Single-leg Squat Research Articles

Lumbopelvic-Hip Complex Contribution During Lower Extremity Screening Tests in Elite Figure Skaters.

Figure skating requires power and stability for take-off and landing from multi-rotational jumps and various on-ice skills. Repetitive forces may cause overuse injuries distally making lumbopelvic-hip endurance, strength, and neuromuscular control imperative. The purpose was to compare lumbopelvic-hip endurance and neuromuscular control in elite figure skaters between sex and limbs using common screening tests. Cross-sectional study. U.S. Olympic and Paralympic Training Center. Forty elite figure skaters (23.2±4.3 years, 169.1±12.2 cm, 20F, 40R landing limb) performed the Y-balance test, single leg squat (SLS), single leg squat jump (SLSJ), and unilateral hip bridge endurance test. Normalized reach difference (% of leg length) and composite scores (((Anterior + Posteromedial + Posterolateral)/Limb length x 3) x100) were calculated for Y-balance test. Skaters held the unilateral hip bridge until failure with a maximum allotted time of 120s. Participants performed 5 SLS and SLSJ, barefooted with the contralateral limb held behind them to mimic a landing position. Both tests were scored by the number of times the patella moved medially to the first ray (medial knee displacement (MKD)). MANOVA with post-hoc independent t-tests were performed between groups and sex. Paired t-tests were used to analyze limb differences. Females had a larger composite Y-balance score (R:+10.8, p=.002; L:+10.5, p=.001) and hip bridge hold time (R:+26.4 sec, p=.004; L:+28.2 sec, p=.002) on both limbs compared to males. Males held the hip bridge longer on their landing limb. During the SLS and SLSJ, 6 skaters performed worse on their non-landing limb during the SLS, and 11 skaters had no MKD with either test. Females performed better on the Y-balance and unilateral hip bridge tests. Increased MKD for some skaters in the SLS and SLSJ may indicate hip abductor weaknesses. Understanding proximal lumbopelvic-hip variables during take-off and landing may elucidate contributing factors to distal overuse injuries.

The Running Readiness Scale as an Assessment of Kinematics Related to Knee Injury in Novice Female Runners.

Frontal- and transverse-plane kinematics have been prospectively identified as risk factors for running-related injuries in females. The Running Readiness Scale (RRS) may allow for clinical evaluation of these kinematics. To determine the reliability and validity of the RRS as an assessment of frontal- and transverse-plane running kinematics. Cross-sectional study. University research laboratory. A total of 56 novice female runners (median [interquartile range] age = 34 years [26-47 years]). We collected 3-dimensional kinematics during running and RRS tasks: hopping, plank, step-ups, single-legged squats, and wall sit. Five clinicians assessed RRS performances 3 times each. Interrater and intrarater reliabilities of the total RRS score and individual tasks were calculated using the intraclass correlation coefficient and Fleiss κ, respectively. Pearson product moment correlation coefficients between peak joint angles measured during running and the same angles measured during RRS tasks were computed. Peak joint angles of high- and low-scoring participants were compared. Interrater and intrarater reliabilities of assessment of the total RRS scores were good (intraclass correlation coefficients = 0.75 and 0.80, respectively). Reliability of assessing individual tasks was moderate to almost perfect (κ = 0.58-1.00). Peak hip adduction, contralateral pelvic drop, and knee abduction during running were correlated with the same angles measured during hopping, step-ups, and single-legged squats (r = 0.537-0.939). Peak knee internal rotation during running was correlated with peak knee internal rotation during step-ups (r = 0.831). Runners who scored high on the RRS demonstrated less knee abduction during running (P ≤ .01). The RRS may effectively assess knee abduction in novice runners, but evaluation criteria or tasks may need to be modified to effectively characterize pelvic and transverse-plane knee kinematics.

Early Findings on the Use of Motion Capture during Simulated Sports Activities to Better Understand Hemophilic Arthropathy

