Double-leg Squat Research Articles

Abductor hallucis muscle activity during short foot exercise in combination with static and dynamic functional tasks

BackgroundShort foot exercise (SFE) can be combined with dynamic functional tasks such as squats; however, it is unclear whether this combination increases intrinsic foot muscle activity. Research questionThis study aimed to investigate and compare the abductor hallucis muscle (AbdH) activity during SFE in static and dynamic functional tasks. MethodsThe AbdH electromyography data of 17 healthy participants with and without SFE were analyzed during static tasks (sitting, double-leg standing, and single-leg standing) and dynamic tasks (double-leg squat, single-leg squat, split squat, and heel-raise). The static tasks were performed with SFE for 5 seconds, and the dynamic tasks were performed while performing SFE. AbdH activity with or without SFE during the task was compared using the Friedman and Wilcoxon signed-rank tests. ResultsAbdH activity was significantly greater in conditions with SFE than in those without SFE for all tasks (P < 0.01) except for heel-raise (P = 0.163). AbdH activity during SFE in single-leg standing was significantly higher than that in sitting, double-leg standing, and double-leg squats (P < 0.05). AbdH activity during SFE in the single-leg squat was also significantly greater than that in the sitting position (P = 0.024). No significant differences were found in any other between-task comparisons of AbdH activity during SFE. AbdH activity during tasks without SFE revealed significantly lower levels for sitting and double-leg standing compared to single-leg squat, split squat, and heel-raise (P < 0.001). Additionally, the activity in double-leg squat was significantly lower than in both single-leg squat and heel-raise (P < 0.05). SignificanceCombining dynamic tasks, except for the heel-raise task, with SFE can increase AbdH activity more than dynamic tasks without SFE. However, clinicians should note that combining dynamic tasks with the SFE may not increase AbdH activity compared to combining static tasks with the SFE.

Knee-ankle kinematics and coupling responses to SportsMetrics training programs in females athletes with dynamic knee valgus: A sport-specific approach

ObjectivesThis study aimed to investigate the impact of SportsMetrics programs on knee and ankle kinematics, as well as knee-ankle coupling responses during double leg landings among female athletes with dynamic knee valgus (ligament dominance). MethodsEighty-four female athletes, including 30 volleyball players, 30 basketball players, and 24 soccer players, were randomly divided into two equal training (TG) and a control groups (CG). The TG underwent 18 sessions of SportsMetrics exercises, while the CG maintained their regular exercise routine. Dynamic knee valgus, lower limb kinematics, and coordination were assessed using the double leg squat and landing error scoring system tests. Main outcome measuresThe main outcome measures encompassed knee sagittal and frontal kinematics, ankle sagittal kinematics, as well as knee-ankle coordination and its variability. ResultsSignificant reduction in knee range of motion in the frontal plane was observed across all three sports during landing. The SportsMetrics program tailored for basketball players led to a specific increase in knee flexion. ConclusionThe implementation of SportsMetrics effectively modifies ACL injury risk factors, addressing dynamic knee valgus and landing techniques in female athletes. Female athletes displaying dynamic knee valgus are advised to incorporate sport-specific SportsMetrics programs into their training regimens for optimal results.

Hip joint contact forces are lower in people with femoroacetabular impingement syndrome during squat tasks.

It remains unknown if hip joint forces during squat tasks are altered in people with femoroacetabular impingement syndrome (FAIS). The aim of this study is to compare hip joint forces between people with FAIS and healthy controls during double leg squat and single leg squat tasks and within limbs during a single leg squat task in people with FAIS. Kinematic and kinetic data were collected in eight people with FAIS and eight healthy matched controls using 3D motion capture and force plates. AnyBody Modeling System was used to perform musculoskeletal simulations to estimate hip joint angles, forces, and moments for all participants. Estimates were postprocessed with AnyPyTools and converted into normalized time series to be compared using a 1D statistical nonparametric mapping (SnPM) approach. SnPM with an independent samples t-test model was used to compare people with FAIS to controls, while a paired samples model was used to compare involved to uninvolved limb in people with FAIS. Patients demonstrated lower proximodistal force compared to controls (p < 0.01) and compared to the uninvolved side (p = 0.01) for single leg squat. The smaller joint contact forces in people with FAIS compared to controls could represent a strategy of reduced muscle forces to avoid pain and symptoms during this high demand task. These findings when combined with imaging data could help assess the severity of FAIS on hip related function during higher demand tasks.

