Specific exercise effects of preventive neuromuscular training intervention on anterior cruciate ligament injury risk reduction in young females: meta-analysis and subgroup analysis

Injury prevention programmes (IPPs) for preventing anterior cruciate ligament injuries

OBJECTIVES

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To determine the benefits and harms of injury prevention programmes on anterior cruciate ligament injuries.

Lower Extremity Strength Relative to Body Mass in Pediatric Female Athletes: Implications for Anterior Cruciate Ligament Injury

This study compared lower extremity (LE) muscular strength by 3 groups of female athletes using chronological age and consideration of age of peak height velocity (PHV). Isometric quadriceps, hamstrings, and hip abductors strength were assessed from physically active, pediatric females. The body mass normalized isometric strength (N m/kg) was compared by the 3 age groups. There were 388 young female athletes (<10 years [14.2%], 11-14 years [48.7%], and 15-18 years [37.1%]). The body mass normalized LE strength was lower in 11-14 years compared with <10 years (quadriceps [P = .001], hamstrings [P = .001], and hip abductors [P = .037]) as well as in 15-18 years relative to <10 years in quadriceps (P = .001) and hamstrings (P = .001). The analysis results were consistent with both chronological age alone and incorporating effects of age of PHV. In short, body mass normalized LE strength (quadriceps, hamstrings, and hip abductors) of 11-14 years females was lower than <10 years females.

The effect of surface on knee landing mechanics and muscle activity during a single-leg landing task in recreationally active females

OBJECTIVE

Investigate the effect of surface on frontal plane knee angle, knee moment and muscle activity.

DESIGN

Randomised cross over.

SETTING

University Laboratory.

METHODS

Twenty females performed single-leg hop-landings onto sand, grass and firm surfaces. Kinematic, kinetic and muscle activity data were obtained. Compatibility curves were used to visualise parameter estimates alongside P- values, and S-value transforms.

RESULTS

Knee angle for firm-sand (mean difference (d)‾ = -2.2°; 95% compatibility interval (CI): -4.6 to 0.28, p = 0.083, s = 3.6) and firm-grass (d‾ = -1.9; 95% CI: -4.3 to 0.5, p = 0.125, S = 3) yielded <4 bits of reputational information against the null hypothesis (H). 5 bits (p = 0.025) of information against H were observed for knee moment between firm-sand (d‾ = 0.17 N m/kg-1. m-1; 95% CI: 0.02 to 0.31) with similar effects for firm-grass (d‾ = 0.14 N m/kg-1. m-1; 95% CI: -0.02 to 0.29, p = 0.055, S = 4). Muscle activity across surfaces ranged from almost no (S = 1) reputational evidence against H (Quadriceps and Hamstrings) to 10-13 'bits' against H for lateral gastrocnemius (lower on sand).

CONCLUSIONS

Our study provides valuable information for practitioners of the observed effect sizes for lower-limb landing mechanics across surfaces in asymptomatic females.

Effects of neuromuscular training on dynamic balance ability in athletes: A systematic review and meta-analysis

Objectives

This study aimed to quantitatively analyze the effects of neuromuscular training (NMT) on dynamic balance in healthy athletes through a systematic review and meta-analysis of randomized controlled trials.

Methods

Searches on six databases for randomized controlled trials examining the impact of NMT on athletes' balance ability. The search period extended from the inception of the database to March 16, 2024, languages are limited to Chinese and English. Review Manager 5.1 was used for literature quality assessment and data analysis. Stata 15.0 software was used for assessing publication bias, employing the clipping method, and conducting sensitivity analysis. The Grading of recommendations assessment development and evaluation (GRADE) was used to assess the certainty of evidence. Effect size (ES) was used to evaluate the impact effect of the results.

Results

(1) Meta-analysis: A total of 7 papers met the inclusion criteria, and the meta-analysis indicated that NMT had a positive impact on the dynamic balance ability of the right (SMD = 0.74) and left (SMD = 0.70) lower limb of athletes, and a statistically significant difference was observed (p < 0.01). Subgroup analysis revealed that NMT did not have a positive effect (p > 0.05) on the right anterior (SMD = 0.35); However, it had a positive effect (p < 0.05) on the right posteromedial (SMD = 1.22), right posterolateral (SMD = 0.82), right composite score (SMD = 0.79), left anterior (SMD = 0.38), left posteromedial (SMD = 1.19), left posterolateral (SMD = 0.57) and left composite score (SMD = 0.86). (2) Reporting bias: Funnel plot indicated evidence of publication bias, but there was no significant asymmetry in the funnel plot after trimming and filling. The results were not reversed, indicating the robustness of the combined results. (3) Sensitivity analysis: The results of the sensitivity analysis suggest that the data in this meta-analysis are relatively stable and credible. (4) Grading the evidence: Based on GRADE scale the certainty of evidence from the included studies was determined to be moderate.

Conclusion

Neuromuscular training can enhance the dynamic balance ability of athletes on both the left and right sides. Therefore, neuromuscular training is an effective method for enhancing the unilateral dynamic balance ability of athletes.

Is an Exercise-Based Injury-Prevention Program Effective in Team Handball Players? A Systematic Review and Meta-Analysis

OBJECTIVE

To assess the effectiveness of exercise-based injury-prevention programs in preventing sports injuries in team handball players.

DATA SOURCES

Scopus, PubMed, Web of Science, SPORTDiscus, and CINAHL from inception until April 2023.

STUDY SELECTION

Studies were included if they were randomized controlled trials or prospective cohort studies, contained a population of competitive team handball players, included an intervention designed specifically to prevent or reduce the risk of team handball injuries, and reported injury incidence rates specific to team handball players. Two researchers independently evaluated studies for inclusion and assessed their methodological quality.

DATA EXTRACTION

Study design, intervention details, participant characteristics, and the number of injuries in each group were extracted from each study by 2 independent researchers. The outcome of interest was the incidence rate of injury. Injury data were classified into 5 groups: shoulder injuries, lower extremity injuries, knee injuries, anterior cruciate ligament injuries, and ankle injuries. Extracted data were analyzed using a random-effects model to compute the overall effect estimates of injury-prevention programs in reducing the risk of injuries. Odds ratios (ORs) with 95% CIs were calculated based on the number of injuries in each group.

DATA SYNTHESIS

Meta-analyses were conducted independently for each injury classification. Results indicated that prevention programs reduced the risk of shoulder injuries (OR = 0.60; 95% CI = 0.42, 0.85; P = .004), lower extremity injuries (OR = 0.59; 95% CI = 0.37, 0.95; P = .03), knee injuries (OR = 0.53; 95% CI = 0.35, 0.78; P = .002), anterior cruciate ligament injuries (OR = 0.66; 95% CI = 0.45, 0.96; P = .03), and ankle injuries (OR = 0.57; 95% CI = 0.40, 0.81; P = .002) in team handball players.

CONCLUSIONS

In team handball players, injury-prevention programs appear to effectively reduce the risk of shoulder, lower extremity, knee, ankle, and anterior cruciate ligament injuries.

Factors Associated With Awareness, Adoption, and Implementation of Anterior Cruciate Ligament Injury Prevention in Youth Sports

BACKGROUND

Anterior cruciate ligament (ACL) injuries are among the most common injuries in adolescent athletes and result in significant financial and physical morbidity. Evidence-based programs designed to prevent ACL injury are effective. However, their adoption remains low. We sought to evaluate the awareness, evidence-based implementation, and barriers to implementation of ACL injury prevention programs (ACL-IPP) among youth athletic coaches.

HYPOTHESIS

Higher education level of the coach, higher level of training, number of teams coached, and coaching female teams would be associated with ACL-IPP implementation.

STUDY DESIGN

Cross-sectional survey.

LEVEL OF EVIDENCE

Level 4.

METHODS

We conducted an email survey sent to all 63 school districts within Section VI of the New York State Public High School Athletic Association. We employed descriptive statistics and tests of correlation to identify factors associated with ACL-IPP implementation.

RESULTS

A total of 73% of coaches said they were aware of ACL-IPP, and only 12% of coaches implemented ACL-IPP according to best evidence. Coaches of higher competitive levels were more likely to adopt ACL-IPP (P = 0.01), more likely to use them multiple times per week (P = 0.03), and for ≥1 seasons (P = 0.02). Coaches of multiple teams were more likely to adopt ACL-IPP (P = 0.01). There were no differences in evidence-based implementation of ACL-IPP with gender coached or level of education of the coach.

