Static stretching neither prevented or induced injury when compared to not stretching before running, according to the results of a first-of-its-kind large scale randomized study presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons in San Diego.
Recreational and competitive running are two of the most popular athletic activities in the world. The question of whether runners should stretch before or after running or even stretch at all has generated considerable controversy. The long-established doctrine of stretching before running has been refuted by several authors, but no controlled study has supported their opinions. Stretch studies in connection with ballistic sports like weight lifting, gymnastics and wrestling suggest that a pre-participation stretch routine does not prevent injury in those sports. Those studies have been extrapolated to running and a popular notion has evolved that stretching before running is detrimental to both performance and health. But other studies have found that stretching and warm-up activities improved flexibility and lessened the risk of injury.
Knowing whether stretching is helpful, harmful or makes no difference in injury prevention would significantly contribute to the training habits of a great many athletes.
Study details
The authors conducted a prospective, randomized, two-arm, unmasked, comparative study of a pre-run stretch vs. no stretch in 2,729 volunteer runners. Volunteers were over the age of 13 and ran at least 10 miles per week. The study committed volunteers to three months of stretching or not stretching before running and collected blinded information via a secure website.
Three static stretches were described and demonstrated for the quadriceps, hamstrings, and calf muscle groups. The stretch time was three to five minutes immediately preceding running. Volunteers selected for the non-stretch group did no stretching before runnning. Runners kept all other aspects of their routines the same for the three-month period. All results were self reported, including compliance information. An injury was defined as a condition that prevented running for at least one week. All injuries were rigorously categorized.
A total of 1,398 (51%) out of 2,729 participants sufficiently complied with the randomized stretching assignments (stretching v. no stretching) and completed the three-month study. This per-protocol cohort included 600 (43%) subjects randomized to the stretch group and 798 (57%) subjects randomized to the no stretch group.
Findings
- The overall injury rate (16%) was the same for both the stretch and no-stretch raw injury rates.
- A total of 115 out of 220 injuries (52%) were diagnosed by a healthcare professional.
- The breakdown by injury types:
- Knee injuries: 41/220 (19%)
- Foot/ankle injuries: 56/220 (25%)
- Hip injuries: 6/220 (3%)
- Back injuries: 10/220 (5%); and
- All other injuries, including stress fractures, muscle tears of all types and groin pulls: 105/220 (48%).
- While all runners who switched routines were more likely to experience an injury than those who did not switch, runners who normally stretched as part of their pre-run routine but who were randomly selected for inclusion in the no-stretch group were far more likely to be injured, with a 40% increase in injuries suffered by this group. There was a statistically significant (40%) increase in the injury rate for runners who normally stretched versus those in the no stretch group.
- Over a three-month period there was no statistically significant difference in injury risk between the pre-run stretching and non-stretching groups. Stretching neither prevented or induced injury when compared to not stretching before running.
Risk factors
The study identified the following significant injury risk factors:
- Body mass index (BMI): the heavier the runner, the higher the risk of injury;
- Age: increasing age, increasing injury risk;
- Average miles per week: higher mileage, higher injury rate;
- Recent history of chronic injury or injury (within four months of initiating the study); and
- Switching normal pre-run routines, with runners most at risk those who normally stretched but then suddenly stopped stretching.
Source: American Academy of Orthopaedic Surgeons
Posted February 15, 2011