Effect of different forms of strength training on lower limb power and speed of professional soccer players

Research objective: The main research objective is to analyze the effects of different forms of strength training on the lower limb power and speed of professional soccer players. The research involves the application of a variation strategy in strength training based on varying the intensity of training. The work focuses on comparing two strength training varying external loads. Materials and Methods: The study material consisted of a group of 56 soccer players of the first Polish league, representing a similar sports level with a minimum of 4 years of training experience in the league and in the age range of 22 to 28 years. The study was carried out in the macro-cycle of the preparatory phase in the period after the end of the fall round league games. A 4-week training program was used, during which the players studied carried out an experimental training unit twice a week. One group worked with a load of 50-60% of 1RM (GB1), while the other group worked with a load of 70-80% of 1RM (GB2). The use of pneumatic devices the Keiser Leg Press A420 and Keiser Air Squat A300 (Keiser, Fresno, CA, USA) was used to measure the generated power of the lower limb muscles. A straight-line running test was used to measure speed abilities. A Microgate Witty photocell measurement system (Bolzano, Italy) was used to record running speed variables over a distance of 30 meters. Before the start of the training program, as well as after its completion, the level of locomotor speed and lower limb power were measured. Results: Analyzing the levels of lower limb muscular power and locomotor speed during training with an external load of 50-60% 1RM versus training with an external load of 70-80% 1RM, statistically significantly better results were noted during training with an external load of 50-60% 1RM. The GB1 group with training using an external load of 50-60% 1RM achieved significantly better results than the GB2 group with training using an external load of 70-80% 1RM for 9 variables: double-leg bench press, single-leg bench press (right limb), single-leg bench press (left limb), double-leg squat, single-leg squat (right limb), and sprints over distances of 5m, 10m, 20m, 30m. It was also possible to observe a certain increasing trend in the results in the single-leg squat (left limb), while not statistically significant. Conclusions: Training with an external load of 50-60% 1RM during the preparatory period after the fall round league games is more effective in improving muscle power and speed than training with an external load of 70-80% 1RM.

Jump-landing kinetic asymmetries persisted despite symmetric squat kinetics in collegiate athletes following anterior cruciate ligament reconstruction

ABSTRACT The purpose was to determine the differences/correlations in anterior cruciate ligament (ACL) loading variables and bilateral asymmetries between injured/uninjured legs and among ascending/descending phases of double-leg squats and jumping/landing phases of countermovement jumps (CMJ) in the collegiate athletes following ACL reconstruction (ACLR). Fourteen collegiate athletes performed squats and CMJ 6-14 months following ACLR. The bilateral knee/hip flexion angles, peak vertical ground reaction force (VGRF) and knee extension moments (KEM), and kinetic asymmetries were calculated. Squats showed the greatest knee/hip flexion angles, while the landing phase of CMJ showed the least (P<0.001). The uninjured leg demonstrated greater VGRF (P≤0.010) and KEM (P≤0.008) than the injured leg in CMJ. Kinetic asymmetries were less than 10% for squats but were greater for the jumping (P≤0.014, 12%-25%) and landing (P≤0.047, 16%-27%) phases of CMJ. Significant correlations were found for KEM asymmetries between phases of CMJ (P=0.050) and squats (P<0.001). Kinetic asymmetries persisted in CMJ, while kinetic symmetries were achieved in squats in collegiate athletes 6-14 months following ACLR. Therefore, the CMJ appears to be a more sensitive assessment to monitor the bilateral kinetic asymmetries compared to squats. It is suggested to assess and screen kinetic asymmetries in different phases and tasks.

