A qualitative screening tool to identify athletes with ‘high-risk’ movement mechanics during cutting: The cutting movement assessment score (CMAS)

The effects of two different fatigue protocols on movement quality during anticipated and unanticipated change of directions in female soccer players

OBJECTIVE

This study compared neuromuscular control under two fatigue protocols during anticipated and unanticipated change of direction (COD) maneuvers and evaluated their effects on the risk of non-contact ACL injuries.

METHOD

Forty-five female soccer players (mean age: 22.22 ± 2.24 years; mean height: 166.24 ± 3.33 cm; mean mass: 59.84 ± 5.03 kg) were divided into three groups: functional fatigue (Soccer specific fatigue ptotocol-SOFT90), non-functional fatigue (Bruce protocol), and control group. Before and after the implementation of neuromuscular control fatigue protocols were evaluated using the cutting motion assessment score tool (CMAS). Two-dimensional (2D) videos were recorded during anticipated and unanticipated COD trials for both dominant and non-dominant legs.

RESULTS

Significant time effects (p < 0.05) and group-time interactions (p < 0.05) were observed in both anticipated and unanticipated conditions for both dominant and non-dominant legs after the fatigue protocols. The functional fatigue group exhibited higher CMAS changes, indicating poorer movement quality following fatigue. Notably, the non-dominant leg displayed amplified deficits during unanticipated COD maneuvers following the functional fatigue protocol.

CONCLUSIONS

Fatigue significantly impairs neuromuscular control, particularly in unanticipated COD situations, which increases the risk of non-contact ACL injuries. To mitigate this risk, coaches, trainers, and medical professionals should prioritize targeted training and injury prevention strategies, focusing on the non-dominant leg during unanticipated COD maneuvers.

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

PURPOSE

To investigate the 90° change of direction (COD) task in an extensive cohort of competitive healthy football players within the CUTtheACL study and to provide normative values and differences between males and females for full-body kinematics based on two-dimensional (2D) video analysis and scoring system.

METHODS

One-thousand-and-two competitive football (soccer) players (age 16.3 ± 2.8 years, 264 females) were prospectively enroled. Each player performed three preplanned 90° COD tasks per limb. The 2D evaluation was performed through objective measures (collected through three high-speed cameras) of frontal and sagittal plane joint kinematics at the cut initial foot contact (IC) and maximum knee flexion angle. A previously published scoring system was adopted to measure the movement quality of the COD task. The scoring system included five criteria (limb stability [LS], pelvis stability [PS], trunk stability [TS], shock absorption [SA], movement strategy [MS]) ranked from 0/2 (nonadequate) to 2/2 (adequate) with a maximum score of 10/10. Normative data were provided for all the variables; statistical differences between male and female players were investigated (p < 0.05).

RESULTS

A total of 6008 valid attempts were included. Frontal plane knee projection angle (FPKPA) at initial contact was 24.4 ± 9.8° (95th percentile: FPKPA > 40°). The total score was ≤4/10 in 71.2% of the trials, the lowest subscores were LS and PS. Female players showed different movement patterns with lower hip and trunk flexion both at IC and maximum knee flexion angle (p < 0.01, ES = 0.41-0.64). Female players also showed worse scores than males in SA, MS and total score (p < 0.01).

CONCLUSION

Female players seem more prone to stiffer lower limb strategy and greater pelvis-trunk frontal plane instability than males. Clinicians could adopt normative data and sex-specific differences in players' movement techniques to improve ACL injury risk mitigation protocols.

LEVEL OF EVIDENCE

Level IV.

Return to sports after an ACL reconstruction in 2024 - A glass half full? A narrative review

A successful return to sports (RTS) after an anterior cruciate ligament reconstruction (ACLR) is multifactorial, and therefore difficult and challenging. Unfortunately, low percentages of patients RTS, and for those who succeed, one-fifth of patients will sustain a second ACL injury. Over the past years, test batteries were developed to assess whether patients can RTS with a low risk for a second ACL injury risk. Low rates of patients who meet RTS criteria were found, coupled with the insufficiency of current RTS test batteries in predicting second ACL injuries suggesting poor sensitivity. The result of an RTS test is likely to reflect the content of a rehabilitation program, raising critical questions regarding what we are offering patients within the rehabilitation programme. Are we preparing our patients well enough for the high demands of complex situations within pivoting team sports? This narrative review offers insights from key lessons of the last 15 years on 1) RTS testing, 2) the content of rehabilitation, and 3) the RTS continuum, all from a "helicopter perspective".

The Sprint Mechanics Assessment Score: A Qualitative Screening Tool for the In-field Assessment of Sprint Running Mechanics

BACKGROUND

Qualitative movement screening tools provide a practical method of assessing mechanical patterns associated with potential injury development. Biomechanics play a role in hamstring strain injury and are recommended as a consideration within injury screening and rehabilitation programs. However, no methods are available for the in-field assessment of sprint running mechanics associated with hamstring strain injuries.

PURPOSE

To investigate the intra- and interrater reliability of a novel screening tool assessing in-field sprint running mechanics titled the Sprint Mechanics Assessment Score (S-MAS) and present normative S-MAS data to facilitate the interpretation of performance standards for future assessment uses.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

Maximal sprint running trials (35 m) were recorded from 136 elite soccer players using a slow-motion camera. All videos were scored using the S-MAS by a single assessor. Videos from 36 players (18 men and 18 women) were rated by 2 independent assessors blinded to each other's results to establish interrater reliability. One assessor scored all videos in a randomized order 1 week later to establish intrarater reliability. Intraclass correlation coefficients (ICCs) based on single measures using a 2-way mixed-effects model, with absolute agreement with 95% CI and kappa coefficients with percentage agreements, were used to assess the reliability of the overall score and individual score items, respectively. T-scores were calculated from the means and standard deviations of the male and female groups to present normative data values. The Mann-Whitney U test and the Wilcoxon signed-rank test were used to assess between-sex differences and between-limb differences, respectively.

RESULTS

The S-MAS showed good intrarater (ICC, 0.828 [95% CI, 0.688-0.908]) and interrater (ICC, 0.799 [95% CI, 0.642-0.892]) reliability, with a standard error of measurement of 1 point. Kappa coefficients for individual score items demonstrated moderate to substantial intra- and interrater agreement for most parameters, with percentage agreements ranging from 75% to 88.8% for intrarater and 66.6% to 88.8% for interrater reliability. No significant sex differences were observed for overall scores, with mean values of 4.2 and 3.8 for men and women, respectively (P = .27).

CONCLUSION

The S-MAS is a new tool developed for assessing sprint running mechanics associated with lower limb injuries in male and female soccer players. The reliable and easy-to-use nature of the S-MAS means that this method can be integrated into practice, potentially aiding future injury screening and research looking to identify athletes who may demonstrate mechanical patterns potentially associated with hamstring strain injuries.

A 2D video-based assessment is associated with 3D biomechanical contributors to dynamic knee valgus in the coronal plane

Introduction

Adolescent athletes involved in sports that involve cutting and landing maneuvers have an increased risk of anterior cruciate ligament (ACL) tears, highlighting the importance of identifying risky movement patterns such as dynamic knee valgus (DKV). Qualitative movement screenings have explored two-dimensional (2D) scoring criteria for DKV, however, there remains limited data on the validity of these screening tools. Determining a 2D scoring criterion for DKV that closely aligns with three-dimensional (3D) biomechanical measures will allow for the identification of poor knee position in adolescent athletes on a broad scale. The purpose of this study was to establish a 2D scoring criterion that corresponds to 3D biomechanical measures of DKV.

