Knee Frontal Plane Projection Angle Research Articles

Risk Factors for Patellofemoral Pain in the Military: Systematic Review with Meta-Analysis.

The main cause for attrition of military training is musculoskeletal injuries to the knee, such as patellofemoral pain (PFP). The purpose of this systematic review was to identify which factors increase the risk of occurrence of PFP in military personnel. Systematic review with meta-analysis. Searches were performed in Medline/PubMed, CINAHL, Embase, SPORTDiscus, Web of Science, Scopus, and OpenGray. We included studies that were prospective cohorts including military personnel and had at least one variable assessing a risk factor for PFP. Extraction was performed by the same two independent evaluators and the data was separated between the military personnel who developed PFP and those who did not. Meta-analyses were performed using standardized mean differences (SMD) and 95% confidence intervals (95%CI) and the levels of recommendation were determined. From 11 articles, this review grouped 7,518 military personnel, of which 572 developed PFP, characterizing a prevalence of 7.61%. We found moderate evidence that isokinetic knee extensor weakness predicts PFP in the military (SMD -0.69, 95%CI -1.02, -0.35). A higher frontal plane knee projection angle (FPKPA) during single-leg squat was also identified as a risk factor for PFP in this population (SMD 0.55, 95%CI 0.14, 0.97) with moderate level of evidence. We found moderate evidence that sex, body mass index, isometric knee extensors strength, and isokinetic knee flexors strength do not predict PFP in military personnel. Finally, there is strong evidence that age and body mass do not predict PFP in this population. Deficits in isokinetic knee extensor strength and a greater FPKPA are risk factors for PFP in military personnel. Since these are modifiable factors, these aspects should be considered in injury prevention interventions in the military.

Females Present Different Single-Leg Squat Kinematics and Muscle Activation Strategies than Males Even after Hip Abductor Fatigue

Background: Despite the potential connection between hip and knee muscle control, there is limited research on the effects of hip abductor fatigue on the hip and knee neuromuscular responses in both males and females. This study aimed to investigate the influence of sex on the hip and knee frontal plane kinematics and the EMG responses of the hip abductors and knee extensor muscles during the single-leg squat before and after hip abductor fatigue. Methods: A total of 30 participants (males, n = 15; females, n = 15) performed single-leg squats before and immediately after a hip abductor fatigue protocol (10° hip abduction position while bearing a 20% load of their estimated 1RM until exhaustion). The frontal plane kinematics (hip adduction and knee frontal plane projection angle) and EMG parameters (amplitude and median frequency) of the gluteus medius (GMed), tensor fascia latae (TFL), vastus lateralis (VL) and vastus medialis (VM) were measured during the single-leg squat. Results: We did not find any effects of hip abductor fatigue or interaction between fatigue and sex on the evaluated parameters (p > 0.05). However, compared to males, females had greater values for the hip and knee frontal plane kinematics (p = 0.030), GMed EMG amplitude (+10.2%, p = 0.012) and median frequency (+10.3%; p = 0.042) and lower VL median frequency (−9.80%; p = 0.007). Conclusions: These findings establish sex-related differences in the kinematics and hip and knee EMG parameters during the single-leg squat, which were not influenced by the hip abductor fatigue protocol.

Kinematics of 90° change of direction in young football players: Insights for ACL injury prevention from the CUTtheACLstudy on 6008 trials.

