Rehabilitation and conditioning professionals (physical therapists, athletic trainers, and strength and conditioning coaches) are often faced with the daunting task of maximizing their resources because of limited space, equipment, or funding to serve their athletes and clients. Because the implementation of weight bearing exercises is a central tenet of rehabilitation from sports injuries, the agility ladder and slideboard can be part of the treatment options for the rehabilitation and conditioning professional when training athletes and clients with upper extremity injuries. They are relatively inexpensive, can be used for multiple objectives, and they do not take up significant amounts of space. Furthermore, they can be used with various ages and activity levels at the discretion of the rehabilitation professional, pending more benefit than risk. To ensure safety, the athlete should be screened for physical readiness by assessing range of motion, pain, and strength before initiation of these exercises. The purpose of this article is to discuss the rationale for upper extremity closed chain exercise as well as ideas on how to implement these devices into a rehabilitation plan or strength and conditioning regimen.
RATIONALE FOR CLOSED CHAIN EXERCISE IN THE UPPER EXTREMITIES
Closed chain exercises are when the terminal joint of several successfully arranged joints meets external resistance, which restrains free motion (9). Closed chain exercises usually involve sustaining body weight or axial compression load, which favors joint congruence, reduces shear load, and promotes dynamic joint stability (12). In the upper extremity, closed chain exercises provide cocontraction of the rotator cuff at submaximal levels and decrease glenohumeral translation (3,11). Furthermore, previous researchers have found that the upper trapezius, deltoid, pectoralis major, triceps brachii, and biceps brachii are synergistic during glenohumeral elevation in patients with shoulder instability (1,2,10). Therefore, even in the open chain movement of shoulder elevation, multiple muscles work synergistically to stabilize the joint. In a study by Prokopy et al. (8), researchers found that closed chain upper-body training even improves throwing performance in National Collegiate athletic Association Division I softball players. Hence, implementation of closed chain exercises for the upper extremity is warranted for both proper function and performance of the upper extremity.
Although the topic is debated, there is a considerable amount of support for closed chain exercises in lower extremity rehabilitation. Therefore, the findings from these studies may be translated to upper extremity rehabilitation and conditioning. Some studies suggest that closed chain exercises should be included in the initial treatment phase of shoulder pathologies (4,5), whereas others suggest later in treatment phases (6,12). McMullen and Uhl (6) propose that a proximal to distal sequence encourages scapular and trunk stability first and it is independent of arm motion. Rehabilitation must restore not only muscle strength but also muscular coordination and balance which are important factors for shoulder function in daily life and recreational or athletic activities (10).
Therefore, it is reasonable to conclude that closed chain exercises should be used for upper extremity rehabilitation and training to promote glenohumeral and scapular strength, stability, power, and potentially for injury prevention.
IMPLEMENTATION OF THE SLIDEBOARD AND AGILITY LADDER INTO UPPER EXTREMITY REHABILITATION AND CONDITIONING
In general, it is advised that the athlete begin in quadruped. Typically, closed chain exercises for the upper extremity begin with the wall push-up, but the wall push-up assumes that the athlete is able to elevate the shoulder to 90° with proper form. The quadruped position enables the rehabilitation professional to begin closed chain exercises safely earlier in the recovery process. The athletes should position their hands directly under the shoulders and should be instructed to perform a “plus” with their scapulae, protracting them around the rib cage. The plus position has been advocated because of its high serratus anterior activation (9). The plus position promotes weight bearing with support on the musculature and not the joint itself (see Video, Supplemental Digital Content 1, http://links.lww.com/SCJ/A88), which can cause more shear forces in the joint. Shear forces may damage a previously repaired shoulder structure and should be discouraged with these exercises. The rehabilitation and conditioning professional should be mindful that this position could cause further injury to a shoulder with posterior instability. Therefore, the rehabilitation professional should screen the athlete for physical readiness. First of all, they should have no posterior shoulder pain with activities of daily living and have no tenderness to palpation in the posterior shoulder. Second, the athlete should be able to tolerate the quadruped position with proper form (i.e., maintain a protracted position) and without pain.
Once in the quadruped position, the athlete is instructed to stabilize with one arm and then “wax on, wax off” with the other arm (see Video, Supplemental Digital Content 2, http://links.lww.com/SCJ/A89). Other alternatives to this include a lateral slide, “windshield wiper,” bilateral wax on, wax off, or the “rollout” (see Video, Supplemental Digital Content 3, http://links.lww.com/SCJ/A90). Once the athletes have shown the ability to properly perform these exercises and report no pain, they can be progressed to a push-up position, which will be more demanding on both the shoulder and the core musculature. Alternatively, perturbations can be added either manually by the professional or with one arm on a labile surface, such as a scooter or wobble board (see Video, Supplemental Digital Content 4, http://links.lww.com/SCJ/A91).
Once the athletes have demonstrated the ability to tolerate weight bearing on the involved upper extremity, they can be progressed to more dynamic activities using the agility ladder. Similar patterns commonly used for the lower extremity can be used for the upper extremity (see Video, Supplemental Digital Contents 5, http://links.lww.com/SCJ/A92; Supplemental Digital Content 6, http://links.lww.com/SCJ/A93; Supplemental Digital Content 7, http://links.lww.com/SCJ/A94; Supplemental Digital Content 8, http://links.lww.com/SCJ/A95; and Supplemental Digital Content 9, http://links.lww.com/SCJ/A96). The rehabilitation or conditioning professional can measure the athlete’s progress based on speed of performance (quantitative) or technique of performance (qualitative). The athlete should be assessed on ability to maintain a protracted position of the involved shoulder as well as the ability to maintain core stability while performing these exercises. Furthermore, the rehabilitation or conditioning professional should be sensitive to the athlete’s hip and spine position during these activities to avoid exacerbation of a concurrent injury. In addition, the rehabilitation and conditioning professional should evaluate for athlete fatigue, indicated by inability to hold the position or from muscle fasciculations during exercise performance.
The agility ladder can also be used for high-intensity upper extremity plyometric exercises (see Video, Supplemental Digital Content 10, http://links.lww.com/SCJ/A97). Here, the athlete is instructed to perform an explosive push-up while moving laterally through the ladder and then back to the beginning. The athletes can be timed for how long it takes to complete one complete trip or how many they can perform to exhaustion. Other plyometric options are available, only limited by the creativity of the professional or potentially, restrictions from a surgery or injury.
Closed chain exercises, both for strength training and neuromuscular stabilization purposes, are an integral part of rehabilitation and conditioning programs. They are part of a multifaceted approach that includes restoration of range of motion, balance, endurance, hypertrophy, strength, and power. The agility ladder and slideboard are versatile tools that can be used for multiple purposes in both the rehabilitation and strength and conditioning environments. Rehabilitation and conditioning professionals are forced to think “outside the box” and maximize both our resources and our creative abilities for the benefits of not only our athletes and clients but also for our budgets.
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