Methods

A total of 41 adolescent female club volleyball athletes performed a three-task movement screen consisting of a single-leg squat (SLS), single-leg drop landing (SLDL), and double-leg vertical jump (DLVJ). A single rater scored 2D videos of each task using four criteria for poor knee position. A motion capture system was used to calculate 3D joint angles, including pelvic obliquity, hip adduction, knee abduction, ankle eversion, and foot progression angle. Receiver operating characteristic curves were created for each 2D scoring criterion to determine cut points for the presence of movement faults, and areas under the curve (AUC) were computed to describe the accuracy of each 2D criterion compared to 3D biomechanical data.

Results

3D measures indicated knee abduction angles between 2.4°-4.6° (SD 4.1°-4.3°) at the time point when the center of the knee joint was most medial during the three tasks. AUCs were between 0.62 and 0.93 across scoring items. The MEDIAL scoring item, defined as the knee joint positioned inside the medial border of the shoe, demonstrated the greatest association to components of DKV, with AUCs ranging from 0.67 to 0.93.

Conclusion

The MEDIAL scoring criterion demonstrated the best performance in distinguishing components of DKV, specifically pelvic obliquity, hip adduction, ankle eversion, and foot progression. Along with the previously published scoring definitions for trunk-specific risk factors, the authors suggest that the MEDIAL criterion may be the most indicative of DKV, given an association with 3D biomechanical risk factors.

Relationship of Knee Abduction Moment to Trunk and Lower Extremity Segment Acceleration during Sport-Specific Movements

The knee abduction moment (KAM) has been identified as a significant predictor of anterior cruciate ligament (ACL) injury risk; however, the cost and time demands associated with collecting three-dimensional (3D) kinetic data have prompted the need for alternative solutions. Wearable inertial measurement units (IMUs) have been explored as a potential solution for quantitative on-field assessment of injury risk. Most previous work has focused on angular velocity data, which are highly susceptible to bias and noise relative to acceleration data. The purpose of this pilot study was to assess the relationship between KAM and body segment acceleration during sport-specific movements. Three functional tasks were selected to analyze peak KAM using optical motion capture and force plates as well as peak triaxial segment accelerations using IMUs. Moderate correlations with peak KAM were observed for peak shank acceleration during single-leg hop; peak trunk, thigh, and shank accelerations during a deceleration task; and peak trunk, pelvis, and shank accelerations during a 45° cut. These findings provide preliminary support for the use of wearable IMUs to identify peak KAM during athletic tasks.

Concurrent Validity of The Expanded Cutting Alignment Scoring Tool (E-CAST)

Background

The Expanded Cutting Alignment Scoring Tool (E-CAST) has been previously shown to be reliable when assessing lower extremity alignment during a 45-degree sidestep cut, however, the validity of this tool remains unknown. The purpose of this study was to assess the concurrent validity of the E-CAST by comparing visually identified movement errors from two-dimensional (2D) video with three-dimensional (3D) biomechanical variables collected using motion capture.

Study Design

Cross Sectional.

Methods

Sixty female athletes (age 14.1 ± 1.5 years) who regularly participated in cutting/pivoting sports performed a sidestep cut with 2D video and 3D motion capture simultaneously recording. One clinician scored the 2D videos for each limb using the E-CAST criteria. Joint angles and moments captured in 3D were computed for the trunk and knee. Receiver operating characteristic (ROC) curve analyses were performed to determine the accuracy of each E-CAST item and to provide cut-off points for risk factor identification.

Results

ROC analyses identified a cut-off point for all biomechanical variables with sensitivity and specificity ranging from 70-85% and 55-89%, respectively. Across items, the area under the curve ranged from 0.67 to 0.91.

Conclusion

The E-CAST performed with acceptable to outstanding area under the curve values for all variables except static knee valgus.

Level of evidence

3b.

Development of a Cutting Technique Modification Training Program and Evaluation of its Effects on Movement Quality and Cutting Performance in Male Adolescent American Football Players

This study developed a cutting technique modification training program and investigated its effects on cutting performance and movement quality in adolescent American football players. For six weeks, an intervention group (IG) of 11 players participated in 25 min cutting technique modification training sessions integrated into team training twice a week, while a control group (CG) of 11 players continued their usual team training. Movement quality was assessed by evaluating 2D high-speed videos, obtained during preplanned 45° and 90° cutting tests, using the Cutting Movement Assessment Score (CMAS) qualitative screening tool. Cutting performance was assessed based on change of direction deficit (CODD). Significant interaction effects of time × group were found for CMAS in 45° and 90° cuttings (p < 0.001, ηp2 = 0.76, p < 0.001, ηp2 = 0.64, respectively), with large improvements in the IG (p < 0.001, g = -2.16, p < 0.001, g = -1.78, respectively) and deteriorations in the CG for 45° cuttings (p = 0.002, g = 1.15). However, no statistically significant differences in CODD were observed pre-to-post intervention. The cutting technique modification training was effective at improving movement quality without impairing cutting performance, and it can be used by practitioners working with adolescent athletes.

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

BACKGROUND

Lateral movements are challenging for 2D video-analysis and are therefore often omitted in functional tests for Anterior Cruciate Ligament (ACL) injury risk assessment. The purpose of the present study was to investigate the association between frontal and transverse plane angles obtained from 2D video-analysis and knee abduction moment (KAM) from gold standard 3D motion capture in a 180° lateral cut task. The hypothesis was that 2D angles other than the knee joint effectively explain variations in KAM.

METHODS

Thirty-four healthy football players (age 22.8 ± 4.1 years) performed a series of 180° lateral cut (lateral shuffles) tasks. The peak KAM was collected through a 3D motion capture system. A 2D video-analysis movement assessment identified frontal and transverse plane joint kinematics: foot projection angle (FPA), Frontal Plane Knee Projection Angle (FPKPA), Pelvis tilt angle (PA), and Trunk tilt angle (TA). A forward stepwise regression model was used to assess significant 2D predictors of KAM (p < 0.05).

RESULTS

FPA and PA were the only significant predictors (R2-ajdusted = 9.2%, p < 0.001), with external foot rotation and contralateral pelvic drop associated with higher KAM. Based on the regression model, the "High FPA & PA group" was defined and showed higher KAM than the rest of the cohort (p = 0.012, ES = 0.71).

CONCLUSIONS

The external foot rotation and the contralateral pelvic drop from 2D video-analysis were associated with higher peak KAM during the 180° lateral cut. A qualitative assessment of the 180° lateral cut could offer precious insights on ACL injury risk mitigation.

LEVEL OF EVIDENCE

Descriptive Laboratory Study.

Two-Dimensional and Three-Dimensional Biomechanical Factors During 90° Change of Direction are Associated to Non-Contact ACL injury in Female Soccer Players

Background

The two-dimensional (2D) video-analysis of the change of direction (COD) technique has never been used to attempt to predict the risk of ACL injury in female football players.

Hypothesis/Purpose

The purpose of the present pilot study was to prospectively investigate the biomechanical predictors of ACL injury during a COD task in female football players using both gold standard 3D motion capture and a qualitative scoring system based on 2D video-analysis.

Study Design

Prospective cohort study.

