of resistance; progress to isotonic exercise as joint integrity/kinematics allows. |
| Continue to maintain condition of noninjured areas | Progressively strengthen and/or recondition noninjured areas with increased intensity/duration of activity as healing of tissue allows. |
The Chronic or Return-to-Sport Phase
Culmination of the earlier phases should provide the athlete with full range of motion and strength of the affected extremity. Connective tissue by this time has improved tensile strength, primarily because the orientation of its fibers is better suited to withstand tensile stress. The intensity of the strengthening exercises increases in this phase. Agility, coordination, and plyometric activities are performed at a more intense level to prepare athletes for the demands of specific activities within their particular sport. Table 4-4 summarizes treatment considerations during the chronic or return-to-sport stage of soft tissue healing.
| Goals | Treatment |
|---|---|
| Decrease pain from adhesions | Appropriate modalities when indicated, mechanical stretching of affected structures |
| Increase extensibility of other structures | Passive stretches, joint mobilizations, cross–soft tissue friction massage, flexibility exercises |
| Progress strengthening of affected and supporting musculature | Isotonic and isokinetic exercises of affected and supporting musculature when indicated |
| Progress proprioception, coordination, and agility | Balance activities, surface modification |
Neurologic Considerations
The neurologic system transmits information, recognizes and interprets the information, and then formulates a response, if necessary. Afferent neurons carry signals from the periphery to the central nervous system (brain and spinal cord) that deliver information about the body or environment, whereas efferent neurons carry impulses to effector organs or muscles to carry out a specific response. Key concepts of neurologic physiology, particularly afferent activity, will now be reviewed because of its crucial role in rehabilitation. This discussion begins with a review of peripheral receptors and finishes with a review of the concepts of motor learning and voluntary neuromuscular activation.
Peripheral Receptors
Sherrington identified and categorized afferent receptors into three groups according to location: articular, deep (muscle-tendon related), and superficial (cutaneous). Our attention now turns to the joint receptors, which have profound effects associated with neuromuscular function.
Peripheral receptors: joints
In 1863, Hilton described the innervation of joints by articular branches of nerves supplying the muscles of each articulation (Hilton’s law). Sherrington was the first to note the presence of receptors in pericapsular structures. He coined the term “proprioception” to include all neural input originating from the joints, muscles, tendons, and associated deep tissues.
Articular receptors are located within the joint capsule, ligaments, and any other joint structures within the body. The human joint capsule has been studied extensively and contains four very distinct types of nerve endings: Ruffini corpuscles, Golgi receptors (also present within the Golgi tendon organ), pacinian corpuscles, and free nerve endings ( Table 4-5 ).
| Nerve Ending | Characteristics |
|---|---|
| Ruffini corpuscles | Sensitive to stretching of the joint capsule |
| Golgi receptors | Intraligamentous and become active when the ligaments are stressed at the extremes of joint movement |
| Pacinian corpuscles | Sensitive to high-frequency vibration |
| Free nerve endings | Sensitive to mechanical stress |
Arthrogenic inhibition
Afferent activity from arthrogenous receptors contributes to the manifestation of arthrogenic inhibition of an affected muscle group. Afferent activity may occur as a result of increased articular pressure or from the transmission of pain signals. Joint trauma often causes fluid to collect inside the joint (effusion), which increases intraarticular pressure. Increased intraarticular pressure subsequently causes the joint capsule to stretch, which activates afferent joint receptors. Joint pain may occur with or without joint effusion and is typically associated with an increased firing rate of free nerve endings. Joint receptor afferents integrate with an inhibitory interneuron at the spinal cord. The interneuron releases an inhibitory neurotransmitter in response to increased activity from the joint afferents. Ultimately, this diminishes the activity of motor neurons supplying muscles that act on the affected joint ( Fig. 4-3 ). Diminished motor unit activity results in atrophy and weakness, most commonly seen in the quadriceps and shoulder after surgery or gross articular trauma. The body attempts to protect the associated joint by “shutting down” the associated musculature, but the resulting atrophy and weakness prolong recovery time unless the rehabilitation specialist takes proper steps to minimize and reverse the adverse effects of arthrogenic inhibition.
