Correlation of Lower Limb Muscle Activity with Knee Joint Kinematics and Kinetics during Badminton Landing Tasks

A study on a single-leg landing task after an overhead stroke in badminton suggests that poor knee biomechanical indicators may be a risk factor for anterior cruciate ligament (ACL) injury. A preventive program targeting neuromuscular control strategies is said to alter the biomechanics of the knee joint and have a beneficial effect on reducing ACL injury. However, the relationship between muscle activity around the knee joint and knee biomechanical risk factors in the badminton landing task is unclear. The purpose of this study was to investigate the relationship between this movement pattern of muscle activity and knee kinematics and kinetics. This experiment analyzed knee muscle activity and biomechanical information in a sample of 34 badminton players (17 male, 17 female) during a badminton landing task. We assessed the relationship between the rectus femoris (RF), medial hamstring (MHAM), lateral hamstring (LHAM), medial gastrocnemius (MGAS), lateral gastrocnemius (LGAS), medial and lateral hamstring to quadriceps co-contraction ratio (MH/Q and LH/Q) with the knee flexion angle, valgus angle, extension moment, valgus moment, and proximal tibial anterior shear force. A moderate negative correlation was found between the peak knee flexion angle and electromyography (EMG) activity in LGAS (r = 0.47, p = 0.0046, R² = 0.23, 95% CI: 0.16 to 0.70). Peak proximal tibial shear force showed strong and positive correlations with RF EMG activity (r = 0.52, p = 0.0016, R² = 0.27, 95% CI: 0.22 to 0.73) and strong and negative correlations with MH/Q (r = 0.50, p = 0.0023, R² = 0.25, 95% CI: 0.20 to 0.72). The knee extension moment showed moderate and positive correlations with RF EMG activity (r = 0.48, p = 0.0042, R² = 0.23, 95% CI: 0.17 to 0.70) and strong and negative correlations with MH/Q (r = 0.57, p = 0.0004, R² = 0.33, 95% CI: 0.29 to 0.76). The peak knee valgus moment showed strong and positive correlations with LH/Q (r = 0.55, p = 0.0007, R² = 0.31, 95% CI: 0.26 to 0.75). Our findings suggest that there is a correlation between lower extremity muscle activity and knee kinematics and kinetics during the single-leg landing task in badminton; therefore, lower extremity muscle activity should be considered when developing rehabilitation or injury prevention programs.

The Safe Landing warm up technique modification programme: An effective anterior cruciate ligament injury mitigation strategy to improve cutting and jump-movement quality in soccer players

The objective of the study was to evaluate the effectiveness of the Safe Landing (SL), a 6-week technique-modification (TM) programme, on cutting and jump-landing movement quality in football players. In a non-randomized design, 32 male semi-professional football players from two Spanish clubs participated in the study: one served as the control group (CG, n = 11), while the other performed the SL (n = 15). Performance and movement quality of drop vertical jump and 70º change of direction (COD70) were evaluated through 2D video footage pre- and post-intervention. In such tasks, the Landing Error Scoring System for first (LESS1) and second (LESS2) landings, and the Cutting Movement Assessment Score (CMAS) were used for assessing movement quality. Pre-to-post changes and baseline-adjusted ANCOVA were used. Medium-to-large differences between groups at post-test were shown in CMAS, LESS1 and LESS2 (p < 0.082, ղ2 = 0.137-0.272), with small-to-large improvements in SL (p < 0.046, ES=0.546-1.307), and CG remaining unchanged (p > 0.05) pre-to-post. In COD70 performance, large differences were found between groups (p < 0.047, ղ2 = 0.160-0.253), with SL maintaining performance (p > 0.05, ES=0.039-0.420), while CG moderately decreasing performance (p = 0.024, ES=0.753) pre-to-post. The SL is a feasible and effective TM program to improve movement quality and thus potential injury risk in cutting and landing, while not negatively affecting performance.