Methods

Sixteen competitive female football (soccer) players (age 21.4 ± 4.3) performed a series of pre-planned 90° COD tasks. 3D motion data was recorded through 10 stereophotogrammetric cameras and a force platform. 2D frontal and transverse plane joint kinematics were computed through video-analysis from three high-speed cameras. A scoring system based on five criteria was adopted: limb stability, pelvis stability, trunk stability, shock absorption, and movement strategy. The players were prospectively followed for the next two consecutive football seasons and the occurrence of severe knee injuries was registered.

Results

Four players (25%) experienced an ACL injury. In 3D analysis, ACL-injured players showed greater knee valgus, knee internal rotation, and lower knee flexion (p= 0.017 - 0.029). Lower hip flexion coupled with greater external rotation (p= 0.003 - 0.042), ankle eversion, and contralateral pelvic drop (p<0.001) were also noted. In 2D analysis, ACL-injured players showed greater internal foot rotation, contralateral pelvic drop, lower knee flexion, and contralateral trunk tilt (moderate-to-large effect size). Pelvis stability and trunk stability showed the highest predictive value towards ACL injury. Total score was significantly lower in ACL-injured players with a moderate effect size (d=0.45).

Conclusions

Both 3D and 2D methodologies depicted biomechanical risk factors and offered predictive insights towards the ACL injury risk. Awareness should rise in women's football regarding the high risk of ACL injury and the strategies to assess and mitigate it.

Level of Evidence

3©The Author(s).

How to improve movement execution in sidestep cutting? Involve me and I will learn

Providing choices, i.e., autonomy, to athletes during practice increases intrinsic motivation and positively influences the motor learning process. The effects of autonomy on the timing of feedback (self-controlled timing of feedback) when optimizing the movement execution of sidestep cutting (SSC), a task that is highly related with ACL injury risk, are unknown. The aim of this study was to investigate the effect of self-controlled timing of video and EF-feedback on movement execution of SSC in team sport athletes. Thirty healthy ball team sport athletes (22.9 ± 1.7 years, 185.5 ± 7.2 cm, 79.3 ± 9.2 kg) were recruited from local sports clubs. Participants were alternately assigned to the self-control (SC) or the yoked (YK) group based on arrival and performed five anticipated and five unanticipated 45° SSC trials as pre-, immediate-post and one-week retention test. Movement execution was measured with the Cutting Movement Assessment Score (CMAS). Training consisted of three randomized 45° SSC conditions: one anticipated and two unanticipated conditions. All participants received expert video instructions and were instructed to 'try to do your best in copying the movement of the expert'. The SC group was allowed to request feedback whenever they wanted during training. The feedback consisted of 1) CMAS score, 2) posterior and sagittal videos of the last trial and 3) an external focus verbal cue on how to improve their execution. The participants were told to lower their score and they knew the lower the score, the better. The YK group received feedback after the same trial on which their matched participant in the SC group had requested feedback. Data of twenty-two participants (50% in SC group) was analyzed. Pre-test and training CMAS scores between groups were equal (p > 0.05). In the anticipated condition, the SC group (1.7 ± 0.9) had better CMAS scores than the YK group (2.4 ± 1.1) at the retention test (p < 0.001). Additionally, in the anticipated condition, the SC group showed improved movement execution during immediate-post (2.0 ± 1.1) compared to pre-test (3.0 ± 1.0), which was maintained during retention (p < 0.001). The YK group also improved in the anticipated condition during immediate-post (1.8 ± 1.1) compared to pre-test (2.6 ± 1.0) (p < 0.001) but showed decreased movement execution during retention compared to immediate-post test (p = 0.001). In conclusion, self-controlled timing of feedback resulted in better learning and greater improvements in movement execution compared to the control group in the anticipated condition. Self-controlled timing of feedback seems beneficial in optimizing movement execution in SSC and is advised to be implemented in ACL injury prevention programs.

No Difference in Two-Dimensional Kinematic Assessment of a 45-Degree Sidestep Cut Compared to Qualitative Assessment

Background and Purpose

The Expanded Cutting Alignment Scoring Tool (E-CAST) is a two-dimensional qualitative scoring system that has demonstrated moderate inter-rater and good intra-rater reliability for the assessment of trunk and lower extremity alignment during a 45-degree sidestep cut. The primary purpose of this study was to examine the reliability of the quantitative version of the E-CAST among physical therapists and to compare the reliability of the quantitative E-CAST to the original qualitative E-CAST. The hypothesis was that the quantitative version of the E-CAST would demonstrate greater inter-rater and intra-rater reliability compared to the qualitative E-CAST.

Study Design

Observational cohort, repeated measures reliability study.

Methods

Twenty-five healthy female athletes (age 13.8±1.4 years) performed three sidestep cuts with two-dimensional video capturing frontal and sagittal views. Two physical therapist raters independently scored a single trial using both views on two separate occasions. Based on the E-CAST criteria, select kinematic measurements were extracted using a motion analysis phone application. Intraclass correlation coefficients and 95% confident intervals were calculated for the total score, and kappa coefficients were calculated per kinematic variable. Correlations were converted to z-scores and compared to the six original criteria for significance (α<0.05).

Results

Cumulative intra- and inter-rater reliability were both good (ICC=0.821, 95% CI 0.687-0.898 and ICC=0.752, 95% CI 0.565-0.859). Cumulative intra-rater kappa coefficients ranged from moderate to almost perfect, and cumulative inter-rater kappa coefficients ranged from slight to good. No significant differences were observed between the quantitative and qualitative criteria for either inter- or intra-rater reliability (Z_obs(intra)= -0.38, p=0.352 and Z_obs(inter)= -0.30, p=0.382).

Conclusion

The quantitative E-CAST is a reliable tool to assess trunk and lower extremity alignment during a 45-degree sidestep cut. No significant differences were observed in reliability of the quantitative versus qualitative assessment.

Level of evidence

3b.

Ecological and Specific Evidence-Based Safe Return To Play After Anterior Cruciate Ligament Reconstruction In Soccer Players: A New International Paradigm

Existing return to play (RTP) assessments have not demonstrated the ability to decrease risk of subsequent anterior cruciate ligament (ACL) injury after reconstruction (ACLR). RTP criteria are standardized and do not simulate the physical and cognitive activity required by the practice of sport. Most RTP criteria do not include an ecological approach. There are scientific algorithms as the "5 factor maximum model" that can identify risk profiles and help reduce the risk of a second anterior cruciate ligament injury. Nevertheless, these algorithms remain too standardized and do not include the situations experienced in games by soccer players. This is why it is important to integrate ecological situations specific to the environment of soccer players in order to evaluate players under conditions closest to their sporting activity, especially with high cognitive load. One should identify high risk players under two conditions: Clinical analyses commonly include assessments such as isokinetic testing, functional tests (hop tests, vertical force-velocity, profile), running, clinical assessments (range of motion and graft laxity), proprioception and balance (Star Excursion Balance Test modified, Y-Balance, stabilometry) and psychological parameters (kinesophobia, quality of life and fear of re-injury). Field testing usually includes game simulation, evaluation under dual-task conditions, fatigue and workload analysis, deceleration, timed-agility-test and horizontal force-velocity profiles. Although it seems important to evaluate strength, psychological variables and aerobic and anaerobic capacities, evaluation of neuromotor control in standard and ecological situations may be helpful for reducing the risk of injury after ACLR. This proposal for RTP testing after ACLR is supported by the scientific literature and attempts to approximate the physical and cognitive loads during a soccer match. Future scientific investigation will be required to demonstrate the validity of this approach.