To investigate the 90° change of direction (COD) task in an extensive cohort of competitive healthy football players within the CUTtheACLstudy and to provide normative values and differences between males and females for full-body kinematics based on two-dimensional (2D) video analysis and scoring system. One-thousand-and-two competitive football (soccer) players (age 16.3 ± 2.8 years, 264 females) were prospectively enroled. Each player performed three preplanned 90° COD tasks per limb. The 2D evaluation was performed through objective measures (collected through three high-speed cameras) of frontal and sagittal plane joint kinematics at the cut initial foot contact (IC) and maximum knee flexion angle. A previously published scoring system was adopted to measure the movement quality of the COD task. The scoring system included five criteria (limb stability [LS], pelvis stability [PS], trunk stability [TS], shock absorption [SA], movement strategy [MS]) ranked from 0/2 (nonadequate) to 2/2 (adequate) with a maximum score of 10/10. Normative data were provided for all the variables; statistical differences between male and female players were investigated (p < 0.05). A total of 6008 valid attempts were included. Frontal plane knee projection angle (FPKPA) at initial contact was 24.4 ± 9.8° (95thpercentile: FPKPA > 40°). The total score was ≤4/10 in 71.2% of the trials, the lowest subscores were LS and PS. Female players showed different movement patterns with lower hip and trunk flexion both at IC and maximum knee flexion angle (p < 0.01, ES = 0.41-0.64). Female players also showed worse scores than males in SA, MSand total score (p < 0.01). Female players seem more prone to stiffer lower limb strategy and greater pelvis-trunk frontal plane instability than males. Clinicians could adopt normative data and sex-specific differences in players' movement techniques to improve ACL injury risk mitigation protocols. Level IV.

Relationship Between Knee Frontal Plane Projection Angle and Lower Limb Muscle Activity in Female Athletes.

Anterior cruciate ligament injuries are directly related to the control of dynamic knee valgus in the landing of a jump, and this is mainly due to the correct activation and neuromuscular function of the lower-extremity muscles. The aim of the study is to assess the relationship between lower limb muscle activity during a single-legged drop jump and knee frontal plane projection angle (FPPA). A correlation study. Thirty healthy collegiate female athletes were included in the study. Main outcomes measures were peak knee FPPA and muscle activity (% of maximal voluntary isometric contraction). Peak knee FPPA during a single-legged drop jump test was identified using a 2-dimensional motion analysis system. Muscle activity was assessed using a surface electromyograph for gluteus maximus, gluteus medius, biceps femoris, semitendinosus, vastus medialis quadriceps, vastus lateralis quadriceps, medial gastrocnemius, and lateral gastrocnemius. All variables were assessed for both dominant and nondominant limbs. A correlation analysis between peak knee FPPA and muscle activity was performed. Statistical significance was set at P <.05. A mean peak knee FPPA of 14.52° and 13.38° was identified for dominant and nondominant limb single-legged drop jump test, respectively. Muscle activity (% of maximal voluntary isometric contraction) for muscles assessed ranged from 43.97% to 195.71% during the single-legged drop jump test. The correlation analysis found no significant correlation between any of the muscles assessed and peak knee FPPA during the single-legged drop jump test (Pearson coefficient between -.3 and .1). There is no association between muscle activity from the lower limb muscles and the knee FPPA during a single-legged drop jump in female athletes. Thus, different muscle properties should be assessed in order to understand such an important movement as the knee FPPA during a jump.

Sex differences in factors of pelvis and lower-limb joint kinematics influencing dynamic knee valgus during single-leg squat.

Dynamic knee valgus (DKV) during dynamic activity is associated with patellofemoral pain, one of the most common sports disorders, especially in females. No studies have examined the factors that can lead to DKV in females as compared to males while addressing the influence of factors on each other. To identify factors of pelvis and lower joints kinematics affecting DKV during single-leg squat (SLS) in females compared to males with multiple regression analysis. Forty-four healthy young people (24 females, 20 males) performed SLS, and pelvis, hip, knee, and ankle 3D kinematics were recorded. The 2D knee frontal plane projection angle (FPPA) was adopted as the DKV measurement. Multiple regression analysis was performed to determine the relationship between FPPA and the kinematics of each joint and segment. Hip adduction and pelvic contralateral rotation were explanatory factors for FPPA in females. Hip adduction, hip internal rotation, and knee external rotation were explanatory factors in males. The lower limb or pelvic motion factors affecting DKV during SLS differ between the sexes, with pelvic contralateral rotation being extracted only in women, possibly due to differences in pelvic width.

