Explosive hamstrings strength asymmetry persists despite maximal hamstring strength recovery following anterior cruciate ligament reconstruction using hamstring tendon autografts.

PURPOSE: To investigate the differences in maximal (isometric and concentric peak torque) and explosive (rate of torque development (RTD)) hamstring and quadriceps strength symmetry between males and females during early- and late-phase rehabilitation after anterior cruciate ligament reconstruction (ACLR) using hamstring tendon (HT) autografts and to determine the interaction of time and sex on maximal and explosive strength symmetry. METHODS: A total of 38 female and 51 male participants were assessed during early (3-6 months post-operative) and late (7-12 months post-operative) phases of rehabilitation following ACLR. Maximal (concentric and isometric peak torque) and explosive (isometric RTD) hamstring and quadriceps strength were assessed and presented as limb symmetry index (LSI). RESULTS: Maximal concentric hamstrings asymmetry (Early: 86 ± 14; Late 92 ± 13; p = 0.005) as well as maximal concentric (Early, 73 ± 15; Late 91 ± 12; p < 0.001) and explosive (Early: 82 ± 30; Late: 92 ± 25; p = 0.03) quadriceps asymmetry decreased from early to late rehabilitation. However, there were no significant changes in maximal isometric quadriceps strength and explosive isometric hamstring strength in the same time period. Females had a larger asymmetry in maximal concentric (Females: 75 ± 17; Males: 81 ± 15; p = 0.001) and explosive (Females: 81 ± 32; Males: 89 ± 25; p = 0.01) quadriceps strength than males throughout rehabilitation. There were no sex differences in maximal and explosive hamstring strength. There were no sex by time interactions for any variables. CONCLUSION: Explosive hamstring strength asymmetry did not improve despite recovery of maximal hamstring strength during rehabilitation following ACLR with HT autografts. While sex did not influence strength recovery, females had larger maximal and explosive quadriceps strength asymmetry compared to males throughout rehabilitation following ACLR. LEVEL OF EVIDENCE: Level III.

Comparison of injury profiles between elite Australian male and female cricket players.

OBJECTIVES: This study presents seven seasons of injury surveillance data for both elite Australian male and female cricket players, revealing injury statistics and allowing for comparison between sexes. DESIGN: Retrospective cohort. METHODS: Participants were elite Australian male and female cricket players who were contracted to play for a national and/or state/territory team and/or T20 franchise between 2015-16 and 2021-22 (7 seasons). Injury data was recorded in Cricket Australia's Athlete Management System database and combined with match data. The STROBE-SIIS statement was used as the relevant guideline for this study. RESULTS: Data for 1345 male player seasons and 959 female player seasons revealed sex-related differences in the injury incidence rates and prevalence. Males had higher incidence (average 136 vs 101 injuries per 1000 match days) and prevalence of match time-loss injuries (average 10.4% vs 6.5% players unavailable). However, the overall incidence of all medical attention injuries were similar between sexes (Incidence Rate Ratio (IRR) 0.9, 95%CI 0.8-1.0). The most frequent match time-loss injuries for males were hamstring strains (7.4 new injuries per 100 players per season), side and abdominal strains (5.5), concussion (5.0), lumbar stress fractures (4.3), and wrist and hand fractures (3.9). The most frequent match time-loss injuries for females over the 7 seasons were hamstring strains (3.1), concussion (2.3), quadriceps strains (2.4) and shin/foot/ankle stress fractures (2.0). The IRR of medical attention injuries for males compared to females was higher for lumbosacral stress fractures (IRR 2.3), elbow and forearm injuries (1.5), and concussion (1.4), and lower for lower leg, foot, and ankle stress fractures (0.6), shoulder and upper arm injuries (0.7), and quadriceps strains (0.6). CONCLUSIONS: Robust long-term injury surveillance enabled the injury profiles of elite Australian male and female cricket players to be understood and compared. Males had a higher incidence and prevalence of match time-loss injuries, likely reflecting a higher match exposure.

Strength and Biomechanical Risk Factors for Noncontact ACL Injury in Elite Female Footballers: A Prospective Study.

PURPOSE: This study aimed to determine if a preseason field-based test battery was prospectively associated with noncontact anterior cruciate ligament (ACL) injury in elite female footballers. METHODS: In total, 322 elite senior and junior female Australian Rules Football and soccer players had their isometric hip adductor and abductor strength, eccentric knee flexor strength, countermovement jump (CMJ) kinetics, and single-leg hop kinematics assessed during the 2019 preseason. Demographic and injury history details were also collected. Footballers were subsequently followed for 18 months for ACL injury. RESULTS: Fifteen noncontact ACL injuries occurred during the follow-up period. Prior ACL injury (odds ratio [OR], 9.68; 95% confidence interval (95% CI), 2.67-31.46), a lower isometric hip adductor to abductor strength ratio (OR, 1.98; 95% CI, 1.09-3.61), greater CMJ peak take-off force (OR, 1.74; 95% CI, 1.09-3.61), and greater single-leg triple vertical hop average dynamic knee valgus (OR, 1.97; 95% CI, 1.06-3.63) and ipsilateral trunk flexion (OR, 1.60; 95% CI, 1.01-2.55) were independently associated with an increased risk of subsequent ACL injury. A multivariable prediction model consisting of CMJ peak take-off force, dynamic knee valgus, and ACL injury history that was internally validated classified ACL injured from uninjured footballers with 78% total accuracy. Between-leg asymmetry in lower limb strength and CMJ kinetics were not associated with subsequent ACL injury risk. CONCLUSIONS: Preseason field-based measures of lower limb muscle strength and biomechanics were associated with future noncontact ACL injury in elite female footballers. These risk factors can be used to guide ACL injury screening practices and inform the design of targeted injury prevention training in elite female footballers.