Level of Evidence

5.

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.

Cutting Movement Assessment Scores during Anticipated and Unanticipated 90-Degree Sidestep Cutting Manoeuvres within Female Professional Footballers

Background: ACL injuries present a considerable burden in female football, with highest incidence being related to change of direction (COD) tasks. The aim was to identify if differences existed between an anticipated and unanticipated 90-degree cutting task using the CMAS. Methods: 11 female professional footballers completed twelve 90-degree COD tasks (6 anticipated, 6 unanticipated). Participants performed the unanticipated task in response to a moving football at the start of their acceleration. All COD tasks were filmed and assessed using the CMAS. Results: The CMAS score for the unanticipated COD task (5.53 ± 0.71) was significantly larger than for the anticipated COD task (3.55 ± 0.85, p < 0.012). Excellent intra-rater reliability was observed (ICC = 0.97) for analysis of CMAS scores. Conclusions: Female footballers in this sample demonstrated a greater CMAS score during an unanticipated COD task compared to an anticipated COD task. These athletes are therefore more likely to display ‘high-risk’ movement patterns, thus greater risk of injury. Reacting to a sporting implement, such as a moving ball, may be a contributing factor to these results. Further research into unanticipated COD tasks should be considered to determine why these differences occur and the impact of anticipation on performance.

Return to sports after ACL injury 5 years from now: 10 things we must do

Background

The outcome after ACL reconstruction (ACLR) is in general disappointing with unacceptable number of athletes that do not return to pre-injury level of sports, high re-injury rates, early development of osteoarthritis and shorter careers. Athletes after ACLR have high expectation to return to sports which is in contrast with the current outcomes. The aim of this manuscript is to present an overview of factors that are needed to be incorporated and to personalize the rehabilitation process for an athlete who has undergone an ACLR.

Level of evidence

4.

Do healthy athletes exhibit at-risk biomechanics for anterior cruciate ligament injury during pivoting movements?

A consistent injury mechanism involving multiple joints has been highlighted in athletes experiencing anterior cruciate ligament (ACL) rupture. However, if and to what extent healthy athletes incur an unsafe biomechanical profile during high-dynamics movements is unknown. The present study aimed to investigate the occurrence of the ACL risk profile in a competitive pivoting sports population.Thirty-four athletes (22.8 ± 4.1 y) performed a frontal deceleration and a change of direction at 90°. Full-body kinematics was collected through 15 wearable inertial sensors (Awinda, Xsens). Nine ACL risk factors were defined based on four categories: limited lower limb flexion, valgus collapse, foot rotation and trunk rotation. A movement trial was considered 'at-risk' in the presence of at least 5 simultaneous risk factors. The rate of athletes with at-risk movements was assessed and multivariate regression for associated outcomes was conducted.The overall rate of injury profile occurrence was 9-12%. The injury profile was identified at least in one trial in 24 athletes (71%) and three trials in 5 athletes (15%). Significant associations were found for higher approaching speed (OR = 4.3) and female sex (OR = 4.8). A large occurrence of the typical ACL injury biomechanical profile was noticed. Large screenings are advisable to identify at-risk athletes and promote preventative strategies.

Comparing lab and field agility kinematics in young talented female football players: implications for ACL injury prevention

Modifiable (biomechanical and neuromuscular) anterior cruciate ligament (ACL) injury risk factors have been identified in laboratory settings. These risk factors were subsequently used in ACL injury prevention measures. Due to the lack of ecological validity, the use of on-field data in the ACL injury risk screening is increasingly advocated. Though, the kinematic differences between laboratory and on-field settings have never been investigated. The aim of the present study was to investigate the lower-limb kinematics of female footballers during agility movements performed both in laboratory and football field environments.Twenty-eight healthy young female talented football (soccer) players (14.9 ± 0.9 years) participated. Lower-limb joint kinematics was collected through wearable inertial sensors (Xsens Link) in three conditions: 1) laboratory setting during unanticipated sidestep cutting at 40-50°; on the football pitch 2) football-specific exercises (F-EX) and 3) football games (F-GAME). A hierarchical two-level random effect model in Statistical Parametric Mapping was used to compare joint kinematics among the conditions. Waveform consistency was investigated through Pearson's correlation coefficient and standardized z-score vector.In-lab kinematics differed from the on-field ones, while the latter were similar in overall shape and peaks. Lower sagittal plane range of motion, greater ankle eversion, and pelvic rotation were found for on-field kinematics (p<0.044). The largest differences were found during landing and weight acceptance.The biomechanical differences between lab and field settings suggest the application of context-related adaptations in female footballers and have implications in ACL injury prevention strategies.Highlights- Talented youth female football players showed kinematical differences between the lab condition and the on-field ones, thus adopting a context-related motor strategy.- Lower sagittal plane range of motion, greater ankle eversion, and pelvic rotation were found on the field. Such differences pertain to the ACL injury mechanism and prevention strategies.- Preventative training should support the adoption of non-linear motor learning to stimulate greater self-organization and adaptability- It is recommended to test football players in an ecological environment to improve subsequent primary ACL injury prevention programs.

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree Side-Step Cut

Background

Current clinical screening tools assessing risky movements during cutting maneuvers do not adequately address sagittal plane foot and ankle evaluations. The Cutting Alignment Scoring Tool (CAST) is reliable in evaluating frontal plane trunk and lower extremity alignment during a 45-degree side-step cut. The Expanded Cutting Alignment Scoring Tool (E-CAST) includes two new sagittal plane variables, knee flexion and ankle plantarflexion angle.

Hypothesis/Purpose

To assess the inter-and intra-rater reliability of the E-CAST to evaluate trunk and lower extremity alignment during a 45-degree side-step cut.

Study Design

Repeated Measures.

Methods

Participants included 25 healthy females (13.8 ± 1.4 years) regularly participating in cutting or pivoting sports. Participants were recorded performing a side-step cut in frontal and sagittal planes. One trial was randomly selected for analysis. Two physical therapists independently scored each video using the E-CAST on two separate occasions, with randomization and a two-week wash-out between rounds. Observed movement variables were awarded a score of "1", with higher scores representing poorer technique. Intraclass correlation coefficients (ICC) and 95% confident intervals (95% CI) were calculated for the total score, and a kappa coefficient (k) was calculated for each variable.

Results

The cumulative intra-rater reliability was good (ICC=0.78, 95% CI 0.59-0.96) and the cumulative inter-rater reliability was moderate (ICC=0.71, 95% CI 0.50-0.91). Intra-rater kappa coefficients ranged from moderate to excellent for all variables (k= 0.50-0.84) and inter-rater kappa coefficients ranged from slight to excellent for all variables (k=0.20-0.90).

Conclusion

The addition of two sagittal plane variables resulted in lower inter-rater ICC compared to the CAST (ICC= 0.81, 95% CI 0.64-0.91). The E-CAST is a reliable tool to evaluate trunk and LE alignment during a 45-degree side-step cut, with good intra-rater and moderate inter-rater reliability.

Level of Evidence

Level 2, Diagnosis.