Influence of self-perceived disability on squatting kinematics in individuals with patellofemoral pain

BackgroundIndividuals with patellofemoral pain have a heterogeneous presentation of symptoms during functional tasks; however, biomechanical data often negates self-reported disability. The single leg squat is common in patellofemoral pain literature but may not be a pain provoking task for all individuals. Therefore, our study examined the influence of self-perceived squatting disability in individuals with patellofemoral pain on lower extremity squatting kinematics. MethodsWe analyzed two-dimensional hip frontal plane projection angle, knee frontal plane projection angle, lateral trunk movement, and pelvic drop in 100 participants, 82 with patellofemoral pain and 18 pain-free controls. Participants with patellofemoral pain were dichotomized based on the level of disability reported during squatting on the anterior knee pain scale. An analysis of variance with post hoc testing was used to compare differences in lower extremity and trunk kinematics between groups, p < 0.05. FindingsParticipants who reported only being able to squat with partial weight bearing had greater hip frontal plane projection angles than those who reported squatting painful each time (p = 0.017). The partial weight bearing group had greater knee frontal plane projection angles compared those who reported pain with repeated squatting and the pain-free group, (p < 0.034). We found no significant differences in lateral trunk motion or pelvic drop between groups. InterpretationIndividuals with patellofemoral pain who self-reported worse squatting disability had greater hip and knee frontal plane motion compared to individuals with less disability and pain-free controls. Clinicians and researchers should consider specific pain provoking tasks when evaluating and treating patients with patellofemoral pain.

Foot rotation and pelvic angle correlate with knee abduction moment during 180° lateral cut in football players

BackgroundLateral movements are challenging for 2D video-analysis and are therefore often omitted in functional tests for Anterior Cruciate Ligament (ACL) injury risk assessment. The purpose of the present study was to investigate the association between frontal and transverse plane angles obtained from 2D video-analysis and knee abduction moment (KAM) from gold standard 3D motion capture in a 180° lateral cut task. The hypothesis was that 2D angles other than the knee joint effectively explain variations in KAM. MethodsThirty-four healthy football players (age 22.8 ± 4.1 years) performed a series of 180° lateral cut (lateral shuffles) tasks. The peak KAM was collected through a 3D motion capture system. A 2D video-analysis movement assessment identified frontal and transverse plane joint kinematics: foot projection angle (FPA), Frontal Plane Knee Projection Angle (FPKPA), Pelvis tilt angle (PA), and Trunk tilt angle (TA). A forward stepwise regression model was used to assess significant 2D predictors of KAM (p < 0.05). ResultsFPA and PA were the only significant predictors (R2-ajdusted = 9.2%, p < 0.001), with external foot rotation and contralateral pelvic drop associated with higher KAM. Based on the regression model, the “High FPA & PA group” was defined and showed higher KAM than the rest of the cohort (p = 0.012, ES = 0.71). ConclusionsThe external foot rotation and the contralateral pelvic drop from 2D video-analysis were associated with higher peak KAM during the 180° lateral cut. A qualitative assessment of the 180° lateral cut could offer precious insights on ACL injury risk mitigation. Level of EvidenceDescriptive Laboratory Study.

Comparison of the Frontal Plane Projection Angle and the Dynamic Valgus Index to Identify Movement Dysfunction in Females with Patellofemoral Pain.

Clinicians typically measure the knee frontal plane projection angle (FPPA) during a single-leg squat to identify females with patellofemoral pain (PFP). A limitation of this measure is minimal attention to movement of the pelvis on the femur that can create knee valgus loading. The dynamic valgus index (DVI) may be a better assessment. The purpose of this study was to compare the knee FPPA and DVI between females with and without PFP and determine if the DVI better identified females with PFP than the knee FPPA. Case-control. Sixteen females with and 16 without PFP underwent 2-dimensional motion analysis when performing five trials of a single-leg squat. The average peak knee FPPA and peak DVI were analyzed. Independent t-tests determined between-group peak knee FPPA and peak DVI differences. Receiver operating characteristic (ROC) curves determined the area under the curve (AUC) scores for sensitivity and 1 - specificity of each measure. Paired-sample area difference under the ROC curves was conducted to determine differences in the AUC for the knee FPPA and DVI. Positive likelihood ratios were calculated for each measure. The significance level was p < 0.05. Females with PFP exhibited a higher knee FPPA (p = 0.001) and DVI (p = 0.015) than controls. AUC scores were .85 (p = 0.001) and .76 (p = 0.012) for the knee FPPA and DVI, respectively. Paired-sample area difference under the ROC curves showed a similar (p = 0.10) AUC for the knee FPPA and DVI. The knee FPPA had 87.5% sensitivity and 68.8% specificity; the DVI had 81.3% sensitivity and 81.0% specificity. Positive likelihood ratios for the knee FPPA and DVI were 2.8 and 4.3, respectively. The DVI during a single-leg squat may be another useful tool for discriminating between females with and without PFP. 3a.

