REHABILITATION (11,16,21), enhances angiogenesis during fracture healing (22), BOX 2: CLINICAL APPLICATIONS

■ Functional rehabilitation should involve the restoration of physical fitness and joint stability unique to each person’s function

■ The clinician should perform an activity-specific needs- analysis

■ Functional rehabilitation of the lower limb should involve closed kinetic chain (CKC)-biased training

■ Traditional rehabilitation is a prerequisite to functional rehabilitation

■ Functional rehabilitation should involve a clinically-rea- soned process of exercise selection, exercise progression, and outcome measurement unique to each person’s lower limb function

■ CKC exercises create unique lines of mechanical stress which enhance the mechanical properties of bone and ligament specific to CKC function

■ CKC exercises should be performed to enhance CKC senso- rimotor control and muscle performance of the lower limb.

increases the mechanical ‘quality’ of callus formation (23), and facilitates the appropriate orientation of ‘trabecular trajectories’ (Figure 4) in spongy (ie. trabecular) bone (21).

Davis’ law Davis’ law states that inert tissue (eg. ligament) remodels along the ‘lines of mechanical stress’ imposed upon it (16) - inert tissue remodels with better ‘quality’ and tensile strength due to appro- priate orientation and organisation of collagen fibres (24). Animal and human studies demonstrate enhanced tensile strength of lig- ament tissue following early controlled functional rehabilitation (17,24). In vitro studies demonstrate that fibroblast proliferation and activation increases in response to controlled tensile forces (25), and that activated fibroblasts align themselves to lay colla- gen down along the lines of such mechanical stress (26,27). Therefore, to increase the tensile strength of inert tissue, con- trolled forces must be deliberately imposed on that tissue throughout the healing process (28).

Sensorimotor control Sensorimotor control is defined as ‘the control of both movement and posture’ (29). Since joint stability refers to the ability of a joint to maintain alignment and resist displacement (11, 30), sen- sorimotor control of joint stability refers to the co-ordination of different muscle groups to control the movement and posture (ie. alignment) of a joint. Specific CKC-biased rehabilitation pro- grammes have demonstrated that inter-muscular co-ordination is altered to optimise muscle synergies which facilitate functional joint stability of the lower limb following ligament injury (31-33). Therefore, progressive functional training of the lower limb is nec- essary to promote lower limb joint stability via the acquisition of an optimal inter-muscular motor programme.

Specificity of muscle training Muscle performance is highly specific to the type of training which is performed (34,35). Research demonstrates that the effects of exercise are mode specific (ie. OKC versus CKC), muscle group spe- cific, range-of-motion specific, muscle action specific, intensity specific, and velocity specific (34,35). For example, CKC muscle

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training of the lower limb significantly enhances CKC force pro- duction defined by a vertical jump (36), whereas OKC muscle training does not (36). The findings of such training studies are supported further by the findings of correlation studies: CKC mus- cle performance demonstrates a stronger relationship to CKC func- tion (eg. jumping, hopping) than OKC muscle performance (9,14,37). These findings are attributed to neurophysiological mechanisms and the preferential recruitment of ‘task-specific’ motor units (35). Therefore, to enhance muscle performance for a specific activity or purpose (ie. function), muscle training must mimic the mode, range-of-motion, muscle action, intensity, and velocity of that specific activity or purpose (34-36). However, to illustrate the importance of traditional rehabilitation (eg. OKC strength training) before functional rehabilitation, isolated quadriceps weakness can impair whole lower limb force absorption (38) and stability (39) during CKC physical activities.

SUMMARY Functional rehabilitation should be specific to each person’s unique activity or purpose. In order to design a functional rehabilitation programme, the clinician should possess a thorough understanding of each person’s activity-specific needs. With regard to the lower limb, since the lower limb predominantly func- tions in a CKC, functional rehabilitation should employ CKC-biased exercises and outcome measures. Following traditional rehabilita- tion, functional rehabilitation of the lower limb will then ensure that bone and connective tissue specifically adapt to tolerate the progressive loads imposed upon them, that optimal motor control and muscle performance is acquired, and that the risk of re-injury on return-to-work or return-to-competition is minimised.

THE AUTHOR ■ Nicholas Clark, MSc, MCSP, MMACP, CSCS, is a chartered neuro- musculoskeletal physiotherapist and certified strength and condi- tioning specialist. He is clinical director of the London-based Integrated Physiotherapy and Conditioning Limited, academy phys- iotherapist to a premiership rugby union football club, vice chair of the Association of Chartered Physiotherapists in Exercise Therapy (ACPET), and a visiting lecturer to the MSc School of Human Health and Performance at University College London.

Figure 4. Cross-section of hip joint illustrating trabecular trajectories of the femur