Integrating Sensorimotor Control Into Rehabilitation BRADY L. TRIPP, PhD, LAT, ATC Florida International University Key Points As evidence accumulates, so does our appreciation of the integral roles that both the scapula and the sensorimotor system (SMS) play in upper extremity function and dysfunction. This article discusses the integration of principles drawn from research into practice, assisting clinicians with the design and implementation of effective shoulder-rehabilitation programs. Scapular control is the foundation for shoulder stability and upper extremity function. The SMS s Role The SMS encompasses the integration of the neurosensory and neuromuscular processes, which provide coordination, joint-position sense, and dynamic stability. 1 The central nervous system collects afferent input from mechanoreceptors (via muscles, tendons, ligaments, joint capsule, skin, etc.), as well as visual and vestibular input. The central nervous system processes and integrates this input to develop efferent responses. Athletes rely on the SMS to maintain form and performance and help avoid injury. Both fatigue 2 and injury, 3 however, lead to SMS dysfunction. Such deficits occur in multiple planes of motion at the scapulothoracic, glenohumeral, elbow, and wrist joints, which affects the Neuromuscular-control and -endurance exercises should be integrated into each rehabilitation phase. Progressive variation of exercises forces reliance on and recalibrates the sensorimotor system. Exercises should progress to include multijoint, multiplanar, functional tasks. Key Words: scapula, shoulder, functional stability performance of the entire extremity. 2 Without intervention, SMS deficits might lead to further injury and dysfunction. Rehabilitation should enhance functional stability through impaired neuromuscular control and endurance and progress to include multijoint, multiplanar functional tasks. Recalibrating the SMS: Progressive Variation Learning novel tasks requires integrating and analyzing afferent input and efferent responses to calibrate the SMS. A healthy athlete balancing on one leg consciously or subconsciously appreciates the force required to gain and maintain stability, experiments with new balancing strategies, and explores the limits of stability. The experience helps preprogram future motor patterns, constituting feed-forward control. This can be recognized as healthy athletes quickly learn novel tasks; the SMS is calibrated. Injury and fatigue, however, affect the system s ability to calibrate; the athlete does not have access to the same quality of afferent input and therefore cannot execute motor patterns as effectively. When an athlete tries to balance on a sprained ankle, this contrast is observed as impaired postural stability; the system cannot calibrate effectively. To recalibrate the SMS and restore stability, the clinician can systematically isolate and stress components of the system by creating novel tasks (i.e., without visual input the athlete is forced to rely on mechanoreceptors). When a novel task is mastered, the clinician can use it to 2006 Human Kinetics ATT 11(5), pp. 24-29 24 september 2006 Athletic Therapy Today
address other goals (power, endurance), manipulating exercise variables to challenge the SMS. Each progressive variation from known to novel tasks forces reliance on the SMS to react and recalibrate, efficiently and effectively. The principle of progressive challenge to the SMS should be integrated into shoulder rehabilitation by adapting traditional exercises in each phase. Variation in rehabilitation allows athletic therapists to incorporate other research-validated principles. The kinetic-chain principle of shoulder rehabilitation dictates that good arm function relies on proximal (scapular and trunk) control. 4 Research findings suggest that the SMS also follows this principle, with position sense of individual joints affecting upper extremity function in a proximalto-distal sequence. 5 Regaining neuromuscular control of the scapula is therefore vital to shoulder motion control and should be addressed early. Rehabilitation should include both open- and closed-chain exercises that address proximal stability before distal mobility. After scapular neuromuscular control is obtained, exercises progress to include distal joints sequentially, followed by the entire extremity. Such programs inherently advance from a short to long lever arm, increasing the intensity of resistance with each progression. By manipulating exercise variables, athletic therapists can integrate progressive challenges, increasing demands of the task to functional levels (Table 1). Neuromuscular Coordination and Postural Awareness (Integrated Into Phase I) Goals. To develop conscious appreciation of scapular position and control. Emphasize. Good scapular movement and neuromuscular endurance. Exercise progression should begin at the least challenging level (indicated in Table 1). Requiring minimal glenohumeral motion, this principle can be integrated into most rehabilitation protocols early (exercises can begin while the arm is still in a sling). Examples. Finding scapular set position and repetitions of arm elevation, wherein the clinician can observe and facilitate consistent scapular motion, progressing to scapular clocks and