Dynamic Taping Improves Landing Biomechanics in Young Volleyball Athletes

Poor landing biomechanics such as hip adduction, internal rotation, and knee valgus have been recognized as modifiable risk factors of anterior cruciate ligament (ACL) injury. Dynamic taping is a newly developed technique with better elasticity and extensibility, which could change the landing biomechanics. The purpose of this study was to identify whether dynamic taping could improve lower limb biomechanics in athletes. Forty-two high school volleyball athletes (21 males and 21 females) participated in the study. Biomechanical properties, including the landing error scoring system (LESS) and anterior-posterior knee laxity, were evaluated before and after the application of dynamic tape while athletes performed the jump-landing task. As a result, we found that dynamic tape significantly reduced the faulty landing strategy by an average of 0.64 errors in all volleyball athletes. The effect induced by dynamic tape was more prominent in female athletes and high-risk athletes (1.1 errors). Furthermore, the application of dynamic tape improved anterior-posterior knee laxity, especially in female athletes (p < 0.001). In conclusion, we found that dynamic tape provided a short-term, passive, and clinically significant means to normalize inadequate biomechanics during landing in athlete groups, which could have a protective effect and further alleviate the risk of ACL injury.

Biomechanical Analysis of the Tuck Jump Assessment

ABSTRACT

Nascimento, N, Sideris, V, and Read, PJ. Biomechanical analysis of the tuck jump assessment. J Strength Cond Res 36(10): 2946-2949, 2022-The tuck jump assessment (TJA) examines plyometric technique flaws associated with the increased risk of anterior cruciate ligament injury. Biomechanical data to investigate the mechanics used during the TJA are limited and assessing each jump individually across the entire test period is time inefficient. This study examined performance characteristics and movement mechanics in 16 professional soccer players during a standardized TJA protocol (10 jumps) to determine if sensitive periods exist within the test period (first 5 vs. last 5). Jump height, average power (PW) reactive strength index (RSI), frontal plane projection angle (FPPA), knee angular velocity (AV), and peak knee flexion angle (PKA) were analyzed using an optoelectrical and inertial measurement unit device. Jump height and PW increased in the past 5 jumps displaying a medium effect size (d = > 0.5). A trend was observed of increased AV, FPPA, and PKA during the past 5 jumps; however, no meaningful differences were observed between respective jump phases, and effect sizes were small (d ≤ 0.2). This study indicates that performance metrics increase during the past 5 jumps of a standardized TJA 10-jump protocol; thus, analyzing the entire test period may not be required, providing a time-efficient approach. Caution should be applied if using this protocol as an injury risk screening tool or to identify fatigue related alterations in male professional soccer players as no obvious movement abnormalities were apparent and minimal differences were present between jump phases in a range of kinematic variables across the recorded test duration.

Preventive Training Program Feedback Complexity, Movement Control, and Performance in Youth Athletes

CONTEXT

Preventive training programs (PTPs) reduce injury risk by improving movement control. Corrective feedback is important; however, many cues at once may be too complicated for athletes.

OBJECTIVE

To compare movement control and long-jump (LJ) changes in youth athletes participating in a season-long PTP, with simplified feedback, traditional feedback, or a warmup of the coaches' choosing.

DESIGN

Cluster-randomized controlled trial.

SETTING

Soccer fields.

PATIENTS OR OTHER PARTICIPANTS

A total of 420 athletes (simplified feedback = 173, traditional feedback = 118, and control = 129; age = 11 ± 3 years).

INTERVENTION(S)

Teams were randomized into the simplified PTP, traditional PTP, or control group. Simplified and traditional PTPs lasted 10 to 12 minutes and used the same exercises. The simplified PTP provided only sagittal-plane feedback (eg, "get low"), and the traditional PTP provided feedback targeting all motion planes (eg, "don't let your knees cave inward"). Research assistants administered the PTP warmups 2 to 3 times/week for the season. Control team coaches chose and ran their own warmup strategies.

MAIN OUTCOME MEASURE(S)

Participants completed 4 sessions (preseason [PRE], postseason [POST] at approximately 8 weeks after PRE, retention 1 [R1] at 6 weeks postseason, and retention 2 [R2] at 12 weeks postseason). They performed 3 trials of a jump-landing task, which was evaluated using the Landing Error Scoring System (LESS) and 2 recorded standing LJ trials at each test session. A time series panel was used to evaluate group differences across time points for the LESS and LJ.

RESULTS

Change score analyses revealed improvements in the LESS score from PRE to POST for all groups. Improvements from PRE were retained at R1 and R2 for the intervention groups (simplified and traditional). The traditional group demonstrated better LJ performance at POST (P < .001) and R1 (P = .049) than the simplified or control group.

CONCLUSIONS

Simplified cues were as effective as traditional cues in improving LESS scores from PRE to POST season. Participating in PTPs, regardless of their complexity, likely provides movement benefits.

Preliminary Report on the Train the Brain Project, Part II: Neuroplasticity of Augmented Neuromuscular Training and Improved Injury-Risk Biomechanics

CONTEXT

Neuromuscular training (NMT) facilitates the acquisition of new movement patterns that reduce the anterior cruciate ligament injury risk. However, the neural mechanisms underlying these changes are unknown.