Reliability of a Qualitative Instrument to Assess High-Risk Mechanisms during a 90° Change of Direction in Female Football Players

Sidestep cuts between 60° and 180° and one-leg landings have been identified as the main mechanisms of ACL injuries in several sports. This study sought to determine intra- and inter-rater reliability of a qualitative tool to assess high-risk movements in a 90° change of direction when the test is applied in a real framework of sport practice. Female footballers from two teams (n = 38) participated in this study and were asked to perform 90° cutting trials to each side, which were simultaneously filmed from a frontal and a sagittal view. A total of 61 cases were selected for 2D qualitative observational analysis by three raters. Poor reliability was found among each pair of raters as well as moderate reliability when the Cutting Movement Assessment Score (CMAS) was given by the same rater at different moments, but with too high a minimum detectable change. On the other hand, raters presented a significant, as well as moderate-to-good intra-rater reliability for most items of the CMAS tool. There was, however, non-significant reliability between observers in rating most check-points of the tool. For these reasons, more objective guidelines and clearer definitions for each criterion within the CMAS, as well as a longer, standardised training period for novel observers, would be highly recommended to improve the reliability of this tool in an applied context with female footballers.

Effects of foot progression angle on kinematics and kinetics of a cutting movement

Purpose

Foot progression angle is a key factor for biomechanical knee load, which is associated with noncontact anterior cruciate ligament (ACL) injury during sports-specific tasks. The purpose of the present study was to assess the biomechanics of trunk, pelvis, and lower extremities during a cutting maneuver under different foot progression angles.

Methods

Nineteen male collegiate athletes (ages 18–24) participated in the present study. Cutting motion was analyzed using eight infrared cameras (250 Hz), two force plates (1250 Hz), and 44 reflective markers. Subjects performed 45-degree side cutting maneuvers under three foot progression angles, including 20 degrees (toe-out: TO), 0 degrees (neutral: TN), and − 20 degrees (toe-in: TI). Peak values of each biomechanical parameters in trunk, pelvis, hip, and knee within a first 40% stance phase and each parameter at the timing of the peak vertical ground reaction force were assessed. A statistical analysis was performed to compare data among the three-foot progression angles using the Friedman test.

Results

Peak angles of knee abduction, tibial internal rotation, hip internal rotation, and hip adduction were significantly greater for TI position than for TO position (p < 0.01). Peak moments of knee abduction and tibial internal rotation under TI position were also significantly larger than TO position (p < 0.01). Moreover, greater peak pelvis-trunk rotation was found for TI position than for TN and TO positions (p < 0.01).

Conclusion

From the present study, TI position could lead to an increased risk of ACL injury during a pre-planned cut maneuver, compared to TO position.

On-Field Tests for Patients After Anterior Cruciate Ligament Reconstruction: A Scoping Review

Background:

After anterior cruciate ligament reconstruction (ACLR), a patient’s physical capacities, such as (repeated) sprint performance, agility performance, and intermittent endurance performance, are often reduced because of detraining effects. Monitoring the progression of these physical capacities is essential for specific training goals before patients return to complex team sports.

Purpose:

To map the existing literature regarding on-field tests for (repeated) sprint performance, agility performance, and intermittent endurance performance in patients after ACLR.

Study Design:

Scoping review; Level of evidence, 4.

Methods:

A search was performed in 4 electronic databases, PubMed, Embase, CINAHL, and PsycInfo, following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for scoping reviews.

Results:

There were 11 studies that met the inclusion criteria and described a total of 14 on-field tests for patients after ACLR. Overall, 2 tests were described for sprint performance, 11 tests were related to agility performance, and 1 test was performed for intermittent endurance performance.

Conclusion:

The results of this scoping review provide an overview of on-field tests to monitor sport-specific progression and to set performance-specific training goals for patients after ACLR before returning to complex team sports.

Current trends in the anterior cruciate ligament part II: evaluation, surgical technique, prevention, and rehabilitation

Clinical evaluation and management of anterior cruciate ligament (ACL) injury is one of the most widely researched topics in orthopedic sports medicine, giving providers ample data on which to base their practices. The ACL is also the most commonly treated knee ligament. This study reports on current topics and research in clinical management of ACL injury, starting with evaluation, operative versus nonoperative management, and considerations in unique populations. Discussion of graft selection and associated procedures follows. Areas of uncertainty, rehabilitation, and prevention are the final topics before a reflection on the current state of ACL research and clinical management of ACL injury. Level of evidence V.

Think outside the box: Incorporating secondary cognitive tasks into return to sport testing after ACL reconstruction

The optimal set of return to sport (RTS) tests after anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) remains elusive. Many athletes fail to pass current RTS test batteries, fail to RTS, or sustain secondary ACL injuries if they do RTS. The purpose of this review is to summarize current literature regarding functional RTS testing after ACLR and to encourage clinicians to have patients "think" (add a secondary cognitive task) outside the "box" (in reference to the box used during the drop vertical jump task) when performing functional RTS tests. We review important criteria for functional tests in RTS testing, including task-specificity and measurability. Firstly, tests should replicate the sport-specific demands the athlete will encounter when they RTS. Many ACL injuries occur when the athlete is performing a dual cognitive-motor task (e.g., attending to an opponent while performing a cutting maneuver). However, most functional RTS tests do not incorporate a secondary cognitive load. Secondly, tests should be measurable, both through the athlete's ability to complete the task safely (through biomechanical analyses) and efficiently (through measures of performance). We highlight and critically examine three examples of functional tests that are commonly used for RTS testing: the drop vertical jump, single-leg hop tests, and cutting tasks. We discuss how biomechanics and performance can be measured during these tasks, including the relationship these variables may have with injury. We then discuss how cognitive demands can be added to these tasks, and how these demands influence both biomechanics and performance. Lastly, we provide clinicians with practical recommendations on how to implement secondary cognitive tasks into functional testing and how to assess athletes' biomechanics and performance.

A 2D video-analysis scoring system of 90° change of direction technique identifies football players with high knee abduction moment

PURPOSE

Abnormal joint biomechanics and poor neuromuscular control are modifiable risk factors for Anterior Cruciate Ligament (ACL) injury. Although 3D motion capture is the gold standard for the biomechanical evaluation of high-speed multidirectional movements, 2D video analysis is a growing-interest alternative because of its higher cost-effectiveness and interpretability. The aim of the present study was to explore the possible association between a 2D evaluation of a 90° change of direction (COD) and the KAM measured with gold standard 3D motion analysis.

METHODS

Thirty-four competitive football (soccer) players (age 22.8 ± 4.1, 18 male and 16 females) were enrolled. Each athlete performed a series of pre-planned 90° COD at the maximum speed possible in a laboratory equipped with artificial turf. 3D motion analysis was recorded using 10 stereophotogrammetric cameras, a force platform, and three high-speed cameras. The 2D evaluation was performed through a scoring system based on the video analysis of frontal and sagittal plane joint kinematics. Five scoring criteria were adopted: limb stability (LS), pelvis stability (PS), trunk stability (TS), shock absorption (SA), and movement strategy (MS). For each criterion, a sub-score of 0/2 (non-adequate), 1/2 (partially adequate), or 2/2 (adequate) was attributed to the movement, based on objective measurements. The intra-rater and inter-rater reliability were calculated for each criterion and the total score. The Knee Abduction Moment (KAM) was extracted from the 3D motion analysis and grouped according to the results of the 2D evaluation.

RESULTS

Excellent intra-rater reliability (ICC > 0.88) and good-to-excellent inter-rater reliability (ICC 0.68-0.92) were found. Significantly higher KAM was found for athletes obtaining a 0/2 score compared to those obtaining a 2/2 score in all the sub-criteria and the total score (20-47% higher, p < 0.05). The total score and the LS score showed the best discriminative power between the three groups.

