of Sport-Specific Rehabilitation

Context

What does the shoulder have to do?

Anchor point

Foot

Hip

Trunk

Release point/action point

Above shoulder

Align with shoulder

Below shoulder

Unilateral

Bilateral

Transverse rotation

Symmetrical

Asymmetrical

Arm(s)

Single arm

Double arm

Characteristic

High force

High rate of force development (RFD)

High endurance

High speed

Since the kinetic chain has a role in optimal function of the shoulder girdle, one must take into consideration the distal parts and their influence on local function; the scapula acts as a link between the lower limb and trunk (e.g. through the fascial connection between gluteus maximus and latissimus dorsi), the glenohumeral joint and upper limb, permitting effective transfer of forces and joint alignment [21]. Establishing a stable scapular platform is essential in minimising stresses to the shoulder during overhead movements, enabling the rotator cuff muscles to help stabilise the humeral head within the glenoid. The scapula will be influenced by the architecture and geometry of the thoracic spine, which will be influenced by the function of the lumbar spine, pelvis and lower limbs [22]. Therefore, it is essential that sub-optimal movement strategies elsewhere in the kinetic chain should be identified and included in the rehabilitation process.

In addition to the prerequisites of the sport, the requirements of the joints need to be considered. It has been proposed that within the kinetic chain, a balance is required between stability and mobility at joints with optimal performance being produced by an alternating sequence of mobility-stability from distal to proximal (Table 13.2) [23].

Table 13.2

Optimal demands of the kinetic chain

Joint	Requirement
Ankle	Mobility
Knee	Stability
Hip	Mobility
Lumbar spine	Stability
Thoracic spine	Mobility
Scapula	Stability
Glenohumeral	Mobility

Integrating the components form Tables 13.1 and 13.2 will lead us to the required screening tools necessary to provide answers (Table 13.3).

Table 13.3

Screening tools for sporting shoulder

Area	Key test	Reference
Thoracic rotation	Locked lumbar rotation	Johnson and Grindstaff [24]
Thoracic extension	Combined elevation test	Dennis et al. [25]
Shoulder Internal rotation		Cools et al. [26]
Shoulder External rotation		Cools et al. [26]
Hip Internal/external rotation		Barbee-Ellison et al. [27]
Trunk endurance	Extensor endurance test	Biering-Sorensen [28]
	Lateral endurance test	McGill et al. [29]
	The flexor endurance test	McGill et al. [30]
	Flexion-rotation trunk test	Brotons-Gil et al. [31]
Trunk muscle strength (the ability of the musculature to generate force through contractile forces and intra-abdominal pressure)	Double leg lowering test	Cutter and Kevorkian [32]
Trunk rate of force development	Front abdominal power test	Cowley and Swensen [33]
Trunk rate of force development	Side abdominal power test	Cowley and Swensen [33]
Single leg power	Single leg counter movement jump	Hewit et al. [34]
Single leg force capacity	Single leg mid-thigh pull/single leg isometric squat	Owens et al. [35]
Single leg reactive strength	Single leg reactive strength index 3 hop for distance	Stalbom et al. [36]
Single leg stability	SEBT	Gribble et al. [37]

13.3 Thoracic Spine (T-spine)

The T-spine is comprised of 12 vertebrae, which allow flexion, extension, and rotation within those 12 segments. The ribs attach from T1 to T10 and the T-spine has thinner intervertebral discs than the lumbar spine, which adds to its relative inflexibility. T-Spine movement is described as “coupled” such that lateral binding and rotation are obligated to occur together. The T-spine essentially works as two distinctly different subgroups. The upper T-spine (T1–T5) has ipsilateral coupling of the lateral bending and rotation whereas the mid-lower T-spine (T6–T12) has contralateral coupling i.e. lateral bending and rotation occur in opposite directions [38]. Crosbie et al. [39] report that the ratio of upper to lower thoracic extension during bilateral arm elevation was 1:3, and with unilateral arm elevation ipsilateral thoracic rotation occurs. Hence the clinical assessment of the spine needs to be incorporated into management.

13.4 Rotation Range of Movement

The physical demands of sport-specific performance on an athlete’s body is responsible for specific musculoskeletal adaptation. Professional athletes are engaged for most of their sporting life in training and competition [40]. Repetitive muscular activity in the upper limb, necessary for optimal performance of overhead activities and specific movement patterns, leads to the development of sport-specific muscular adaptation in overhead players. Muscular imbalances within rotator-cuff and the peri-scapular muscles, combined with sub-optimal muscular endurance and inappropriate biomechanics can be responsible for overuse injury in the glenohumeral joint of overhead activity players [41].