The Effect of Dry Needling on Suprapatellar Tendonitis: A Case Report

Abstract Background Patellar tendinitis is common in jumping sports. Pain from patellar tendinopathy is challenging to manage. Dry needling as a stand-alone treatment for tendinopathy is supported. To our knowledge, dry needling has never been used alone. This case report depicts dry needling on the proximal patellar pole. Case description A 43-year-old male presented with left suprapatellar tendinitis. He was injured four months before beginning dry needling while playing futsal without warming up. The superior pole of the patellar was tender to palpation and caused moderate pain. At 20 degrees of knee flexion, discomfort began during double leg squats. The Clarke’s Sign, Eccentric Step, and Step Up tests showed positive results. The patient received five sessions of DN at the proximal pole of the patella twice weekly. This study’s primary outcomes were the numeric pain rating scale (NPRS), the Kujala Anterior Knee Pain Scale (AKPS), the global rating of change scale (GRC), and the angle of knee flexion during the squat. The researcher collected data at the five stages. Outcomes The patient’s primary outcome measures improved after three weeks of DN and three months of follow-up. The NPRS showed a reduction in pain, while the AKPS demonstrated a decrease in disability. Conclusion The successful treatment of a patient with suprapatellar tendinopathy utilizing DN is possibly described for the first time in this case report. This study demonstrated the efficacy of dry needling as a first-line treatment for managing chronic tendinopathy with a history of trauma.

Lower Limb Ground Reaction Force and Center of Pressure Asymmetry During Bodyweight Squats.

BackgroundPerformance asymmetries between the lower limbs have been reported across a variety of variables and for numerous motor tasks including double leg squats. Additionally, the degree of symmetry is often used as a recovery metric during rehabilitation programs.Hypothesis/PurposeThe purpose of this investigation was to examine leg asymmetry during a bodyweight double leg squat task and assess the effects of squat speed in a physically active population.Study DesignCross-over Study Design.MethodsEighteen healthy individuals completed two sets of 20 squats at two tempos (preferred tempo and 60 bpm) while ground reaction force and center of pressure data were recorded using dual force plates. Peak vertical ground reaction force, force impulse, and center of pressure (COP) standard deviation in the anterior-posterior (AP) and mediolateral (ML) direction were calculated and analyzed to identify any differences between legs, tempo, and as a function of repetitions. Significance was set at ρ ≤ .05.ResultsThe subjects exhibited greater ground reaction forces during the self-paced tempo compared to the metronome-paced tempo (F1,79 = 14.48, p < .001) with the preferred leg generating larger values than the non-preferred leg during the self-paced condition. There was also a significant tempo x leg interaction for force impulse (F1,79 = 5.927, p = 0.015). A greater amount of COP variability was found in the preferred leg compared to the non-preferred leg in both the AP (F1,79 = 30.147, p < 0.001) and ML (F1,79 = 41.204, p < 0.001) directions.ConclusionsThese findings highlight the importance of considering multiple levels of analysis when assessing lower limb symmetry as separate variables may provide differential evidence for asymmetry. Practically, these results emphasize the need for coaches and practitioners to consider different degrees of lower limb asymmetries that may impact the development and design of strength and rehabilitation programs.Level of Evidence3

The center of pressure position in combination with ankle dorsiflexion and trunk flexion is useful in predicting the contribution of the knee extensor moment during double-leg squatting

BackgroundSquatting exercises are commonly used in rehabilitation for knee joint disorders; in these exercises, control of knee extensor moment is important to enhance training effects and to avoid adverse effects. Ankle dorsiflexion and trunk flexion are widely used to reduce knee extensor moments during squatting, but the increased load on the low back is a concern. The purpose of this study was to determine whether the anterior–posterior (AP) center-of-pressure (COP) position and the AP-COP position in combination with ankle dorsiflexion and trunk flexion angles can predict the contribution of the knee extensor moment during double-leg squatting.MethodsTwenty-eight healthy individuals (14 female and 14 male participants, age 22.8 ± 1.3 years) performed three sets of five consecutive double-leg squats. Kinematics and kinetics were analyzed using a three-dimensional motion analysis system with force plates. Univariate and multivariate regression analyses were performed to predict the contribution of the knee extensor moment (% total support moment) from AP-COP position, ankle dorsiflexion, and trunk flexion.ResultsThe AP-COP position was a significant predictor of the knee extensor moment contribution (R2 = 0.168, P = 0.030). Multivariate analysis showed that the ankle dorsiflexion angle (ΔR2 = 0.561, β = 0.842) and AP-COP position (ΔR2 = 0.296, β = − 0.499) predicted the knee extensor moment contribution (model R2 = 0.857, P < 0.001). Additionally, the combination of trunk flexion (ΔR2 = 0.429, β = − 0.613) and AP-COP position (ΔR2 = 0.109, β = − 0.332) predicted the knee extensor moment contribution (model R2 = 0.538, P < 0.001). The limb symmetry index of the knee extensor moment was significantly associated with that of the AP-COP position (R2 = 0.493, P < 0.001) but not with that of the ankle dorsiflexion angle (P = 0.057).ConclusionsThe AP-COP position can predict the contribution of the knee extensor moment and improve the prediction when combined with ankle dorsiflexion and trunk flexion. The present findings suggest that intervention focusing on the AP-COP position in combination with ankle dorsiflexion or trunk flexion would be useful to coordinate the contribution of the knee extensor moment during double-leg squatting.

