Stretching Exercises: can too much stretching slow a runner down?
Can too much stretching actually slow runners down?
The following is offered as an observation on stretching (see the articles on the science of flexibility by Chris Mallac in issues 131 and 132 of PP). It is not in any way meant to invalidate the obvious benefits of flexibility programmes, especially in terms of injury rehabilitation and possible prevention, and as one who has had a 30-year close association with the British Gymnastics Association and with Dance, I am hardly in a position to criticise flexibility work! However, it is possible that some running disciplines may not benefit from over-enthusiastic stretching programmes.
In the years before and during my setting up the physiological side of the BOMC, I asked a number of middle-distance running coaches 'What part does flexibility training play in your overall training programme?' A number replied 'Very little, apart from a pre-run warm-up and stretch'. When I asked why they did not advocate specific flexibility work, they answered: 'Because it tends to make the runners slower'. The sadly-missed Harry Wilson, trainer of gold-medallist and world-record holder Steve Ovett, was particularly strong on this point. As I am a firm believer in listening to the observations of the great coaches, I thought seriously about what he had said. Not long after, I came across two interesting and relevant studies.
One was by Gilbert Gleim and colleagues in the orthopaedics department of Lennox Hill Hospital, New York (J. Orthop. Res. 1990. 8; 814-823), who studied the relationship between 11 measures of trunk and lower-limb flexibility and the economy of treadmill walking and running in 100 subjects, aged 20 to 68, of both genders. Based on the combined scores from all the tests, the subjects were allocated to three groups, 'tightest', 'normal' and 'loosest'. They were then tested for walking/jogging economy at six speeds between 53.6 and 187.7 m/min on the treadmill. The 'tightest' third had significantly better (8-12%) walking/running economy than the 'loosest' third. Gilbert Gleim and his colleagues concluded that non-pathological musculo-skeletal tightness was associated with a lowered steady-state oxygen uptake for treadmill walking and jogging, i.e., the less flexible subjects used less oxygen at the given speeds.
The other study was work by Professor McNeill Alexander, the authority on animal (and human) locomotion, well summed up in his New Scientist article in the issue of April 30, 1987. He noted that a typical runner at middle-distance speed loses and regains about 100 Joules of energy at each step. Of this, his work appeared to show that 35 Joules are stored elastically in the Achilles tendon, and 17 Joules in the ligaments of the arch of the foot. In other words, it appears that about half the energy of the running stride comes from muscular work, and the other half from the elastic properties of the collagen in tendon and ligament, which serve as passive springs.
If one integrates the information from these two sources, then one might conclude that runners whose relevant tendons/ligaments are too 'loose' i.e., with possibly too much 'slack' in the system, might not be able to access the full potential of their elastic energy-return system (which appears to be even more important in horses, camels and kangaroos).
Thus when Harry Wilson expressed caution about over-flexibility in his runners, he was possibly intuitively and pragmatically reaching a conclusion which would appear to have a possible scientific basis. If I might adapt a quote from Humphrey Lyttleton, 'we sports scientists often ride in the dungcart of progress, telling the sportsworld the way it has gone'. Either way, the observations of other sports scientists, physiotherapists, coaches and runners would be of interest.
Professor of Sports Science, Brunel University
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