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Background: Identifying risk factors for lower limb injury is an important step in developing injury risk reduction training and testing for player monitoring. Female athletes are distinct from male athletes, warranting separate investigation into risk factors.Objective: To systematically review the literature and synthesise the evidence for intrinsic risk factors for lower limb injury in female team field and court sports.Method: Five online databases were searched from inception to April 2020. To be eligible for inclusion, studies were required to be a prospective study presenting intrinsic risk factors for lower limb injury in female team field or court sport athletes. Risk of bias was assessed using the Quality of Prognosis Studies tool. Results: Sixty-nine studies, capturing 2902 lower limb injuries in 14,492 female athletes, and analysing 80 distinct factors met the inclusion criteria. Risk factors for any lower limb injury included greater body mass (standardised mean difference [SMD]=0.24, 95% confidence interval [95%CI]=0.18-0.29), greater body mass index (BMI) (SMD=0.22, 95%CI=0.05-040), older age (SMD=0.20, 95%CI=0.09-0.31), greater star excursion balance test (SEBT)anterior reach distance (SMD=0.18, 95%CI=0.12-0.24), and smaller single-leg hop distance (SMD=-0.09, 95%CI=-0.12--0.06). Lower knee injury and osteoarthritis outcome score (KOOS) increased the risk of knee injury. Anterior cruciate ligament (ACL) injury risk factors included prior ACL injury (odds ratio [OR]=3.94, 95%CI=2.07-7.50), greater doubleleg postural sway (SMD=0.58, 95%CI=0.02-1.15), and greater body mass (SMD=0.25, 95%CI=0.12-0.39). Ankle injury risk factors included smaller SEBT anterior reach distance (SMD=-0.13, 95%CI=-0.14--0.13), greater single-leg hop distance asymmetry (OR=3.67, 95%CI=1.42-9.45), and slower agility course time (OR=0.20, 95%CI=0.05-0.88). Remaining factors were not associated with injury or had conflicting evidence. Key points• Prior injury, older age, greater body mass, greater body mass index, and lower KOOS are risk factors for lower limb injury in female athletes.• Performance tests associated with injury include star excursion balance test anterior reach, single-leg hop distance and asymmetry, double-leg postural sway, and agility course time.• The majority of test/factors commonly proposed to be associated with injury have limited evidence, predominantly due to conflicting results between studies.

Tendon geometry and tissue properties are important determinants of tendon function and injury risk and are altered in response to ageing, disease, and physical activity levels. The purpose of this study was to compare free Achilles tendon geometry and mechanical properties between trained elite/sub-elite middle-distance runners and a healthy control group. Magnetic resonance imaging (MRI) was used to measure free Achilles tendon volume, length, average cross-sectional area (CSA), regional CSA, moment arm, and T2 * relaxation time at rest, while freehand three-dimensional ultrasound (3DUS) was used to quantify free Achilles tendon mechanical stiffness, Young’s modulus, and length normalised mechanical stiffness. The free Achilles tendon in trained runners was significantly shorter and the average and regional CSA (distal end) were significantly larger compared to the control group. Mechanical stiffness of the free Achilles tendon was also significantly higher in trained runners compared to controls, which was explained by the group differences in tendon CSA and length. T2 * relaxation time was significantly longer in trained middle-distance runners when compared to healthy controls. There was no relationship between T2 * relaxation time and Young’s modulus. The longer T2 * relaxation time in trained runners may be indicative of accumulated damage, disorganised collagen, and increased water content in the free Achilles tendon. A short free Achilles tendon with large CSA and higher mechanical stiffness may enable trained runners to rapidly transfer high muscle forces and possibly reduce the risk of tendon damage from mechanical fatigue.

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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.

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Purpose: This study established the relationship between isometric midthigh pull (IMTP) peak force and court-based jumping, sprinting, and change of direction (COD) performance in professional netball players. The change in IMTP peak force in response to sport-specific training was also examined. Methods: IMTP peak force and court-based jumping, sprinting, and COD were collected in 18 female athletes contracted to a Suncorp Super Netball team. Linear regression models established the relationship between absolute and normalized strength values and court-based performance measures in the participant cohort. Changes in IMTP peak force and court-based performance measures were examined following 2 consecutive preseason training blocks in a subset of participants. Results: The IMTP peak force values normalized to body mass were found to be determinants of court-based jumping, sprinting, and COD performance in the participant cohort (R2 = .34–.65, P ≤ .016). The participants showed increases in absolute (mean ± SE = 398 ± 68.5 N, P < .001, Hedge g = 0.70 [−0.05 to 1.35]) and normalized IMTP peak force (mean ± SE = 4.6 ± 0.78 N·kg−1, P < .001, Hedge g = 0.47 [−0.04 to 0.97]) over 2 consecutive training blocks that coincided with improvements in jumping, sprinting, and COD performances. Conclusion: IMTP peak force is a determinant of court-based jumping, sprinting, and COD performance and is sensitive to training in professional netball players. These results support the utility of the IMTP test to monitor the development and maintenance of maximal lower body muscular strength in these athletes.

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