OBJECTIVE

To determine the relationship between brain activation and biomechanical changes after NMT with biofeedback.

DESIGN

Cohort study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty female high school soccer athletes, with 10 in an augmented NMT group and 10 in a control (no training) group.

MAIN OUTCOME MEASURE(S)

Ten participants completed 6 weeks of NMT augmented with real-time biofeedback to reduce knee injury-risk movements, and 10 participants pursued no training. Augmented neuromuscular training (aNMT) was implemented with visual biofeedback that responded in real time to injury-risk biomechanical variables. A drop vertical jump with 3-dimensional motion capture was used to assess injury-risk neuromuscular changes before and after the 6-week intervention. Brain-activation changes were measured using functional magnetic resonance imaging during unilateral knee and multijoint motor tasks.

RESULTS

After aNMT, sensory (precuneus), visual-spatial (lingual gyrus), and motor-planning (premotor) brain activity increased for knee-specific movement; sensorimotor cortex activity for multijoint movement decreased. The knee-abduction moment during landing also decreased (4.66 ± 5.45 newton meters; P = .02; Hedges g = 0.82) in the aNMT group but did not change in the control group (P > .05). The training-induced increased brain activity with isolated knee movement was associated with decreases in knee-abduction moment (r = 0.67; P = .036) and sensorimotor cortex activity for multijoint movement (r = 0.87; P = .001). No change in brain activity was observed in the control group (P > .05).

CONCLUSIONS

The relationship between neural changes observed across tasks and reduced knee abduction suggests that aNMT facilitated recruitment of sensory integration centers to support reduced injury-risk mechanics and improve sensorimotor neural efficiency for multijoint control. Further research is warranted to determine if this training-related multimodal neuroplasticity enhances neuromuscular control during more complex sport-specific activities.

Comparing the Effects of Differential Learning, Self-Controlled Feedback, and External Focus of Attention Training on Biomechanical Risk Factors of Anterior Cruciate Ligament (ACL) in Athletes: A Randomized Controlled Trial

The current study aimed to compare the possible effects of differential learning strategy, self-controlled feedback, and external focus of attention on kinetic and kinematic risk factors of anterior cruciate ligament (ACL) injury in athletes. Forty-eight male athletes from three sports of handball, volleyball and basketball were selected for this study and were randomly divided into four groups: differential learning (n = 12), self-control feedback (n = 12), external focus (n = 12), and control (n = 12) group. All groups followed the intervention for eight weeks with three sessions per week. Data were analyzed by means of 4 × 2 repeated measures ANOVA followed by post hoc comparison (Bonferroni) at the significance level of p ≤ 0.05. A significant group × time interaction and the main effect of time was found for most kinetic and kinematic variables. The main effect of the group was significant only at the knee abduction angle. Differential learning and external focus of attention methods positively reduced the kinetic and kinematic variables that are considered risk factors for ACL injury. However, the effect sizes (Cohen's d) for the changes in most of the variables were larger for the differential learning group. Tailoring the boundary conditions that are based on the manipulations created in the exercise through variability and variety of movements associated with differential learning methods rather than repeating movements could reduce the risk of ACL injury.

Prevention of Non-Contact Anterior Cruciate Ligament Injuries among Youth Female Athletes: An Umbrella Review

Anterior cruciate ligament (ACL) injuries account for a large percentage of knee injuries, disproportionately affecting female athletes. To help health professionals stay current, we performed an umbrella review to evaluate the effectiveness of ACL injury prevention programs in reducing non-contact ACL injury rates, determine the effective components within interventions, and provide clinical recommendations. Twelve databases (Medline, Embase, Cochrane Database of Systematic Reviews, SPORTDiscus, Cumulative Index to Nursing and Allied Health Literature, PEDro, Web of Science Core Collection, Epistemonikos, TRIP, BC Guidelines and Protocols, CPG Infobase, ProQuest Dissertations and Theses Global) were searched in May 2021 to identify relevant systematic reviews and meta-analyses. Four databases were searched again in September 2021 to identify recent primary literature. Non-contact ACL injury data were extracted to calculate incidence rate ratios (IRRs) and these were combined using an inverse variance random-effects model. A qualitative assessment of included reviews was performed. The methodological quality of the studies was assessed using a Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) or Cochrane Risk-of-Bias Tool for Randomized Trials (RoB 2). Sixteen reviews and two primary studies met the inclusion criteria. Across 11 primary studies, prevention programs were effective in reducing non-contact ACL injuries by 64% (IRR = 0.36 (95% CI: 0.18–0.70)). A multi-faceted exercise program, beginning in the pre-season and containing at least three exercise types, may be beneficial in reducing ACL injury risk.