Many persons with hemophilia (PwH) have joint bleeding despite prophylaxis. We hypothesize that movement biomechanics play a significant and largely unexplored role in joint bleeding, which could be exploited to develop personalized rehabilitation programs. We have designed a clinical study to test this hypothesis. Here we show data from the first 3 enrollees as case studies of what could potentially be learned.Data were collected from 3 participants with hemophilia A, ages 10-30 years, on prophylaxis with emicizumab, with at least 1 joint bleed in the lower extremity in the past year, using motion capture techniques with force plates and reflective markers collected through a Vicon system. Motion lab activities were designed to simulate sports activities and included walking (barefoot and shod), squatting (double and single leg), hopping on one foot, and jumping from a 30-cm box. Two patients (B and C) routinely take additional factor VIII prophylaxis prior to physical activity and did so before coming to the motion lab. Hemophilia Joint Health Score (HJHS) was obtained by an experienced physical therapist prior to motion lab collection to gauge degree of hemophilic arthropathy by physical exam. A subset of participants and activities are shown graphically.Participant A (not shown) had a higher HJHS in the right knee than left (3 vs 0) and had HJHS of 4 in bilateral ankles, with most recent bleed in the right ankle 8 months prior; primary physical activity was walking. This participant showed subtle differences between the right and left in all activities, including less weight on the right leg during double leg squat, and right single leg hop lower than the left.Participant B had a higher HJHS in the right knee than the left (3 vs 0) and in the right ankle than the left (7 vs 6), and he had had multiple episodes of knee pain but no change in HJHS since 2 years prior. Knee MRIs performed outside of the study were consistent with tendinosis of bilateral quadriceps rather than bleeding. Primary sports were basketball, hiking, biking, and skiing. Participant B had subtle differences between the right and left side that seemed to protect the right, including mildly decreased right knee flexion with weight acceptance during walking (more pronounced when wearing shoes), lower power generation by the right ankle than the left in walking, and lower peak ground reaction force (GRF) on the right than left in forward hopping. Some motions seemed to protect the left side more, with less power generation and absorption by the ankle (double and single leg squats) and hip (single leg squat only), right single leg squat somewhat deeper than the left, and slower time to step onto the left foot than the right.Participant C had a higher HJHS in the right knee than left (2 vs 1) and in the right ankle than left (5 vs 3) but had had worsening HJHS in bilateral ankles compared to his previous scores, with bleeds in both knees in the past year. Primary physical activities were baseball (pitching), basketball, biking, skiing, and golf. He had recently been diagnosed with Osgood Schlatter (patellar tendon/tibial tuberosity inflammation) of the left knee, which had been causing pain for several months, but no bleeding in that knee. Movement analysis reflected left knee pain, including very little flexion with weight acceptance when walking; very little power absorption or generation from the knee in walking, hopping, and squatting; shallower squats and lower hops on the left; and lower ground reaction force on the left than the right with walking. Perhaps related to the left knee protection, both ankles were consistently more plantarflexed in walking, and there was increased power generation in the right ankle compared to the left.These findings suggest the presence of subtle asymmetry related to hemophilic arthropathy and previous bleeding, which were more pronounced in more strenuous activities than with walking. The results of participant C could suggest that pain, even if unrelated to hemophilia, could cause compensatory movement mechanisms that could lead to increased bleeding risk in other lower extremity joints.Ongoing analysis will include tracking of bleeding over 1 year following motion analysis, enrollment of additional participants, comparison with controls, and performing detailed statistical analysis to determine which movement parameters correlate best with HJHS and lower extremity bleeding risk. [Display omitted] DisclosuresWarren: Novo Nordisk: Consultancy; Hema Biologics: Consultancy; Bayer: Research Funding; CSL Behring: Research Funding; Genentech: Research Funding. Funk: Biomarin: Consultancy; Sanofi Genzyme: Speakers Bureau; Toronto Sick Kids Hospital: Patents & Royalties: Hemophilia Joint Health Score Royalties; Partners: Honoraria.

Analysis of Single Leg Squat and Single Leg Landing Performance Variability among Professional Soccer Players Across a Season

Objectives: This study investigated the performance variability between limb type (dominant versus non-dominant leg) with regard to time (over season with three categories: pre-, start- and end-season) of professional soccer players. Methods: A total of 88 out of 124 male soccer players aged 16-30 years were asked to perform the specific athletic tasks single leg squat (SLS) and single leg landing (SLL) during different times in a full sports season. These functional tasks were evaluated using outcome measures of coefficient of variation, including frontal plane projection angle (FPPA) and hip adduction angle (HAA). Results: No significant difference was observed across all events between the dominant and non-dominant leg of the participants between screening sessions over time, for both SLS and SLL functional activities, except for one event in both second-order coefficient of variation for FFPA (FPPA V2) and HAA in SLS (at the start of season, p =0.006). The variations in FPPA and HA are clinically irrelevant, as no statistically significant differences were observed between limb types (dominant versus non-dominant leg) between screening sessions over a season, thereby suggesting that the performance variability is fairly consistent over time. Conclusions: There is consistency across the sports season in the performance variability of SLS and SLL.

