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SPORTS MEDICINE STRETCHING
JOINT MOBILITY Maintaining a good range of joint movement can have long-term beneficial effects on articular cartilage. If limited joint mobility in older athletes results in the periphery of the articular cartilage being denied nutrition, encouraging good joint mobility in younger athletes may help to alleviate future problems of joint “wear and tear”.
MUSCLE MOBILITY Muscles that usually require most attention are the ones that pass over more than one joint or have a multi-action effect. The most beneficial static stretching exercises influence the viscous properties of the parallel elastic components of muscle, resulting in plastic deformation (9). The most suitable exercises are those which: n Reduce the effects of the stretch reflex n Take advantage of the inverse stretch reflex (using the Golgi tendon organ), frequently termed autogenic inhibition n Occur at increased muscle temperature, which enhances the viscous stress relaxation of collagen tissue. In other words, LOW forces for LONG duration at HIGHER than normal muscle temperatures. Reviewing the literature, there is a lack of consistency
in the selection of stretching durations and whether active or passive movement is assessed. According to Roberts and Wilson (10), recommendations for the duration of static stretches range from 5 to 60 seconds, yet justifications have been largely absent. McNair (11) suggests that when undertaking holds toward the end of range of motion, the most economical time to hold a stretch is between 20-30 seconds and that whether the athlete is performing static holds or dynamic stretches, the greatest reductions in resistive torque occur in the first repetition.
The total amount of time spent in a stretched position (ie. the duration of the hold x the number of repetitions) appears to be important, although this is not supported by Bandy et al’s study (12). Kibler and Chandler (13) suggested that the effectiveness of static stretching appeared to be related to the period of time it was practised, ie. weeks/month, rather than the number of repetitions per day.
The optimal duration for stretching may vary by muscle group because their viscoelastic response to heat plus stretching may differ (14). Shrier and Gossal (15) stated that with longer duration of stretching there would be an increase in the stretch tolerance, resulting in less pain for the same force applied to the muscle, allowing more force to be applied to the muscle.
Roberts and Wilson (10) suggested that active stretching produced an exercise overload in the agonist muscle group that was contracting to sustain the stretch position. A longer hold time (15 seconds compared to 5 seconds) would result
in greater improvement in muscular strength, which would then help to increase the active range of movement, but not the passive. Practically, the following regimes have been suggested:
n Perform the stretches immediately after training/ competition or after a warm/hot bath or shower (9, 16) n Practice a minimum of four repetitions per exercise (17) n Longer duration static stretching (ie. 45 seconds) appears to be significantly better than shorter duration stretches in improving hamstring flexibility, as shown in studies where static stretching duration is altered, and the total amount of time spent in a stretched position is controlled (18) n Higher number of repetitions appears to be significantly better at maintaining the gain in hamstring flexibility (18). The principles described above are very different to ballistic stretching exercises, which are repetitive, short duration, high velocity exercises that take muscles beyond their normal range of movement in an effort to improve mobility. Although ballistic stretching exercises may improve muscle flexibility, they cause muscle soreness as the muscle reflexly contracts to protect itself. Any stretching exercise that puts a “bounce” at the end of the stretch could be defined as ballistic and it is wise to avoid this type of exercise when trying to improve mobility. Compared to ballistic stretching, static stretching is unlikely to exceed the muscle’s extensibility limit, requires less energy to perform and alleviates muscle soreness (19). Many sports now incorporate proprioceptive
neuromuscular facilitation (PNF) techniques into their mobility programmes. The active and passive techniques used in sport are modifications of the slow reversal-hold relax and hold relax techniques. Active PNF stretching utilises reciprocal inhibition and is perceived as the safer method because the athlete is in control. Passive PNF stretching is not under the control of the athlete and relies on the integrity and sensible approach of the second person (coach or other athlete). Feland and Marin (20) showed that using sub-maximal contractions during contract-relax PNF stretching of the hamstrings (three 6-second stretches with a 10-second rest between contractions, once a day for five days) was as beneficial at improving hamstring flexibility as maximal contractions. Athletes would probably derive even greater benefit if they also used the PNF patterns of movement - utilising three planes of movement, in particular rotation, in one pattern is more realistic and more applicable to almost all sporting actions. Waddington (21) outlines PNF patterns from a medical perspective, and athletes can use the patterns during active exercise/dynamic warm-up as well as during exercises to improve muscle mobility. Different areas of a muscle can also be targeted by fixing either the proximal or
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