Stretching is often part of a runner's exercise routine, but lengthening out those muscles before you hit the track might hamper your performance, a new study suggests.
The results show stretching before a long-distance run lowers endurance , which can prevent athletes from running as far as they could sans stretches. In addition, pre-run stretching also increases the amount of energy needed while running, so well-stretched athletes use up more calories.
However, the study was quite small and involved only male athletes. More research is needed to confirm the findings and to see whether they apply to women as well, the researchers say.
Stretching and running
So-called static stretching, or stretching in place, involves stretching a muscle and holding it in a stretched position for around 30 seconds to several minutes. While many athletes stretch as part of their warm up, recent studies have suggested this type of stretching may have negative consequences, including reducing the muscle strength and decreasing the stiffness between the muscle and the tendon holding it to the bone.
The new study involved 10 men who were members of the Florida State University track and field team. The guys took part in two experimental sessions. In one session, they stretched muscles in their lower body using static stretches for 16 minutes before completing a 60-minute run on a treadmill. In the other session, they ran without prior stretching. In both cases, the runners were not allowed to see how far they had run or how many calories they had burned.
If the subjects stretched prior to the run, their running distance was reduced on average by 3.4 percent, or 0.12 miles (0.2 kilometers). They also burned 20 more calories during their run if they stretched beforehand.
Although the negative impact of stretching appears small, it may mean the difference between winning and losing in a close competition, the researchers said.
Why might stretching be bad?
The researchers suggest that stretching before running may decrease the muscle efficiency, reducing how much force a muscle is able to produce.
Stretching might also change the frequency of a runner's stride, causing them to use up more energy.
"Therefore, in events such as long-distance running, where success is related to producing work with minimal energy cost, it may be unfavorable for coaches to have athletes warm up in a manner that has them perform long, static stretches immediately before a middle- or long-distance running event," the researchers write in the September issue of the Journal of Strength & Conditioning Research.
The study was conducted by Jacob Wilson of The Florida State University, in Tallahassee, and colleagues.
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