Biomechanical differences between military patients with patellar tendinopathy and asymptomatic controls during single-leg squatting and gait – A statistical parametric mapping study

BackgroundPrior identification of biomechanical differences between patients with patellar tendinopathy and healthy controls has utilised time-discrete analysis which is susceptible to type I error when multiple comparisons are uncorrected. We employ statistical parametric mapping to minimise the risk of such error, enabling more appropriate clinical decision-making. MethodsLower-limb biomechanics of 21 patients with patellar tendinopathy and 22 controls were captured during walking and three types of squats. A statistical parametric mapping two-sample t-test was used to identify kinematic and kinetic differences between groups for each joint. Paired t-tests were used to compare pain before and after tasks, in patients with patellar tendinopathy. FindingsDuring walking, cases demonstrated reduced knee joint power during initial contact and hip joint power during terminal stance. In squatting, cases demonstrated increased knee abduction angles at various time points of the small knee bend and single-leg squat. Cases demonstrated reduced knee internal rotation moment during the deepest portion of the single-leg squat and single-leg decline squat. InterpretationGait appears unaffected by patellar tendinopathy, likely due to low task difficulty. Elevated knee abductions angles during squatting were confirmed as a key difference in patients with patellar tendinopathy. Reduced knee internal rotation moments in patients were attributed to a potential reduction in hip external rotator strength and possible pain avoidance strategy; however further evidence is required to substantiate these claims. Findings provide a clear rationale for rehabilitation programs to focus on knee stabilisation and strengthening of the muscles surrounding the hip.

International female rugby union players’ anthropometric and physical performance characteristics: A five-year longitudinal analysis by individual positional groups

ABSTRACT Longitudinal changes in anthropometric and physical performance characteristics of International female rugby union players were evaluated across 5-seasons, according to field position. Sixty-eight international female rugby union players from a top 2 ranked international team, undertook anthropometric and physical performance measurements across five seasons. Anthropometric and physical performance changes occurred, with skinfolds decreasing between 2015 and 2017 and body mass increasing between 2017 and 2019. Single-leg isometric squat (SL ISO), 0–10 m momentum (0–10 Mom) and 20–30 m momentum (20–30Mom) were higher in 2018 and 2019 than all years. Front-row players were characterised by greater SL ISO and 1-RM bench press than inside and outside backs, with higher skinfolds and lower endurance levels than all positions. Between 2017 and 2019, front-row players had larger decreases and increases in endurance and one repetition maximum (1-RM) bench press, respectively, compared to all other positions. Forwards had the highest 0–10Mom and 20–30Mom, and scrum-half the lowest, while outside backs had faster 0–10, 30–40, and 40 m (TT40 m) times, and greater peak velocity (Vmax) compared to forward positions. These longitudinal findings show that physical performance has increased, with anthropometric and performance characteristics becoming more distinctive between positions, among elite female rugby union players.

Visual assessment of dynamic knee joint alignment in patients with patellofemoral pain: an agreement study.

BackgroundAssessment of knee kinematics plays an important role in the clinical examination of patients with patellofemoral pain (PFP). There is evidence that visual assessments are reliable in healthy subjects, but there is a lack of evidence in injured populations. The purpose of this study was to examine the intra- and interrater agreement in the visual assessment of dynamic knee joint alignment in patients with PFP.MethodsThe study was a cross-sectional agreement study. Sixty participants (42 females) were included. We assessed the intra- and interrater agreement of two functional tests: The single leg squat (SLS) and the forward lunge (FL). One investigator scored the movement according to preset criteria while video recording the movement for retest. Moreover, the performance was scored by another investigator using the video recording. Agreement was assessed using weighted kappa statistics.ResultsThe intrarater agreement ranged from moderate to good (Kappa 0.58 (FL) to 0.70 (SLS)) whereas the interrater agreement ranged from fair to moderate (Kappa 0.22 (SLS) to 0.50 (FL)).ConclusionThe agreement within raters was better than between raters, which suggests that assessments should preferably be performed by the same tester in research and in a clinical setting, e.g., to evaluate any treatment effect. We promote FL as a reliable clinical tool for evaluating dynamic knee alignment, since it shows equally good intra- and interrater agreement, and it is an inexpensive and easy method to use.

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.

Gluteal muscle activation during rehabilitation exercises in female field hockey players.

