Clinical Question: Can a rigorous, specific warm-up routine decrease knee and ankle injuries in high school athletes?
Study Design: Randomized controlled trial (single-blinded)
Synopsis: The authors of this study evaluated a structured warm-up program to prevent sports-related injuries in 1,837 adolescents of both sexes who were 15 to 17 years of age. The warm-up program lasted 20 minutes and involved four sets of exercises. The program began with jogging, progressed to technique exercises that focused on specific movements such as cutting and jumping, moved to balance exercises designed to increase awareness of knee movements on wobble boards and balance mats, and finished with strength exercises for the quadriceps and hamstrings. These warm-ups were repeated daily for 15 days and then performed once weekly afterward. The study was conducted in 145 handball clubs in Norway, with the intervention randomized by team (cluster randomization). Knee and ankle injuries were evaluated by investigators unaware of treatment assignment.
During the single season in which the exercises were used, injuries occurred in 14 percent of the players; 81 percent were acute knee and ankle injuries and 19 percent were overuse injuries. Only 9.9 percent of the players in the warm-up group experienced an injury compared with 19 percent of those in the control group (P < .001; number needed to treat [NNT] = 11; 95 percent confidence interval [CI], 8.2 to 16.4). Acute knee injuries occurred in 2 percent of athletes in the warm-up group and 4.3 percent in the control group (P = .007; NNT = 43; 95 percent CI, 31 to 122). Ankle injuries were not reduced statistically, although upper limb injuries were reduced (1.8 versus 4.4 percent; P = .002; NNT = 38). Injuries did not differ by sex.
Bottom Line: Injuries in high school athletes can be reduced by 50 percent if coaches insist on a rigorous warm-up routine at the beginning of the season. This warm-up routine includes a series of exercises specifically designed to improve muscle awareness, balance, and strength. Typical stretching protocols do not decrease injury (Herbert RD, Gabriel M. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review. BMJ 2002;325:468–70). The effective routine is illustrated online (http://www.BMJ.com). Physicians who are involved in high school sports can forward this article to the coaches and trainers of sports that involve quick movements. (Level of Evidence: 1b–)