Performance in field-tests and dynamic knee valgus in soccer players psychologically ready and not ready to return to sports after ACL reconstruction

BackgroundThe objective was to compare the performance in field tests, dynamic knee valgus, knee function, and kinesiophobia of soccer players who were psychologically ready and not ready to return to unrestricted training or competitions after ACL reconstruction. MethodsThirty-five male soccer players who had undergone primary ACL reconstruction at least 6 months were divided based on the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) questionnaire score into ready (≥60) and not-ready (<60) groups. The modified Illinois change of direction test (MICODT) and reactive agility test (RAT) were used to impose the demand for directional change and reactive decision-making. We assessed the frontal plane knee projection angle (FPKPA) during a single-leg squat and distance in crossover hop test (CHD). In addition, we assessed kinesiophobia through the shortened version of the Tampa Scale of Kinesiophobia (TSK-11) and knee function using the International Knee Documentation Committee Subjective Knee Form (IKDC). Independent t-tests were used to compare the groups. ResultsThe not-ready group had lower performance on the MICODT (effect size (ES) = −1.2; p < 0.001) and RAT (ES = −1.1; p = 0.004) tests and higher FPKPA (ES = 1.5; p < 0.001). In addition, they presented lower IKDC (ES = 3.1; p < 0.001) and higher TSK-11 (ES = −3.3; p < 0.001) scores. ConclusionsPhysical and psychological deficits may persist in some individuals after rehabilitation. On-field tests and dynamic knee alignment evaluation should be included in the athlete evaluation before the decision-making about clearance to sports participation, especially in athletes who perceive themselves as psychologically not ready.

Examination of overhead and single-leg squat kinematics and lower extremity injury in female collegiate athletes.

Overhead squat (OHS) and single-leg squat (SLS) tests have been used as screening tools to identify injury risk in athletic populations. Yet, no study has examined the association between specific trunk and lower extremity (LE) kinematic measures acquired during OHS and SLS performance and LE injury incidence in female collegiate athletes. The purpose of this study was to examine the association between LE and trunk kinematics captured during OHS and SLS performance and LE injury in female collegiate athletes. This was a prospective cohort study. One hundred eight Division I female collegiate athletes underwent OHS and SLS testing before the start of their competitive season. A Microsoft Kinect sensor using Athletic Movement Assessment software (PhysiMax®) was used to capture kinematic variables: hip flexion, knee flexion, knee frontal plane projection angle (FPPA), and trunk flexion. Participants were tracked during one competitive season for incidence of LE injury. Logistic regression models were used to examine the association between OHS and SLS measures and injury. Twenty-three (21.3%) participants suffered a LE injury. No significant associations were found between any OHS (odds ratio [OR] range: 0.91-1.08) or SLS (OR range: 0.81-1.22) kinematic measure and incidence of LE injury. Sagittal plane LE and trunk kinematics and knee FPPA during OHS and SLS performance were not associated with LE injury in this cohort of athletes. Our findings do not support the use of these select kinematic measures captured during OHS and SLS testing as stand-alone injury risk assessments in female collegiate athletes.

Reliability of the Frontal Plane Knee Alignment Measurement Based on a Remote Protocol.