BackgroundField hockey, a team sport played by both men and women at both recreational and professional levels, requires maintaining a forward flexed posture putting stress on the lumbar spine. Hence, it is necessary to assess the muscles supporting the lumbar spine, especially those surrounding the hip, to inform strengthening exercises for this population.ObjectivesTo establish the best body weight rehabilitation exercises shown to produce high muscle activation (≥ 61%MVIC – maximal voluntary isometric contraction) for both the gluteus maximus (Gmax) and medius (Gmed) muscles. Four exercises fell into this category.MethodSurface electromyography (sEMG) was used to record the muscle activation of Gmax and Gmed of four body weight rehabilitation exercises in 26 high-performance female field hockey players. The %MVIC activation data of both Gmax and Gmed were analysed using a three-way ANOVA.ResultsThe single-leg squat generated the highest %MVIC activation of both Gmax (125.65%MVIC) and Gmed (126.30%MVIC). The only statistically significant difference for Gmax was between the single-leg squat and plank with hip extension (p = 0.0487). No statistically significant difference was observed for Gmed between the four body weight rehabilitation exercises (p = 0.6285).ConclusionThe four exercises generated similar %MVIC activation levels. The single-leg squat produced the highest observed %MVIC of Gmax and Gmed in high-performance female field hockey players and is, therefore, recommended.Clinical implicationsImplementation of the findings could result in benefits during prehabilitation, injury prevention programmes and the later stages of rehabilitation for high-performance female field hockey players.

The Effect of Resistance Training on Lower Extremity Pain, Strength and Kinematical Parameters in Women With Patellofemoral Complications

Purpose: The aim of this study was to evaluate the effect of strengthening the abductor and external rotator of the hip joint muscles on pain, thigh muscle strength, and lower limb kinematics in volleyball players with patellofemoral complications. Methods: Twenty-four volleyball players with patellofemoral pain were randomly divided into the experimental and control groups. The experimental group received three sessions of strengthening exercises for the abductor muscles and external rotators of the hip joint using Traband for eight weeks. The control group received no training intervention. The pain was assessed by visual acuity scale, hip muscle strength by hand dynamometer, and lower limb kinematics using video analysis before and after the intervention. Samples included volleyball players with patellofemoral pain who had pain in one or both knees. If the pain was bilateral, the exercises were performed bilaterally on both lower limbs, but measurements were taken only from the lower extremity, which was most in pain. Analysis of covariance was used by SPSS software for statistical analysis. Results: The results of this study showed that after training, in the experimental group, pain decreased and the strength of the abductor’s muscles and external rotator of the hip joint muscles increased. Knee dynamic valgus and pelvic drop were observed in single-leg squat only in the experimental group. Conclusion: The results showed that the strengthening of the hip joint can decrease the pain of volleyball players with patellofemoral, increase the strength of the muscles and change the kinematics of the lower limbs on the frontal plane, and this can be the mechanism of the effect of this intervention on the symptoms of pain.

Hip-Focused Neuromuscular Exercise Provides Immediate Benefits in Foot Pronation and Dynamic Balance: A Sham-Controlled Cross-Over Study.

Knowledge on how to utilize a kinetic chain approach in foot and ankle rehabilitation is important. The aim of this study was to investigate the immediate effects of hip-focused neuromuscular exercise on foot pronation and single-leg neuromuscular control. Cross-over study. University laboratory. This cross-over study included 44 asymptomatic volunteers with foot pronation. All participants performed (1)a hip-focused neuromuscular exercise and (2)a sham exercise in randomized order. Foot pronation was assessed by the navicular drop test, and lower-extremity neuromuscular control was assessed by the Modified Star Excursion Balance Test and frontal plane projection angle during single-leg squat before and after the experiments. Navicular drop test scores were significantly lower after the hip-focused neuromuscular exercise than after the sham exercise (mean difference [95% CI] = 2.84 [-1.08 to 6.77], P = .003). Modified Star Excursion Balance Test scores in the anterior (P = .008), posteromedial (P = .04), and posterolateral (P < .001) directions were significantly increased after hip-focused neuromuscular exercise. No statistically significant condition × time interaction was found for the frontal plane projection angle (P > .05). However, a main effect of time (P = .003) indicated that less dynamic knee valgus occurred during single-leg squat after both experiments. Hip-focused neuromuscular exercise produced immediate alterations in foot pronation and dynamic balance. Thus, the hip-focused neuromuscular exercise may be used to control foot posture in foot rehabilitation integrated with a kinetic chain approach and could be an effective prevention and treatment strategy.