A cross-sectional study of functional movement quality in school-aged children

BackgroundDuring the growth period, before and after maturity, considerable biological changes occur. It seems that these changes are related to neuromuscular patterns and have significant differences in the functional movements performed of young boys and girls during the maturation process. The current study aimed to look at the movement quality scores of school-aged girls and boys.MethodsThis Cross-Sectional Study assessed the movement quality of 700 school-aged boys and girls aged 8 to 17, divided into 10 groups of 35 girls and 10 groups of 35 boys. Movement quality was evaluated by the Fusionetics scoring system, which includes 7 tasks: two-leg squat, two-leg squat with heel raise, one-leg squat, push-up, shoulder, trunk, and cervical movements that require a person to complete different movement patterns. The data was analyzed using the Wilcoxon signed-rank and McNemar tests (p <0.05).ResultsThis is the first study to our knowledge to examine the movement quality scores in a large school age child with Fusionetics. The overall results showed that the most errors were recorded in all age groups during the double leg squat, double leg squat with heel lift, single leg squat, and push-up and school-age children showed less errors during the shoulder movements, trunk/lumbar spine movements and cervical spine movements. Furthermore, younger girls and boys made more errors than older girls and boys. In relation to gender, this study found that girls scored better on the total Fusionetics score than boys.ConclusionsThe Fusionetics scoring system explains how well school-aged children perform fundamental movements. Under the guidance of coaches and physical educators, students' movement compensation should be assessed and relevant training interventions implemented. Taking steps to address movement compensation could help to avoid injuries and improve school-age children performance.

The Effect of Sportsmetrics on the Performance and Knee Valgus During Landing of Female Soccer Players

Purpose: Dynamic knee valgus and poor technique during landing are not only key risk factors for lower extremity injuries especially knee injury, but also can reduce the performance of athletes in the field. Sportsmetrics soccer training is one of the successful knee injury prevention and enhancement performance protocols for female soccer players. Because the effect of sportsmetrics soccer training has not been investigated on the performance and knee valgus during landing in female soccer players, we aimed to investigate this subject. Methods: The current field-trial study was conducted on 24 female soccer players with dynamic knee valgus that were randomly divided into two groups: the training group (TG) and the control group (CG). The assessment tests were the agility t-test, 40-yard test, vertical jump test, double leg squat test, and valgus landing error scoring system test (LESS). The TG group participated in sportsmetrics soccer training regularly for 6 weeks, three 90-min sessions a week. Analysis of covariance was used to analyze the obtained data (P&lt;0.05). Results: Six weeks of sportsmetrics soccer training in the TG group not only reduced dynamic knee valgus during landing (51% reduction, F=171.8, P=0.01) but also improved performance factors significantly: agility (0.50 s reduction, F=23.29, P=0.01), power (2.50 cm increase, F=13.20, P=0.01) and speed (0.30 s reduction, F=23.66, P=0.01). Conclusion: Sportsmetrics soccer training is strongly suggested for soccer players exposed to knee injuries due to dynamic knee valgus during landing.

