The strength and conditioning professional must consider both the athlete’s subjective response to injury and the physiological mechanisms of tissue healing; both are essential in relation to an athlete’s return to optimal performance. The process of returning to competition following injury involves healing of the injured tissues, preparation of these tissues for the return to function, and use of proper techniques to maximize rehabilitation and reconditioning. While the goal is a rapid resumption of activity, it is important to remember that each athlete responds differently to injury and thus progresses uniquely during rehabilitation.
As a preface to discussion of the goals of treatment during injury rehabilitation, two points must be made. First, healing tissue must not be overstressed (44, 45). During tissue healing, controlled therapeutic stress is necessary to optimize collagen matrix formation (1, 4, 6, 16, 20), but too much stress can damage new structures and significantly slow the athlete’s return to competition. This means choosing a level of loading that neither overloads nor underloads the athlete’s healing tissue (figure 20.3). It should be obvious that when one is choosing the load, it is necessary to consider the phase of healing and athlete type. For example, a stress that underloads a tissue during remodeling probably overloads it during inflammation. Further, a stress that underloads a professional basketball center probably overloads an amateur cross-country runner. The plane of movement is another necessary consideration. As an example, the medial collateral ligament of the knee is most loaded in the frontal plane during terminal knee extension. Therefore, frontal plane movements should be avoided during early healing phases. However, those frontal plane movements should probably be included in some form during the later phases.
Second, the athlete must meet specific objectives to progress from one phase of healing to the next (44, 45). These objectives may depend on range of motion, strength, or activity. It is the responsibility of the team physician, athletic trainer, physical therapist, or a combination of these professionals to establish these guidelines, which assist the entire team with the athlete’s rehabilitation.
The body’s first response to an injury is inflammation, a reaction that is essential for subsequent healing but also important to manage properly so as to not retard the rehabilitation process.
Treatment Goal The goal for treatment during the inflammatory phase is to prevent disruption of new tissue. A healthy environment for new tissue regeneration and formation is essential for preventing prolonged inflammation and disruption of new blood vessel and collagen production. To achieve these goals, relative rest, ice, compression, and elevation are the primary treatment options. Passive modalities that help reduce inflammation (e.g., ice, ultrasound, and electrical stimulation) are common treatment choices. The athletic trainer provides the majority of passive treatment for the athlete during this acute phase.
It is also important to realize that a quick return to function relies on the health of other body tissues. Therefore, the power, strength, and endurance of the musculoskeletal tissues and the function of the cardiorespiratory system must be maintained. The strength and conditioning professional can provide significant knowledge and expertise in this area. To accomplish these tasks, the strength and conditioning professional should consult with the athletic trainer to determine which types of exercises are indicated and contraindicated for the specific injury. Maximal protection of the injured structures is the primary goal during this phase. Assuming that this requirement is fulfilled, exercises may include general aerobic and anaerobic training and resistance training of the uninjured extremities. If movement of the injured limb is not contraindicated, isolated exercises that target areas proximal and distal to the injured area may also be permissible provided that they do not stress the injured area. Examples include hip abduction and rotation exercises following knee injury (22, 24, 31) or scapula stabilizing exercises following glenohumeral joint injury (25, 42).
Exercise Strategies Although a rapid return to competition is crucial, rest is necessary to protect the damaged tissue from additional injury. Therefore, exercise involving the injured area is not recommended during this phase.
After the inflammatory phase, the body begins to repair the damaged tissue with similar tissue, but the resiliency of the new tissue is low. Repair of the weakened injury site can take up to eight weeks if the proper amount of restorative stress is applied, or longer if too much or too little stress is applied.
Treatment Goal The treatment goal during the repair phase is to prevent excessive muscle atrophy and joint deterioration of the injured area. In addition, a precarious balance must be maintained in which disruption of the newly formed collagen fibers is avoided but low-load stresses are gradually introduced to allow increased collagen synthesis and prevent loss of joint motion. To protect the new, relatively weak collagen fibers, the athlete should avoid active resistive exercise involving the damaged tissue. Too little activity, though, can also have a deleterious effect, as newly formed fibers will not optimally align and may form adhesions, thereby preventing full motion. Early protected motion hastens the optimal alignment of collagen fibers and promotes improved tissue mobility. As in the inflammatory phase, therapeutic modalities are permissible, but their goal during repair is to promote collagen synthesis. Ultrasound, electrical stimulation, and ice are continued in order to support and hasten new tissue formation (5, 23, 34). Again, the maintenance of muscular and cardiorespiratory function remains essential for the uninjured areas of the body. The strength and conditioning professional has considerable expertise to offer the other members of the sports medicine team regarding selection of the appropriate activities. Possible exercise forms during the repair phase include strengthening of the uninjured extremities and areas proximal and distal to the injury, aerobic and anaerobic exercise, and improving strength and neuromuscular control of the involved areas.
