Findings support use of strengthening
By Jill R. Dorson
Hip strengthening may be as important for preventing lateral ankle sprains in youth soccer players as it is in adults, according to a recent Belgian study.
Researchers from the University of Ghent found that 12 of 133 (9%) male youth soccer players, ranging in age from 10 to 16 years, sustained ankle injuries over a three-year reporting period.
After adjusting for body weight and strength of other hip muscles, the authors found that players with greater hip extension strength than the cohort average had a significantly lower risk of a lateral ankle sprain than those with weaker hip extensors (hazard ratio of .3). Mean survival time—or the time span for which a player remained injury free—was up to 10% longer for players whose hip extension strength was higher than the group average.
The findings, published in the American Journal of Sports Medicine (AJSM) in November 2016, echo those of a study of 210 male semiprofessional Iranian soccer players that was presented at the 2016 meeting of the American College of Sports Medicine in Boston.
In that study, conducted jointly by researchers from the University of Isfahan in Iran and the University of Southern California (USC) in Los Angeles, 11.9% of players sustained lateral ankle sprains, and isometric hip abductor weakness was associated with a higher incidence of lateral ankle sprains.
In contrast with the Isfahan-USC study, hip abductor strength was not significantly associated with ankle sprain risk in the Belgian study of youth athletes. However, both studies underscore the growing recognition among researchers and clinicians that hip strength can contribute to ankle sprain risk in soccer players of varying ages.
“Basically, the theory is when the hip muscles are weak, two things happen—the foot and ankle muscles overcompensate, and you alter your trunk position [ie, lean toward the weak side]. The idea is that the foot and ankle muscles overcompensate and allow the ankle to roll,” said Chris Powers, PT, PhD, owner of Movement Performance Institute in Los Angeles and a faculty member in the Department of Physical Therapy at USC. “Hip weakness and altered trunk motions change the biomechanics of the ankle.”
— Chris Powers, PT, PhD
Khalil Khayambashi, PT, PhD, a professor in the Department of Sports Sciences at the University of Isfahan, implemented and oversaw the data collection for the Isfahan-USC study.
“The hip is the focal point between the heavier trunk and upper and lower extremities,” Khayambashi said. “To have good balance, superior hip muscle strength is mandatory.”
The Belgian authors hypothesized that the ability to attenuate impact during high-velocity maneuvers may be limited or inadequate in youth soccer players with poor hip extension strength, and that this limitation may be exacerbated under fatigued conditions.
The authors of both studies suggested hip-strengthening exercises can be integrated into soccer training programs to help reduce ankle sprain risk. Simple exercises to improve hip strength that could easily be added to soccer training programs include lunges and resistance-band exercises.
Interestingly, the findings of the two soccer studies appear to contrast with those of a 2006 AJSM study of high school athletes from multiple sports, in which three measures of hip strength (hip abduction, hip adduction, hip flexion strength) were not significantly associated with ankle sprain risk over a two-year period.
That study, conducted at the Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT) in New York, included 169 high school athletes (68 girls) representing football, boys and girls basketball, boys and girls soccer, and girls gymnastics; all were involved in strength training.
The ages of the athletes in the NISMAT study ranged from 14 to 18 years. In the Belgian study, though the ages of the athletes in the study population ranged from 10 to 16 years, there were no ankle sprains in the youngest athletes (aged 10 to 12 years). Still, the older mean age of the players in the NISMAT study could have contributed to the difference in findings between the two studies, according to Tim Tyler, MS, PT, ACT, owner of PRO Sports Physical Therapy in Westchester, NY, and a coauthor of the NISMAT study.
“We looked at not only soccer players, but other athletes, too,” said Tyler, who added that he found the Belgian findings surprising. “In such a young population—of young adolescent kids who might not be fully developed—I’m wondering if they really have hip weakness or poor neuromuscular control of the muscles?”
The experts also noted the mechanisms contributing to ankle sprain are likely multifactorial. As just one example, all three studies reported a direct relationship between an athlete’s weight and the risk of ankle sprain; the heavier the athlete, the more likely he or she is to sustain an ankle sprain.
Jill R. Dorson is a freelance writer based in San Diego, CA.
De Ridder, R, Witvrouw E, Dolphens M, et al. Hip strength as an intrinsic risk factor for lateral ankle sprains in youth soccer players: a 3-season prospective study. Am J Sports Med 2017;45(2):410-416.
Straub R, Khayambashi K, Ghoddosi N, Powers C. Hip abductor strength predicts lateral non-contact ankle sprains in male soccer players: a prospective study. Med Sci Sports Exerc 2016;48(5 Suppl):S18-S19.
McHugh MP, Tyler TF, Tetro DT, et al. Risk factors for noncontact ankle sprains in high school athletes: the role of hip strength and balance ability. Am J Sports Med 2006;34(3);464-470.