Neuromuscular Considerations
The motor cortex does not think in terms of activation of specific motor units; rather, our bodies attempt to achieve a specified movement by activating certain muscles or muscle groups. Movements often require complicated neuromuscular coordination, which we learn over time through experience or practice. However, injury often causes temporary loss of the ability to activate specific muscles or muscle groups. Measures that directly improve volitional motor control and activation of motor units while concomitantly decreasing arthrogenic inhibition by controlling joint effusion and pain are essential to rehabilitation. Physical training in conjunction with motor-learning principles assists the process of muscle reactivation and motor skill reacquisition.
More complicated movement patterns associated with functional and sport-specific activities are not possible until muscle inhibition is reduced or removed. Furthermore, performance of complex sport-specific activities in the advanced stages of rehabilitation ensures that athletes reacquire the motor skills inherent in their particular sport.
Many rehabilitation professionals often unknowingly use motor-learning concepts in one capacity or another during athletic rehabilitation. Whether the athlete is acutely recovering from surgical reconstruction or is in the final return-to-sport phase, it is imperative that the rehabilitation specialist use instructions, verbal or visual feedback, and practice conditions that match the learning needs of the athlete. It is beyond the scope of this brief synopsis on motor learning to cover all theories and issues related to this important topic, and the reader is referred to other sources for more information. Rather, key concepts pertinent to teaching athletes movement patterns related to therapeutic exercise, which should ultimately prepare them to return to their sport, are presented. Nonetheless, before discussing some of these concepts, two major theories concerning motor learning are briefly reviewed: the three-stage model and the two-stage model.
Three-Stage Model
In 1967, Paul Fitts and Michael Posner presented a classic motor-learning theory known as the three-stage model. The three-stage model consists of the cognitive, associative, and autonomous stages ( Table 4-6 ).
| Three-Stage Model | Two-Stage Model | ||
|---|---|---|---|
| Stage | Characteristics | Stage | Characteristics |
| Cognitive | Athlete puts forth conscious effort to either learn new movements or reacquire movements previously mastered. | “Getting the idea” | The correct movement pattern is selected on the basis of various regulatory conditions, such as distance, size, and shape of the object. |
| Associative | Athlete begins to associate certain environmental cues with the performance of movements. | Fixation and diversification | Fixation implies that the athlete performs the movement in a nonchanging environment. |
| Autonomous | Activity becomes automatic and requires very little cognitive processing for proper performance. | Diversification refers to a changing environment that requires the athlete to make modifications in the skill for proper performance. | |
The cognitive stage requires a great deal of attention from the athlete because of the need to focus on cognitively oriented problems. In this stage, athletes must generally put forth conscious effort to either learn new movements or reacquire movements previously mastered. During rehabilitation, the athlete’s neurologic system must “relearn” how to accomplish a given task as the appropriate movement patterns are selected and proper muscle groups are recruited to perform the task. Frequently, the athlete may be fearful of using the involved extremity, and the apprehension in doing so invokes cognitive activity on the task at hand. The athlete commits numerous errors while performing the task but begins to get a “feel” for the activity with repetition and feedback. Thus, the rehabilitation specialist plays an important role in this stage by providing appropriate extrinsic feedback. As the athlete’s practice level increases in this phase, the athlete begins to obtain a sense of correct and incorrect or safe and unsafe movements within the exercise or activity.
Cognitive activity changes somewhat in the associative stage as the athlete begins to associate certain environmental cues with performance of the movements. The athlete performs the task with fewer errors and refines the movement; in fact, Fitts and Posner refer to the associative stage as the refining stage. The timing and distance of the movement are examples of how the athlete refines the activity or exercise and begins to decrease variability in performance. Coordination of muscle activity improves, which produces more efficient movements. Feedback is still important in the associative stage, but the athlete depends less on it for proper performance. The athlete begins to detect errors independently and make corrections in performance. Additionally, as the practice level increases during this stage, the athlete may explore modifications of the movement, such as environmental variation.