CONCLUSION

The 2D video-analysis scoring system here described was a simple and effective tool to discriminate athletes with high and low KAM in the assessment of a 90° COD and could be a potential method to identify athletes at high risk of non-contact ACL injury.

LEVEL OF EVIDENCE

IV.

Anterior cruciate ligament injury prevention in sport: biomechanically informed approaches

This paper reviews a series of studies contributing to a framework for preventing anterior cruciate ligament (ACL) injuries in sport. As the majority of these injuries are non-contact in nature, theoretically, these injuries are preventable. The studies presented in this paper focus on understanding biomechanical countermeasures of ACL injury and how this knowledge can inform both screening and training intervention research and practice in sport. These countermeasures include: 1) modifying an athlete's technique to reduce externally applied loads to the knee; 2) increasing the muscle support around the knee and hip to counter elevated loads applied to the knee and; 3) improving an athlete's perception during dynamic sports tasks to increase planning time to coordinate desirable movement patterns. By furthering the empirical evidence of modifiable biomechanical countermeasures of ACL injury risk, we can better understand best practices for developing interventions on a mass scale to prevent ACL injuries in the sporting community.

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.

Training Management of the Elite Adolescent Soccer Player throughout Maturation

Professional soccer clubs invest significantly into the development of their academy prospects with the hopes of producing elite players. Talented youngsters in elite development systems are exposed to high amounts of sports-specific practise with the aims of developing the foundational skills underpinning the capabilities needed to excel in the game. Yet large disparities in maturation status, growth-related issues, and highly-specialised sport practise predisposes these elite youth soccer players to an increased injury risk. However, practitioners may scaffold a performance monitoring and injury surveillance framework over an academy to facilitate data-informed training decisions that may not only mitigate this inherent injury risk, but also enhance athletic performance. Constant communication between members of the multi-disciplinary team enables context to build around an individual's training status and risk profile, and ensures that a progressive, varied, and bespoke training programme is provided at all stages of development to maximise athletic potential.

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.

Deceleration Training in Team Sports: Another Potential 'Vaccine' for Sports-Related Injury?

High-intensity horizontal decelerations occur frequently in team sports and are typically performed to facilitate a reduction in momentum preceding a change of direction manoeuvre or following a sprinting action. The mechanical underpinnings of horizontal deceleration are unique compared to other high-intensity locomotive patterns (e.g., acceleration, maximal sprinting speed), and are characterised by a ground reaction force profile of high impact peaks and loading rates. The high mechanical loading conditions observed when performing rapid horizontal decelerations can lead to tissue damage and neuromuscular fatigue, which may diminish co-ordinative proficiency and an individual’s ability to skilfully dissipate braking loads. Furthermore, repetitive long-term deceleration loading cycles if not managed appropriately may propagate damage accumulation and offer an explanation for chronic aetiological consequences of the ‘mechanical fatigue failure’ phenomenon. Training strategies should look to enhance an athlete’s ability to skilfully dissipate braking loads, develop mechanically robust musculoskeletal structures, and ensure frequent high-intensity horizontal deceleration exposure in order to accustom individuals to the potentially damaging effects of intense decelerations that athletes will frequently perform in competition. Given the apparent importance of horizontal decelerations, in this Current Opinion article we provide considerations for sport science and medicine practitioners around the assessment, training and monitoring of horizontal deceleration. We feel these considerations could lead to new developments in injury-mitigation and physical development strategies in team sports.

Biomechanical Effects of a 6-Week Change-of-Direction Technique Modification Intervention on Anterior Cruciate Ligament Injury Risk

ABSTRACT

Dos'Santos, T, Thomas, C, Comfort, P, and Jones, PA. Biomechanical effects of a 6-week change-of-direction technique modification intervention on anterior cruciate ligament injury risk. J Strength Cond Res 35(8): 2133-2144, 2021-The aim of this study was to evaluate the biomechanical effects of a 6-week change-of-direction (COD) technique modification intervention on anterior cruciate ligament (ACL) injury risk (i.e., multiplanar knee joint loads) during 45° (CUT45) and 90° (CUT90) side-step cutting. A nonrandomized, controlled 6-week intervention study was administrated. Fifteen male multidirectional sport athletes formed the intervention group (IG) who participated in two 30-minute COD technique modification sessions per week, whereas 12 male multidirectional sport athletes formed the control group and continued their normal training. Subjects performed 6 trials of the CUT45 and CUT90 task whereby pre-to-post intervention changes in lower-limb and trunk kinetics and kinematics were evaluated using three-dimensional motion and ground reaction force analysis. Two-way mixed analyses of variance revealed no significant interaction effects of group for CUT45 and CUT90 multiplanar knee joint loads (p ≥ 0.116, η2 ≤ 0.096); however, considerable individual variation was observed (positive (n = 5-8) and negative responders (n = 7-8)). Based on IG group means, COD technique modification resulted in no meaningful reductions in multiplanar knee joint loads. However, individually, considerable variation was observed, with "higher-risk" subjects generally responding positively, and subjects initially considered "low-risk" tending to increase their multiplanar knee joint loads, albeit to magnitudes not considered hazardous or "high-risk." Change-of-direction technique modification training is a simple, effective training method, requiring minimal equipment that can reduce knee joint loads and potential ACL injury risk in "higher-risk" subjects without compromising performance.

The Relationship Between Performance and Asymmetries in Different Multidirectional Sprint Tests in Soccer Players

Practitioners usually include change of direction (COD) and linear speed measurements in the testing batteries of soccer players; however, despite being a commonly occurring action, curve sprint (CS) ability is rarely assessed in soccer. The aims of this study were to analyze the association between linear sprint, CS, and COD speed performances, and compare the association and direction of asymmetries between these skills. Thirty-three male soccer players performed linear sprint (17 m), CS (17 m), and COD-90^⍛ speed tests (COD [8.5 + 8.5 m]). Our main findings were (a) a large relationship between linear and multidirectional tasks (COD-90^⍛ and CS tests) (r = from 0.6 to 0.64, p < 0.05), (b) a moderate relationship between CS and COD-90^⍛ tests (r = from 0.33 to 0.41, p < 0.05), with a certain opposite tendency (higher relationships between opposing directions [Curve_LEFT - COD_RIGHT; r = 0.41] than between equal directions [Curve_LEFT - COD_LEFT; r = 0.33]), and (c) no relationship (p > 0.05) between COD and CS asymmetries, with opposing directional dominance in ~70% of players (e.g., curve left and COD right dominance). These results indicate that performance in linear sprints is strongly related to performance in multidirectional trajectories, whereas CS and COD-90^⍛ seem to be more independent actions. Additionally, the direction of asymmetry or dominance is generally opposite between the non-linear tasks measured.

Maximizing Acceleration and Change of Direction in Sport: A Case Series to Illustrate How the Force-Velocity Profile Provides Additional Information to That Derived from Linear Sprint Time

Sprint running and change of direction (COD) present similar mechanical demands, involving an acceleration phase in which athletes need to produce and apply substantial horizontal external force. Assessing the mechanical properties underpinning individual sprint acceleration might add relevant information about COD performance in addition to that obtained through sprint time alone. The present technical report uses a case series of three athletes with nearly identical 20 m sprint times but with different mechanical properties and COD performances. This makes it possible to illustrate, for the first time, a potential rationale for why the sprint force-velocity (FV) profile (i.e., theoretical maximal force (F₀), velocity (V₀), maximal power output (P_max), ratio of effective horizontal component (RF_peak) and index of force application technique (D_RF)) provides key information about COD performance (i.e., further to that derived from simple sprint time), which can be used to individualize training. This technical report provides practitioners with a justification to assess the FV profile in addition to sprint time when the aim is to enhance sprint acceleration and COD performance; practical interpretations and advice on how training interventions could be individualized based on the athletes' differential sprint mechanical properties are also specified.

