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.

Are Recreational Sports a Relic of the Past OR a Solution for the Future?

ABSTRACT: Children's participation in sport is a critical component to their physical and social development and as such, efforts should be made to provide all children with the opportunity to play. In recent years, there has been an observed shift in the focus of youth sports from that of participation for the health benefits of physical activity and fun to that of winning and competing. As a result, there has been a rise in club sports offerings and a subsequent reduction in recreational sports opportunities. This change presents unique challenges to children's access to sport and may not adequately support their overall physical, social, and emotional development. This commentary will discuss the benefits and barriers to increasing recreational sport opportunities using the Social Ecological Model as a framework. It also will propose solutions that can be implemented at the intrapersonal, interpersonal, organizational, community, and public policy levels to revive recreational sports.

Independent data collectors decrease bias in the measurement of adherence to anterior cruciate ligament injury prevention programs.

OBJECTIVES: Studies on adherence to neuromuscular training (NMT) for anterior cruciate ligament (ACL) injury prevention are frequently biased due to the use of self-reporting by coaches or the athletes themselves. Few NMT studies use data collectors (aside from the athletes or the individuals administering the NMT program) to decrease bias when assessing the adherence of coaches and sports teams. We hypothesized that the use of a data collector who is independent of the team to evaluate adherence to NMT programs would be reliable. METHODS: In a prior a cluster-randomized controlled trial evaluating adherence to NMT training trial, twelve boys' and nine girls' high school athletic teams in a variety of sports were enrolled. Eight data collectors (unaffiliated with the NMT program) were hired specifically to record adherence of the athletes to the NMT exercises at each team's warm-ups 2-3 times a week, prior to practices and games. In addition to the data collectors, a control group of independent observers made visits throughout the season to also record adherence (solely for the purpose of this study, alongside the data collectors and in the same fashion) in order to evaluate the data collectors' performance and determine inter-observer reliability. The inter-observer reliability between data collectors and independent observers was measured using the Kappa statistic. RESULTS: A total of 399 warm-ups for practices or games were observed by data collectors to obtain adherence data. Independent observers also measured adherence at 58 practices or games for inter-observer reliability. Exercise instruction and alignment cues for 29 different exercises were analysed. The Kappa values ranged from 0.63 to 1.0, indicating substantial to perfect agreement. The overall Kappa values of 0.89 and 0.90 for exercise instruction and alignment cues, respectively, indicated almost perfect agreement. CONCLUSION: The use of a data collector who is independent of the team to evaluate adherence to NMT programs (rather than athlete or coach self-reporting), was shown to be a reliable method for measurement of adherence in studies of NMT for injury prevention. Avoiding self-reporting in adherence research to NMT training may decrease bias. LEVEL OF EVIDENCE: I.

A Controlled Trial of the Effects of Neuromuscular Training on Physical Performance in Male and Female High School Athletes.

BACKGROUND: Neuromuscular training (NMT) has demonstrated efficacy as an intervention to decrease the risk of anterior cruciate ligament injuries and improve sports performance. The effect of this training on the mechanisms that contribute to improved physical performance has not been well defined. HYPOTHESIS: Athletes in the NMT group will have better mechanisms of fundamental movements and agility tests that may contribute to improved sports performance. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 2. METHODS: Eight high school teams (111 athletes, 53% male, mean age 16 years) participated, with half performing NMT. Physical performance was measured using the dorsaVi ViPerform system, a US Food and Drug Administration-cleared wireless sensor system. Agility was assessed using a timed 3-cone test. Independent sample t tests were used to compare differences between the intervention and control groups. RESULTS: Matched pre- and postseason data were collected from 74 athletes after excluding athletes with injury and those lost to follow-up. Significant improvements were observed in the NMT group for loading/landing speed ratios during a single-leg hop test (right lower extremity = -0.19 [-0.37, 0.03], P = 0.03 and left lower extremity = -0.27 [-0.50, -0.03], P = 0.03). The control group had lower ground reaction forces compared with the NMT group (P < 0.02), while significant improvements were found in the NMT group for initial peak acceleration (P < 0.02) and cadence (P = 0.01) during a straight-line acceleration/deceleration test. For the 3-cone agility test, the postseason time decreased compared with preseason in the NMT group, whereas the time for the control group increased (-0.37 s vs 0.14 s, P < 0.00). CONCLUSION: The results demonstrate that NMT administered by sports medicine clinicians can significantly improve some physical performance of fundamental movements in high school athletes. CLINICAL RELEVANCE: Coaches should be trained to effectively deliver NMT in order to improve sports performance.

