Injury prevention: does pre-workout stretching help?

Does stretching before a workout increase the risk of injury? Owen Anderson investigates

Even though about 65 per cent of all runners will be injured during 1994 and the average runner misses from 5-10 per cent of scheduled workouts each year because of injuries, many runners feel they know how to keep their own risk of injury at a minimum. The solution, they say, is to stretch before workouts. In one respect, pre-workout stretching is a logical thing to do. After all, overly tight muscles and tendons probably are more susceptible to little tears and strains during exercise, compared to relaxed, flexible sinews and connective tissues. And studies have shown that pre-workout stretches can improve flexibility in the hamstrings and is especially effective at unkinking tautness in the lower back. But can stretching really reduce injury rates?

 Not according to David A. Lally, Ph.D., an exercise physiologist at the University of Hawaii-Manoa. Lally has just completed a careful study of 1543 individuals who participated in the Honolulu Marathon, and his investigations actually link pre-workout stretching with a higher risk of injury.

When Lally analyzed the training habits of the marathon runners, he uncovered some of the usual relationships between training and injuries. For example, high-mileage runners and individuals who conducted unusually long individual workouts tended to have significantly higher rates of injury, compared to low-mileage people. To count as an actual injury, a physical problem had to prevent usual training for at least five days.

But Lally’s key finding – that stretching was associated with more injuries – was a shocker. After all, many runners believe that stretching has a protective effect, and a prior study carried out by Dutch researchers had indicated that although stretching might not lower injury frequency, it wouldn’t lead to greater muscle mayhem, either.

White males get hurt
In Lally’s survey, 47 per cent of all male runners who stretched regularly were injured during a one-year period, while only 33 per cent of male runners who didn’t stretch were hurt, a statistically significant difference. However, this link between stretching and injury didn’t apply to female marathoners; female stretchers had the same rate of injury as female non-stretchers. The relationship also didn’t apply to Oriental runners of either sex (a large number of Japanese runners compete in the Honolulu Marathon each year). Only in white male marathoners was there a connection between stretching and injury.

An adept researcher, Lally was able to control for the possibility that those individuals who had been injured before his study began had taken up stretching as a prophylactic measure, a linkage which would have strongly biased his results. After all, the strongest predictor of a future running injury is a past injury. Thus, including runners who had taken up stretching after a prior injury would automatically make stretching look bad. When Lally threw the males with previous injuries out of his study, things still were bad for the stretchers, who had a 33-per cent greater risk of injury, compared to non-stretching runners. The stretched runners did not run more miles than the non-stretched individuals, so higher mileage was not a possible explanation for the stretching & injury phenomenon.

‘I don’t know why stretching is associated with a higher risk of injury,or why the relationship is only true for white males,’ said Lally in a recent interview with PEAK PERFORMANCE. ‘But there’s certainly no a priori reason why stretching should limit injury risk. After all, most running injuries are caused by overuse, and stretching your muscles before workouts is not going to prevent you overusing them.’
One weakness in the Lally study is that there was no control of the actual stretching process. As a result, white males may have carried out larger amounts of ballistic stretching or might have overstretched their muscles – lengthening them well beyond their normal range of motion, a process which could have increased the risk of injury. However, there’s little evidence that this is what actually happened.

Could the timing make a difference? Lally’s analysis did yield one fascinating bit of information. Those marathoners who stretched before training sessions had higher rates of injuries, compared to runners who didn’t stretch. However, athletes who stretched after their workouts actually had lower frequencies of injuries.

When you think about the role that stretching should play, this latter finding makes good sense. Although it’s popular to include stretching before the beginning of a workout, there’s actually very little resemblance between the act of stretching out a muscle and the rapid shortenings (contractions) which muscles undergo during a workout. In other words, stretching doesn’t represent specific preparation for a real-life training session. In a stretch, a muscle is elongated and then held in a static position; in a workout, a muscle shortens repeatedly.

On the other hand, muscles are often fairly tight – and in some cases are even close to going into a spasm – after a very strenuous workout ends. At that point, stretching is a fine way to transform a hypercontracted muscle into a relaxed collection of fibres which can comfortably adapt to the more passive activities which follow a training session.

So, while stretching is good after a workout, it probably makes sense to carry out some more specific preparatory activities before one. Walking, jogging slowly, and completing the hops, skips, vertical jumps, and ‘duck walks’ described in the recent Sports Injury issue of PEAK PERFORMANCE will in most cases prepare you for a workout more effectively than sitting on your rump and trying to lengthen your hamstrings by a fraction of an inch or so (see the article ‘Staying Strong Between Your Knees and Feet,’ on page S of that issue). Such specific activities ‘wake up’ your cardiovascular, muscular and nervous systems so that you’re fully ready to train intensely. If you carry out the specific activities regularly, you’ll be surprised at the improved quality of both your workouts and your competitive efforts.

Owen Anderson

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