PRINCIPLES OF REHABILITATION

TABLE 2. SUBQUALITIES OF STRENGTH Subquality of strength definition Maximal strength

Relative strength

The ability of a muscle or group of muscles to produce a maximal voluntary concentric contraction against a load (referred to as 1 repetition maximum)

The strength per unit of body mass (ie. ratio between maximum strength and bodyweight)

Isometric strength Maximum force generated by a muscle without a change in muscle length

Eccentric strength Maximum force that a muscle can generate while experiencing an increase in length (ie. maximum that can be lowered).

In order to facilitate prioritisation of proposed interventions it may be helpful to complete a needs analysis which links the initial injury to subsequent impairment and functional deficits as summarised in Table 1.

SENSORIMOTOR TRAINING Sensorimotor motor control occurs during all activities and enables an individual to maintain a position, move voluntarily and react to perturbation (19). It is the product of the complex integration of afferent proprioceptive input, central nervous system (CNS) processing and neu- romuscular activation. As outlined above, injury to the joint capsule or ligaments can result in partial deafferentation of proprioceptors giving rise to reduced activity of cortical, subcortical, cerebellar, and spinal structures leading to reduced motor unit recruitment and reduced muscle reflex potentiation. Consequently, following injuries to joint structures there is frequently a significant reduction in sensorimotor control, which is often associated with functional joint instability.

During the early stages of rehabilitation, particular emphasis should be placed upon strategies to restore proprioceptive input and enhance processing of these inputs into coordinated motor strategies. Lephart (20) has described four consecutive stages of sensorimotor training based upon motor learning principles: ■ Kinaesthetic and proprioceptive activity ■ Dynamic joint stabilisation ■ Reactive neuromuscular activation ■ Functionally specific motor patterns.

Exercises where attention is given to 12

enhancing joint position awareness can be used to restore kinaesthesia and proprio- ceptive ability. Such exercises, should be carried out as soon as possible following injury and include techniques such as joint repositioning, movement memory and movement mirroring. Due to the dimin- ished excitation of motor units, it is advised that adequate time between exercises is allowed to facilitate neuromuscular recovery. As a result it is suggested that during the early stages of rehabilitation, proprioceptive exercises are carried out regularly for short periods of time.

Once adequate tissue healing has taken place and there has been a noticeable improvement in kinaesthetic and proprio- ceptive activity, dynamic joint stabilisation exercises are indicated. This involves the use of simple uni-planar functional activi- ties such as walking, lunging onto one foot, single leg squats and balance training (eg. standing on one leg with eyes closed). Following this, reactive neuromuscular training, which involves more advanced forms of balance training and includes exercises such as balancing on labile surfaces and responding to sudden perturbations, may be commenced. A wide range of unstable surfaces are commercial- ly available, each of which provide slightly different sensorimotor challenges; exam- ples of unstable surfaces include, balance mats, mini-trampolines, rocker boards, wobble boards, balance cushions and Bosu®. The difficulty of the neuromuscular challenge can be enhanced by carrying out a skill task such as throwing and catching a ball or performing sudden upper limb movements whilst maintaining one’s

balance or by closing one’s eyes. The application of external perturbations can be highly effective in enhancing reactive neuromuscular control. In the early stages gentle perturbations in the form of rhythmic stabilisation while standing on a solid surface may be useful. As the athlete's ability improves, sudden unexpected perturbations can be intro- duced; examples of this include suddenly moving an unstable platform, pushing the athlete or the application of a sudden force to a resistance belt applied around the athlete's waist.

Sensorimotor training continues through- out the rehabilitation process and is gradually progressed to provide propriocep- tive and neuromuscular challenges during sport-specific drills. Examples of sports- specific drills are outlined below.

MOTOR CONTROL STABILITY TRAINING Motor control stability training addresses altered patterns of muscle recruitment and seeks to improve the central nervous system's ability to fine tune muscle coordination and improve the efficiency of movement. Faulty movement patterns can both result from and result in pain and injury. For example, altered recruitment of shoulder girdle stabilisers may result in reduced scapular control and an increased likelihood of secondary subacromial impingement. On the other hand, an injury to the rotator cuff may result in shoulder pain and associated inhibition of scapular stabilisers. Motor control stability training seeks to retrain muscles with a predomi- nantly stabilising role, to work more effectively in order to facilitate automatic

sportEX medicine 2007;32(Apr):10-16