Summary

Women’s ice hockey players exhibited greater measures of core strength as well as lesser lateral trunk lean, and knee valgus angles upon knee joint loading, suggesting greater core strength may contribute to restraining external perturbations associated with dynamic loading tasks that laterally displace the trunk, and increase knee valgus angle commonly linked to ACL injury.

Abstract

Objectives: Anterior cruciate ligament (ACL) injury incidence rates are disparate among women’s collegiate sports; specifically, ice hockey players display a markedly lower rate (0.02 per 1,000 athletic exposures) compared with lacrosse (0.23), and field hockey (0.11). While characteristics of each sport may contribute to these diverse rates, the identification of modifiable factors is necessary to help explain this phenomenon, and for incorporating preventative interventions. Poor core performance measures have been proposed to contribute to increased risk during dynamic loading tasks in sports, such as landing, as the result of the center of mass displacing in a manner that heightens knee valgus angle, an ACL injury mechanism. Therefore, our specific aims were to compare core performance variables, and body segment kinematic responses upon knee joint loading among these three specific women’s stick-carrying sports. We hypothesized that ice hockey players would demonstrate greater core performance measures as well as lesser lateral trunk lean (LTL), and knee valgus (KV) angles upon landing compared with lacrosse, and field hockey players.

Methods

Twenty-six healthy women (age = 19.5±1.2 years; height = 1.67±0.09 m; mass = 67.1±5.5 kg) from Division-I collegiate ice hockey, lacrosse, and field hockey programs were enrolled. Women performed a standardized landing task on the non-dominant leg, and core strength assessment at baseline, and following a core fatiguing protocol. Video analysis computed body segment kinematics, and dynamometry measured strength normalized to body mass. Kruskal-Wallis tests, and related post-hoc pairwise comparisons analyzed differences among groups. P = 0.05 denoted statistical significance a priori. Cohen’s d effect size, and accompanying 95% confidence interval (CI) were assessed for clinical significance.

Results

Ice hockey players produced statistically, and clinically significant greater peak trunk flexion force (2.85 N/kg) than lacrosse players [1.50 N/kg, P = 0.030; d = 1.62 (95% CI = 1.34, 1.90)] at baseline; furthermore, ice hockey players generated statistically, and clinically significant greater peak trunk flexion force (2.71 N/kg) than lacrosse [1.14 N/kg,
P = 0.002; d = 2.26 (95% CI = 1.98, 2.54)], and field hockey (1.30 N/kg, P = 0.020; d = 2.15 (95% CI = 1.77, 2.53)] players after the core fatiguing protocol. Ice hockey players also revealed large effect sizes for lesser baseline peak LTL angle, and KV angle at initial contact compared with field hockey players. A similar effect size trend existed with peak
LTL angle following the core fatiguing protocol.

Conclusion

Women’s ice hockey players exhibited greater measures of core strength as well as lesser LTL, and KV angles upon knee joint loading, which may potentially underpin documented lower ACL injury incidence rates compared with lacrosse, and field hockey players. Our outcomes suggest greater core strength may contribute to restraining external perturbations associated with dynamic loading tasks that laterally displace the trunk, and increase knee valgus angle commonly linked to ACL injury. Considering that core strength is a modifiable factor, related injury prevention programs should target addressing such deficiencies in an effort to reduce ACL injury risk in women’s collegiate sports such
as lacrosse, and field hockey.