Evaluation of proprioception in patients who underwent ACL reconstruction: measurement in functional position

Background/aimAnterior cruciate ligament (ACL) injuries cause mechanoreceptor loss in the joint; therefore, proprioceptive deficits are observed after injury. In particular, proprioceptive measurements made in the functional position give more accurate results, and this is an area that requires further studies. This study aimed to evaluate proprioception in patients who had undergone ACL reconstruction (ACLR) in functional positions used in daily life (closed kinetic chain position), according to joint angles where ACL injuries occur more frequently, in comparison with healthy controls.Materials and methodsThirty-four participants who underwent ACLR using a hamstring tendon graft (aged 29.18 ± 8.16 years; body mass index (BMI), 26.58 ± 4.02 kg/cm2) and 31 healthy participants (aged 27.35 ± 5.74 years; BMI, 24.76 ± 2.98 kg/cm2) were included. Proprioception was assessed with an active angle repetition test, using an inclinometer in the closed kinetic chain position while standing. Participants were asked to perform single-leg squats until the angle at the knee joint was 30°. After the targeted angle was defined, the participants were asked to find the targeted angle. The difference between the targeted angle and the angle reached by the participants was calculated.ResultsA statistically significant difference in the active joint position sense was found among the ACLR extremity, uninvolved extremity, and control extremity (p < 0.05). The proprioceptive sense between the two extremities in the ACLR group was similar, and the proprioceptive sense was worse than that of the control group.ConclusionTo our knowledge, this is the first study to evaluate closed kinetic chain position in patients who underwent ACLR, and it showed that proprioceptive sense was still poor in patients with ACLR compared with the control group, even if an average of 24 months have elapsed since surgery.

Association between movement patterns and risk of musculoskeletal injuries in navy cadets: A cohort study

ObjectiveTo investigate the association of movement patterns evaluated by the Dynamic Movement Assessment (DMA) with the occurrence of musculoskeletal injuries in navy cadets. DesignCohort study. SettingParticipants were filmed performing the six functional tests of the DMA (deep squat, step up, single-leg squat, hop, plank and side-plank tests). Participants240 navy cadets. Main outcome measurementsDepending on the number of certain movement patterns on the Dynamic Movement Assessment (DMA), participants were classified as high, moderate, medium or low risk of developing injuries. Predictive associations between injuries and risk classification were examined using logistic regression analysis. ResultsConsidering sex, previous injuries and the type of secondary school as covariates, participants who were classified as high risk were not more likely to develop injuries. Non-military high school was an independent risk factor for any injuries (OR = 3.14, 95% CI [1.43,6.91]; OR = 4.57, 95% CI [1.92,10.83]), overuse injuries (OR = 2.58, 95% CI [1.05,6.30]; OR = 2.55, 95% CI [1.06, 6.14]) and acute injuries (OR = 4.88, 95% CI [1.19,19.99]), respectively. Previous musculoskeletal symptoms also increased the chance of AI (OR = 4.45, 95% CI [1.15,17.18]; OR = 5.91, 95% CI [1.13,30.88]). ConclusionsMovement patterns evaluated by DMA are not associated with an increased risk of injuries. However, attendance of a non-military high school and previous musculoskeletal symptoms are associated with musculoskeletal injuries.

Treatment decisions after interdisciplinary evaluation for nonarthritic hip pain: A randomized controlled trial.

Physical therapy and hip arthroscopy are two viable treatment options for patients with nonarthritic hip pain (NAHP); however, patients may experience considerable decisional conflict when making a treatment decision. Interdisciplinary evaluation with a physical therapist and surgeon may better inform the decision-making process and reduce decisional conflict. To identify the extent to which an interdisciplinary evaluation between a surgeon, physical therapist, and patient influences treatment plans and decisional conflict of persons with NAHP. Randomized controlled trial. Hip preservation clinic. Adults with primary NAHP. Participants were randomized to receive a standard (surgeon) or interdisciplinary (surgeon+physical therapist) evaluation. Surgeon evaluations included patient interview, strength and range-of-motion examination, palpation, gross motor observation, and special testing. Interdisciplinary evaluations started with the surgeon evaluation, then a physical therapist evaluated movement impairments during sitting, sit-to-stand, standing, single-leg stance, single-leg squat, and walking. All evaluations concluded with treatment planning with the respective provider(s). Treatment plan and decisional conflict were collected pre- and postevaluation. Inclusion of physical therapy in participants' postevaluation treatment plans and postevaluation decisional conflict were compared between groups using chi-square tests and Mann-Whitney U tests, respectively. Seventy-eight participants (39 in each group) met all eligibility criteria and were included in all analyses. Sixty-six percent of participants who received an interdisciplinary evaluation included physical therapy in their postevaluation treatment plan, compared to 48% of participants who received a standard evaluation (p= .10). Participants who received an interdisciplinary evaluation reported 6.3 points lower decisional conflict regarding their postevaluation plan (100-point scale; p= .04). The interdisciplinary and standard groups reduced decisional conflict on average 24.8± 18.9 and 23.6± 14.6 points, respectively. Adding a physical therapist to a surgical clinic increased interest in physical therapy treatment, but this increase was not statistically significant. The interdisciplinary group displayed lower postevaluation decisional conflict; however, both groups displayed similar reductions in decisional conflict from pre- to postevaluation. This study also demonstrated the feasibility of an interdisciplinary evaluation in a hip preservation clinic.