Pediatric and Adolescent Knee Injuries: Risk Factors and Preventive Strategies.

It is estimated that approximately 2.5 million sports-related knee injuries occur in the pediatric population annually in the United States. Thus, identifying appropriate screening tools and injury prevention strategies is imperative. To develop successful injury prevention strategies, risk factor identification is the first step. There are two types of risk factors: non-modifiable (age, gender, injury history, and anatomical alignment) and modifiable risk factors (biomechanical and neuromuscular control, training loads, and body mass index). These risk factors can be addressed by three types of preventive interventions: primary, secondary, and tertiary. To translate study evidence to clinical practices and routine trainings, awareness of injury prevention and health promotion needs to be further strengthened.

Concurrent Validity of Movement Screening Criteria Designed to Identify Injury Risk Factors in Adolescent Female Volleyball Players.

Anterior cruciate ligament (ACL) injuries in female adolescent athletes occur at disproportionately high levels compared to their male counterparts. However, limited prospective data exist on the validity of low-cost screening tools that can proactively identify ACL injury risk, specifically for female athletes. The purpose of this study was to assess the concurrent validity of a three-task injury risk factor assessment by comparing visually derived outcome scores from two-dimensional (2D) video data with dichotomized three-dimensional (3D) biomechanical variables collected using motion capture technology. A total of 41 female club volleyball athletes (14.7 ± 1.4 years) were tested and asked to perform three tasks: double-leg vertical jump (DLVJ), single-leg squat (SLS), and single-leg drop landing (SLDL). One rater was trained on the scoring criteria for the 2D data and independently scored one forward-facing and one side-facing video for each task. Risk factors identified included poor knee position, lateral trunk lean, and excessive trunk flexion/extension. In addition, 3D joint angles were calculated for the trunk and knee in the sagittal and frontal planes and converted to dichotomous variables based on biomechanical thresholds of injury risk. For comparison of 2D and 3D outcomes, percent agreement and Cohen's kappa were calculated for each risk factor individually. Overall, 2D scores were found to exhibit moderate to excellent percent agreement with 3D outcomes for trunk position (69.1-97.1%). Specifically, ipsilateral trunk lean during single-leg tasks exhibited the highest agreement (85.3-88.2%) with moderate reliability (κ = 0.452-0.465). In addition, moderate to substantial reliability was found for trunk flexion during double-leg tasks (κ = 0.521-0.653); however, an evaluation of single-leg tasks resulted in only fair reliability (κ = 0.354). Furthermore, 2D scores were not successful in identifying poor knee position as percent agreement fell below 50% for both the single-leg tasks and averaged 60% agreement across both the phases of the DLVJ. Kappa coefficients further emphasized these trends indicating no to slight concurrent validity (κ = -0.047-0.167) across tasks. Overall, these findings emphasize the potential for valid, low-cost screening tools that can identify high-risk movement patterns. Further study is needed to develop improved assessment guidelines that may be employed through visual assessment in sports environments.

Coach Education Improves Adherence to Anterior Cruciate Ligament Injury Prevention Programs: A Cluster-Randomized Controlled Trial.

OBJECTIVE: To determine the effect of an educational workshop on adherence to neuromuscular training (NMT) among high-school coaches. DESIGN: Cluster-randomized controlled trial. SETTING: High school. PARTICIPANTS: A total of 21 teams in 8 high schools (unit of randomization) were randomized to the intervention or control group. Twelve boys' and 9 girls' teams in a variety of sports were enrolled. INTERVENTION: Coaches in the intervention group participated in a 60-minute education workshop to teach effective implementation of a NMT program and also received print materials. Coaches in the control group received the same print materials. MAIN OUTCOME MEASURES: Eight data collectors were trained to observe each team's practice/game 2 to 3 times a week. They completed a study questionnaire to identify the NMT exercise and whether the coach (1) delivered exercise instructions and (2) provided alignment cues (both yes/no). RESULTS: A total of 399 practices/games were observed over 2 seasons. A greater proportion of coaches in the intervention group provided alignment cues to correct improper technique compared with the control group {difference = 0.04 [95% confidence interval (CI), 0.01-0.07], P = 0.006}. There was a similar proportion of coaches in the intervention and control groups who provided exercise instructions [difference = 0.01 (95% CI, -0.02 to 0.04), P = 0.44]. More coaches in the intervention group completed a full NMT program [OR = 4.62 (1.22, 17.50), P = 0.02]. CONCLUSIONS: Coach education can improve adherence to a NMT program and delivery of alignment cues. Coaches should receive in-person training on NMT and how to deliver alignment cues to their athletes while performing the exercises.