Exercise-Based Training Strategies to Reduce the Incidence or Mitigate the Risk Factors of Anterior Cruciate Ligament Injury in Adult Football (Soccer) Players: A Systematic Review

Anterior cruciate ligament (ACL) is one of the most concerning injuries for football players. The aim of this review is to investigate the effects of exercise-based interventions targeting at reducing ACL injury rate or mitigating risk factors of ACL injury in adult football players. Following PRISMA guidelines, a systematic search was conducted in CINAHL, Cochrane Library, PubMed, Scopus, SPORTDiscus and Web of Science. Studies assessing the effect of exercise-based interventions in ACL injury incidence or modifiable risk factors in adult football players were included. 29 studies evaluating 4502 male and 1589 female players were included (15 RCT, 8 NRCT, 6 single-arm): 14 included warm-up, 7 resistance training, 4 mixed training, 3 balance, 1 core stability and 1 technique modification interventions. 6 out of 29 studies investigated the effect of interventions on ACL injury incidence, while the remaining 23 investigated their effect on risk factors. Only 21% and 13% studies evaluating risk of injury variables reported reliability measures and/or smallest worthwhile change data. Warm-up, core stability, balance and technique modification appear effective and feasible interventions to be included in football teams. However, the use of more ecologically valid tests and individually tailored interventions targeting specific ACL injury mechanisms are required.

When puberty strikes: Longitudinal changes in cutting kinematics in 172 high-school female athletes

OBJECTIVES

Young female athletes involved in high-speed cutting and change-of-direction sports are particularly susceptible to anterior cruciate ligament (ACL) injuries. Little is known if maturational changes in cutting technique contribute to the increased injury risk. Our objective was to examine longitudinal changes in cutting kinematics in female athletes as they matured through puberty.

DESIGN

Longitudinal cohort study METHODS: High school female athletes (n=172) performed an unanticipated 45° cutting task in the biomechanics laboratory across two or more pubertal stages. Pubertal stages were classified using a modified Pubertal Maturational Observational Scale (pre-, mid-, or post-pubertal stages). Generalized linear mixed models were used to compare kinematics across pubertal stages.

RESULTS

As girls matured through puberty, they displayed a decrease in sagittal-plane hip (1.8-2.6°, p<0.03) and knee range-of-motion (ROM) (2.7-2.9°, p≤0.01), and decreased peak hip (2.9-3.2°, p≤0.02) and knee flexion angles (2.7-2.9°, p≤0.01), which is indicative of greater quadriceps dominance. Peak knee abduction angles also increased as girls progressed through puberty (0.9-1.4°, p≤0.02), suggesting greater ligament dominance. In terms of trunk dominance, there were mixed findings with a decrease in trunk frontal- (2.5-5.7°, p≤0.03) and sagittal-plane ROM (2.0°, p≤0.01), but an increase in trunk transverse-plane ROM (2.8-3.6°, p≤0.02) observed as girls mature. Other significant changes in cutting technique were decreased peak trunk flexion (3.8-7.8°, p≤0.01), and decreased hip flexion (2.9-3.3°, p≤0.02) and knee flexion angles (2.0-3.0°, p≤0.03) at initial contact, suggesting a more upright and stiffer cutting posture.

CONCLUSIONS

As girls mature through puberty, there is a change in cutting strategy characterized by greater quadriceps and ligament dominance.

Muscle Activity Estimation at Drop Vertical Jump Landing Using Passive Muscle Mechanical Model

Among the various elements that facilitate the movement of the lower limbs, the anterior cruciate ligament (ACL) is prone to injury. An adequate joint control of the lower limb can prevent ACL injury. Balancing activities between the agonist and the antagonist muscles is vital for joint control. However, prior studies on muscle activities were limited since they could not determine passive muscle activities. In this study, we develop a muscle model considering the passive properties to analyze the movement mechanism of the ACL under heavy loads, such as those produced during jump landing. We estimated the muscle activities occurring during a drop vertical jump (DVJ) by applying to the proposed method the physiological constraint that muscle activities are constant during a short time around landing. In addition, the knee joint torque and muscle forces were calculated from the estimated muscle activities, which were thereafter compared with those obtained using the conventional method. The results revealed that this passive muscle model appropriately represented the knee joint torque at DVJ landing by decreasing the passive muscle strain and increasing the isometric maximum muscle force. Moreover, the estimated muscle activities were larger than those obtained using the conventional method, which may be caused by the co-contraction between agonist and antagonist muscles that cannot be represented by the conventional method. This muscle co-contraction estimation algorithm would estimate the muscle load under heavy loads, and applying this knowledge to training would help to prevent ACL injuries.