Tibial internal and external rotation taping for improving pain in patients with patellofemoral pain syndrome

ObjectivesThe aim of this study was to assess the effects of two rigid taping methods, tibial internal rotation taping and external rotation taping, on knee pain during three clinical function tests in individuals with patellofemoral pain syndrome. DesignRepeated measures study. MethodsFifteen participants (male, height 174.9 ± 5.8 cm, weight 68.3 ± 10.2 kg) with unilateral patellofemoral pain syndrome were treated by applying internal rotation taping and external rotation taping, in randomized order. While taped, participants were asked to perform three clinical tests in random order: single-leg squat, double-leg squat, and quadriceps maximum isometric contraction. Pain was scored using a Visual Analog Scale. ResultsCompared with no taping, both internal rotation taping and external rotation taping significantly improved pain during each of the three clinical tests (F = 224.10, p < 0.001, partial η² = 0.94). Furthermore, there was a tape direction effect, where external rotation taping was more effective than internal rotation taping (F = 4.90, p = 0.044, partial η² = 0.26). For each test, the amount of pain improvement after taping was positively correlated with initial pain level (0.539 ≤ rho ≤ 0.921, all p < 0.05). ConclusionsBoth internal rotation taping and external rotation taping were effective in improving pain in individuals with patellofemoral pain syndrome, and external rotation taping was more effective than internal rotation taping. The significant correlations observed between initial pain levels and pain improvement after taping suggest that those with greater patellofemoral pain achieve greater relief from tibial rotation taping.

Activation training facilitates gluteus maximus recruitment during weight-bearing strengthening exercises

Given its tri-planar action at the hip, strengthening of gluteus maximus (GMAX) has been advocated as part of rehabilitation and injury prevention protocols for various musculoskeletal conditions. However, recruitment of GMAX during weight-bearing strengthening exercises can be challenging owing to the muscular redundancy at the hip for a given joint motion. The current study sought to determine if a 1-week activation program could result in greater GMAX recruitment during functional strengthening exercises. Pre- and post-training surface electromyography were collected from 12 healthy participants as they performed double- and single-leg squats. Between testing sessions, participants completed a GMAX activation training program consisting of isometric exercises with band resistance (twice per day for 7 days). Following the 1-week activation program, GMAX recruitment was found to increase by 57% during the double-leg squat (p = 0.005, Cohen’s r = 0.73) and 53% during the single-leg squat (p = 0.006, Cohen’s r = 0.70). Implementation of an initial GMAX activation program should be considered to facilitate neuromuscular adaptations that facilitate utilization of GMAX during hip strengthening exercises.

Reliability and Repeatability of ACL Quick Check®: A Methodology for on Field Lower Limb Joint Kinematics and Kinetics Assessment in Sport Applications.

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic sport injuries. Even though clinical screenings aiming at identifying subjects at risk of injuries are gaining popularity, the use of sophisticated equipment still represents a barrier towards their widespread use. This study aimed to test both reliability and repeatability of a new methodology to assess lower limb joints kinematics and kinetics directly on field with the aid of video cameras and plantar pressure insoles. Ten athletes and one case study (post ACL surgery) were assessed in a gait laboratory, while performing double leg squats, through the simultaneous acquisition of stereophotogrammetry, force plates, commercial video cameras and plantar pressure insoles. Different sources of errors were investigated and both reliability and repeatability analysis performed. Minimum and maximum RMSE values of 0.74% (right knee joint center trajectory) and 64.51%, respectively (ankle dorsi-plantarflexion moment), were detected. Excellent to good correlation was found for the majority of the measures, even though very poor and inverse between-trials correlation was found on a restricted number of trials especially for the ankle dorsi-plantarflexion moment. These findings could be used in combination with already available screening tools in order to provide more repeatable results.