CONCLUSION

Overall awareness, adoption, and evidence-based implementation of ACL-IPP remain low. These results suggest that coaches at higher levels of play and multiple teams tend to use ACL-IPP more often. Gender coached and level of education do not appear to be associated with awareness or implementation.

CLINICAL RELEVANCE

Evidence-based ACL-IPP implementation remains low. Targeting coaches of younger athletes and fewer teams with local outreach programs and ACL-IPP may increase the implementation of ACL-IPP.

Rehabilitation and Return to Sport After Anterior Cruciate Ligament Reconstruction

Rehabilitation after an anterior cruciate ligament (ACL) reconstruction requires patience, devotion, and discipline. Rehabilitation should be individualized to each patient's specific need and sport. Return to sport is a continuum throughout the rehabilitation, and patients should not return to performance before passing a battery of muscle function tests and patient-reported outcomes, as well as change of direction-specific tests. Return to full participation should be an agreement between the patient, physical therapist, surgeon, and coach. For minimal risk for second ACL injury, patients should continue with maintenance and prevention training even after returning to sport.

Effects of a Preseason Neuromuscular Training Program vs. an Endurance-Dominated Program on Physical Fitness and Injury Prevention in Female Soccer Players

BACKGROUND

The pre-season preparatory period is considered key for optimizing the physical fitness levels needed to withstand congested match periods and preventing injuries during the regular soccer season. This study contrasted the effects s of neuromuscular training (NMT) versus an endurance-dominated training (ET) program conducted during the preseason on measures of physical fitness and injury occurrence in female soccer players.

METHODS

Twenty-four female soccer players aged 17.0 ± 1.3 years from a professional soccer club participated in this study. Players were randomly assigned to NMT (n = 12) or ET (n = 12) groups according to their playing position. The preseason intervention program lasted six weeks, with three weekly sessions with a duration of 45-60 min per session. Exercises in the NMT group included muscle strengthening exercises, plyometrics, agility and dynamic stability exercises, while the ET group practiced a traditional pre-season training program consisting of running and sprinting exercises, fartlek, and high-intensity interval training. The training volumes were similar in the two study groups. Anthropometric measurements, physical fitness tests (i.e., linear and change-of-direction speed, muscle strength and power tests) and the overall injury rate per 1000 h of exposure (training, match) were recorded throughout the season.

RESULTS

No between group differences were found at pre (T1). Significant group-by-time interactions were observed for the 5, 10, and 30-m linear sprint speed tests (p < 0.001, 2.16 < d < 2.58), the T-test (p = 0.024, d = 1.03), the squat (p < 0.001, d = 4.04), and the countermovement jump test (p < 0.001, d = 2.21), the Loughborough soccer passing test (LSPT) (p = 0.019, d = 1.08), and the 1-RM back squat test (p < 0.001, d = 2.53). Post-hoc tests indicated that NMT provided larger improvements for SJ, CMJ, 1-RM back squat, the 5-m sprint, 10-m sprint, 30-m sprint, T-test and LSPT compared to ET (1.07 > d > 2.77). The injury rate across the season was significantly lower in the NMT (5.1/1000 h exposure) compared to ET (11.8/1000 h exposure) (p = 0.014).

CONCLUSIONS

The findings support that six-weeks of preseason NMT versus ET induced larger performance improvements, and significantly reduced injury occurrence in elite female soccer players.

Asymmetry in kinematics of dominant/nondominant lower limbs in central and lateral positioned college and sub-elite soccer players

Change of direction, stops, and pivots are among the most common non-contact movements associated with anterior cruciate ligament (ACL) injuries in soccer. By observing these dynamic movements, clinicians recognize abnormal kinematic patterns that contribute to ACL tears such as increased knee valgus or reduced knee flexion. Different motions and physical demands are observed across playing positions, which may result in varied lower limb kinematic patterns. In the present study, 28 college and sub-elite soccer players performed four dynamic motions (change of direction with and without ball, header, and instep kick) with the goal of examining the effect of on-field positioning, leg dominance, and gender in lower body kinematics. Motion capture software monitored joint angles in the knee, hip, and ankle. A three-way ANOVA showed significant differences in each category. Remarkably, centrally positioned players displayed significantly greater knee adduction (5° difference, p = 0.013), hip flexion (9° difference, p = 0.034), hip adduction (7° difference, p = 0.016), and dorsiflexion (12° difference, p = 0.022) when performing the instep kick in comparison to their laterally positioned counterparts. These findings suggest that central players tend to exhibit a greater range of motion when performing an instep kicking task compared to laterally positioned players. At a competitive level, this discrepancy could potentially lead to differences in lower limb muscle development among on-field positions. Accordingly, it is suggested to implement position-specific prevention programs to address these asymmetries in lower limb kinematics, which can help mitigate dangerous kinematic patterns and consequently reduce the risk of ACL injury in soccer players.

Coach perspectives on factors that influence the implementation of injury prevention programs in community netball: A qualitative study

OBJECTIVE

The Netball KNEE Program is an injury prevention program (IPP) developed by Netball Australia. It is promoted to coaches, but implementation is limited. This study explored community netball coaches' perspectives on factors that influence IPP implementation, and ideas on how it could be improved.

METHODS

Twenty-four coaches from 16 netball clubs participated in semi-structured interviews that asked about their beliefs about injury prevention, use of and confidence in delivering IPP, barriers and facilitators to implementation, and suggestions to ease IPP implementation. Interviews were analysed using inductive thematic analysis.

RESULTS

Two themes were identified - Factors that influence IPP implementation (4 sub-themes), and Suggestions to improve IPP implementation (2 sub-themes). Coaches thought early development of injury prevention habits was important. Life roles, coaching experience and engagement with development courses influenced IPP delivery. Coaches expressed concerns about Netball KNEE program length and complexity and lack of implementation support. They suggested the need for a short simple IPP and engagement with health/exercise professionals for implementation.

CONCLUSIONS

This study engaged with stakeholders to identify barriers that need to be addressed to improve IPP implementation in netball. Coaches desired a short simple standardised IPP, and training from physiotherapists or exercise professionals on implementation.

Variables Associated With Knee Valgus in Male Professional Soccer Players During a Single-Leg Vertical Landing Task

Prior studies have explored the relationship between knee valgus and musculoskeletal variables to formulate injury prevention programs, primarily for females. Nonetheless, there is insufficient evidence pertaining to professional male soccer players. Here, the aim was to test the correlation of lateral trunk inclination, hip adduction, hip internal rotation, ankle dorsiflexion range of motion, and hip isometric strength with knee valgus during the single-leg vertical jump test. Twenty-four professional male soccer players performed a single-leg vertical hop test, hip strength assessments, and an ankle dorsiflexion range of motion test. A motion analysis system was employed for kinematic analysis. Maximal isometric hip strength and ankle dorsiflexion range of motion were tested using a handheld dynamometer and a digital inclinometer, respectively. The correlation of peak knee valgus with peak lateral trunk inclination was .43 during the landing phase (P = .04) and with peak hip internal rotation was -.68 (P < .001). For knee valgus angular displacement, only peak lateral trunk inclination presented a moderate positive correlation (r = .40, P = .05). This study showed that trunk and hip kinematics are associated with knee valgus, which could consequently lead to increased knee overload in male professional soccer players following a unilateral vertical landing test.

The effect of a task-specific training on upper limb performance and kinematics while performing a reaching task in a fatigued state

BACKGROUND

Fatigue impacts motor performance and upper limb kinematics. It is of interest to study whether it is possible to minimize the potentially detrimental effects of fatigue with prevention programs.

OBJECTIVE

To determine the effect of task-specific training on upper limb kinematics and motor performance when reaching in a fatigued state.

METHODS

Thirty healthy participants were recruited (Training group n = 15; Control group n = 15). Both groups took part in two evaluation sessions (Day 1 and Day 5) during which they performed a reaching task (as quickly and accurately as possible) in two conditions (rested and fatigued). During the reaching task, joint kinematics and motor performance (accuracy and speed) were evaluated. The Training group participated in three task-specific training sessions between Day 1 and Day 5; they trained once a day, for three days. The Control group did not perform any training. A three-way non-parametric ANOVA for repeated measures (Nonparametric Analysis of Longitudinal Data; NparLD) was used to assess the impact of the training (Condition [within subject]: rested, fatigued; Day [within subject]: Day 1 vs. Day 5 and Group [between subjects]: Training vs. Control).

RESULTS

After the training period, the Training group significantly improved their reaching speed compared to the Control group (Day x Group p < .01; Time effect: Training group = p < .01, Control group p = .20). No between-group difference was observed with respect to accuracy. The Training group showed a reduction in contralateral trunk rotation and lateral trunk flexion in Day 2 under the fatigue condition (Group x Day p < .04; Time effect: Training group = p < .01, Control group = p < .59).

