Longitudinally Decreased Knee Abduction and Increased Hamstrings Strength in Females with Self-Reported Resistance Training

Abstract

PURPOSE: During adolescent growth, increased knee abduction likely increase risk of ACL injury in females. The purpose was to determine the effects of participation in resistance training on longitudinal alterations in landing biomechanics and strength in pubertal and post-pubertal female athletes. The hypothesis tested was that knee abduction motion and moment would be improved in athletes that reported participation in structured resistance training during maturation. METHODS: 259 female subjects, 145 pubertal (P) and 114 post-pubertal (PP), were assessed for landing biomechanics and isokinetic hamstrings strength during two testing sessions one year apart. Knee abduction motion and moments were calculated during the landing phase of a drop vertical jump (DVJ). Subjects were classified based on their maturation status as either P or PP. Self-reported resistance training was assessed with a questionnaire at the second session to determine if the subject participated in a preseason or off-season program (Resistance Training (RT) or No Training (NT). ANOVAs (p<0.05) tested the effects of a year of growth (repeat measures), maturation (pubertal, post-pubertal) and self-reported resistance training (no, yes) on the dependent variables (knee abduction motion and moment and hamstrings strength). RESULTS: A 3-way interaction was observed in knee abduction moment (p<0.05). Post-hoc analysis determined that pubertal athletes that self-reported previous participation in resistance training (P-RT) had a 13.4% decrease in knee abduction moment from the first to second year testing compared to an average increase of 21.7% in the other groups (PP-RT, P-NT, PP-NT)(p<0.05). P-RT and PP-RT subjects had significantly greater improvements in knee abduction motion compared to subjects that did not self-report RT (p<0.05). Hamstrings strength was significantly greater in P-RT and PP-RT compared to P-NT and PP-NT groups (p<0.05). CONCLUSIONS: Knee abduction and hamstrings strength was positively altered in athletes that self-reported participation in resistance training compared to those who did not and P-RT athletes were altered to a greater extent than PP-RT. Further evaluation of the effects of resistance training targeted towards pubertal females should occur via randomized control trials.