Finally, the athlete reaches the autonomous stage whereby the activity becomes automatic, with very little cognitive processing required for proper performance. This allows the athlete to incorporate the activity into more complex exercises or to concentrate on other simultaneous tasks. Variability in performance decreases tremendously, and the athlete consistently performs the task well in this stage. However, many healthy noninjured athletes may never reach this level of learning; therefore, it is rarely accomplished during rehabilitation because of the amount of practice time required to achieve it. Nonetheless, the minimal goal of rehabilitation is to return the athlete to preinjury levels of motor functioning.
An important concept to consider is that one typically moves through the three stages in a continuum manner. Consistent practice of the activity over time moves the athlete from the cognitive stage into the associative stage and finally into the autonomous stage. It may be difficult for the rehabilitation professional to determine exactly what stage an athlete is in at any given moment, especially because there is overlap to a degree across the continuum.
Two-Stage Model
Another motor-learning theoretic model, the two-stage model, was described by Gentile in 1972 and 1987 (see Table 4-6 ). In the two-stage model, the learner moves from “getting the idea” in the first stage to fixation and diversification in the second stage. For the athlete to “get the idea” in the first stage, the correct movement pattern must be selected while taking into consideration the various regulatory conditions (environmental mandates). Regulatory conditions regulate performance based on certain variables: distance, speed, and the weight, size, and shape of the object. Nonregulatory conditions pertain to environmental qualities that do not affect the movement strategy, such as whether the person uses a broomstick or a T-bar for active assisted shoulder range-of-motion exercises. As practice continues in the first stage, skills improve and the athlete gradually moves into the second stage.
Fixation and diversification occur in the second stage. Briefly, fixation implies that the athlete refines the movement in a closed (nonchanging) environment, whereas diversification occurs in an open or changing environment, which requires the athlete to make modifications in the skill for proper performance.
Applying Principles of Motor Learning to Rehabilitation
Before injury, athletes attain the advanced motor-learning skills necessary to accomplish complex motor tasks. However, with injury, the athlete is unable (because of reflex inhibition) or unwilling (because of pain or guarding) to use an affected extremity, and motor skills become repressed. Motor-learning principles assist the rehabilitation professional in properly reintroducing the movement patterns to the athlete. The two primary motor-learning principles to consider during rehabilitation are the amount and type of practice and the feedback available to the athlete.
Practice
Practicing the activity or movement is perhaps the most important factor in the learning process. The athlete should deliberately and purposefully practice to achieve optimal motor-learning results. Additionally, the type of practice is also important to consider, as well as obtaining adequate sleep to promote “off-line learning.” Systematic manipulation of practice may assist the motor-learning process, especially variability in practice conditions in the later stages of rehabilitation. Types of practice include mental and physical; whole versus part; and random, blocked, and random-blocked ( Table 4-7 ).
| Type | Characteristics |
|---|---|
| Physical | Athlete physically performs an exercise or activity. |
| Mental | Athlete uses mental images to rehearse the movement. |
| Whole | Athlete performs the entire task from start to finish. |
| Part | Exercise is divided into different segments or phases. |
| Blocked | Practice or exercise conditions remain constant or unchanging. |
| Random | Practice or exercise conditions are randomly alternated, thereby introducing variability into the performance. |
| Random-blocked | Qualities of random and blocked practice both prevail within an exercise session. |
Physical practice implies that the athlete physically performs an exercise or activity during the rehabilitation process, whereas mental practice indicates that the athlete uses mental images to rehearse the movement. Mental imagery and visualization are two common terms used to describe the cognitive processes that occur during mental practice. Frequently, the rehabilitation specialist focuses more on the physical performance of an exercise and overlooks the potential benefits of using mental practice to achieve positive motor-learning outcomes. Research in this area has documented the effect of mental practice on physical performance. , An example of an athlete using mental practice is as follows: during rehabilitation an athlete recovering from a shoulder injury performs a unilateral active range-of-motion exercise with the unaffected extremity, and before performing the exercise with the affected shoulder, the athlete uses mental practice to rehearse the movement. The mental practice before actual performance with the affected upper extremity prepares the athlete by allowing him or her to gauge the requirements necessary for the movement. The specific preparation offered by mental practice relies on some type of movement experience; in this case it was from the unaffected shoulder.