A standardised template for reporting lower limb kinematic waveform movement compensations from a sensor-based portable clinical movement analysis toolkit

ObjectivesTo develop a standardised template to support physiotherapist reporting of lower limb kinematic waveform data DesignWithin and between user agreement identification of movement compensation strategies. SettingUniversity Health Board Physiotherapy Department ParticipantsFourteen individuals with anterior cruciate ligament reconstruction performed overground gait, double-leg squat, and stair ascent wearing body-worn sensors. Six users viewed 252 kinematic waveforms of hip, knee and ankle joint angles in the sagittal and frontal planes. Main outcome measuresBetween and within-user observed agreement and themes from movement analysis reports ResultsBetween-user observed agreement for presence of a movement compensation was 0.6–0.9 for the sagittal plane and 0.75–1.0 for the frontal place. Within-user observed agreement was 0.57–1.00 for the sagittal plane and 0.71–1.00 for the frontal plane. Three themes and seven categories were identified from the waveform interpretations: Amount (qualitative and quantitative description), timing (phase, discrete time point, cycle), and nature (peak, range of motion, timing) of the compensation. ConclusionThere was good agreement between users at identifying the presence of movement compensation from the kinematic waveforms, but there was variation in how movement compensations were described. An interactive report, a standardised template for interpretation of kinematic waveforms, and training to support the clinical application of a movement analysis toolkit are proposed.

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.

Medial-lateral hip positions predicted kinetic asymmetries during double-leg squats in collegiate athletes following anterior cruciate ligament reconstruction

ACL re-injury rates are high in collegiate athletes, and double-leg squats have been used as a functional weight-bearing exercise to strengthen the lower extremities and assess bilateral kinetic asymmetries. The primary purpose was to quantify the correlations between medial–lateral shoulder/hip positions and lateral bending angles and bilateral asymmetries in vertical ground reaction forces (VGRF) and knee extension moments during double-leg squats in collegiate athletes at two assessments following anterior cruciate ligament reconstruction (ACLR). Seventeen National Collegiate Athletic Association Division I athletes performed double-leg squats between 0 and 6 months and/or between 6 and 12 months following their ACLR while kinematic and kinetic data were collected. Medial-lateral shoulder positions strongly and significantly correlated with VGRF asymmetries at both assessments (p ≤ 0.007, r ≥ 0.68). Medial-lateral hip positions strongly and significantly correlated with VGRF asymmetries and knee moment asymmetries at both assessments (p ≤ 0.018, r ≥ 0.62). Additionally, participants demonstrated decreased VGRF asymmetries and knee moment asymmetries, more neutral shoulder and hip positions, and increased knee moments for the injured leg at the second assessment compared to the first assessment with large effect sizes (p ≤ 0.008, Cohen’s d ≥ 1.06). In conclusion, medial–lateral hip positions correlated and predicted VGRF and knee moment asymmetries during double-leg squats in collegiate athletes at two assessments (0–6 and 6–12 months) following ACLR. The bilateral asymmetries support the need for an individual approach for kinetic asymmetry assessments. A commercially available camera can be utilized as a low-cost and convenient tool to monitor and potentially train bilateral kinetic symmetries during double-leg squats in patients following ACLR.

Relationship Between Selected Performance Tests and Non-contact Sports Injuries in Male Wushu Players

Purpose: Several tests have been proposed as injury predictor inventories in various sports; however, it is important to recognize which test is more appropriate to predict the injuries of a particular sport. Therefore, the present study aimed to investigate the relationship between selected functional tests and lower limb injuries in elite male wushu athletes. Methods: In total, 40 wushu player were recruited from the national league (Mean±SD age: 25.1±4.9 y, weight: 67.3±7.7 kg, height: 175.3±4.7 cm). Functional Movement Screening (FMS), Tuck jump, single and double leg squats, Star Excursion Balance Test (SEBT), and Stork balance tests were performed in this research. All of the study variables were measured before the national competition, and after the competition, the rate of the injuries were assessed. The correlation between them was evaluated, subsequently. Descriptive data were used to describe the collected results. Besides, multivariate linear regression analysis was used to explore the relationship between the study variables. Results: Multivariate linear regression analysis data suggested that LESS, stroke balance test, single-leg squat, and SEBT failed to predict lower extremities injuries; however, Tuck jump, FMS, and double leg squat could predict lower extremities injuries. Conclusion: Based on the collected results, among the studied tests, trainers and researchers are suggested to employ the Tuck jump, FMS, and double leg squat tests to predict injuries in wushu male players; this test can also be used to prevent injuries in players.