CONCLUSION

After the 3-day training, participants demonstrated improved speed and reduced reliance on trunk compensations to complete the task under fatigue conditions. Task-specific training could help minimizing some effects of fatigue.

Anterior cruciate ligament injury occurrence, return to sport and subsequent injury in the Australian High Performance Sports System: A 5-year retrospective analysis

OBJECTIVES

To report anterior cruciate ligament (ACL) injury occurrence, return to sport (RTS) timeframes and ACL subsequent injuries recorded in the Australian High Performance Sports System according to athlete sex.

METHODS

ACL injury data of injured athletes were prospectively collected by the treating sports and exercise physicians and physiotherapists within the Australian High Performance Sports System between January 1, 2015 and May 31, 2020. RTS time frames for ACL injuries and the proportion of subsequent ACL injuries were calculated. The RTS time was compared between sexes, age groups and ACL injury categories using the Mann-Whitney U test and the Kruskal-Wallis test.

RESULTS

A total of 132 ACL injuries were reported in 108 athletes (77 female, 31 male). ACL injuries accounted for 6.4% of all reported knee injuries, with almost half (48.5%) of the ACL injuries reported to occur during training. Median RTS time was 369 days (IQR = 273-487), with RTS times reducing with increasing age (X2 (Zbrojkiewicz et al., 2018) = 11.781, p = 0.008). The presence of concurrent knee pathology did not significantly affect the RTS timeframes. ACL injuries were most frequently reported in netball, winter sports, basketball, field hockey and gymnastics. One quarter of the ACL reported (n = 34, 25.8%) were subsequent to a prior ACL injury, with the majority of these injuries occurring to the ipsilateral knee (n = 26) as opposed to contralateral knee (n = 6).

CONCLUSIONS

Despite ACL injuries accounting for a small proportion of all knee injuries reported in the Australian High Performance Sports System, more than a quarter are subsequent to a previous ACL injury. Shorter RTS times were observed in older athletes; however, considerable periods of time-loss occur as a consequence of ACL injuries. Effective primary prevention, rehabilitation processes, and ongoing tertiary prevention strategies are warranted in this population.

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.

Impact of COVID-19 Era on the Anterior Cruciate Ligament Injury Rehabilitation: A Scoping Review

The surgical intervention rate and the subsequent rehabilitation plan for anterior cruciate ligament (ACL) injury was crucially affected by the COVID-19 pandemic due to the necessity in the face of the emergency. This review aimed to evaluate potential persistent and residual symptoms after COVID-19 disease, including fatigue and neuromuscular disorders. A scoping review design and methodology were used due to the exploratory nature of the research question, according to literature searches on PubMed/Medline, Scopus, Web of Science (WoS), and Physiotherapy Evidence Database (PEDro) electronic databases using the following keywords: "Anterior Cruciate Ligament", "ACL", "SARS-CoV-2", and "COVID-19". Undertraining and muscular knee imbalance might cause inefficient movement strategies, lack of knee stability, and increasing load with negative implications in ACL injuries. In the post-surgery period, during COVID-19, telerehabilitation approaches appeared to be successfully applied to maintain strength and range of motion in this condition. However, no definitive data are available regarding the most effective interventions. This scoping review showed the influence of the COVID-19 pandemic and associated restrictions on postoperative and rehabilitative care of ACL injuries.

Correlation between core stability and the landing kinetics of elite aerial skiing athletes

Core stability is critical for improving athletic performance, reducing injury risks and is one of the most important elements of athletic training. However, the effect of core stability on landing kinetics during aerial skiing remains unclear, making relevant analysis and discussion an urgent issue to address. To enhance core stability training and landing performance aerial athletes, this study proposed a correlation analysis to investigate the effect of core stability on landing kinetics. Previous studies on aerial athletes have overlooked landing kinetics and lacked correlation analyses, leading to unsatisfactory analysis outcomes. The correlation analysis can be integrated with core stability training indices to analyze the effect of core stability on vertical and 360° jump landings. Therefore, this study can provide guidance for core stability training and athletic performance in aerial athletes.

The Kinetic Chain Has a Brain: Could Adding Cognitive Demands in Lower Limb Injury Prevention Programs Improve Outcomes?

SYNOPSIS: The most effective lower limb injury prevention programs include strength training, balance exercises, and instructions on how to land safely from a jump or hop. Yet, the programs are not 100% effective-lower extremity noncontact injuries continue to be a significant problem. We suggest that adding cognitive training to motor tasks that currently comprise current lower limb injury prevention programs might help clinicians, athletes, and coaches continue to make inroads into preventing knee injuries. We ground our hypotheses in robust findings from cognitive neuroscience and rehabilitation, suggesting that when task demands exceed the attentional capacity of an individual, the risk for noncontact lower extremity injuries increases. In this editorial, we explain the concepts of attentional capacity and attentional demands, and the interplay of the two in sport, to justify including cognitive tasks to injury prevention programs to improve outcomes. J Orthop Sports Phys Ther 2023;53(4):1-3. doi:10.2519/jospt.2023.11403.

Predictive simulation of single-leg landing scenarios for ACL injury risk factors evaluation

The Anterior Cruciate Ligament (ACL) rupture is a very common knee injury during sport activities. Landing after jump is one of the most prominent human body movements that can lead to such an injury. The landing-related ACL injury risk factors have been in the spotlight of research interest. Over the years, researchers and clinicians acquire knowledge about human movement during daily-life activities by organizing complex in vivo studies that feature high complexity, costs and technical and most importantly physical challenges. In an attempt to overcome these limitations, this paper introduces a computational modeling and simulation pipeline that aims to predict and identify key parameters of interest that are related to ACL injury during single-leg landings. We examined the following conditions: a) landing height, b) hip internal and external rotation, c) lumbar forward and backward leaning, d) lumbar medial and lateral bending, e) muscle forces permutations and f) effort goal weight. Identified on related research studies, we evaluated the following risk factors: vertical Ground Reaction Force (vGRF), knee joint Anterior force (AF), Medial force (MF), Compressive force (CF), Abduction moment (AbdM), Internal rotation moment (IRM), quadricep and hamstring muscle forces and Quadriceps/Hamstrings force ratio (Q/H force ratio). Our study clearly demonstrated that ACL injury is a rather complicated mechanism with many associated risk factors which are evidently correlated. Nevertheless, the results were mostly in agreement with other research studies regarding the ACL risk factors. The presented pipeline showcased promising potential of predictive simulations to evaluate different aspects of complicated phenomena, such as the ACL injury.

Differences in Thigh Muscle Activation Between Standing and Landing Exercises for Knee Injury Prevention and Rehabilitation

Background

In injury prevention or rehabilitation programs, exercises that facilitate enhanced hamstring activity may be beneficial when aiming to enhance knee joint stability during movements in sports with higher risk of acute knee injury. Information about neuromuscular activation of the hamstring muscles in commonly used exercises may improve exercise selection and progression in programs for knee injury prevention or rehabilitation.

Purpose

To investigate (1) how balance devices with progressing degrees of instability influence the activity of muscles controlling the knee joint in typical balance exercises with different demands on postural control, and (2) if any between-sex differences exist.

Study design

Cross-sectional study.

Methods

Twenty habitually active healthy adults (11 males) participated in this cross-sectional study. Single-leg stance, single-leg squat and single-leg landing were performed on the floor and two different balance devices imposing various levels of challenge to postural control. Three-dimensional motion analysis was used to obtain hip and knee joint angles, and as primary outcomes, and peak normalized EMG activity from the hamstrings and quadriceps muscles was measured for comparison between exercises.

Results

The more challenging in terms of maintaining stable balance the devices were, the higher hamstring muscle activity levels were observed. There was a clear progression across balance devices from single-leg stance to single-leg squat and further to single-leg landing displaying increasing hamstring activity levels. The change in medial hamstring activity across all devices when changing from single-leg squat to single-leg landing was significantly higher for the female participants than for the males reaching a higher level of activity.

Conclusion

The muscle activity of the hamstrings and quadriceps increased when the motor task was more dynamic. Specifically, single-leg landings were effective in increasing the hamstring muscle activity over the single-leg stance to single-leg squat exercises, and muscle activity was significantly increased with the most unstable device. Increases in hamstring muscle activation was greater in female subjects than males with increasing instability of the balance devices.

Trial identifier

Not registered.

Level of evidence

3.