Sensor-Based Indices for the Prediction and Monitoring of Anterior Cruciate Ligament Injury: Reliability Analysis and a Case Study in Basketball.

The possibility of measuring predictive factors to discriminate athletes at higher risk of anterior cruciate ligament (ACL) injury still represents an open research question. We performed an observational study with thirteen female basketball players who performed monopodalic jumps and single-leg squat tests. One of them suffered from an ACL injury after the first test session. Data gathered from twelve participants, who did not suffer from ACL injury, were used for a reliability analysis. Parameters related to leg stability, load absorption capability and leg mobility showed good-to-excellent reliability. Path length, root mean square of the acceleration and leg angle with respect to the vertical axis revealed themselves as possible predictive factors to identify athletes at higher risk. Results confirm that six months after reconstruction represents the correct time for these athletes to return to playing. Furthermore, the training of leg mobility and load absorption capability could allow athletes to reduce the probability of new injuries.

A cross-sectional study to assess variability in knee frontal plane movement during single leg squat in patients with anterior cruciate ligament injury

BackgroundSingle leg squat (SLS) tests help predict anterior cruciate ligament injuries. However, the variability in joint movement during this test has not been fully investigated. The aim of this study was to examine the knee frontal plane movement variability during SLS in patients with anterior cruciate ligament (ACL) injury. MethodsIn this cross-sectional study, we enrolled 56 patients with ACL injury (28 males; 28 females) and 46 healthy subjects (23 males; 23 females). All participants underwent SLS tests. All kinematic variables were joint angle of trunk, pelvis and lower limb, center of gravity (COG), center of pressure (COP). These data were obtained at the frontal plane and the coefficient of variation (CV) were calculated. Multiple comparisons were performed between healthy subjects and the injured leg and uninjured leg of patients with ACL injury. The correlation of the CV in knee varus/valgus range of motion (ROM) with the CV in other kinematic variables were investigated in patients with ACL injury. ResultsCompared with healthy subjects, patients with ACL injury exhibited significantly larger the CV in knee varus/valgus ROM. A positive correlation was observed between the CV in knee varus/valgus ROM and the CV in pelvic lateral inclination ROM in patients with ACL injury. ConclusionsKnee frontal plane movement variability during SLS may help evaluate the risk of ACL injury/re-injury. In addition, pelvic lateral inclination variability during SLS may need to be evaluated in conjunction with knee frontal plane movement variability.

Impaired Lower Extremity Biomechanics, Hip External Rotation Muscle Weakness, and Proximal Femoral Morphology Predict Impaired Single-Leg Squat Performance in People With FAI Syndrome