The analysis of movement quality is important for better exercise prescription. This study tested the reproducibility of a protocol for remote assessment of dynamic knee alignment using images taken by patients. Thirteen women filmed themselves performing single-leg squats on two days at a 15-day interval. Three raters measured the knee frontal plane projection angle using the resultant images. Two participants (15.4%) were excluded for not performing the protocol correctly. The intraclass correlation coefficient was between 0.880 and 0.999 for the intra-rater comparison, and between 0.817 and 0.987 for the inter-rater comparison. The success of the protocol in 84.6% of participants and the excellent reproducibility suggest that the methodology of analyzing patient-captured cell phone images might be a plausible alternative for remote evaluation of dynamic knee alignment.

Are proximal and distal neuromuscular parameters able to predict hip and knee frontal plane kinematics during single-leg landing?

ObjectiveTo determine if proximal and distal neuromuscular parameters (EMG amplitude and median frequency – MDF) can predict frontal plane kinematics during single-leg landing. Study designCross sectional study. SettingLaboratory. ParticipantsFifteen participants (7 female) performed six single-leg landings with measures of frontal plane kinematics and EMG obtained 230 ms after first foot contact, totalizing 90 landings. Main outcome measures(i) 2D hip adduction [hip ADD] and knee frontal plane projection angle [knee FPPA]; (ii) EMG amplitude and MDF of gluteus medius [GMed], tensor fascia latae [TFL], peroneus longus [PL] and tibialis anterior [TA]. ResultsWe observed that MDF of TA was a significant predictor of hip ADD (p = 0.037; β = −0.049 Hz; R2c = 0.30). Also, MDF of PL was significant predictor of knee FPPA (p = 0.043; β = 0.042 Hz; R2c = 0.37). Hip muscles and EMG amplitude parameters were not considered predictors of frontal plane kinematics. ConclusionThe firing frequency of ankle muscles predicted the variance of hip and knee frontal plane kinematics during single-leg landing.

Reliability and criterion validity of two-dimensional movement assessments in those with patellofemoral pain

ObjectivesDetermine criterion validity and intra/inter-rater reliability of 2-dimensional (2D) knee frontal plane projection angle (kFPPA), hip frontal plane projection angle (hFPPA), and dynamic valgus index (DVI) during forward step-downs in those with patellofemoral pain (PFP). DesignCross-sectional. SettingUniversity research laboratory. Participants39 participants with PFP (34.18 ± 7.41years, 170± .1 cm, 81.03 ± 19.36 kg, duration of pain: 68.67 ± 85.08months, anterior knee pain scale: 80.49 ± 7.87, visual analog scale:2.08 ± 2.02) Main outcome measuresAverage 3D hip and knee sagittal, frontal, and transverse joint angles and 2D kFPPA, hFPPA, and DVI at maximum knee flexion were variables of interest. 3D DVI was calculated as the sum of hip and knee frontal and transverse angles. 2D kFPPA, hFPPA, and DVI were calculated by two raters independently on two occasions. ResultsIntra- and inter-rater reliability of all 2D angles were excellent. kFPPA was moderately correlated to 3D knee transverse angles. hFPPA was moderately correlated to 3D hip frontal and transverse angles and largely correlated to 3D DVI. 2D DVI was moderately correlated to hip transverse angles. ConclusionkFPPA, hFPPA, and DVI are reliable. hFPPA may be reflective of 3D hip and knee frontal and transverse motion during forward step-downs in those with PFP.

Assessment of Dynamic Knee Valgus between Lateral Step-Down Test and Running in Female Runners with and without Patellofemoral Pain Using Two-Dimensional Video Analysis.

