HAMSTRINGS

hamstrings within conditioning practices, in order to strengthen them. Indeed in my own experiences as a coach, it is not uncommon to observe athletes of all standards tirelessly working away on isolation movements such as lying leg curls and gluteal/hamstring raises in an effort to strengthen the posterior chain muscles of the thighs. While isolation exercises can, and to some extent should, contribute to the approach to hamstring conditioning, they should by no means form the foundations of all hamstring training. Though these exercises can work the hamstrings eccentrically, the fact remains that they isolate the hamstrings by working single joints only, they do not contribute to holistic inter-muscular coordination, and they often do not occur at the velocities required for transfer to sports performance.

the knee, only acting as knee flexors during non-functional settings (5).

HAMSTRING CONDITIONING The mechanical and physiological aspect of any approach to strength and conditioning should be to correspond to the key mechanical or physiological components of an associated sporting movement. When it comes to a systematic approach to muscular conditioning, an integrated method, whereby the combination of joints involved, the specific ranges of motion experienced, and the nature of the muscle action undertaken, be they eccentric, concentric, or isometric, are all taken into consideration. The muscles that extend the hip, especially the hamstrings, are still often mistakenly trained as knee flexors, and it is felt that many of the issues relating to injury susceptibility due to suboptimal approaches to tr ainin g . Science now tells us that the hamstrings are actually powerful hip

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Hamstrings are powerful hip extensors and stabilisers of

extensors and stabilisers of the knee, with the hamstrings only acting as knee flexors during non-functional settings (5).

The effect of training the muscles in traditional non-functional patterns may explain the frequent reoccurrence of hamstring strains in athletes who have rehabilitated using non-functional exercises such as lying machine leg curls, as well as those who rely on this type of activity as their primary approach to hamstring conditioning. The development of strength in the hamstrings, specific to hip extension and not knee flexion, should therefore form the fundamental component in any approach to injury prevention, rehabilitation and performance enhancement.

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Effective strength- ening exercises must

share very defined charac- teristics of movement and contractile function.

In order to hold true value to the process of minimising susceptibility to injury and promoting physical performance, the inclusion of any conditioning activity into

the portfolio of hamstring strengthening exercises should ultimately be determined by its relationship to the function of the hamstring group during running (ie. hip extension).

While strengthening exercises do not necessarily have to look like sprinting movements to be specific, they must however share very defined characteristics of movement and contractile function.

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Brandon and Cleather (2) recommend that the hamstrings be trained in two primary ways: ■ as hip extensors, via closed chain movements corresponding to the action of the hamstring during the stance phase of running

■ using exercises that stress the eccentric muscle action seen during the swing phase, and are characterised by open chain, stretch-shortening type events.

Holistically the goal of all conditioning activities should be multifaceted, with the aims of: ■ improving functional strength ■ improving intramuscular coordination ■ enhancing the mechanics of sprinting by promoting the ability to manage the eccentric forces encountered (4).

Effective hamstring injury prevention and performance enhancement exercises are: ■ multi-joint ■ both open and closed-kinetic chain events ■ include a predominance of eccentric muscle actions.

In some instances conditioning exercises should also reflect stretch-shortening cycle characteristics, as seen during the late swing phase of running, where many hamstring strains occur.

The focus should be on two distinct types of hip extension: ■ straight-leg hip extensions ■ bent leg hip extensions.

Both straight-leg and bent-leg hip extensions target the glutes and hamstrings, and are therefore highly effective approaches to strengthening in these areas. Indeed a functional approach to training that focuses on functional biomechanics, not isolated muscle actions, should be taken. Caution should be adopted when prescribing an exercise that resists a muscle's nonfunctional motion for the sake of simply strengthening that isolated muscle alone. Doing so may just create a large and strong, yet possibly dysfunctional muscle unit which is susceptible to hamstring injury during dynamic exercise. It is also important to note that knee flexion exercises such as squats and their variations affect the hamstrings only as they relate to knee extension and hip extension to achieve a neutral standing position. These exercises do not expose the musculature to the ranges of motion encountered during the running action, but instead focus movement more intensely around the knee joint.

Hip extension exercise Exercise specificity is an essential consideration when designing training programmes to strengthen the hamstrings and minimise their susceptibility to strain during dynamic activity. By no means an exhaustive list, the following exercises represent some key muscle actions that will act to strengthen the hamstring group through multi-joint, open and closed-kinetic chain movements. Furthermore, by adopting these exercises, athletes will be exposed to force development across the force-velocity spectrum, thereby exposing the musculature to both high load and high velocity contractile activity. It is important when selecting exercises that these considerations are taken, as it is through the strengthening of hamstrings during movement-specific exercises for running that true gains in attenuating the susceptibility to injury will be made.

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