Do ACL Injury Risk Reduction Exercises Reflect Common Injury Mechanisms? A Scoping Review of Injury Prevention Programs

CONTEXT

Anterior cruciate ligament (ACL) injury risk reduction programs have become increasingly popular. As ACL injuries continue to reflect high incidence rates, the continued optimization of current risk reduction programs, and the exercises contained within them, is warranted. The exercises must evolve to align with new etiology data, but there is concern that the exercises do not fully reflect the complexity of ACL injury mechanisms. It was outside the scope of this review to address each possible inciting event, rather the effort was directed at the elements more closely associated with the end point of movement during the injury mechanism.

OBJECTIVE

To examine if exercises designed to reduce the risk of ACL injury reflect key injury mechanisms: multiplanar movement, single limb stance, trunk and hip dissociative control, and a flight phase.

DATA SOURCES

A systematic search was performed using PubMed, Medline, EBSCO (CINAHL), SPORTSDiscus, and PEDro databases.

STUDY SELECTION

Eligibility criteria were as follows: (1) randomized controlled trials or prospective cohort studies, (2) male and/or female participants of any age, (3) exercises were targeted interventions to prevent ACL/knee injuries, and (4) individual exercises were listed and adequately detailed and excluded if program was unable to be replicated clinically.

STUDY DESIGN

Scoping review.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

A total of 35 studies were included, and 1019 exercises were extracted for analysis.

RESULTS

The average Consensus on Exercise Reporting Template score was 11 (range, 0-14). The majority of exercises involved bilateral weightbearing (n = 418 of 1019; 41.0%), followed by single limb (n = 345 of 1019; 33.9%) and nonweightbearing (n = 256 of 1019; 25.1%). Only 20% of exercises incorporated more than 1 plane of movement, and the majority of exercises had sagittal plane dominance. Although 50% of exercises incorporated a flight phase, only half of these also involved single-leg weightbearing. Just 16% of exercises incorporated trunk and hip dissociation, and these were rarely combined with other key exercise elements. Only 13% of exercises challenged more than 2 key elements, and only 1% incorporated all 4 elements (multiplanar movements, single limb stance, trunk and hip dissociation, flight phase) simultaneously.

CONCLUSION

Many risk reduction exercises do not reflect the task-specific elements identified within ACL injury mechanisms. Addressing the underrepresentation of key elements (eg, trunk and hip dissociation, multiplanar movements) may optimize risk reduction in future trials.

Epidemiological Comparison of ACL Injuries on Different Playing Surfaces in High School Football and Soccer

Background:

Anterior cruciate ligament (ACL) injuries are among the most common serious injuries to athletes in the United States. Among high school sports, the highest rates of ACL injury occur in soccer and football.

Purpose:

To compare ACL injuries on artificial turf and natural grass using a nationally representative sample of high school athletes participating in football and boys’ and girls’ soccer.

Study Design:

Descriptive epidemiology study.

Methods:

ACL injuries among high school athletes participating in football and soccer were obtained from the High School Reporting Information Online surveillance system during the 2007-08 through 2018-19 school years. National estimates and injury proportion ratios (IPRs) with 95% CIs were calculated for ACL injuries that occurred on artificial turf versus natural grass.

Results:

A total of 1039 ACL injuries were reported, which represented an estimated 389,320 (95% CI, 358,010-420,630) injuries nationally. There were 74,620 estimated football-related ACL injuries on artificial turf and 122,654 on natural grass. Likewise, 71,877 of the estimated soccer-related ACL injuries occurred on artificial turf and 104,028 on natural grass. A contact-injury mechanism accounted for 50.2% of football-related ACL injuries on artificial turf and 60.8% on natural grass. For soccer-related ACL injuries, a noncontact mechanism predominated on artificial turf (61.5%) and natural grass (66.4%). Among all injuries, ACL injuries were more likely to occur on artificial turf than natural grass in both football (IPR, 1.23 [95% CI, 1.03-1.47]) and girls’ soccer (IPR, 1.53 [95% CI, 1.08-2.16]); however, no significant association was found in boys’ soccer (IPR, 1.65 [95% CI, 0.99-2.75]). Among lower extremity injuries, ACL injuries were more likely to occur on artificial turf than natural grass in both boys’ soccer (IPR, 1.72 [95% CI, 1.03-2.85]) and girls’ soccer (IPR, 1.61 [95% CI, 1.14-2.26]); however, the association was not significant in football (IPR, 1.17 [95% CI, 0.98-1.39]).

Conclusion:

ACL injuries were more likely to occur (ie, had larger IPRs) on artificial turf than natural grass; however, this relationship was not statistically significant for all sports.

Sex difference in frontal plane hip moment in response to lateral trunk obliquity during single-leg landing

BACKGROUND

Lateral trunk obliquity during landing is a characteristic of anterior cruciate ligament (ACL) injuries in female athletes and affects their knee and hip kinetics and kinematics. However, it is unclear whether these effects differ between females and males. The purpose of this study was to compare the effects of lateral trunk obliquity on knee and hip kinetics and kinematics in females and males during single-leg landing.

METHODS

Eighteen female (aged 22.1 ± 1.5 years) and 18 male participants (aged 21.8 ± 1.1 years) performed single-leg landings under two conditions: (1) without any instructions about trunk position (natural) and (2) with leaning their trunks laterally 15° from the vertical line (trunk obliquity). The kinetics and kinematics of their hip and knee were analyzed using a three-dimensional motion analysis with a force plate. Two-way repeated-measures ANOVA (sex × trunk obliquity) and Bonferroni pairwise comparisons were conducted.

RESULTS

The trunk obliquity angle at initial contact was significantly greater in the trunk-obliquity landing condition than in the natural landing condition (natural 4.0 ± 2.2°, trunk-obliquity 15.1 ± 3.6°, P < 0.001) with no sex difference (95% CI - 1.2 to 2.2°, P = 0.555). The peak knee abduction moment was significantly larger in the trunk-obliquity landing condition than in the natural landing condition (trunk-obliquity, 0.09 ± 0.07 Nm/kg/m; natural, 0.04 ± 0.06 Nm/kg/m; P < 0.001), though there was no sex or interaction effect. A significant interaction between sex and landing condition was found for the peak hip abduction moment (P = 0.021). Males showed a significantly larger peak hip abduction moment in the trunk-obliquity landing condition than in the natural landing condition (95% CI 0.05 to 0.13 Nm/kg/m, P < 0.001), while females showed no difference in the peak hip abduction moment between the two landing conditions (95% CI - 0.02 to 0.06 Nm/kg/m, P = 0.355).

CONCLUSIONS

The knee abduction moment increased with a laterally inclined trunk for both female and male participants, while the hip abduction moment increased in males but not in females. It may be beneficial for females to focus on frontal plane hip joint control under lateral trunk-obliquity conditions during single-leg landing.

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.

An 8-Week Neuromuscular Training Program After Concussion Reduces 1-Year Subsequent Injury Risk: A Randomized Clinical Trial

BACKGROUND

Existing data suggest that after concussion, athletes experience an increased risk of subsequent injury. Exploring methods that may reduce injury risk after successful postconcussion return to play may lead to new treatment approaches.

PURPOSE

To examine the efficacy of a neuromuscular training (NMT) intervention on acute sports-related time-loss injury over the subsequent year relative to standard of care.

STUDY DESIGN

Randomized clinical trial; Level of evidence, 1.

METHODS

A total of 27 youth athletes were assessed initially postconcussion (median, 7 days postconcussion; interquartile range [IQR], 5-10) and after return-to-play clearance (median, 40 days postconcussion; IQR, 15-52). After return-to-play clearance, they were randomly assigned to NMT intervention (n = 11; mean ± SD age, 14.7 ± 1.7 years; 36% female) or standard of care (n = 16; mean ± SD age, 15.3 ± 1.8 years; 44% female). The intervention (duration, 8 weeks; frequency, 2 times per week) included guided strength exercises with landing stabilization focus. Standard of care received no recommendations. For the subsequent year, athletes prospectively completed a monthly log of sports-related injuries and organized sports competitions.

RESULTS

During the first year after postconcussion return-to-play clearance, sports-related time-loss injuries were more common among standard of care relative to NMT intervention (75% [95% CI, 48%-93%] vs 36% [95% CI, 11%-69%]). After adjusting for age and sex, the hazard of subsequent injury in the standard-of-care group was 3.56 times (95% CI, 1.11-11.49; P = .0334) that of the NMT intervention group. Sports participation was similar between NMT intervention and standard of care during the year-long monitoring period (hours of organized sports per month; median, 12 [IQR, 2.6-32.1] vs 15.6 [IQR, 3.5-105.9]; P = .55). The age- and sex-adjusted incidence of injuries was 10.2 per 1000 competitive exposures (95% CI, 3.7-28.4) in the standard-of-care group as opposed to 3.4 per 1000 (95% CI, 0.9-13.4) in the NMT intervention group. After adjusting for age and sex, incidence of injuries was higher for standard of care vs NMT intervention (rate ratio, 2.96 [95% CI, 0.89-9.85]; P = .076).