proprioceptive neuromuscular facilitation. For scapular setting, first help the athlete recognize the effect of posture on scapular position and appreciate the role the scapula plays in restoring upper extremity function (mobile and stable base). From normal resting posture (Figure 1[a]), identify the ideal starting or set scapular position. Manually placing the scapula in an ideal depressed and retracted set position provides tactile feedback to help enhance the athlete s appreciation (Figure 1[b]). Isometric contractions hold the position, allowing the athlete to feel proper activation of scapular stabilizers and inhibition of the upper trapezius. Enhance awareness of the Table 1. Exercise Variables Clinicians Can Manipulate to Progressively Advance the Demands, Stress the Sensorimotor System, and Address Goals of Rehabilitation Variable Joints included Plane of motion Kinetic chain Lever arm Muscle contraction Resistance applied Resistance intensity Task speed Environment Visual input Tactile input Progression Proximal 2-proximal entire extremity functional Single plane multiplane functional Closed open variable functional Short long variable functional Isometric isotonic plyometric functional Single plane multiplane functional Low high variable functional Slow fast variable functional Stable unstable variable functional Eyes open eyes closed functional Manual none functional Athletic Therapy Today september 2006 25
position and muscles activated by pressing the medial border and inferior angle to the thorax or palpating or tapping over the lower and middle trapezius (Figure 1[c]). Verbal cues might include hold, pinch down and back, or pull to your back pocket. For visual input use a mirror or real-time video. Once set, scapular motion during arm elevation should include progressive upward rotation, external rotation, and posterior tilt that are controlled and consistent. Conversely, pathologic shoulders that display excessive anterior tilt at rest and during arm elevation lack posterior tilt and upward and external rotation. 6 Such uncontrolled, inconsistent, or asymmetric scapular motion might be caused by upper trapezius dominance, weakness of the scapular stabilizers (serratus, lower and middle trapezius) or poor flexibility (pectoralis major and minor). Table 2 describes a progression from this basic setting exercise to more functional exercises. 7 (a) (b) (c) Figure 1 Finding the scapular set position. Starting from (a) the athlete s resting posture, the clinician uses tactile feedback, (b) manually placing the scapula (depressing and externally rotating [retracting]) in a position that facilitates normal scapulothoracic and glenohumeral motion. (c) The clinician helps the athlete identify scapular-stabilizing muscles using tactile feedback 26 september 2006 Athletic Therapy Today
Static Stability (Integrated Into Phase II) Goals. Static, multiplanar stability; neuromuscular endurance throughout (pain-free) range of motion; and establishment of motor patterns that begin with scapular setting. Emphasize. Isometric, reactive, multiplane exercises that facilitate coactivation of scapulothoracic and glenohumeral stabilizers. This principle can be integrated into rehabilitation protocols as soon as isometric rotator-cuff exercise is appropriate. Protocols may include open-chain or stable-environment axialload (closed-chain) exercise. Although isometric, these tasks challenge the SMS to rapidly integrate new input while maintaining stability throughout the progression and manipulation of exercise difficulty (i.e., increasing length of the lever arm, applying perturbations at variable speeds and in multiple planes, adding an unstable environment, removing visual input). As appropriate, exercises should include positions throughout the available range of motion, progressing to functional, multijoint positions (i.e., arm abducted and externally rotated or horizontally adducted). Table 2. Exercise Progression Facilitating Neuromuscular Coordination and Postural Awareness During Phase I of Rehabilitation Progression Variable Scapular Setting Scapular Clock Scapular PNF Joints included 1-Proximal joint Plane of motion Single plane Multiplane Kinetic chain Open Closed or open Open Lever arm Short Muscle contraction Isometric Isotonic Resistance applied Single plane Multiplane Resistance intensity Low Low moderate Task speed Slow Slow moderate Visual input Eyes open Eyes open closed Tactile input Manual None Manual Note. PNF = proprioceptive neuromuscular facilitation. Examples. Closed-chain rhythmic stabilization: multijoint, rhythmic stabilization with minimal axial loads (e.g., standing, outstretched arm on a plinth or wall) or moderate axial loads (e.g., kneeling or in a push-up position) progressing to open-chain exercises. Openchain rhythmic stabilization: manual resistance or an oscillatory device. The O.T.I.S. (Oscillating Technique for Isometric Stabilization; Angler Medical Inc., Tolland, CT) stresses control and endurance of the scapular stabilizers (Figure 2[a]). Resistance-band flips : Isolating scapular stabilizers, progressing to variable resistance applied in single and multiple planes (Figure 2[b]). (a) (b) Figure 2 Rhythmic stabilization (a) using an oscillatory device and (b) progressing to resistance-band flips during which the athletic therapist applies variable resistance while the athlete maintains stability of his scapula. Loss of control is evident if the scapula flips away from the thorax (lifting the medial border and inferior angle) when stronger glenohumeral muscles overcome scapular stabilizers. Athletic Therapy Today september 2006 27