Exercise Strategies The following exercises should be used during the repair phase only after consultation with the team physician, athletic trainer, or physical therapist. Isometric exercise may be performed provided that it is pain free and otherwise indicated. Submaximal isometric exercise allows the athlete to maintain neuromuscular function and improve strength with movements performed at an intensity low enough that the newly formed collagen fibers are not disrupted. Unfortunately, isometric strengthening is joint angle specific; that is, strength gains occur only at the angles used (26). Therefore, if indicated, it may be appropriate for the athlete to perform isometric exercises at multiple angles (26).
Resistance training is velocity specific (26); therefore, isokinetic exercise can be an important aspect of strengthening following injury. Isokinetic exercise uses equipment that provides resistance to movement at a given speed (e.g., 60°/s or 120°/s). Because no sport is performed at one speed, however, isokinetic exercise is somewhat limited in its real-world application. Furthermore, most isokinetic equipment allows single-joint exercise only, which permits concentration on a specific muscle or joint but is not always the most functional method of strengthening.
While isotonic exercise involves movements with constant external resistance, the amount of force required to move the resistance varies, depending primarily on joint angle and the length of each agonist muscle. Isotonic exercise uses several different forms of resistance, including gravity (i.e., exercises performed without equipment, with gravitational effects as the only source of resistance), dumbbells, barbells, and weight-stack machines. The speed at which the movement occurs is controlled by the athlete; movement speed can be a program design variable, with more acute injuries calling for slower movement and the later phases of healing amenable to faster, more sport-specific movement.
Proprioception is an afferent response to stimulation of sensory receptors in skin, muscles, tendons, ligaments, and the joint capsule. Proprioception contributes to the conscious and unconscious control of posture, balance, stability, and sense of position (35).
Neuromuscular control, on the other hand, is the ability of muscle to respond to afferent proprioceptive information to maintain joint stability (35). For example, when running on an uneven surface, cross-country runners require their lower extremities-especially their ankles-to adjust to the ground to prevent falls and injuries; that ability to adjust is neuromuscular control. After an injury, neuromuscular control, like strength and flexibility, is usually impaired (12). Specific types of exercises exist to improve neuromuscular control following injury and can be manipulated through alterations in surface stability, vision, and speed. Mini-trampolines, balance boards, and stability balls can be used to create unstable surfaces for upper and lower extremity training. Athletes can perform common activities such as squats and push-ups on uneven surfaces to improve neuromuscular control. Exercises may also be performed with eyes closed, thus removing visual input, to further challenge balance. Finally, increasing the speed at which exercises are performed provides additional challenges to the system. Specifically controlling these variables within a controlled environment will allow the athlete to progress to more challenging exercises in the next stage of healing.
Exercise Strategies Ultimately, rehabilitation and reconditioning exercises must be functional to facilitate a return to competition. Examples of functional training include joint angle-specific strengthening, velocity-specific muscle activity, closed kinetic chain exercises, and exercises designed to further enhance neuromuscular control. Strengthening should transition from general exercises to sport-specific exercises designed to replicate movements common in given sports. For example, for a basketball guard who has rotator cuff tendinitis, rotator cuff strengthening may progress from a specific rotator cuff exercise to lateral dumbbell raises to machine seated shoulder presses to push-press exercises (figure 20.5). Specificity of movement speed is another important program design variable. Strengthening exercises are velocity specific; that is, the speed at which an athlete trains is directly related to the speed at which strength increases. Consider a sprinter with a hamstring muscle strain. Whereas initial reconditioning may concentrate on the recovery of flexibility and strength of the injured muscles, the nature of this athlete’s sport necessitates exercises performed at rapid speeds during the later phases of rehabilitation and reconditioning. Exercise selection for a sprinter with an improving hamstring muscle strain might progress from hamstring flexibility to eccentric strength to concentric strength to dynamic stretching and finally to rapid isotonic strengthening. Examples of velocity-specific exercise include isokinetic, plyometric, and speed training. Please refer to chapters 16 and 17 for a thorough discussion of plyometric and speed training, respectively.The kinetic chain is the collective effort or involvement of two or more sequential joints to create movement (38). A closed kinetic chain exercise is one in which the terminal joint meets with considerable resistance that prohibits or restrains its free motion (38); that is, the distal joint segment is stationary. Lower extremity closed kinetic chain exercises have often been classified as a more functional form of exercise compared with open kinetic chain exercises (7, 21, 41) because most sport-related activities are performed with the feet "fixed" to the surface. For example, during the closed kinetic chain squat exercise, the feet are "fixed" to the floor and essentially do not move, providing a base upon which movement occurs (figure 20.6a). Closed kinetic chain exercises have several advantages, including increased joint stability and functional movement patterns; during sport activity, joints are not typically used in isolation but rather work in concert with the adjacent joints and surrounding musculature. Although closed kinetic chain exercises are commonly viewed as lower extremity exercises, closed chain upper extremity exercises exist as well (figure 20.6b) (3).