Background: Impairments in squat depth have been reported in patients with femoroacetabular impingement syndrome (FAIS). However, little is known about single-leg squat (SLS) performance in these patients, despite this task being commonly used in the rehabilitation and training settings. Purpose/Hypothesis: The aims of this study were (1) to investigate whether patients with FAIS demonstrate differences in SLS performance compared with healthy controls and (2) to determine whether dynamic range of motion (ROM), muscle strength, hip morphologic measures, hip pain, and hip-specific function predict SLS performance in patients with FAIS. We hypothesized that patients with FAIS would demonstrate impaired SLS performance and that impaired hip biomechanics, muscle strength, and hip-specific function would predict squat performance in patients with FAIS. Study Design: Controlled laboratory study. Methods: Three-dimensional (3D) kinematic data were collected at 100 Hz using a 20-camera 3D motion capture system during 3 SLS trials in 34 patients with FAIS and 26 healthy controls. Isometric muscle strength was tested with a stationary handheld dynamometer in all participants. Squat performance was quantified by squat depth (in meters), and the biomechanical variables of dynamic ROM of the pelvis, the hip, the knee, and the ankle in all planes were calculated. In patients with FAIS, femoral and acetabular morphology were measured using radiographic alpha angles and lateral center-edge angles. Hip pain and hip-specific function were measured using the visual analog scale for pain and the Hip Outcome Score Activities of Daily Living subscale, respectively. Two-tailed independent-samples t tests were used to determine between-group differences for squat depth, dynamic ROM variables, and muscle strength. A hierarchical multiple linear regression (MLR) model was used to determine whether biomechanical variables, muscle strength, hip morphology measures, hip pain, and hip-specific function were predictors of squat depth. All statistical analyses were performed using SPSS Version 26. Results: There were no between-group differences in age (FAIS, 30.0 ± 7.0 years vs controls, 27.3 ± 7.0 years; P = .18) or body mass index (FAIS, 23.1 ± 2.8 vs controls, 22.6 ± 3.2; P = .51). Squat depth was less in patients with FAIS compared with healthy controls (FAIS, 0.24 ± 0.4 m vs controls, 0.29 ± 0.05 m; P < .001). In the sagittal plane, patients with FAIS demonstrated less dynamic ROM of the hip (FAIS, 67.8°± 12.4° vs controls, 79.2°± 12.5°; P = .001) and the knee (FAIS, 71.9°± 9.4° vs controls, 78.9°± 13.2°; P = .02) compared with controls. Patients with FAIS also demonstrated a less dynamic coronal plane pelvis ROM (FAIS, 11.3°± 5.0° vs controls, 14.4°± 6.7°; P = .044). Patients with FAIS had reduced hip muscle strength of the hip external rotator (FAIS, 1 ± 0.3 N/kg vs controls, 1.2 ± 0.3 N/kg; P = .034), hip internal rotator (FAIS, 0.8 ± 0.3 N/kg vs controls 1 ± 0.3 N/kg; P = .03), and hip flexor (FAIS, 4 ± 1.1 N/kg vs controls, 4.8 ± 1.2 N/kg; P = .013) muscle groups. The hierarchical MLR revealed that the dynamic ROM of the hip, the knee, and the pelvis, the hip external rotation muscle strength, and the femoral alpha angles were all significant predictors of squat performance, and the final MLR model explained 92.4% of the total variance in squat depth in patients with FAIS. Conclusion: Patients with FAIS demonstrate impaired SLS squat performance compared with healthy controls. This impaired squat performance is predominantly predicted by sagittal plane knee and hip biomechanics and hip external rotator strength, and less by frontal plane pelvic ROM and hip morphology in patients with FAIS. Clinical Relevance: Clinicians should focus treatment on improving dynamic ROM and hip external rotator muscle strength to improve squat performance; however, femoral morphology should also be considered in the treatment paradigm.

Establishing Age- and Sex-Specific Norms for Pediatric Return-to-Sports Physical Performance Testing.

Background:Graft tears and contralateral anterior cruciate ligament (ACL) tears are common in pediatric athletes after ACL reconstruction. Use of objective return-to-sports (RTS) criteria, in particular physical performance tests (PPTs), is believed to reduce the incidence of secondary injury; however, pediatric norms for these tests are unknown.Purpose:To establish a proof of concept for the creation of age- and sex-based norms for commonly used RTS PPTs in healthy pediatric athletes, allowing the creation of growth curves for clinical referencing.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 100 healthy people who were between the ages of 6 and 18 years and involved in organized sports were enrolled, with even distributions of age and sex. All participants underwent 9 common RTS PPTs: stork test, stork test on Bosu, single-leg squat, single-leg squat on Bosu, clockwise and counterclockwise quadrant hops, single-leg hop for distance, 6-m timed hop, and triple crossover hop for distance. Mean performance across limbs was calculated for each individual. Chronological age, height, weight, sex, and self-reported Pubertal Maturational Observational Scale (PMOS) score were recorded. Univariable and multivariable models were created for each PPT, assessing the importance of the recorded descriptive variables. Quantile regression was used to create growth curves for each PPT.Results:The cohort was 52% female, and the mean ± standard deviation age was 11.7 ± 3.6 years. PMOS was highly correlated with age (r = 0.86) and was excluded from the regressions. In univariable regression, age, height, and weight were strong predictors of performance for all PPTs, whereas sex was a predictor of performance on the single-leg and triple crossover hops for distance (with males outperforming females). Height and weight were excluded from multivariable regression because of multicollinearity with age. Multivariable regression showed predictive patterns for age and sex that were identical to those shown in the univariable analysis. Given ceiling effects, quantile regression for the stork tests was not possible, but quantile regression growth curves were successfully created for the 7 remaining PPTs.Conclusion:Chronological age and sex accurately predicted performance on common RTS PPTs in pediatric patients. The growth curves presented herein could assist clinicians with benchmarking pediatric patients postoperatively against a healthy athletic cohort.