CONCLUSION

Although preliminary, our findings suggest that an NMT intervention initiated after return-to-play clearance may significantly reduce sports-related time-loss injuries over the subsequent year.

REGISTRATION

NCT03917290 (ClinicalTrials.gov identifier).

The effects of eccentric hamstring exercise training in young female handball players

Purpose

The multidimensional role of hamstring muscle group strength in athletic performance and injury prevention is well documented, and nordic hamstring exercise (NHE) is a popular method for the development of hamstring strength. Our aim was to examine the EMG characteristics of the eccentric NHE as well as the effects of long-term eccentric NHE training on muscle strength and vertical jump performance in 10- to 11-year-old female handball players.

Methods

Players from the same handball team were randomly assigned to an eccentric NHE training (13 players) or a control group (10 players). Both groups continued their regular handball training routine, but the NHE group performed additional eccentric NHE exercises once or twice a week, with progressively increasing volume, over 20 weeks. To test training effects, countermovement jump (CMJ) height, eccentric hamstring impulse, peak torque, and angle of peak torque were evaluated before, during and after the training period. In the pre-exercise test, EMG activity of the medial and lateral hamstring muscle was also assessed during NHE.

Results

Hamstring activities ranged between 98 and 129%. Lateral hamstring activity was greater than medial only in the right leg during NHE. Eccentric hamstring impulse improved in both legs at 10 weeks in both groups. Then, at 20 weeks, it remained unchanged in the NHE but decreased in controls. A similar adaptation was seen in eccentric hamstring torque, without change in the optimum knee angle. CMJ height improved only in the NHE.

Conclusion

It is concluded that NHE activates the hamstring musculature effectively, and a favourable mechanical adaptation to long-term NHE exercise in girls can be triggered as early as 11 years of age.

Differences in strength and landing biomechanics between female jumpers and swimmers

BACKGROUND: It remains unclear if plyometric training as a single component could improve landing mechanics that are potentially associated with lower risk of ACL injury in the long term OBJECTIVE: The purpose of this study was to investigate the influence of experience undertaking plyometrics on landing biomechanics in female athletes. METHODS: Non-jumpers with little experience in plyometric training (12 female college swimmers) and jumpers with five years of experience in plyometric training (12 female college long jumpers and high jumpers) were recruited to participate in two testing sessions: an isokinetic muscle force test for the dominant leg at 120∘/s and a 40-cm drop landing test. An independent t test was applied to detect any significant effects between cohorts for selected muscle force, kinematic, kinetic, and electromyography variables. RESULTS: While female jumpers exhibited greater quadriceps eccentric strength (P= 0.013) and hamstring concentric strength (P= 0.023) during isokinetic testing than female swimmers, no significant differences were observed in kinematics, kinetics, and muscle activities during both drop landing and drop jumping. CONCLUSIONS: The results suggest that the female jumpers did not present any training-induced modification in landing mechanics regarding reducing injury risks compared with the swimmers. The current study revealed that plyometric training as a single component may not guarantee the development of low-risk landing mechanics for young female athletes.

Injury Prevention, Safe Training Techniques, Rehabilitation, and Return to Sport in Trail Runners

This current concept, narrative review provides the latest integrated evidence of the musculoskeletal injuries involved with trail running and therapeutic strategies to prevent injury and promote safe participation. Running activities that comprise any form of off-road running (trail running, orienteering, short-long distance, different terrain, and climate) are relevant to this review. Literature searches were conducted to 1) identify types and mechanisms of acute and chronic/overuse musculoskeletal injuries in trail runners, 2) injury prevention techniques most relevant to running trails, 3) safe methods of participation and rehabilitation timelines in the sport. The majority of acute and chronic trail running-related musculoskeletal injuries in trail running occur in the lower leg, primarily in the knee and ankle. More than 70% are due to overuse, and ankle sprains are the most common acute injury. Key mechanisms underlying injury and injury progression include inadequate neuromotor control-balance-coordination, running through fatigue, and abnormal kinematics on variable terrain. Complete kinetic chain prehabilitation programs consisting of dynamic flexibility, neuromotor strength and balance, and plyometrics exercise can foster stable, controlled movement on trails. Patient education about early musculoskeletal pain symptoms and training adjustment can help prevent injury from progressing to serious overuse injuries. Real-time adjustments to cadence, step length, and knee flexion on the trail may also mitigate impact-related risk for injury. After injury occurs, rehabilitation will involve similar exercise components, but it will also incorporate rest and active rest based on the type of injury. Multicomponent prehabilitation can help prevent musculoskeletal injuries in trail runners through movement control and fatigue resistance.

The top 100 most impactful articles on the anterior cruciate ligament: An altmetric analysis of online media

Objectives:

To identify the top 100 most impactful anterior cruciate ligament articles in online media as measured by the Altmetric Attention Score and compare their characteristics to the most-cited anterior cruciate ligament articles in the scientific literature.

Methods:

The Altmetric database was queried to identify all published articles pertaining to the anterior cruciate ligament. The search yielded 9445 articles, which were stratified by highest to lowest Altmetric Attention Score. The top 100 articles were included. Collected data included article type, article topic, journal name, and online mentions in news, blogs, Twitter, Facebook, Wikipedia, and other sources. The geographic origin of each article was also determined based on the institutional affiliation of the first author.

Results:

Altmetric Attention Score of the top 100 anterior cruciate ligament articles ranged from 109 to 2193 (median 172.0, interquartile range 137.5–271.5). Of the 100 articles, 65 were published in three journals: American Journal of Sports Medicine, British Journal of Sports Medicine, and Journal of Orthopaedic & Sports Physical Therapy. The most prevalent article type was original research (60%), followed by systematic review/meta-analysis (18%). The most prevalent article topic was rehabilitation and return to play after anterior cruciate ligament reconstruction (22%), followed by epidemiology/risk factors (16%), injury prevention (14%), and biomechanics of anterior cruciate ligament injuries (14%). Of the top 100 articles, 54% were American, 31% were European, and 15% were published in other countries outside of the United States and Europe.

Conclusion:

This study used Altmetric Attention Score to identify the 100 most engaged anterior cruciate ligament articles in online media. The characteristics of these articles differed substantially from the most-cited anterior cruciate ligament articles in the literature with regard to article type, article topic, geographic origin, and publication journal. These findings suggest that alternative metrics measure distinct components of anterior cruciate ligament article engagement and add an important dimension to understanding the overall impact of published research on the anterior cruciate ligament.

The "SHRed Injuries Basketball" Neuromuscular Training Warm-up Program Reduces Ankle and Knee Injury Rates by 36% in Youth Basketball

OBJECTIVE

To evaluate the effectiveness of a neuromuscular training warm-up prevention program, Surveillance in High school and community sport to Reduce (SHRed) Injuries Basketball, for reducing all-complaint ankle and knee injuries in youth basketball players.

DESIGN

Quasi-experimental study.

METHODS

High school/club basketball teams (male and female players aged 11-18 years) in Calgary, Canada participated in 2016-2017 (control; season 1) and 2017-2018 (intervention; season 2). The control season included a standard-of-practice warm-up. In season 2, a SHRed Injuries Basketball coach workshop was completed by participating team coaches. Teams were randomized by school/club to an unsupervised or a supervised (weekly supervision by study personnel) implementation of the coach-delivered SHRed Injuries Basketball program. The 10-minute SHRed Injuries Basketball program included 13 exercises (ie, aerobic, agility, strength, balance). All-complaint ankle and knee injuries were collected weekly using validated injury surveillance. Multilevel, multivariable Poisson regression analyses (considering important covariates, clustering by team and individual, and offset by exposure hours) estimated incidence rate ratios (IRRs) by intervention group (season 1 versus season 2) and secondarily considered the control versus completion of the SHRed Injuries Basketball program, unsupervised and supervised.

RESULTS

Sixty-three teams (n = 502 players) participated in season 1 and 31 teams (n = 307 players: 143 unsupervised, 164 supervised) participated in season 2. The SHRed Injuries Basketball program was protective against all-complaint knee and ankle injuries (IRR = 0.64; 95% confidence interval [CI]: 0.51, 0.79). Unsupervised (IRR = 0.62; 95% CI: 0.47, 0.83) and supervised (IRR = 0.64; 95% CI: 0.49, 0.85) implementations of the SHRed Injuries Basketball program had similar protective effects.