Biomechanical Determinants of Performance and Injury Risk During Cutting: A Performance-Injury Conflict?

BACKGROUND

Most cutting biomechanical studies investigate performance and knee joint load determinants independently. This is surprising because cutting is an important action linked to performance and non-contact anterior cruciate ligament (ACL) injuries. The aim of this study was to investigate the relationship between cutting biomechanics and cutting performance (completion time, ground contact time [GCT], exit velocity) and surrogates of non-contact ACL injury risk (knee abduction [KAM] and internal rotation [KIRM] moments) during 90° cutting.

DESIGN

Mixed, cross-sectional study following an associative design. 61 males from multidirectional sports performed six 90° pre-planned cutting trials, whereby lower-limb and trunk kinetics and kinematics were evaluated using three-dimensional (3D) motion and ground reaction force analysis over the penultimate (PFC) and final foot contact (FFC). Pearson's and Spearman's correlations were used to explore the relationships between biomechanical variables and cutting performance and injury risk variables. Stepwise regression analysis was also performed.

RESULTS

Faster cutting performance was associated (p ≤ 0.05) with greater centre of mass (COM) velocities at key instances of the cut (r or ρ = 0.533-0.752), greater peak and mean propulsive forces (r or ρ = 0.449-0.651), shorter FFC GCTs (r or ρ = 0.569-0.581), greater FFC and PFC braking forces (r = 0.430-0.551), smaller hip and knee flexion range of motion (r or ρ = 0.406-0.670), greater knee flexion moments (KFMs) (r = 0.482), and greater internal foot progression angles (r = - 0.411). Stepwise multiple regression analysis revealed that exit velocity, peak resultant propulsive force, PFC mean horizontal braking force, and initial foot progression angle together could explain 64% (r = 0.801, adjusted 61.6%, p = 0.048) of the variation in completion time. Greater peak KAMs were associated with greater COM velocities at key instances of the cut (r or ρ = - 0.491 to - 0.551), greater peak knee abduction angles (KAA) (r = - 0.468), and greater FFC braking forces (r = 0.434-0.497). Incidentally, faster completion times were associated with greater peak KAMs (r = - 0.412) and KIRMs (r = 0.539). Stepwise multiple regression analysis revealed that FFC mean vertical braking force and peak KAA together could explain 43% (r = 0.652, adjusted 40.6%, p < 0.001) of the variation peak KAM.

CONCLUSION

Techniques and mechanics associated with faster cutting (i.e. faster COM velocities, greater FFC braking forces in short GCTs, greater KFMs, smaller hip and knee flexion, and greater internal foot progression angles) are in direct conflict with safer cutting mechanics (i.e. reduced knee joint loading, thus ACL injury risk), and support the "performance-injury conflict" concept during cutting. Practitioners should be conscious of this conflict when instructing cutting techniques to optimise performance while minimising knee joint loading, and should, therefore, ensure that their athletes have the physical capacity (i.e. neuromuscular control, co-contraction, and rapid force production) to tolerate and support the knee joint loading during cutting.

Reliability of the Cutting Alignment Scoring Tool (CAST) to Assess Trunk and Limb Alignment During a 45-Degree Side-Step Cut

BACKGROUND

Three-dimensional (3D) motion analysis is considered the gold standard for evaluating human movement. However, its clinical utility is limited due to cost, operating expertise, and lengthy data processing time. Numerous qualitative scoring systems have been introduced to assess trunk and lower extremity biomechanics during functional tasks. However, the reliability of qualitative scoring systems to evaluate cutting movements is understudied. Purpose/Hypotheses: To assess the inter-rater and intra-rater reliability of the Cutting Alignment Scoring Tool (CAST) among sports medicine providers and to evaluate rater agreement of each component of the CAST. The hypotheses were: 1) there would be good-to-excellent inter-rater and intra-rater reliability among sports medicine providers, 2) there would be good to almost perfect agreement for cut width and trunk lean variables and moderate to good agreement for valgus variables of the CAST.

STUDY DESIGN

Repeated Measures.

METHODS

Ten videos of a 45-degree side-step cut performed by adolescent athletes were independently rated on two occasions by six raters (2 medical doctors, 2 physical therapists, and 2 athletic trainers). The variables assessed include trunk lean to the opposite direction of the cut, increased cut width, knee valgus at initial load acceptance (static), and knee valgus throughout the task (dynamic). Variables were scored as either present, which were given a score of "1", or not present, which were given a score of "0". Video sequence was randomized in each rating session, and a two-week wash out period was given.

RESULTS

The cumulative inter-rater and intra-rater reliabilities were good (ICC: 0.808 and ICC: 0.753). Almost perfect kappa coefficients were recorded for cut width (k=0.949). Moderate kappa coefficients were found for trunk lean (k= 0.632) and fair kappa coefficients were noted for dynamic and static valgus (k=0.462 and k= 0.533 respectively).

CONCLUSION

These findings suggest that the CAST is a reliable tool to evaluate trunk and LE alignment during a cutting task by sports medicine providers.

LEVEL OF EVIDENCE

Level 2 Diagnosis.

Impaired motor control after sport-related concussion could increase risk for musculoskeletal injury: Implications for clinical management and rehabilitation

This review presents a conceptual framework and supporting evidence that links impaired motor control after sport-related concussion (SRC) to increased risk for musculoskeletal injury. Multiple studies have found that athletes who are post-SRC have higher risk for musculoskeletal injury compared to their counterparts. A small body of research suggests that impairments in motor control are associated with musculoskeletal injury risk. Motor control involves the perception and processing of sensory information and subsequent coordination of motor output within the central nervous system to perform a motor task. Motor control is inclusive of motor planning and motor learning. If sensory information is not accurately perceived or there is interference with sensory information processing and cognition, motor function will be altered, and an athlete may become vulnerable to injury during sport participation. Athletes with SRC show neuroanatomic and neurophysiological changes relevant to motor control even after meeting return to sport criteria, including a normal neurological examination, resolution of symptoms, and return to baseline function on traditional concussion testing. In conjunction, altered motor function is demonstrated after SRC in muscle activation and force production, movement patterns, balance/postural stability, and motor task performance, especially performance of a motor task paired with a cognitive task (i.e., dual-task condition). The clinical implications of this conceptual framework include a need to intentionally address motor control impairments after SRC to mitigate musculoskeletal injury risk and to monitor motor control as the athlete progresses through the return to sport continuum.

Which jump-landing task best represents lower extremity and trunk kinematics of unanticipated cutting maneuver?

BACKGROUND

The double-leg jump-landing (DLJL) task is commonly used as a movement screen that can be implemented in large cohorts of athletes. However, it is debatable whether the DLJL is ecologically valid and reflects sporting requirements or injury-prone situations, such as cutting and pivoting.

RESEARCH QUESTION

Which jump-landing movement variation best represents the kinematics of unanticipated side-step cutting?