Repetitive overhead movements commonly lead to the overuse injuries seen in athletes [42]. The deceleration phase of overhead sporting activity has been identified as being most damaging because of the extreme forces placed on the shoulder [20]. The issue of arm dominance has been reported in literature as being responsible for changes in the range of rotation in unilateral sports played above 90° of elevation [43]. Typically, these athletes present with functional increases in external rotation (ER) and concomitant decreases in internal rotation (IR) (Table 13.4).

Table 13.4

Adaptive changes in shoulder rotation ranges in selected sports

Sport	Internal rotation	External rotation
Non-athlete	70°	90°
College swimming [44]	49°	100°
Professional baseball [45]	57°	109°
Junior tennis [46]	55°	105°

Range of motion changes have also been reported in painful throwing shoulders [47–49]. Burkhart et al. [48] suggest that primary posterior inferior capsular contracture could be the potential source of the disabled throwing shoulder and that it can be measured by a glenohumeral internal rotation deficit (GIRD), and report that GIRD occurs before any other motion adaptation occurs.

Measurement of GIRD is assessed relative to the total arc of motion of the glenohumeral joint; total arc of motion is the sum of the measured glenohumeral IR + ER. It has been proposed that a healthy shoulder should present with a 180° arc of motion or, to be more functionally correct, the arc of motion should be equal bilaterally [11]. Previous researchers have documented <20° side difference for IR, and <10% side difference for total ROM as being acceptable values that are unlikely to contribute to pathology [50–54]. Predictive findings have been proposed as; loss of >25° into IR [55] in baseball and softball, and a loss of 20° IR and a loss of 5% in total ROM doubles the risk for injury in professional baseball pitchers. Although Clarsen et al. [56] were unable to find any associations between glenohumeral internal rotation deficits, external rotation deficits or total range of movement differences and injury.

13.5 Shoulder Strength

One of the contributing factors to shoulder injury, and detected on clinical assessment of symptomatic patients is reduction in shoulder strength around the rotator cuff and scapular muscles. The existence of an imbalance between the agonist and antagonist muscle groups has been shown to be one of the major risk factors for developing shoulder injuries [57], with a reduction in the external rotator strength conceivably causing an injury [58].

Controversy exists in the literature as to whether absolute strength or the IR:ER strength ratio should be utilised to quantify the ideal levels of dynamic shoulder stability, particularly in overhead athletes [59]. Several researchers [11, 46–48, 60] have advocated that the combination of forceful, eccentric contractions coupled with high distraction forces may cause microtrauma to the external rotators and posterior cuff during the follow through/deceleration that will re-model in accordance with Wolff’s Law, which states that tissues will adapt to the stresses placed on them [61].

Many methods of assessing the strength around the shoulder girdle have been used; isokinetic dynamometers [62, 63], weight lifting [64], manual muscle testing (MMT) [65, 66], and hand held dynamometers (HHD) [26, 65].

Isokinetic dynamometers have been used as a clinical measure of muscle strength and endurance of the rotator cuff and the scapular stabilisers [26] and have the capability to measure strength at different speeds [67, 68], but these dynamometers are not readily available and the clinical validity of the results can be brought into question.

MMT has good clinically utility but is highly subject to user error and bias [65, 69] and it is difficult to assess small changes in muscle strength and present objective data utilising this method [65]. The results can be influenced by the experience and strength of the examiner [70, 71].

HHD is a more objective method of evaluation and is far superior to MMT when evaluating changes in muscle strength caused by dysfunction [72]. Numerous studies have reported the reliability of HHD to assess upper limb muscle strength including scapular muscles [65, 73, 74].

13.6 Methods of Testing

The reliability of HHDs has been examined in many studies and found to have reasonable inter-rater and intra-rater reliability of shoulder internal and external rotation [65, 75, 76]. Although several different positions have been reported in literature, recent investigations have shown good to excellent intra- and inter-tester reliability established for IR and ER isometric strength measurements, regardless of patient or shoulder position used [26, 77] (Tables 13.5 and 13.6).

Table 13.5

Outcome measures and return to play decision

Outcome measurements and return to play decision	Glenohumeral joint [26, 78]	Scapulothoracic joint [51]
	GH IR and ER ROM	Scapular upward rotation
	GH rotator cuff strength	Strength of the scapular stabilisers
	Eccentric strength of the external rotators	PM length/PM index