Foot Muscle Strengthening and Lower Limb Injury Prevention

Background and objectives: The active and passive structures of the foot act in unison to not only be compliant enough to assist in ground reaction force attenuation but also resist deformation to provide a stable base of support. A foot that is unable to adjust to the imposed demands during high-intensity sporting activities may alter the moments and forces acting on the joints, increasing the risk of non-contact anterior cruciate ligament ruptures (ACLR) and lateral ankle sprains (LAS). Prophylactic strengthening programs are often used to reduce the risk of these injuries, but at present, very few prophylactic programs include foot-specific strengthening strategies. The aim of this theoretical review is to ascertain the prophylactic role strengthening muscles acting on the foot may have on ACLR and LAS injury risk. Methods: Literature relating to risk factors associated with ACLR and LAS injury and the anatomy and biomechanics of normal foot function was searched. In addition, ACLR and LAS injury prevention programs were also sought. A theoretical, narrative approach was followed to synthesize the information gathered from the articles. Results: The foot segments are governed by the congruity of the articulations and the activity of the foot muscles. As such, there is a coupling effect between shank, calcaneus, midfoot, and hallux movement which play a role in both ACLR and LAS injury risk. Conclusions: Strengthening the muscles acting on the foot may have a significant impact on ACLR and LAS injury risk.

The Effect of a Brief, Web-Based Animated Video for Improving Comprehension and Implementation Feasibility for Reducing Anterior Cruciate Ligament Injury: A Three-Arm Randomized Controlled Trial

Neuromuscular injury prevention training (IPT) has been shown to reduce anterior cruciate ligament (ACL) injury risk by approximately 50%, but the implementation rate is low. One of the most important modifiable barriers for implementation is coaches' comprehension of risk and intervention strategies. This study aimed to evaluate the effect of a brief, web-based, animated video on ACL injury prevention comprehension and IPT implementation feasibility. Coaches in landing and cutting sports were recruited and randomized into three groups. (1) Intervention: brief multimedia animated video about ACL injury and prevention. (2) Active control: commonly accessed, text-based web resource about ACL injury and prevention. (3) Placebo control: brief multimedia video about concussions. Overall ACL comprehension-composed of basic ACL knowledge, risk knowledge, prevention knowledge, and severity knowledge-as well as implementation feasibility were all measured prior to and immediately following the interventions. Overall ACL comprehension improved the most in the animated video group (Cohen's d = 0.86) and, to a lesser degree, in the active control web-based article group (Cohen's d = 0.39). Both video and web-based article groups had greater implementation feasibility compared to the control group (p = 0.01). Overall, these initial results suggest that a brief, web-based, animated video has the potential to be a superior method for informing stakeholders in order to reduce traumatic injuries in sport.

Can a Knee Brace Prevent ACL Reinjury: A Systematic Review

This systematic review aimed to investigate whether the use of a knee brace when returning to sport (RTS) could prevent a second injury after anterior cruciate ligament reconstruction (ACLR). This study was registered with the PROSPERO database and followed PRISMA guidelines. A systematic search of PubMed, Ovid Medline, Ovid All EBM Reviews, Ovid Embase, EBSCO Sportdiscus and ISI Web of Science databases for meta-analysis, randomized controlled trials and prospective cohort studies published before July 2020 was undertaken. The inclusion criteria were: (1) Comparing with and without a brace at RTS, (2) follow up of at least 18 months after ACLR, (3) reinjury rates included in the outcomes. Two reviewers independently extracted the data. Quality appraisal analyses were performed for each study using the Cochrane Collaboration tools for randomized and nonrandomized trials. A total of 1196 patients in three studies were included. One study showed a lower rate of reinjury when wearing a knee brace at RTS. One study found the knee brace to have a significant protective effect for younger patients (≤17 years). The effectiveness of knee bracing when RTS remains ambiguous. Current data cannot support that using a knee brace when RTS will decrease the rate of reinjury after ACL reconstruction.