METHODS

Forty-two participants (25 males and 17 females) performed unanticipated side-step cutting and four jump-landing tasks: DLJL, rotated DLJL (DLJL_rot), single-leg jump-landing (SLJL), and rotated SLJL (SLJL_rot). Ankle, knee, hip, pelvis, and trunk angles and angular velocities, and pelvic linear accelerations were collected at initial contact and during the first 100 milliseconds after initial contact (minimum, maximum, and range values) using a three-dimensional infrared camera system and inertial measurement units. Pre-contact foot-ground angles and subjective task difficulty ratings were also recorded. Intraclass correlation coefficients (ICC) between cutting and jump-landing kinematics were calculated for each participant and jump-landing variation. Friedman tests with pairwise comparisons were then used to compare the degree of association between the four different jump-landing tasks at the specified time events and to compare the difficulty ratings.

RESULTS

Considering the ICC values across the events of interest, the kinematics of the DLJL were the least associated with those of cutting (ICC = 0.00 to 0.81), and DLJL_rot (ICC = 0.34 to 0.81) and SLJL_rot (ICC = 0.31 to 0.80) biomechanics the most. Participants rated the perceived challenge of the single-leg tasks in a similar manner to cutting (p > 0.103), and the SLJL_rot as the most difficult task (median = "neutral", mode = "neutral").

SIGNIFICANCE

Due to their biomechanical associations with cutting maneuver and subjectively-rated difficulty levels, both DLJL_rot and SLJL_rot may be more appropriate and ecologically valid for screening for risk of injury across a range of sports.

A 2D qualitative movement assessment of a deceleration task detects football players with high knee joint loading

PURPOSE

The deceleration (pressing) is a common situational pattern leading to anterior cruciate ligament (ACL) injury in football. Although mainly assessed for performance purposes, a stronger focus on movement quality might support the screening of at-risk athletes. The aim of the present study was to describe a 2D scoring system for the assessment of the deceleration task and to associate it with the knee joint loading (knee abduction moment) evaluated through the gold standard 3D motion capture. The hypothesis was that lower 2D scores would be associated with higher knee joint loading.

METHODS

Thirty-four competitive football (soccer) players (age 22.8 ± 4.1, 16 females) performed a series of deceleration tasks. 3D motion analysis was recorded using ten stereophotogrammetric cameras, a force platform, and three high-speed cameras. The 2D qualitative assessment was performed via a scoring system based on the video analysis of frontal and lateral planes joint kinematics for five scoring criteria. The intra- and inter-rater reliabilities were calculated for each 2D scoring criteria. The peak knee abduction moment was extracted and grouped according to the results of the 2D evaluation.

RESULTS

An ICC > 0.94 was found for all the 2D scoring criteria, both for intra-rater and inter-rater reliability. The players with low 2D frontal plane scores and low total scores (0-4) showed significantly higher peak knee abduction moment values (p < 0.001). A significant negative rank correlation was found between the total score and the peak knee abduction moment (ρ = - 0.25, p < 0.001).

CONCLUSIONS

The qualitative 2D scoring system described successfully discerned between athletes with high and low knee joint loading during a deceleration task. The application of this qualitative movement assessment based on a detailed and accurate scoring system is suitable to identify players and patients with high knee joint loading (high knee abduction moments) and target additional training in the scenario of the primary and secondary ACL injury risk reduction.

LEVEL OF EVIDENCE

Level IV.

Landing Error Scoring System scores change with knowledge of scoring criteria and prior performance

OBJECTIVE

To examine if the knowledge of scoring criteria and prior performance influence Landing Error Scoring System (LESS) outcomes.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Thirty individuals.

MAIN OUTCOME MEASURES

The LESS was tested at Baseline and one week later under two conditions: Pre and Post information. For the Post condition, LESS items were explained to participants, as were their individual Baseline scores. Mean LESS scores and number of individuals categorized at high and low risk were compared between Pre and Post using paired t-tests and McNemar's tests, respectively. McNemar's tests were also used to compare proportions of specific LESS errors between Pre and Post conditions.

RESULTS

Mean LESS Post scores (4.7 ± 1.2 errors) were significantly lower than Pre scores (6.6 ± 2.0 errors, p < 0.001) as was the number of individuals at high risk (25 vs 10 participants, p < 0.001). A significantly lower proportion of participants scored an error for the joint displacement item of LESS Post compared to Pre condition (p < 0.001).

CONCLUSION

When using the LESS, it is important that tested individuals have no knowledge of scoring criteria or previous errors for a valid assessment of innate jump-landing movement patterns and injury risk.

The ‘DEEP’ Landing Error Scoring System

The Landing Error Scoring System (LESS) is an injury-risk screening tool used in sports; but scoring is time consuming, clinician-dependent, and generally inaccessible outside of elite sports. Our aim is to evidence that LESS scores can be automated using deep-learning-based computer vision combined with machine learning and compare the accuracy of LESS predictions using different video cropping and machine learning methods. Two-dimensional videos from 320 double-leg drop-jump landings with known LESS scores were analysed in OpenPose. Videos were cropped to key frames manually (clinician) and automatically (computer vision), and 42 kinematic features were extracted. A series of 10 × 10-fold cross-validation experiments were applied on full and balanced datasets to predict LESS scores. Random forest for regression outperformed linear and dummy regression models, yielding the lowest mean absolute error (1.23) and highest correlation (r = 0.63) between manual and automated scores. Sensitivity (0.82) and specificity (0.77) were reasonable for risk categorization (high-risk LESS ≥ 5 errors). Experiments using either a balanced (versus unbalanced) dataset or manual (versus automated) cropping method did not improve predictions. Further research on the automation would enhance the strength of the agreement between clinical and automated scores beyond its current levels, enabling quasi real-time scoring.

The Effects of Six-Weeks Change of Direction Speed and Technique Modification Training on Cutting Performance and Movement Quality in Male Youth Soccer Players

Cutting manoeuvres are important actions associated with soccer performance and a key action associated with non-contact anterior cruciate ligament injury; thus, training interventions that can improve cutting performance and movement quality are of great interest. The aim of this study, therefore, was to determine the effects of a six-week change of dire[ction (COD) speed and technique modification training intervention on cutting performance and movement quality in male youth soccer players (U17s, n = 8) in comparison to a control group (CG) (U18s, n = 11) who continued ‘normal’ training. Cutting performance was assessed based on completion time and COD deficit, and the field-based cutting movement assessment score (CMAS) qualitative screening tool was used to assess cutting movement quality. Significant main effects for time (pre-to-post changes) (p ≤ 0.041, η² = 0.224–0.839) and significant interaction effects of time and group were observed for cutting completion times, COD deficits, and CMASs. Improvements in completion time (p < 0.001, g = 1.63–1.90, −9% to −11% vs. −5% to 6%) and COD deficit (p ≤ 0.012, g = −1.63 to −2.43, −40–52% vs. −22% to −28%) for the COD intervention group (IG) were approximately two-times greater than the CG. Furthermore, lower CMASs (i.e., improved cutting movement quality) were only observed in the IG (p ≤ 0.025, g = −0.85 to −1.46, −23% to −34% vs. 6–19%) compared to the CG. The positive changes in CMASs were attributed to improved cutting technique and reduced incidences of high-risk deficits such as lateral trunk flexion, extended knee postures, knee valgus, hip internal rotation, and improved braking strategies. The results of this study indicate that COD speed and technique modification training, in addition to normal skills and strength training, improves cutting performance and movement quality in male youth soccer players. Practitioners working with male youth soccer players should implement COD speed and technique modification training to improve cutting performance and movement quality, which may decrease potential injury-risk.