Age Is More Predictive of Safe Movement Patterns Than Are Physical Activity or Sports Specialization: A Prospective Motion Analysis Study of Young Athletes.

BACKGROUND: Movement quality and neuromuscular balance are noted predictors of acute injury. Early sports specialization and extremely high activity levels have been linked to elevated risk of injury. PURPOSE: To investigate for any relationships among quality of physical movement, quantity of physical activity, and degree of sports specialization in a healthy cohort of active children and adolescents. STUDY DESIGN: Cross-sectional study with prospectively collected data. METHODS: Healthy children between the ages of 10 and 18 years were recruited and completed the Hospital for Special Surgery Pediatric Functional Activity Brief Scale to assess quantity of physical activity and the Jayanthi scale to assess degree of sports specialization (high, score of 2 or 3; low, score of 0 or 1). Movement quality was assessed using motion analysis sensors during 5 repetitions of 4 different jumping and squatting motions, with a maximum score of 100 per participant. Independent-samples t tests were used to compare participants with high versus low specialization on physical activity and movement quality. A Spearman correlation was used to determine the relationship between quantity of physical activity and movement quality, and linear regression was used to assess for the effect of participant age on relevant covariables. RESULTS: Final analyses included 147 participants (72% male) with a mean ± SD age of 13.4 ± 2.2 years. Participants who were highly specialized displayed better movement quality than did participants with low sports specialization (27.6 ± 14.0 vs 19.8 ± 10.1; P < .01). Participants who were highly specialized had significantly higher activity levels (24.6 ± 5.9 vs 18.1 ± 6.9; P < .001). Movement quality was moderately correlated with physical activity level (r = 0.335; P < .001). Physical activity; hours of organized sports activity; hours of free, unorganized physical activity; and specialization level were not significant predictors of movement quality when controlling for age. Age alone predicted 24.2% of the variance in the overall movement quality score (R2 = 0.242; B = 3.0; P < .001). CONCLUSION: This study found that sports specialization and physical activity levels were not associated with movement quality when controlling for age, which was the most important variable predicting athletic movement quality. Although all participants displayed movement patterns that were associated with high risk for injury, overall movement quality improved with advancing chronological age. CLINICAL RELEVANCE: All young athletes should ensure that neuromuscular training accompanies sport-specific training to reduce risk of injury.

Feedback cues improve the alignment and technique of children performing ACL injury prevention exercises.

OBJECTIVES: The appropriateness of neuromuscular training exercises across different age groups has not yet been investigated, particularly in younger children. The purpose of this study was to determine which neuromuscular training exercises can be performed with proper neutral alignment in various age groups. METHODS: Seven exercises were selected for evaluation in children ranging from 8 to 17 years of age who were recruited from schools and youth sports organisations. Participants completed two trials of each exercise and were judged on maintaining neutral body alignment after receiving visual/verbal instruction on the first trial and feedback cues on the second trial. Three evaluators judged each exercise, which was deemed as correct when at least two evaluators agreed that neutral alignment was maintained. Comparisons were made across ages and between sex using the χ² test or Fisher's exact test. The proportions of participants who performed the exercise correctly were also compared before and after feedback cues were provided. RESULTS: A total of 360 participants were evaluated (8-11 years: 165, 54% female; 12-15 years: 136, 40% female, 16-17 years: 59, 53% female). There were no significant differences in performance across ages and sex for nearly all exercises. The majority of children were not able to complete the exercises with proper alignment. The use of feedback cues significantly increased the proportion of participants who correctly completed the exercise (p<0.001). CONCLUSIONS: These results demonstrate the importance of training coaches and physical education teachers to provide cues that reinforce proper technique during anterior cruciate ligament injury prevention exercises. Children should perform common neuromuscular training exercises with feedback on proper technique. LEVEL OF EVIDENCE: IV (case series).