Dynamic knee valgus (DKV) is a frontal plane knee kinematic alteration that has been associated with patellofemoral pain (PFP) in female runners. DKV is commonly assessed in clinical practice by measuring frontal plane knee projection angle (FPPA) during squat tests. However, it remains unclear whether the DKV observed in these tests is similar to or correlates with that observed during running in female runners. The aims of this cross-sectional study were to correlate and compare DKV, by measuring FPPA values, in a lateral step-down (LSD) squat test and running in female runners with and without PFP. A two-dimensional (2D) video analysis of the LSD test and running was carried out for 21 asymptomatic female runners and 17 PFP female runners in order to determine FPPA values. A Pearson correlation test and a factorial ANOVA with Bonferroni post hoc correction were used for statistical analysis. The FPPAs recorded in the LSD test were significantly higher than those recorded during running in the asymptomatic (16.32° ± 5.38 vs. 4.02° ± 3.26, p < 0.01) and PFP groups (17.54° ± 7.25 vs. 4.64° ± 3.62, p < 0.01). No significant differences were found in FPPA values between asymptomatic and PFP runners during the LSD test (16.32° ± 5.38 vs. 17.54° ± 7.25, p = 0.55) and running (4.02° ± 3.26 vs. 4.64° ± 3.62, p = 0.58). There was a small (r < 0.3) and non-significant (p > 0.05) correlation in FPPAs between the LSD test and running in both groups. According to our results, DKV was not similar during the LSD test and running, and there was no significant correlation in FPPA values between the LSD test and running in both groups. Therefore, clinicians and therapists should be aware of these findings when using the LSD test in clinical practice to evaluate DKV in female runners with or without PFP.

The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee Valgus.

BackgroundThe single leg squat (SLS) motion imitates various maneuvers in sports. It is commonly used as a functional test for the lower limb. SLS with two-dimensional (2-D) video analysis is regularly performed in the clinical setting to assess dynamic knee valgus (DKV). However, 2-D video analysis may not be able to demonstrate the same level of accuracy as three-dimensional (3-D) motion analysis.PurposeThis study aimed to determine the within- and between-day reliability as well as the concurrent validity of 2-D and 3-D motion analysis of lower limb kinematics during 45° and 60° SLS among physically active females with and without DKV.Study DesignCross-sectional studyMethodsA total of 34 physically active females (17 individuals with excessive DKV and 17 without DKV) participated in the study. Their DKV was determined based on the cut-off values of knee frontal plane projection angle during drop landing. Their lower limb kinematics during SLS at 45° and 60° knee flexion were captured simultaneously by digital cameras (2-D motion capture) and infrared cameras (3-D motion capture). Intraclass Correlation Coefficient (ICC) was used as an indicator for within- and between-day reliability tests of both groups. Bland-Altman Plot and Pearson correlation were used to examine the validity of 2-D and 3-D motion capture methods in evaluating knee valgus angle.ResultsTwo-dimensional knee FPPA and 3-D knee angle measured during 45° and 60° SLS in normal and excessive DKV groups showed moderate to excellent within-day and between-day reliability (ICC≥ 0.50). The current study showed that the 2-D knee frontal plane projection angle (FPPA) during 45° SLS were valid for the non-dominant leg in both groups. Additionally, the 2-D knee FPPA during 60° SLS were valid for non-dominant leg in excessive DKV group and dominant leg in normal group.ConclusionTwo-dimensional knee FPPA during 45° and 60° SLS also showed high within-and between-day reliability for both groups. The validity of 2-D knee FPPA during SLS depends on the squat depth, stance leg, and presence of DKV.Level of Evidence2B

Examining the effects of femoral anteversion and passive hip rotation on ACL injury and knee biomechanics: a systematic review and meta-analysis.

PurposeGreater femoral internal rotation (via anteversion or passive hip ROM) is associated with knee biomechanics thought to contribute to anterior cruciate ligament (ACL) injury, but it is unknown if femoral internal rotation contributes to actual ACL injury occurrence. The objective of this systematic review and meta-analysis was to quantify the extent to which femoral anteversion and hip range of motion (ROM) influence knee biomechanics consistent with ACL injury and actual ACL injury occurrence.MethodsUsing PRISMA guidelines, PubMed, CINAHL, SportDiscus, and Scopus databases were searched. Inclusion criteria were available passive hip ROM or femoral anteversion measure, ACL injury OR biomechanical analysis of functional task. Two reviewers independently reviewed titles, abstracts, and full texts when warranted. Included studies were submitted to Downs & Black Quality Assessment Tool. Meta-analyses were conducted for comparisons including at least two studies.ResultsTwenty-three studies were included (11 injury outcome, 12 biomechanical outcome). Decreased internal rotation ROM was significantly associated with history of ACL injury (MD -5.02°; 95% CI [-8.77°—-1.27°]; p = 0.01; n = 10). There was no significant effect between passive external rotation and ACL injury (MD -2.62°; 95% CI [-5.66°—- 0.41°]; p = 0.09; n = 9) Participants displaying greater frontal plane knee projection angle had greater passive external rotation (MD 4.77°; 95% CI [1.17° – 8.37°]; p = 0.01; n = 3). There was no significant effect between femoral anteversion and ACL injury (MD -0.46°; 95% CI [-2.23°—1.31°]; p = 0.61; n = 2). No within-sex differences were observed between injured and uninjured males and females (p range = 0.09 – 0.63).ConclusionThough individuals with injured ACLs have statistically less passive internal and external rotation, the observed heterogeneity precludes generalizability. There is no evidence that femoral anteversion influences biomechanics or ACL injury. Well-designed studies using reliable methods are needed to investigate biomechanical patterns associated with more extreme ROM values within each sex, and their prospective associations with ACL injury.Level of evidence: IV.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40634-022-00479-7.