A Comparison of Inertial Motion Capture Systems: DorsaVi and Xsens

Background: dorsaVi Professional Suite, founded in 2018, is a 3D wearable sensor technology system that monitors the kinematic data of the lower extremity and lumbar spine. The dorsaVi system is used in the clinical setting to assist with clinical rehabilitation and preventive measures. Objective: The purpose of this study was to compare the inertial motion capture systems: the dorsaVi Professional Suite and Xsens to determine validity and reliability. Methods: This study utilized nine participants (7 female, 2 male) with data collected on two separate sessions. Each subject performed 15 repetitions each of double leg squats, left single leg squat, and right single leg squat during session one and then repeated the same testing procedure 7-10 days later. Kinematic variables measured were tibial inclination, knee varus, and knee valgus. Pearson product moment correlation coefficients were used to demonstrate the relationship within and between the motion capture systems across the knee positions and squat trials. Results: Within system reliability measurements demonstrated strong correlations (r&gt;0.90) of the lower extremity kinematic data between testing sessions. Between system validity measurements also demonstrated strong correlations (r&gt;0.90) across all lower extremity movements. Conclusions: The dorsaVi Professional Suite knee module kinematic data showed strong correlations to the validated motion capture system (Xsens). Thus, a clinician should be confident in using the dorsaVi in the evaluation, diagnosis, and treatment of patients.

POSTEROMEDIAL MENISCAL AND ANTERIOR CRUCIATE LIGAMENT STRAINS DURING DYNAMIC ACTIVITIES FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Background: Meniscal strain patterns are not well understood during dynamic activities. Furthermore, the impact of ACL reconstruction on meniscal strain has not been thoroughly investigated. The purpose of this study was to characterize ACL and meniscal strain during dynamic activities and investigate the strain difference between ACL-intact and ACL-reconstructed ligament conditions. Methods: ACL and medial meniscal strain were measured in-vitro during gait, a double leg squat, and a single leg squat. For each activity kinematics and muscle forces were applied to seven cadaveric specimens using a dynamic knee simulator. Testing was performed in the ACL-intact and ACL-reconstructed ligament conditions. Results: Both the ACL and meniscus had distinct strain patterns that were found to have a significant interaction with knee angle during gait and double leg squat ([Formula: see text]). During gait, both tissues experienced lower strain during swing than stance (ACL: 3.0% swing, 9.1% stance; meniscus: 0.2% swing, 1.3% stance). Meniscal strain was not found to be different between ACL-intact and ACL-reconstructed conditions ([Formula: see text]). Conclusions: During dynamic activities, the strain in the meniscus was not altered between ACL ligament conditions. This indicates that meniscal mechanics after ACL reconstruction are similar to a healthy knee. These results help further the understanding of osteoarthritis risk after ACL reconstruction.

Free-leg side elevation of pelvis in single-leg jump is a substantial advantage over double-leg jump for jumping height generation

In single-leg jumps, humans achieve more than half the jumping height that they can reach for double-leg jumps. Although this bilateral deficit in jumping has been believed to be due to the reduction of leg extensor force/work exertions, we hypothesised that the three-dimensional biomechanical differences between double-leg and single-leg jumps also influence the bilateral deficit in jumping. Here, we show the substantial effect of the elevation of the pelvic free-leg side in single-leg squat jumps on the bilateral deficit in jumping in addition to extensor force reduction. We collected the kinematic and ground reaction force data during single-leg and double-leg squat jumps from ten male participants using motion capture systems and force platforms. We determined the components of the mechanical energy directly contributing to the height of the centre of mass due to segment movement. The energy due to rotations of the foot, shank, thigh, and pelvis were significantly greater in single-leg squat jumps than in double-leg squat jumps. The magnitudes of the difference in energy between single-leg and double-leg squat jumps due to the pelvis (0.54 ± 0.22 J/kg) was significantly larger than that due to any other segment (<0.30 J/kg). This indicates that pelvic elevation in single-leg jump is a critical factor causing bilateral deficit in jumping, and that humans generate the jumping height with a single leg not just by an explosive leg-extension but also by synchronous free-leg side elevation of the pelvis. The findings suggest that this pelvic mechanism is a factor characterising human single-leg jumps.