Whole practice implies that the athlete performs the entire task from start to finish, whereas part practice occurs when the exercise is divided into different segments or phases. Complicated movement tasks and activities occurring in the early phases of rehabilitation are usually divided into smaller, less complex activities for the athlete to practice. When the athlete masters the smaller tasks, progression of activity occurs by adding the smaller tasks together to ultimately form the larger and more complex movement pattern. For example, an athlete “relearns” how to voluntarily activate the quadriceps after knee surgery by first performing and mastering the basic quadriceps-setting exercise. As muscle control improves, the athlete builds on the basic quadriceps-setting exercise by lifting the lower extremity in a straight leg raise exercise. Straight leg raises require the isometric activity of quadriceps setting to maintain knee extension during the dynamic activity of hip flexion. In this simplified example, quadriceps-setting exercises could be considered “part practice,” whereas the straight leg raises would be “whole practice.”
As rehabilitation progresses, the athlete should be able to perform the newly acquired or reacquired task under more functional or sport-specific conditions because clinical situations often do not match those in real life. The ability to perform the skill under different conditions, or practice variability, enforces retention of the motor skill and allows the athlete to “generalize” the skill to new conditions. Examples of varying practice include alternating the surface, implementing distractions, and adding secondary tasks, such as an athlete progressing from stationary balance activities on one foot to throwing and catching a ball while balancing on one foot.
Practice variability leads us to a brief definition of random, blocked, and random-blocked practice. Essentially, blocked practice implies that the practice or exercise conditions remain constant or unchanging. Blocked practice is beneficial for enhancement of performance during the early phases of rehabilitation. However, blocked practice is not necessarily best for retention of motor skills. Random practice requires the rehabilitation specialist to randomly alternate practice conditions, thereby introducing variability into the performance. Random practice, because of the inherent variability in practice, leads to better retention of motor skills. Random-blocked practice implies that qualities of random and blocked practice both prevail within an exercise session. Typically, in random-blocked practice, an exercise or activity is performed for more than one repetition before new conditions are implemented. This allows the athlete to correct errors before making adjustments to new practice conditions. An example of random-blocked practice is having an athlete perform a task for two repetitions, followed by an adjustment in the conditions of the exercise, and then having the athlete perform the activity with the new practice conditions.
Feedback
Feedback, or the information that an athlete receives during or after execution of a movement, is perhaps the second most important factor affecting motor learning. Although many different types of feedback exist, only several specific types of feedback relevant to physical rehabilitation are presented here. The major types of feedback are intrinsic and extrinsic ( Table 4-8 ).
| Intrinsic | Extrinsic |
|---|---|
| Information is acquired by the athlete’s own sensory system. | Information about the performance of an exercise is derived from a source other than the athlete. |
| Usually, the visual, proprioceptive, and auditory sensory systems are involved. | This information can come from the clinician or a piece of equipment. |
| Two types of extrinsic feedback: | |
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Intrinsic feedback is the information acquired by the athlete’s own sensory system. The senses most commonly used to acquire information during physical movement are the visual, proprioceptive, and auditory sensory systems.
Vision provides a large amount of information to the human nervous system about movement and allows corrective actions to take place during performance of an exercise. We rely on our vision for many tasks, whether performing an activity of daily living or an activity specific to a given sport. We use vision to aim and reach for objects, both in static and dynamic environments and during complex motor activities that involve walking, running, and jumping. Because of vision’s role in providing feedback during and after performance of an exercise, the rehabilitation specialist should incorporate visual stimuli into rehabilitation exercises. Visual targets on a wall that correspond to a targeted range of motion during active assisted shoulder exercise are an example of visual stimuli that allow the athlete to make adjustments during movement.
Proprioception offers the second greatest amount of information about movements during exercise. This discussion of proprioceptive feedback is brief because Chapter 24 is devoted entirely to proprioception. We rely on proprioceptive feedback during motor learning to develop a “feel” for the exercise, which improves muscle activation during the movement. An example would be having the athlete perform an exercise bilaterally and then instructing the athlete to concentrate on how each extremity feels during the movement. The athlete should understand that the goal is to attempt to have the involved side work or “feel” like the uninvolved extremity during the movement. This is accomplished by the athlete attempting to activate the function of the involved extremity similar to that of the uninvolved extremity by using proprioceptive discernment, or feedback, of the discrepancy in motor activation between the extremities. Proprioceptive feedback also has an impact on spatial accuracy and the timing of motor commands. However, proprioceptors may incur damage from soft tissue injury that diminishes their ability to transmit afferent information. Activities designed to restore and retrain proprioception in previously injured tissues are outlined in Chapter 24 .
