Laird Harrison

June 07, 2012

June 7, 2012 (San Francisco, California) — Girls can learn movements that might reduce damage to their anterior cruciate ligaments (ACL), researchers reported here at the American College of Sports Medicine 59th Annual Meeting.

After learning a set of techniques for jumping and changing direction, none of the girls on a high-school soccer team sustained ACL injuries the following season, said first author Amelia Goodfellow, a researcher at the University of California, Davis.

The team was highly competitive; in previous seasons, there were typically 1 or 2 knee injuries, according to coach reports.

ACL injuries are common among female athletes, particularly soccer and basketball players, Goodfellow told Medscape Medical News. "It's a humungous problem, especially with young athletes; they have not developed the skills and coaches are not focusing on them."

To see if they could reduce the risk for this injury, Goodfellow and her researchers taught 23 girls (age, 16 ± 1 years) on varsity and junior varsity high-school soccer teams movements based on the Prevent Injury and Enhance Performance protocol.

Girls learned to keep their knees flexed and aligned with their hips while staying low and balanced, Goodfellow explained. The girls also learned to land on the balls of their feet, following through to their heels.

Keeping these goals in mind, the girls practiced running and cutting to the side and other typical soccer movements. "A lot of ACL injuries happen during transitions — cutting side to side or jumping for a header," said Goodfellow.

The girls also practiced movements like jumping for a head ball and kicking a volley shot on a balance disc. "We strove to incorporate natural movements into conditioning," Goodfellow said.

The players did exercises to build core strength and stretched their quadriceps and hamstrings.

The girls completed 8 sessions of this 20- to 30-minute warm-up protocol.

To see whether the program worked, the researchers measured the girls' force of landing from a 28 cm drop jump. They also measured the girls' knee flexion angle and the extent of their valgus/varus collapse.

They took measurements before and after training using a Kistler Quattro Jump force plate and Dartfish video analysis.

None of the girls got injured during the practice or games during the season.

The distance between the girls' knees increased from 27.4 ± 6.0 cm to 29.9 ± 8.2 cm (a decreased valgus), which was statistically significant (P < .01).

Knee flexion angle improved from 119.7 ± 11.9 degrees to 110.5 ± 13.4 degrees.

The force of landing decreased, but the difference was not statistically significant.

After the training, 65% of the girls showed improvement in knee width, 78% in knee flexion, and 91% in ground reaction.

Andrea Fradkin, PhD, associate professor of exercise science at Bloomsburg University in Pennsylvania, told Medscape Medical News she is impressed by the study.

"This is definitely showing some performance improvement at the same time as reducing injury," said Dr. Fradkin, who was not involved with this study. "That's what a warm-up program is meant to do."

The study makes an important contribution to the literature, she noted. "There is not much out there," she added. "It's difficult to study injuries."

Ms. Goodfellow and Dr. Fradkin have disclosed no relevant financial relationships.

American College of Sports Medicine (ACSM) 59th Annual Meeting: Abstract 1218. Presented June 2, 2012.


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