Acute Effects of ACL Injury-Prevention Warm-Up and Soccer-Specific Fatigue Protocol on Dynamic Knee Valgus in Youth Male Soccer Players

Childhood anterior cruciate ligament (ACL) injuries—which can pose a major risk to a child’s sporting career—have been on the rise in the last few decades. Dynamic knee valgus (DKV) has been linked to an increased risk of ACL injury. Therefore, the aim of this study was to analyze the acute effects of an ACL injury prevention protocol (ACL-IPP) and a soccer-specific fatigue protocol (SSFP) on DKV in youth male soccer players. The research hypothesis was that DKV would be reduced by the ACL-IPP and increased by the SSFP. Eighteen youth male soccer players were divided according to baseline DKV. Those with moderate or large DKV performed a neuromuscular training protocol based on activation of the abductor and external rotator hip muscles. Those with little or no DKV performed a soccer-specific fatigue protocol. DKV was assessed using the single-leg squat pre- and post-protocols in both legs. The ACL-IPP significantly decreased DKV during single-leg squat (p < 0.01, effect size = 1.39), while the SSFP significantly increased baseline DKV in the dominant leg during single-leg squat (p = 0.012; effect size = 1.74). In conclusion, the ACL-IPP appears to acutely reduce the DKV in youth male soccer players, and the SSFP seems to acutely increase the DKV in those players who showed a light or no DKV in a non-fatigue situation. By using the SSFP, it may be possible to determine which players would benefit from injury prevention programs due to increased DKV during game scenarios, while hip abductor and external rotator neuromuscular training may be beneficial for players who have moderate and severe DKV during single-leg squat under non-fatigued scenarios.

Muscles Cooperation Analysis Using Akaike Information Criteria for Anterior Cruciate Ligament Injury Prevention

In this paper, we propose the analysis method for finding out the similarity of the muscle force patterns to mine the risk factor of the anterior cruciate ligament (ACL) injury. Akaike information criteria (AIC) under the assumption of the auto-regression model is adapted to analyze the similarities of muscle force patterns in time-series. The difference of AIC values between 2 muscles is considered to be the distance between 2 muscle force patterns and the dexterity of the maneuver is expected to be discussed. We measured drop vertical jump (DVJ) and use the data around the contact timing of whom hadn't had ACL injury experiments. The results showed that we could successfully calculate AIC distance according to the similarity of the time-series data pattern and it can be useful to discuss one's dexterity of controlling body maneuvers soon after contact timing of DVJ motion.

[Preventing anterior cruciate ligament injury in children is effective]

An anterior cruciate ligament (ACL) injury in children is a devastating injury. After an ACL injury 1 in 3 children obtain a second injury of the ipsilateral or contralateral ACL. Children who suffer an ACL injury also have a ten times higher risk of osteoarthritis. Preventative training programmes can decrease the risk of acute knee injuries in young sportspeople; however, implementation of these prevention programmes is challenging, so it is important to inform associations, clubs, youth trainers and parents about the added value of these programmes. Children with ACL injuries must receive specialized guidance during rehabilitation, regardless of whether they have been treated conservatively or surgically. Because of the risk of a second ACL injury,we recommend that children should not to return to pivoting sports until at least 12 months after surgery for ACL.

Is Fatigue a Risk Factor for Anterior Cruciate Ligament Rupture?

Neuromuscular fatigue is a commonly accepted risk factor for anterior cruciate ligament (ACL) injury. It has been proposed that fatigue leads to transient reductions in muscle strength, and deleterious changes in lower limb kinematics and kinetics, during potentially hazardous tasks such as cutting or landing. The purpose of this clinical commentary is to (1) highlight the complexity of fatigue; (2) discuss the theoretical basis by which it is thought to contribute to ACL injury; and (3) critically discuss the evidence underpinning this hypothesis. Despite a significant amount of research, none of the published fatigue protocols appear to have any consistent effect on any lower limb kinematic or kinetic variables known to increase ACL injury risk. On the contrary, fatigued athletes appear to land with greater peak knee and hip flexion angles, and lower landing forces than unfatigued athletes-all of which are considered favourable movement strategies for reducing ACL loading. These data support recent analyses demonstrating no relationship between player workload in training and competition and the occurrence of ACL injury in sport.

Co-creation of a sport-specific anterior cruciate ligament injury risk reduction program for women: A concept mapping approach

OBJECTIVES

To engage physiotherapists experienced in female elite sport and athletes to co-create a sport-specific anterior cruciate ligament (ACL) injury risk reduction program.