Auditory feedback is sound information associated with a movement or physical performance. The auditory feedback associated with rehabilitation is not usually intrinsic; that is, we do not rely on sound to gather information about our movements unless it comes from another source, which is technically extrinsic feedback. A biofeedback apparatus that interprets and then converts physiologic information into auditory information during an exercise is an example of auditory information assembled from an extrinsic source.
Extrinsic feedback is information about the performance of an exercise that is derived from a source other than the athlete. This extrinsic information is processed by the same intrinsic sensory systems of the athlete mentioned earlier for auditory feedback. When deciding whether feedback information is intrinsic or extrinsic to the athlete, it is important to remember who or what is providing the actual information about the performance and not necessarily what sensory registers of the athlete acquire the information. For example, an athlete uses vision to observe the rehabilitation professional providing an initial introductory demonstration. Similarly, the athlete observing his or her reflection in a mirror integrates visual information of the activity. In both cases, demonstration of the exercise and use of the mirror, information about the movement originated from an external source. We may not always have a demonstration or a mirror to use for feedback when we perform a given task.
The rehabilitation specialist or a sophisticated apparatus may provide extrinsic information about physical performance at different points in time in execution of the exercise. Extrinsic feedback supplied during an activity is known as concurrent augmented feedback, whereas information occurring after the performance of an activity is terminal augmented feedback.
The two primary types of extrinsic feedback are known as knowledge of performance (KP) and knowledge of results (KR).
KP provides the athlete with information about the characteristics of movement that lead to a certain outcome, thus making it pertinent to physical rehabilitation. KP is especially useful in identifying patterns of substitution or compensation during movements. The two types of KP are verbal and visual. Verbal KP includes the descriptive and prescriptive varieties. Descriptive verbal KP merely identifies the error in performance of the exercise, whereas prescriptive KP identifies the error and then prescribes the remedy to correct the error. Visual KP implies that the rehabilitation professional uses a visual display to provide information about the performance. The rehabilitation specialist typically acquires information about the performance and then passes along the information in some sort of visual display to the athlete. Another source of visual information during performance may arise from biofeedback equipment. Heart rate and electromyographic traces are two common types of biofeedback used in rehabilitation settings.
When providing KP, the rehabilitation specialist must use some type of performance analysis to acquire information about the exercise. The analysis can be either quantitative or qualitative. In quantitative analysis, certain characteristics of the performance are quantified; equipment such as high-speed cameras, motion analysis software packages, force platforms, and research-quality electromyographic equipment are required. Qualitative analysis describes the qualities of the movement, and this is usually sufficient for rehabilitation. Rehabilitation professionals must possess the ability to at least qualitatively analyze the movement patterns associated with performance of an exercise to provide this type of feedback. Videotaped rehabilitation sessions also allow qualitative analysis, which the rehabilitation professional may use as an educational tool to provide the athlete with KP feedback. In later stages of rehabilitation, such as when an athlete begins sport-specific activities, quantitative analysis of an activity may be more appropriate.
KR feedback provides information relating the outcome of performance of an exercise to the goal for a particular exercise. For example, the rehabilitation specialist provides an athlete with knowledge of the amount of knee flexion achieved during a rehabilitation session and relates it to the rehabilitation goal for knee flexion. However, Winstein defined KR feedback as the “augmented extrinsic information about task success provided to the performer.” She continued by stating that the information serves as a basis for correction of errors on the next trial and thus can be used to achieve more effective performance as practice continues. Several variables of KR feedback are important to consider when one uses it as a tool to enhance motor learning during rehabilitation: the form used (e.g., verbal or visual), the precision or amount of information contained in the KR, and the frequency or schedule of the KR. The precision or amount of information contained in the KR feedback influences the number of performance errors: specifically, the greater the precision of the KR, the smaller the amount of performance errors. There is perhaps a ceiling effect with the amount of precision, and the optimal levels necessary to improve performance may depend on the type of performer (i.e., novice versus elite performers). Research has demonstrated that the frequency of KR feedback influences the acquisition and retention of a task. Specifically, KR presented after every trial produces better acquisition of a skill, whereas KR presented after several trials actually produces better learning over time. KR feedback presented after every trial leads the athlete to become sensory dependent on the externally presented information for improving performance and to ignore information available from intrinsic acquisition systems. Decrements in performance occur when KR is removed as a source of feedback after the athlete becomes dependent on extrinsic feedback.