CONCLUSION

The SHRed Injuries Basketball program was associated with a 36% lower rate of ankle and knee injuries. Neuromuscular training warm-ups are recommended as the minimal standard of practice for injury prevention in youth basketball. J Orthop Sports Phys Ther 2022;52(1):40-48. doi:10.2519/jospt.2022.10959.

ACL injury prevention: Where have we come from and where are we going?

Anterior cruciate ligament (ACL) injuries are one of the most common and severe knee injuries across sports. As such, ACL injury prevention has been a focus of research and sports medicine practice for the past three-plus decades. Examining the current research and identifying both clinical strategies and research gaps, the aim of this review is to empower clinicians and researchers with knowledge of where the ACL injury prevention literature is currently and where it is going in the future. This paper examines the mechanism of ACL injury prevention, screening, implementation, compliance, adherence, coronavirus, and areas of future research. Clinical significance: The time lag between research and practical implementation in general healthcare settings can be as long as 17 years; however, athletes playing sports today are unable to wait that long. With effective programs already established, implementation and adherence to these programs is essential. Strategies such as coaching education, increasing awareness of free programs, identifying barriers, and overcoming implementation obstacles through creative collaboration are just a few ways that could help improve both ACL injury prevention implementation and adherence.

Developmental Training Model for the Sport Specialized Youth Athlete: A Dynamic Strategy for Individualizing Load-Response During Maturation

CONTEXT

Most available data on athletic development training models focus on adult or professional athletes, where increasing workload capacity and performance is a primary goal. Development pathways in youth athletes generally emphasize multisport participation rather than sport specialization to optimize motor skill acquisition and to minimize injury risk. Other models emphasize the need for accumulation of sport- and skill-specific hours to develop elite-level status. Despite recommendations against sport specialization, many youth athletes still specialize and need guidance on training and competition. Medical and sport professionals also recommend progressive, gradual increases in workloads to enhance resilience to the demands of high-level competition. There is no accepted model of risk stratification and return to play for training a specialized youth athlete through periods of injury and maturation. In this review, we present individualized training models for specialized youth athletes that (1) prioritize performance for healthy, resilient youth athletes and (2) are adaptable through vulnerable maturational periods and injury.

EVIDENCE ACQUISITION

Nonsystematic review with critical appraisal of existing literature.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

A number of factors must be considered when developing training programs for young athletes: (1) the effect of sport specialization on athlete development and injury, (2) biological maturation, (3) motor and coordination deficits in specialized youth athletes, and (4) workload progressions and response to load.

CONCLUSION

Load-sensitive athletes with multiple risk factors may need medical evaluation, frequent monitoring, and a program designed to restore local tissue and sport-specific capacity. Load-naive athletes, who are often skeletally immature, will likely benefit from serial monitoring and should train and compete with caution, while load-tolerant athletes may only need occasional monitoring and progress to optimum loads.

STRENGTH OF RECOMMENDATION TAXONOMY (SORT)

B.

Effect of Strength Training on Jump-Landing Biomechanics in Adolescent Females

BACKGROUND

Sex-based differences in neuromuscular characteristics relevant to anterior cruciate ligament (ACL) injury risk may arise as compensation for divergent strength development during puberty. Strength training during this period may prevent the development of these undesirable neuromuscular characteristics.

HYPOTHESIS

Strength-trained middle school girls will have improved jump-landing biomechanics compared with control participants.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Maximum voluntary isometric contraction in hip extension and abduction and knee extension and flexion as well as Landing Error Scoring System (LESS) scores were collected for healthy female middle school students of grades 6 to 8. Strength-training participants (STR: N = 30; height, 1.63 ± 0.07 m; mass, 48.1 ± 7.6 kg; age, 12.5 ± 1.0 y) were matched with control participants (CON: N = 30; height, 1.60 ± 0.09 m; mass, 47.2 ± 8.9 kg; age, 12.6 ± 0.9 y). The training consisted of a 6-month strength-training program administered through a gym class curriculum that targeted the lower extremity. A repeated-measures mixed-model analysis of variance was used for comparisons between groups and across time (α = 0.05). Stepwise linear regression was used to examine the relationship between strength change and LESS score change.

RESULTS

Strength values (N·m/kg) increased across time and to a greater degree in STR for hip extension (baseline 3.98 ± 1.15 vs follow-up 4.77 ± 1.80), hip abduction (4.22 ± 1.09 vs 5.13 ± 2.55), and knee flexion (3.27 ± 0.62 vs 3.64 ± 1.40) compared with CON. LESS grades significantly decreased across time in STR (5.58 ± 1.21 vs 4.86 ± 1.44) and were significantly lower than CON (5.98 ± 1.42) at follow-up (P < 0.001). The change in hip extension and knee extension strength explained 67% of the variance (P < 0.001) in the LESS change score in the STR group.

CONCLUSION

A school-based strength-training program that focused on hip and knee musculature significantly improved jump-landing biomechanics (as determined by LESS) relevant to ACL injury risk. Further investigation using different strength-training approaches in this age group is warranted.

CLINICAL RELEVANCE

Strength training during adolescence holds promise as an injury prevention program. The use of a school-based approach is novel and may represent a robust opportunity for injury prevention programs, as physical education class is often mandatory in this age group.

A Comprehensive Summary of Systematic Reviews on Sports Injury Prevention Strategies

Background

A large volume of systematic reviews and meta-analyses has been published on the effectiveness of sports injury prevention programs.

Purpose

To provide a qualitative summary of published systematic reviews and meta-analyses that have examined the effectiveness of sports injury prevention programs on reducing musculoskeletal injuries.

Study Design

Systematic review; Level of evidence, 4.

Methods

We searched the PubMed, CINAHL, EMBASE, and the Cochrane databases for systematic reviews and meta-analyses that evaluated the effectiveness of sports injury prevention programs. We excluded published abstracts, narrative reviews, articles not published in English, commentaries, studies that described sports injury prevention strategies but did not assess their effectiveness, studies that did not assess musculoskeletal injuries, and studies that did not assess sports-related injuries. The most relevant results were extracted and summarized. Levels of evidence were determined per the Oxford Centre for Evidence-Based Medicine, and methodological quality was assessed using the AMSTAR-2 (A MeaSurement Tool to Assess systematic Reviews, revised version).

Results

A total of 507 articles were retrieved, and 129 were included. Articles pertaining to all injuries were divided into 9 topics: sports and exercise in general (n = 20), soccer (n = 13), ice hockey (n = 1), dance (n = 1), volleyball (n = 1), basketball (n = 1), tackle collision sports (n = 1), climbing (n = 1), and youth athletes (n = 4). Articles on injuries by anatomic site were divided into 11 topics: general knee (n = 8), anterior cruciate ligament (n = 34), ankle (n = 14), hamstring (n = 11), lower extremity (n = 10), foot (n = 6), groin (n = 2), shoulder (n = 1), wrist (n = 2), and elbow (n = 1). Of the 129 studies, 45.7% were ranked as evidence level 1, and 55.0% were evidence level 2. Based on the AMSTAR-2, 58.9% of the reviews reported a priori review methods, 96.1% performed a comprehensive literature search, 47.3% thoroughly described excluded articles, 79.1% assessed risk of bias for individual studies, 48.8% reported a valid method for statistical combination of data (ie, meta-analysis), 45.0% examined the effect of risk of bias on pooled study results, and 19.4% examined the risk for publication bias.

Conclusion

This comprehensive review provides sports medicine providers with a single source of the most up-to-date publications in the literature on sports injury prevention.

Hamstrings Contraction Regulates the Magnitude and Timing of the Peak ACL Loading During the Drop Vertical Jump in Female Athletes

Background

Anterior cruciate ligament (ACL) injury reduction training has focused on lower body strengthening and landing stabilization. In vitro studies have shown that quadriceps forces increase ACL strain, and hamstring forces decrease ACL strain. However, the magnitude of the effect of the quadriceps and hamstrings forces on ACL loading and its timing during in vivo landings remains unclear.

Purpose

To investigate the effect and timing of knee muscle forces on ACL loading during landing.

Study Design

Descriptive laboratory study.

Methods

A total of 13 young female athletes performed drop vertical jump trials, and their movements were recorded with 3-dimensional motion capture. Lower limb joint motion and muscle forces were estimated with OpenSim and applied to a musculoskeletal finite element (FE) model to estimate ACL loading during landings. The FE simulations were performed with 5 different conditions that included/excluded kinematics, ground-reaction force (GRF), and muscle forces.