Sex Moderates the Relationship between Perceptual-Motor Function and Single-Leg Squatting Mechanics.

To examine the isolated and combined effects of sex and perceptual-motor function on single-leg squatting mechanics in males and females. We employed a cross-sectional design in a research laboratory. Fifty-eight females (22.2 ± 3.5 yrs, 1.60 ± .07 m, 64.1 ± 13.0 kg) and 35 males (23.5 ± 5.0 yrs, 1.80 ± .06m, 84.7 ± 15.3 kg) free from time-loss injury in the six months prior, vertigo, and vestibular conditions participated in this study. Independent variables were sex, perceptual-motor metrics (reaction time, efficiency index, conflict discrepancy), and interaction effects. Dependent variables were peak frontal plane angles of knee projection, ipsilateral trunk flexion, and contralateral pelvic drop during single-leg squatting. After accounting for the sex-specific variance and perceptual-motor function effects on frontal plane squatting kinematics, female sex amplified the associations of: higher reaction time, lower efficiency index, and higher conflict discrepancy with greater right ipsilateral peak trunk lean (R2 = .13; p = .05); higher reaction time, lower efficiency index, and higher conflict discrepancy with decreased right contralateral pelvic drop (R2 = .22; p < .001); higher reaction time and lower conflict discrepancy with greater right frontal plane knee projection angle (R2 = .12; p = .03); and higher reaction time with greater left frontal plane knee projection angle (R2 = .22; p < .001). Female sex amplified the relationship between perceptual-motor function and two-dimensional frontal plane squatting kinematics. Future work should determine the extent to which perceptual-motor improvements translate to safer movement strategies.

Risk factors for ACL, hamstring strain, and hip/groin injuries in elite Australian female footballers: A prospective study.

Introduction: Female footballers are at high risk of sustaining lower limb injuries, with some of the most prevalent and severe injuries being hamstring strains, hip/groin pain, and knee ligament sprains. However, there is currently limited evidence to guide injury prevention strategies and injury risk assessment testing in female footballers. The aim of this study was to assess risk factors for ACL, hamstring, and hip/groin injuries in elite female footballers. Methods: Data were collected from 321 elite female Australian Football, soccer, and Rugby League players during pre-season. Players underwent field-based assessments of isometric hip adductor and abductor strength (ForceFrame), eccentric knee flexor strength during the Nordic hamstring exercise (NordBord), countermovement jump (CMJ) on dual forceplates (ForceDecks), and a single-leg triple vertical hop (TVH) using a makerless motion capture system (HumanTrak). Players were subsequently followed for injuries for 18 months. Risk factors were identified prospectively using simple and multiple logistic regression and decision tree learning. Results: A total of 12 anterior cruciate ligament (ACL) ruptures, 17 hamstring strains, and 12 hip/groin injuries were recorded. Risk factors for ACL injury included prior ACL injury (standardised odds ratio [OR]=12.3, P<.001), lower body weight normalised adductor torque (OR=2.1, P=.028), greater body weight normalised CMJ peak force (OR=1.9, P=.013), lower CMJ impulse (OR=2.0, P=.037), greater triple vertical hop knee frontal plane projection angle (OR=2.3, P=.014), and greater triple vertical hop lateral trunk flexion (OR=1.7, P=.038). Multiple logistic regression and decision tree models classified ACL injured players with high accuracy (sensitivity=67% and 75% respectively, and specificity=88% and 100% respectively). Risk factors for time-loss hamstring injury included smaller stature (OR=1.8, P=.030), greater between-leg asymmetry in CMJ peak force (OR=2.0, P=.011) and eccentric impulse (OR=1.9, P=.016). There were no statistically significant risk factors for hip/groin injury. Discussion: This is the first study to explore risk factors for lower limb injury in elite female Australian football codes. These results provide insight into the potential modifiable factors associated with subsequent injury in elite female footballers, which may inform player testing batteries and the design of targeted injury risk reduction strategies. Conflict of interest statement: Funding for travel was provided by Vald Performance (Brisbane, Australia) and SMA Research Foundation. My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.