DESIGN

Concept Mapping.

METHODS

The Concept Systems Global MAX™ web platform was used to collect and analyse data from 27 context and content experts (22 physiotherapists, 5 athletes). Participants brainstormed statements representing the critical elements that should be included in an ACL injury risk reduction program for women playing elite Australian Football (AF).

RESULTS

Twenty-two participants brainstormed 56 statements that were synthesised and edited to 62 statements. Statements were sorted into clusters by twenty-three participants and rated on importance and feasibility using six-point scales. Multidimensional scaling and cluster analysis identified a 5-cluster solution as follows: Football-specific preparation (15 statements); Movement skills (17 statements); Strength and conditioning (15 statements); Individual preparation (7 statements); and Education (8 statements). Calculation of mean ratings for each cluster and statement identified the Movement skills cluster as most important (mean=3.61 out of 5) and the Football-specific preparation cluster as most feasible (3.75 out of 5). By contrast, the Individual preparation cluster was rated the least important (mean=2.9 out of 5), and the least feasible (3.12 out of 5), to include in the program.

CONCLUSIONS

The five clusters of critical elements to include in an ACL injury risk reduction program for women playing elite AF, in order of most to least importance were: movement skills, football-specific preparation, education, strength and conditioning and individual preparation.

A Technical Report on the Development of a Real-Time Visual Biofeedback System to Optimize Motor Learning and Movement Deficit Correction

This technical report describes the design and implementation of a novel biofeedback system to reduce biomechanical risk factors associated with anterior cruciate ligament (ACL) injuries. The system provided objective real-time biofeedback driven by biomechanical variables associated with increased ACL injury risk without the need of a present expert. Eleven adolescent female athletes (age = 16.7 ± 1.34 yrs; height = 1.70 ± 0.05 m; weight = 62.20 ± 5.63 kg) from the same varsity high school volleyball team were enrolled in the experiment. Participants first completed 10 bodyweight squats in the absence of the biofeedback (pretest), 40 bodyweight squats while interacting with the biofeedback, and a final 10 bodyweight squats in the absence of the biofeedback (posttest). Participants also completed three pretest drop vertical jumps and three posttest drop vertical jumps. Results revealed significant improvements in squat performance, as quantified by a novel heat map analysis, from the pretest to the posttest. Additionally, participants displayed improvements in landing mechanics during the drop vertical jump. This study demonstrates that participants were able to interact effectively with the real-time biofeedback and that biomechanical improvements observed during squatting translated to a separate task.

Modelling the loading mechanics of anterior cruciate ligament

BACKGROUND AND OBJECTIVES

The anterior cruciate ligament (ACL) plays a crucial role in knee stability and is the most commonly injured knee ligament. Although ACL loading patterns have been investigated previously, the interactions between knee loadings transmitted to ACL remain elusive. Understanding the loading mechanism of ACL during dynamic tasks is essential to prevent ACL injuries. Therefore, we propose a computational model that predicts the force applied to ACL in response to knee loading in three planes of motion.

METHODS

First, a three-dimensional (3D) computational model was developed and validated using available cadaveric experimental data to predict ACL force. This 3D model was then combined with a neuromusculoskeletal model of lower limb and used to estimate in vivo ACL forces during a standardised drop-landing task. The neuromusculoskeletal model utilised movement data collected from female participants during a dynamic task and calculated lower limb joint kinematics and kinetics, as well as muscle forces.

RESULTS

The total ACL force predicted by the 3D computational ACL force model was in good agreement with cadaveric data, as strong correlation (r² = 0.96 and P < 0.001), minimal bias, and narrow limits of agreement were observed. The combined model further illustrated that the ACL is primarily loaded through the sagittal plane, mainly due to muscle loading.

CONCLUSIONS

The proposed computational model is the first validated model that can provide an accessible tool to develop and test knee ACL injury prevention programs for people with normal ACL. This method can be extended to study the abnormal ACL upon the availability of relevant experimental data.