Dynamic Stability (Integrated Into Phase III) Goals. Dynamic, multijoint, multiplanar stability and neuromuscular endurance through full range of motion. Emphasize. Smooth movement with scapular control, reacting to sudden unpredictable changes in resistance. Depending on the specific needs of the athlete, this phase may begin with dynamic open-chain, long-leverarm, unweighted exercises and progress to open-chain, multijoint, multiplanar tasks with the distal segment weighted. A wrestler or football lineman might begin with closed-chain, stable axial-load exercises and progress to closed-chain, unstable axial-loaded tasks. Each exercise begins with the scapula in a set position before arm movement. Examples. Single-plane towel slides starting on a table; progress to multiplane wall slides, slide-board exercises, and diagonal patterns with weights or resistance bands. Dynamic scapular stabilizations: The athlete moves through a functional pattern, maintaining consistent scapula and arm control in response to variable resistance applied using an oscillatory device or elastic band (Figure 3[a]). Upper trapezius compensation (Figure 3[b]), observed in a dysfunctional motor pattern or when fatigued, should be avoided. Functional Stability (Integrated Into Phase IV) Goals. Dynamic stability throughout functional movement patterns. Emphasize. Smooth motion and neuromuscular endurance, through a variety of exercise demands. The exercises will vary to reflect the athlete s sport. The athletic therapist continues manipulating variables (Table 1) to stimulate SMS calibration, with exercises progressing to meet and exceed the functional demands of the athlete s normal activities. Examples. For overhead throwers, exercises progress to using resistance bands or an oscillatory device, incorporating functional patterns, with high speed and intensity of movement, in an unstable environment, without visual input, and so on. Plyometrics such as wall bounces with a weighted ball (Figure 4), eccentric weighted-ball catches, weighted-ball throws, and upper extremity step-ups or step-up-and-over from a push-up or kneeling position (Figure 5) might reproduce functional demands and recalibrate the system. Summary I have outlined the clinical integration of SMS training and scapular control into shoulder rehabilitation. (a) (b) Figure 3 (a) Dynamic scapular-stabilization exercises. The athlete moves through a functional pattern while maintaining control of scapula and arm motion in response to variable resistance applied using elastic bands. (b) This type of upper trapezius compensation should be avoided. 28 september 2006 Athletic Therapy Today
R1 L1 R2 L2 R3 L3 Figure 4 Wall bounces with a weighted ball for overhead throwers. The athlete builds power, stability, and endurance, bouncing the ball off the wall rapidly. He moves between targets on the wall while maintaining scapular stability and ball control. Figure 5 Upper extremity step-up-and-overs for football lineman. The athlete crosses the right hand under the left to step up on the box (R1 to R2). The left hand then crosses over the right (L1 to L2), continuing over the box and back (R2 to R3, L2 to L3, etc.). Progression can be objectively measured by counting the number of times the athlete can travel over and back in a set period of time. Control of proximal joints facilitates normal upper extremity function. Exercises advance in a proximalto-distal manner to include multijoint, multiplanar functional tasks. Recalibrating the SMS after injury requires increasing exercise difficulty to force reliance on the SMS. Clinicians should address neuromuscular control and endurance, postural awareness, static and dynamic stability, and joint-position sense during rehabilitation. References 1. Lephart SM, Riemann BL, Fu FH. Proprioception and Neuromuscular Control in Joint Stability. Champaign, Ill: Human Kinetics; 2000. 2. Tripp BL, Uhl TL, Mattacola CG, Srinivasan C, Shapiro R. Functional multijoint position reproduction acuity in overhead-throwing athletes. J Athl Train. 2006;41(2):146-153. 3. Lephart SM, Warner JP, Borsa PA, Fu FH. Proprioception of the shoulder joint in healthy, unstable, surgically repaired shoulders. J Shoulder Elbow Surg. 1994;3(6):371-380. 4. McMullen J, Uhl TL. A kinetic chain approach for shoulder rehabilitation. J Athl Train. 2000;35(3):329-337. 5. Tripp BL, Uhl TL, Mattacola CG, Srinivasan C, Shapiro R. A comparison of individual joint contributions to multijoint position reproduction acuity in overhead-throwing athletes. Clin Biomech (Bristol Avon). 2006;21(5):466-473. 6. Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Phys Ther. 2000;80(3):276-291. 7. Voight M, Thomson B. The role of the scapula in the rehabilitation of shoulder injuries. J Athl Train. 2000;35(3):364-372. Brady Tripp is an assistant professor and director of clinical education athletic training/sports medicine at Florida International University in Miami. Athletic Therapy Today september 2006 29