Basic Strategies for Implementing Concepts of Motor Learning in Rehabilitation
Learning is not directly observable; rather, the effects of learning are manifested in certain types of behavior or performance characteristics. According to Kisner and Colby, several specific instructional strategies can be used by the rehabilitation specialist to maximize patient learning during exercise instruction. First, select an environment that allows the athlete to pay attention to your instructions. If it is not feasible or possible to interact one on one with the athlete without distractions, it may be necessary to schedule rehabilitation sessions at times when relatively fewer distractions or interruptions occur. Use clear and concise verbal instructions followed by proper demonstration of the exercise or activity. The athlete should follow the demonstration with a performance of the exercise while the rehabilitation professional guides movements and provides feedback on the performance both during (KP) and after (KR) the exercise. As exercises and activities become more complicated throughout the progression of rehabilitation, it may be useful to break down complex movements into simple ones. The athlete may then synthesize simple movements into more complex ones.
Crossover Training Effect
A well-documented phenomenon, the crossover training effect or crossover education, associates improved muscle activation of an affected or unexercised extremity with physical exercise of the unaffected extremity. Physical performance indices, such as strength, power, speed, endurance, and range of motion, may improve with crossover education. An intriguing characteristic of the crossover effect is that it occurs not only in normal, unaffected extremities but also in extremities affected by immobilization, orthopedic surgery, and stroke. , Crossover training may occur in occupationally embedded tasks, as well with the untrained extremity, to improve the speed and accuracy of movement as a result of training the contralateral limb.
Clinical implications
Knowledge of the crossover effect offers several advantages for physical rehabilitation:
- 1.
It prevents deconditioning of the unaffected extremity.
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It augments early exercise efforts of the affected extremity.
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It is useful for conditions in which movement of the affected extremity is contraindicated (e.g., it is beneficial for early postoperative rehabilitation of an extremity after surgical repair of muscles, tendons, or both).
According to the work of Stromberg and others, the major benefit of using the crossover phenomenon resides in gains in strength. , Gains in muscle strength attributed to the crossover effect range from 30% to 50%, although others report more modest improvements. Nonetheless, any gain in muscle strength is advantageous for an affected extremity undergoing a rehabilitation program, especially when exercise of the affected side is contraindicated.
Using both extremities simultaneously at low levels (submaximal) of force intensity also promotes neuromuscular facilitation. Simultaneous bilateral activation of the affected and unaffected extremities has implications for rehabilitation because the patient is able to “feel” the difference between the affected and unaffected muscle groups while also benefiting from the effects of crossover training. The patient’s ability to detect differences during simultaneous bilateral muscle activation is a proprioceptive feedback mechanism that increases motor learning and control.
As rehabilitation progresses and force intensity increases, specific training considerations may contraindicate performance of simultaneous bilateral activities to a degree. Deemphasis of bilateral actions later in rehabilitation may be necessary if the sport of interest requires maximal power of unilateral muscle activation and because higher intensities of resistance during bilateral homologous limb activity may actually inhibit relative force production. Beutler and associates found that muscle activation increases when the affected extremity is exercised alone as opposed to when both extremities are exercised together during closed kinetic chain exercises, which is in agreement with data on the bilateral deficit phenomenon.
Types of therapeutic exercise
Therapeutic exercise is physical activity prescribed to restore or favorably alter specific functions in an individual after injury. These specific physical functions include joint range of motion, soft tissue flexibility, muscle strength and power, and neuromuscular coordination and balance. Figure 4-4 classifies the various therapeutic exercises that a clinician can incorporate into a therapeutic rehabilitation program.