By failing to prepare, you are preparing your anterior cruciate ligament to fail

There is strong evidence linking an athlete's movement technique during sidestepping with anterior cruciate ligament (ACL) injury risk. However, it is unclear how these injurious postures are influenced by prior movement. We aim to describe preparatory trunk and thigh kinematics at toe-off of the penultimate-step and flight-phase angular momenta, and explore their associations with frontal-plane risk factors during unplanned sidestepping maneuvers. We analyzed kinematic and kinetic data of 33 male Australian Football players performing unplanned sidestepping tasks (103 trials). Linear mixed models tested for reliable associations between ACL injury risk during weight acceptance of the execution-step, with preparatory kinematics and angular momenta of the trunk and thigh during the penultimate-step. Multi-planar flight-phase trunk momenta along with hip abduction angle at penultimate-step toe-off were significantly associated with peak knee valgus moments during the execution-step (R2  = .21, P < .01). Execution-step trunk lateral flexion was significantly predicted by frontal and sagittal-plane preparatory trunk positioning at toe-off of the penultimate-step (R2  = .44, P < .01). Multi-planar flight-phase trunk momenta as well as multi-planar trunk and hip positioning at penultimate-step toe-off were associated with hip abduction during the execution-step (R2  = .53, P < .01). Preparatory positioning of the trunk and hip, along with flight-phase trunk momentum adjusting this positioning are linked to known ACL injury risk factors. We recommend that during the penultimate-step athletes maintain an upright trunk, as well as minimize frontal-plane trunk momentum and transverse-plane trunk momentum toward the sidestep direction to reduce risk of ACL injury during unplanned sidesteps.

[Handball injuries and their prevention]

BACKGROUND

Handball is one of the most popular team sports in Germany, as well as one of the most dangerous ones. Injury rates in Germany are higher amongst handball professionals than in soccer, with the knee being the most commonly injured joint. To prevent injuries, a functional inert stability is necessary, but definitions and objective measures are lacking.

OBJECTIVES

Establishing valid reference data of functional knee stability in amateur handball players with use of an established test battery giving objective measures METHODS: 261 athletes (f:130; m:131), mean age 25.1 ± 5.8 y were screened during the preseason. The test battery consisted of double and single-leg counter movement jumps, balance tests, agility, parkour, quick feet test and plyometric jumps.

RESULTS

Significant differences between males and females were noted in regard to balance scores (favour for females p ≤ 0.001), as well as jump height, agility and speed tests (favour for males [p ≤ 0.002-0.001]).

CONCLUSION

The noted differences once again bring focus to the interindividual presence of risk factors, because female and male handball athletes have gender-specific ground levels. These attributes have to be considered in further screening and prevention programs, as well as in the context of the return-to-sports decision after injury. The given data may serve as objective reference measures.

Musculoskeletal modeling to predict and reduce Antetrior Cruciate Ligament injury during single leg drop jump activity: Synergistic muscle co-activation approach

This paper presents a `drop jump' modeling to study the effect of synergistic muscle activation on controlling Anterior Cruciate Ligament (ACL) injury. ACL injuries are mostly caused during high impact loading. A full body musculoskeletal model with knee ligaments have been developed in `OpenSim platform' to simulate ACL injury during drop jump activity. The model is used to quantify the effect of change in muscle activation on different kinetic and kinematic parameters, which are associated with ACL injury. A neuromusculoskeletal controller have been designed which selects optimal muscle activation of Quadriceps, Hamstrings, Gastrocnemius and Tibilias anterior muscle group so as to reduce the chance of ACL injury and ankle inversion risk while jumping from elevated platforms. The OpenSim model along with the neuro-muscular controller forms an injury `predict-adapt' system, which can be useful in designing specific training sessions for athletics or for planning personalized rehabilitation therapy.

Systematic Selection of Key Logistic Regression Variables for Risk Prediction Analyses: A Five-Factor Maximum Model

GENERAL AND CRITICAL REVIEW FORMAT

The evolution of clinical practice and medical technology has yielded an increasing number of clinical measures and tests to assess a patient's progression and return to sport readiness after injury. The plethora of available tests may be burdensome to clinicians in the absence of evidence that demonstrates the utility of a given measurement.

OBJECTIVE

Thus, there is a critical need to identify a discrete number of metrics to capture during clinical assessment to effectively and concisely guide patient care.

DATA SOURCES

The data sources included Pubmed and PMC Pubmed Central articles on the topic. Therefore, we present a systematic approach to injury risk analyses and how this concept may be used in algorithms for risk analyses for primary anterior cruciate ligament (ACL) injury in healthy athletes and patients after ACL reconstruction.

MAIN RESULTS

In this article, we present the five-factor maximum model, which states that in any predictive model, a maximum of 5 variables will contribute in a meaningful manner to any risk factor analysis.

CONCLUSIONS

We demonstrate how this model already exists for prevention of primary ACL injury, how this model may guide development of the second ACL injury risk analysis, and how the five-factor maximum model may be applied across the injury spectrum for development of the injury risk analysis.