Prevalence and Pain Distribution of Anterior Knee Pain in Collegiate Basketball Players.

Causes of anterior knee pain (AKP) in jumping athletes include patellofemoral pain and patellar tendinopathy. The differential diagnosis of AKP is challenging, with variations in clinical presentations. No previous research has used pain location to describe AKP in basketball players. To (1) describe the prevalence and pain distribution of AKP in collegiate basketball players and (2) report the prevalence of focal inferior pole pain using 2 outcome measures. Cross-sectional study. University and collegiate basketball facilities in Alberta, Canada. A total of 242 collegiate basketball athletes (138 women, 104 men). The single-legged decline squat test (SLDS) was used to capture pain location via pain mapping (dichotomized as focal or diffuse) and pain severity (numeric rating scale). The Oslo Sports Trauma Research Centre Knee questionnaire (OSTRC-Knee) and adapted version for patellar tendinopathy (OSTRC-Patellar Tendinopathy Questionnaire [OSTRC-P]) were used to report the prevalence of AKP and patellar tendinopathy, respectively. Focal inferior pole pain during the SLDS was used to classify patellar tendinopathy. Of the 242 players, 146 (60%) reported pain with the SLDS (unilateral = 64 [26%]; bilateral = 82 [34%]). A total of 101 (43%) described knee pain using the OSTRC-Knee. Pain mapping captured the variability in pain locations. Diffuse pain was more prevalent (left, 70%; right, 72%) than focal pain (left, 30%; right, 28%). Low prevalence of patellar tendinopathy was noted using the OSTRC-P (n = 21, 8.7%) and inferior pole pain during the SLDS (n = 25, 10.3%). Diffuse AKP was common in Canadian basketball players; however, pain mapped to the inferior pole of the patella was not common. Few players reported tendinopathy using the OSTRC-P, suggesting that patellar tendinopathy was not a primary knee pain presentation in this jumping cohort. Pain location, rather than the presence or severity of pain alone, may better describe the clinical presentation of AKP in jumping athletes.

Consequences of Juvenile Idiopathic Arthritis on Single Leg Squat Performance in Youth.

Juvenile idiopathic arthritis (JIA) affects body structure and function outcomes that may increase the risk of acute joint injury. The purpose of this study was to examine single leg squat (SLS) biomechanics for youth with JIA and their healthy peers. The study design was a matched pair cohort study. Sixty-five youth (JIA n = 30; control n = 35) participated in this ethics-approved study. Participants performed 3 sets of 5 consecutive SLS tasks. Disease activity and functional status were assessed using the Juvenile Arthritis Disease Activity Score and Child Health Assessment Questionnaire. Indexed (most-affected leg [JIA]; dominant leg [control]) and contralateral extremity biomechanics were obtained using a 12-camera system. Outcomes included hip flexion/extension (FE), adduction/abduction (AA), and internal/external (IE) rotation range of motion (ROM). Data were analyzed using a multivariate random coefficient model in R (α⍺ = 0.05). A total of 29 matched pairs were analyzed. Youth with JIA had low disease activity and performed the SLS with a more internally rotated hip (indexed leg P = 0.023, β = -1.9°). Female participants displayed greater hip FE (indexed leg P = 0.015, β = -4.3°; contralateral leg P = 0.005, β = -4.8°) and IE ROM (indexed leg P = 0.021, β = -2.1°) than male participants. Associations were observed for body mass index and hip IE ROM (contralateral leg P = 0.001, β = -0.4°), knee flexion angle, and hip FE ROM (indexed leg P = 0.001, β = 0.4°; contralateral leg P = 0.001, β = 0.5°) and AA (indexed leg P = 0.010, β = 0.1°; contralateral leg P = 0.002, β = 0.2°). This study identified functional alterations for an SLS in youth with JIA. These findings support the use of physical therapy as part of a multidisciplinary management approach, to restore normal hip posture and movement.