Results

Simulation of landing kinematics without GRF or muscle forces yielded an estimated median ACL strain and force of 5.1% and 282.6 N. Addition of GRF to kinematic simulations increased ACL strain and force to 6.8% and 418.4 N (P < .05). Addition of quadriceps force to kinematics + GRF simulations nonsignificantly increased ACL strain and force to 7.2% and 478.5 N. Addition of hamstrings force to kinematics + GRF simulations decreased ACL strain and force to 2.6% and 171.4 N (P < .001). Addition of all muscles to kinematics + GRF simulations decreased ACL strain and force to 3.3% and 195.1 N (P < .001). With hamstrings force, ACL loading decreased from initial contact (time of peak: 1-18 milliseconds) while ACL loading without hamstrings force peaked at 47 to 98 milliseconds after initial contact (P = .024-.001). The knee flexion angle increased from 20.9° to 73.1° within 100 milliseconds after initial contact.

Conclusion

Hamstrings activation had greater effect relative to GRF and quadriceps activation on ACL loading, which significantly decreased and regulated the magnitude and timing of ACL loading during in vivo landings.

Clinical Relevance

Clinical training should focus on strategies that influence increased hamstrings activation during landing to reduce ACL loads.

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.

Safety and Effectiveness of a Perturbation-based Neuromuscular Training Program on Dynamic Balance in Adolescent Females: A Randomized Controlled Trial

BACKGROUND

Adolescent females are at much greater risk for ACL injury than their male counterparts when participating in the same sports. Preventative and pre-operative rehabilitation neuromuscular (NM) exercise programs are often recommended to improve knee function and reduce injury rates. The effectiveness of perturbation-based NM training program has been established in an adult population but has yet to be investigated in the at-risk adolescent female population.

PURPOSE

To determine the effectiveness of a perturbation-based NM exercise program in a group of physically active adolescent females.

STUDY DESIGN

Prospective randomized trial.

METHODS

Twenty-four healthy and an exploratory group of 10 ACL-injured females (ages 12-18) were equally randomized into a perturbation-based NM training or control group and evaluated before and after a five-week intervention period. The primary outcome of dynamic balance was measured using the Y-Balance test (YBT); secondary outcome measures included lower limb strength, proprioception, and flexibility.

RESULTS

The perturbation-based NM training intervention was safely completed by all participants but had no significant effect on YBT scoring, lower limb strength, proprioception or flexibility in either the healthy or ACL-injured groups.

CONCLUSIONS

Perturbation-based NM training is safe, but may offer little preventative benefit for healthy or pre-operative rehabilitation benefit for ACL-injured adolescent females. Future research should examine whether the effectiveness of perturbation-based NM training is influenced by the length of the training intervention, training intensity, or when it is combined with other forms of prophylactic or pre-surgical rehabilitation frequently used with at-risk adolescent females who regularly participate in sport.

LEVEL OF EVIDENCE

Level 3.

Effects of Open Skill Visuomotor Choice Reaction Time Training on Unanticipated Jump-Landing Stability and Quality: A Randomized Controlled Trial

Adapting movements rapidly to unanticipated external stimuli is paramount for athletic performance and to prevent injuries. We investigated the effects of a 4-week open-skill choice-reaction training intervention on unanticipated jump-landings. Physically active adults (n = 37; mean age 27, standard deviation 2.7 years, 16 females, 21 males) were randomly allocated to one of two interventions or a control group (CG). Participants in the two intervention groups performed a 4-week visuomotor open skill choice reaction training, one for the upper and one for the lower extremities. Before and after the intervention, two different types of countermovement jumps with landings in split stance position were performed. In the (1) pre-planned condition, we informed the participants regarding the landing position (left or right foot in front position) before the jump. In the (2) unanticipated condition, this information was displayed after take-off (350–600 ms reaction time before landing). Outcomes were landing stability [peak vertical ground reaction force (pGRF) and time to stabilization (TTS)], and landing-related decision-making quality (measured by the number of landing errors). To measure extremity-specific effects, we documented the number of correct hits during the trained drills. A two-factorial (four repeated measures: two conditions, two time factors; three groups) ANCOVA was carried out; conditions = unanticipated versus pre-planned condition, time factors = pre versus post measurement, grouping variable = intervention allocation, co-variates = jumping time and self-report arousal. The training improved performance over the intervention period (upper extremity group: mean of correct choice reaction hits during 5 s drill: +3.0 hits, 95% confidence interval: 2.2–3.9 hits; lower extremity group: +1.6 hits, 0.6–2.6 hits). For pGRF (F = 8.4, p < 0.001) and landing errors (F = 17.1, p < 0.001) repeated measures effect occurred. Significantly more landing errors occurred within the unanticipated condition for all groups and measurement days. The effect in pGRF is mostly impacted by between-condition differences in the CG. No between-group or interaction effect was seen for these outcomes: pGRF (F = 0.4, p = 0.9; F = 2.3, p = 0.1) landing errors (F = 0.5, p = 0.6; F = 2.3, p = 0.1). TTS displayed a repeated measures (F = 4.9, p < 0.001, worse values under the unanticipated condition, improvement over time) and an interaction effect (F = 2.4, p = 0.03). Healthy adults can improve their choice reaction task performance by training. As almost no transfer to unanticipated landing successfulness or movement quality occurred, the effect seems to be task-specific. Lower-extremity reactions to unanticipated stimuli may be improved by more specific training regimens.

Canadian High School Rugby Coaches Readiness for an Injury Prevention Strategy Implementation: Evaluating a Train-the-Coach Workshop

Background: Canadian rugby coach injury prevention beliefs and attitudes have not been studied, yet are key to informing injury prevention strategy implementation. Despite neuromuscular training (NMT) warm-up success in reducing injury, adoption of these programs is variable. Therefore, objectives of this study included (1) describing Canadian youth rugby coach injury prevention beliefs and attitudes and current warm-up practices and (2) evaluating intention to use a rugby-specific NMT warm-up.

Methods: High school rugby coaches completed a questionnaire before and after a rugby-specific NMT warm-up workshop. The pre-workshop questionnaire captured demographics, current warm-up practice, and NMT warm-up knowledge and use. Both questionnaires captured injury prevention beliefs, attitudes and behavioral intention.

Results: Forty-eight coaches participated in the workshops. Pre-workshop, 27% of coaches were aware of NMT warm-ups. Coaches primarily included aerobic and stretching components, while balance components were not common in their warm-ups over the past year. Additionally, 92% of coaches agreed to some extent they would “complete a rugby-specific warm-up program prior to every game and training session this season.” Post-workshop, 86% of coaches agreed to some extent that they would use the program in every rugby session. No differences were observed between pre- and post-workshop intention to implement the warm-up (p = 0.10).

Interpretation: This is the first study to examine current Canadian youth rugby coach warm-up practices and intention to use NMT warm-ups. Canadian rugby coach intention to use a rugby-specific NMT warm-up is high, providing ample opportunity to investigate the efficacy of a NMT warm-up in youth rugby.

Integrating neurocognitive challenges into injury prevention training: A clinical commentary

Despite the efforts of many traditional lower extremity injury prevention programs (IPP), the incidence of anterior cruciate ligament injuries in young athletes continues to rise. Current best practices for IPPs include training lower extremity neuromuscular control and movement quality during cutting, jumping, and pivoting. Emerging evidence indicates neurocognition may contribute to injury incidence and injury risk biomechanics. Therefore, IPP outcomes may improve if clinicians also consider neurocognitive contributions to neuromuscular control and athletic performance. A substantial barrier to neurocognitive challenge integration during injury prevention training in the group setting is the lack of structured neuromuscular and neurocognitive progressions. Therefore, our aim is to provide clinicians with a defined framework and recommendations from clinical experience for how to implement neurocognitive challenges within group IPPs that requires minimal extra time and resources. This clinical commentary proposes a three-phase model adopted from motor learning literature to simultaneously progress neuromuscular and neurocognitive challenges through a structured IPP.

Anterior cruciate ligament injury: towards a gendered environmental approach

BACKGROUND

The anterior cruciate ligament (ACL) injury rate for girls/women has not changed in over 20 years, and they remain 3-6 times more likely to experience injury compared with boys/men. To date, ACL injury prevention and management has been approached from a sex-based biological point of view which has furthered our understanding of injury risk factors, mechanisms, and prevention and rehabilitation programmes. However, the traditional sex-based approach does not take into account the growing recognition of how sex and gender (a social construct) are 'entangled' and influence each other.