Effects of task and hip-abductor fatigue on lower limb alignment and muscle activation

PurposeFatigue-induced hip-abductor weakness may exacerbate lower-limb misalignments during different dynamic single-leg tasks. We sought to evaluate the effects of fatigue and task on lower limb kinematics and muscle activation and to find associations between measurements obtained in two tasks.MethodsOne-group pretest–posttest design. Seventeen healthy adults (9 W) performed the single-leg squat (SLSQUAT) and the single-leg hop (SLHOP) before and after a hip-abduction fatigue protocol. Hip adduction, knee frontal plane projection angle (knee FPPA) and heel inversion displacement were measured during the eccentric phase of the SLSQUAT and the SLHOP, as well as activation of the gluteus medius (GMed), tensor fascia latae (TFL), peroneus longus (PER) and tibialis anterior (TA). Moments and tasks were compared using a repeated-measures two-way ANOVA. Correlation between tasks was evaluated using Spearman’s correlation.ResultsNo differences in kinematics or activation were found between moments. Hip-adduction displacement (P = 0.005), GMed (P = 0.008) and PER (P = 0.037) activation were higher during SLSQUAT, while TA activation was higher during SLHOP (P < 0.001). No differences were found between tasks in knee FPPA and heel inversion. Hip-adduction and knee FPPA were not correlated between tasks, while ankle inversion displacement was positively correlated (rs = 0.524–0.746). ConclusionDifferent characteristics of SLSQUAT (slower and deeper) seem to have led to increased hip adduction displacement, GMed, and PER activation and decreased TA activation, likely due to higher balance requirements. However, hip-abductor fatigue didn’t influence lower-limb alignment during the tasks. Finally, evaluations should be performed with different single-leg tasks since they don’t give the same lower-limb alignment information.

Upper limb muscle strength and knee frontal plane projection angle asymmetries in female water-polo players

ABSTRACT Water-polo players frequently perform overhead throws that could result in shoulder imbalances. For overhead throws, execution of the ‘eggbeater kick’ (cyclical movement of the legs) is required to lift the body out of the water. Although a symmetrical action, inter-limb differences in task execution could lead to knee frontal plane projection (FPPA) differences. The present study examined imbalances shoulder and knee FPPA in female players. Eighteen competitive female field players (24.1 ± 5.5 years, 1.68 ± 0.06 m, 72.9 ± 13.3 kg) had their shoulder strength assessed in a shot-mimicking position with a portable dynamometer, standing and seated (isolating the shoulder contribution). Anterior: posterior and shooting: non-shooting shoulder comparison were made. Additionally, players performed a drop jump. Knee FPPA was recorded from digitising and comparing the frames just before landing and at stance phase. During standing, players exhibited higher shooting: non-shooting asymmetry (p = 0.032) in the anterior contraction direction, while during seated the shooting shoulder anterior: posterior asymmetry was higher (p = 0.032). Interlimb knee FPPA asymmetry was higher in the stance phase (p = 0.02). Despite the overhead throwing and egg-beater demands impacting differently on each limb, considerable asymmetries do not develop, suggesting the overall training requirements (e.g. swimming, resistance training) were sufficient to maintain the asymmetry within desirable limits.