OBJECTIVE

This paper discusses the curious absence of gender as an influencer in the dialogue surrounding ACL injuries. We propose adding gender as a pervasive developmental environment as a new theoretical overlay to an established injury model to illustrate how gender can operate as an extrinsic determinant from the presport, training and competition environments through to ACL injury and the treatment environment.

APPROACH

We draw on social epidemiological theories of the embodiment of gender and health to provide plausible examples of how gender may influence ACL injury, and demonstrate the opportunity for new, interdisciplinary research in the field.

CONCLUSION

Over 20 years of research has failed to decrease the ACL injury rate disparity between girls/women and boys/men. Embedding gender in the study of ACL injury will heighten awareness of possible influences outside the traditional biological elements, challenge us to think about the inextricable 'entanglement' of sex and gender, and inform more effective approaches to ACL injury prevention and treatment.

Anterior Cruciate Ligament Loading Increases With Pivot-Shift Mechanism During Asymmetrical Drop Vertical Jump in Female Athletes

Background:

Frontal plane trunk lean with a side-to-side difference in lower extremity kinematics during landing increases unilateral knee abduction moment and consequently anterior cruciate ligament (ACL) injury risk. However, the biomechanical features of landing with higher ACL loading are still unknown. Validated musculoskeletal modeling offers the potential to quantify ACL strain and force during a landing task.

Purpose:

To investigate ACL loading during a landing and assess the association between ACL loading and biomechanical factors of individual landing strategies.

Study Design:

Descriptive laboratory study.

Methods:

Thirteen young female athletes performed drop vertical jump trials, and their movements were recorded with 3-dimensional motion capture. Electromyography-informed optimization was performed to estimate lower limb muscle forces with an OpenSim musculoskeletal model. A whole-body musculoskeletal finite element model was developed. The joint motion and muscle forces obtained from the OpenSim simulations were applied to the musculoskeletal finite element model to estimate ACL loading during participants’ simulated landings with physiologic knee mechanics. Kinematic, muscle force, and ground-reaction force waveforms associated with high ACL strain trials were reconstructed via principal component analysis and logistic regression analysis, which were used to predict trials with high ACL strain.

Results:

The median (interquartile range) values of peak ACL strain and force during the drop vertical jump were 3.3% (–1.9% to 5.1%) and 195.1 N (53.9 to 336.9 N), respectively. Four principal components significantly predicted high ACL strain trials, with 100% sensitivity, 78% specificity, and an area of 0.91 under the receiver operating characteristic curve (P < .001). High ACL strain trials were associated with (1) knee motions that included larger knee abduction, internal tibial rotation, and anterior tibial translation and (2) motion that included greater vertical and lateral ground-reaction forces, lower gluteus medius force, larger lateral pelvic tilt, and increased hip adduction.

Conclusion:

ACL loads were higher with a pivot-shift mechanism during a simulated landing with asymmetry in the frontal plane. Specifically, knee abduction can create compression on the posterior slope of the lateral tibial plateau, which induces anterior tibial translation and internal tibial rotation.

Clinical Relevance:

Athletes are encouraged to perform interventional and preventive training to improve symmetry during landing.

Orthopaedic medical examination for young amateur athletes: a repeated cross-sectional study from 2014 to 2018

OBJECTIVES

Medical examinations for adult elite athletes are performed all over the world, however, no studies in the relevant English literature have reported on orthopaedic medical examinations for young amateur athletes. The purpose of this study was to report the results of orthopaedic medical examinations of the spine and lower extremities in young amateur athletes.

METHODS

This repeated cross-sectional study from 2014 to 2018 included a total of 323 young amateur athletes (age, 12-18 years) who were active in one of the following four sports: boxing, canoeing, weightlifting and track and field. The orthopaedic medical examination consisted of six assessments (physical examinations, the generalised joint laxity, muscle and joint tightness, static alignment and muscle volume of the lower extremities and the medial longitudinal arch of the foot). Questions regarding pain in the spine and lower extremities were also performed.

RESULTS

Among 323 young amateur athletes, 17 (5.3%) had received orthopaedic treatment at the time of the medical examination, with spondylolysis being the most common cause (29.4%, 5/17). Among 306 young athletes who had not received orthopaedic treatment, 61 (19.9%) had at least one positive finding in physical examinations or had pain in the spine or lower extremities. Anterior drawer test of the ankle and Kemp test for the spine accounted for 34% and 28% of positive findings, respectively. Low back pain and knee pain accounted for 58% and 16% of pain, respectively.

CONCLUSIONS

The present study showed that approximately one-fifth of young amateur athletes who had not received orthopaedic treatment had pain in the spine and lower extremities and positive findings in physical examinations that may require orthopaedic treatments. In addition to the early detection of injuries, orthopaedic medical examinations for young amateur athletes provide an opportunity to educate such athletes.

BIOMECHANICAL MEASURES DURING TWO SPORT-SPECIFIC TASKS DIFFERENTIATE BETWEEN SOCCER PLAYERS WHO GO ON TO ANTERIOR CRUCIATE LIGAMENT INJURY AND THOSE WHO DO NOT: A PROSPECTIVE COHORT ANALYSIS

Background

Decelerating and cutting are two common movements during which non-contact anterior cruciate ligament (ACL) injuries occur in soccer players. Retrospective video analysis of ACL injuries has demonstrated that players are often in knee valgus at the time of injury.

Purpose

To determine whether prospectively measured components of valgus collapse during a deceleration and 90 ° cut can differentiate between collegiate women's soccer players who go on to non-contact ACL injury.

Design

Secondary analysis of prospectively collected data.

Methods

51 NCAA women's soccer players completed motion analysis of a deceleration and 90 ° before the competitive season. Players were classified as Injured (noncontact ACL injury during the season) or Uninjured at the end of the season. Differences between groups for peak hip adduction, internal rotation, and knee abduction angles, and knee valgus collapse were analyzed with a MANOVA.

Results

Four non-contact ACL injuries were reported at the end of the season. There was a significant difference between groups for hip adduction angle during the 90 ° cut (p = 0.02) and deceleration (p = 0.03). Players who went on to ACL injury were in more hip adduction.

Conclusions

Hip adduction angle is larger in players who go on to ACL injury than those who do not during two sport-specific tasks. The components of knee injury prevention programs that address proximal control and strength are likely crucial for preventing ACL injuries.

Level of Evidence

2b.

Prospective Frontal Plane Angles Used to Predict ACL Strain and Identify Those at High Risk for Sports-Related ACL Injury

Background:

Knee abduction moment during landing has been associated with anterior cruciate ligament (ACL) injury. However, accurately capturing this measurement is expensive and technically rigorous. Less complex variables that lend themselves to easier clinical integration are desirable.

Purpose:

To corroborate in vitro cadaveric simulation and in vivo knee abduction angles from landing tasks to allow for estimation of ACL strain in live participants during a landing task.

Study Design:

Descriptive laboratory study.

Methods:

A total of 205 female high school athletes previously underwent prospective 3-dimensional motion analysis and subsequent injury tracking. Differences in knee abduction angle between those who went on to develop ACL injury and healthy controls were assessed using Student t tests and receiver operating characteristic analysis. A total of 11 cadaveric specimens underwent mechanical impact simulation while instrumented to record ACL strain and knee abduction angle. Pearson correlation coefficients were calculated between these variables. The resultant linear regression model was used to estimate ACL strain in the 205 high school athletes based on their knee abduction angles.

Results:

Knee abduction angle was greater for athletes who went on to develop injury than for healthy controls (P < .01). Knee abduction angle at initial contact predicted ACL injury status with 78% sensitivity and 83% specificity, with a threshold of 4.6° of knee abduction. ACL strain was significantly correlated with knee abduction angle during cadaveric simulation (P < .01). Subsequent estimates of peak ACL strain in the high school athletes were greater for those who went on to injury (7.7-8.1% ± 1.5%) than for healthy controls (4.1-4.5% ± 3.6%) (P < .01).

Conclusion:

Knee abduction angle exhibited comparable reliability with knee abduction moment for ACL injury risk identification. Cadaveric simulation data can be extrapolated to estimate in vivo ACL strain. Athletes who went on to ACL injury exhibited greater knee abduction and greater ACL strain than did healthy controls during landing.

Clinical Relevance:

These important associations between the in vivo and cadaveric environments allow clinicians to estimate peak ACL strain from observed knee abduction angles. Neuromuscular control of knee abduction angle during dynamic tasks is imperative for knee joint health. The present associations are an important step toward the establishment of a minimal clinically important difference value for ACL strain during landing.