The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study

Immediate effects of kinesiology tape on quadriceps muscle peak torque and knee joint repositioning error in healthy males: Effects of different tensions and directions

BACKGROUND

Knee joint injuries may result from compromised quadriceps muscle strength or diminished knee joint proprioception. The application of Kinesio tape (KT) on the quadriceps muscle from origin to insertion (OTI-KT) or insertion to origin (ITO-KT) could impact knee joint proprioception and quadriceps muscle strength. This study aims to assess the effects of different tensions and directions of KT application on active and passive knee joint repositioning errors (AJRE and PJRE) and peak concentric and eccentric peak torque (CPT and EPT) of the quadriceps muscles in healthy males.

METHOD

Twenty-one healthy males participated in this repeated-measures study design. CPT, EPT, AJRE, and PJRE of the dominant limb were measured by a Biodex dynamometer before and after applying OTI-KT with 0%, 15%, and 40% extra tensions and ITO-KT with 0% tension.

RESULTS

ITO-KT demonstrated a significant reduction in AJRE (p < 0.05). Meanwhile, for OTI-KT, a statistically significant difference was observed in both AJRE and PJRE concerning time (F1,126 = 19.74, p < 0.05 for AJRE; F1,126 = 9.96, p < 0.05 for PJRE) and tension (F2,126 = 22.14, p < 0.05 for AJRE; F2,126 = 20.67, p < 0.05 for PJRE).

CONCLUSION

Applying KT, especially OTI KT with 40% and 15% extra tension, shows potential in enhancing knee proprioception without immediate impacts on quadriceps muscle torque. This suggests applications in sports performance and knee injury rehabilitation.

Effect of Strength and Plyometric Training on Kinematics in Female Novice Runners

ABSTRACT

Harrison, K, Williams, DSB III, Darter, BJ, Zernicke, RF, Shall, M, and Finucane, S. Effect of strength and plyometric training on kinematics in female novice runners. J Strength Cond Res 38(6): 1048-1055, 2024-Both running performance and injury have been associated with running kinematics. Plyometric training improves run performance and reduces injury risk in court-sport and field-sport athletes. The aim of this study was to assess longitudinal changes in kinematics in novice runners before and after a typical beginners' running program, compared with those who perform a plyometric intervention before running. Fifty-seven novice female runners were assigned to the control group (8 weeks walking +8 weeks running) or the intervention group (8 weeks strength or plyometric training +8 weeks running). Kinematics were assessed at baseline, 8 weeks, and 16 weeks. Joint angles throughout the stride of those who completed the training ( n = 21) were compared between groups and assessment time points using a statistical parametric mapping 2-way analysis of variance, with group and study time point as independent variables. There was no interaction effect of group and study time point ( p > 0.05), indicating that both training programs had similar effects on running kinematics. There was a main effect of time for sagittal plane knee and hip kinematics ( p < 0.001); after training, subjects ran with a more extended leg, particularly during swing. Programs of 8 weeks of preparatory training, followed by 8 weeks of running, resulted in altered sagittal plane biomechanics, which have previously been related to improved running economy. A greater volume of plyometric, run training or concurrent plyometric and run training may be required to elicit changes in running form associated with lower injury risk.

Relative Energy Deficiency in Sport (RED-S) and Knee Injuries: Current Concepts for Female Athletes

In athletes, a mismatch between caloric intake and energy expended in exercise can result in Low Energy Availability (LEA). LEA can lead to Relative Energy Deficiency in Sport (RED-S), where the athlete suffers from physiological derangements and decreased sport performance. The prevalence of RED-S is higher in females than males. RED-S more comprehensively describes the syndrome originally known as "Female Athlete Triad" (FAT). FAT encompasses the triad of LEA (with or without disordered eating), menstrual dysfunction and low bone mineral density. RED-S includes other physiological derangements such as poor cardiovascular health, abnormalities of metabolic rate, immunity, and protein synthesis. Females are already at a higher risk of knee injuries, which has been attributed to a multitude of factors such as hormonal influences, differences in musculoskeletal anatomy and neuromuscular control compared to males. The literature demonstrates an even higher risk of knee injuries in female athletes with symptoms of RED-S. We propose the various factors that influence this risk. A reduction in anabolic hormones can affect muscle development and tendon repair. A relationship between poor neuromuscular control and knee injury has been established, and this can be further worsened in patients with menstrual dysfunction. Chronic deficiency in nutrients such as collagen and vitamin D can result in poorer recovery from microtrauma in tendon and ligaments. All these factors may contribute to increasing the risk of knee injuries, which may include anterior cruciate ligament tears, patella tendinopathy and patellofemoral pain syndrome. This review aims to educate sports clinicians to have a high index of suspicion when treating knee injuries in females; to screen and then manage for RED-S if present, for holistic patient care.

Effects of various load magnitudes on ACL: an in vitro study using adolescent porcine stifle joints

INTRODUCTION

The escalating incidence of anterior cruciate ligament (ACL) injuries, particularly among adolescents, is a pressing concern. The study of ACL biomechanics in this demographic presents challenges due to the scarcity of cadaveric specimens. This research endeavors to validate the adolescent porcine stifle joint as a fitting model for ACL studies.

METHODS

We conducted experiments on 30 fresh porcine stifle knee joints. (Breed: Yorkshire, Weight: avg 90 lbs, Age Range: 2-4 months). They were stored at - 22 °C and a subsequent 24-h thaw at room temperature before being prepared for the experiment. These joints were randomly assigned to three groups. The first group served as a control and underwent only the load-to-failure test. The remaining two groups were subjected to 100 cycles, with forces of 300N and 520N, respectively. The load values of 300N and 520N correspond to three and five times the body weight (BW) of our juvenile porcine, respectively.

RESULT

The 520N force demonstrated a higher strain than the 300N, indicating a direct correlation between ACL strain and augmented loads. A significant difference in load-to-failure (p = 0.014) was observed between non-cyclically loaded ACLs and those subjected to 100 cycles at 520N. Three of the ten samples in the 520N group failed before completing 100 cycles. The ruptured ACLs from these tests closely resembled adolescent ACL injuries in detachment patterns. ACL stiffness was also measured post-cyclical loading by applying force and pulling the ACL at a rate of 1 mm per sec. Moreover, ACL stiffness measurements decreased from 152.46 N/mm in the control group to 129.42 N/mm after 100 cycles at 300N and a more significant drop to 86.90 N/mm after 100 cycles at 520N. A one-way analysis of variance (ANOVA) and t-test were chosen for statistical analysis.

CONCLUSIONS

The porcine stifle joint is an appropriate model for understanding ACL biomechanics in the skeletally immature demographic. The results emphasize the ligament's susceptibility to injury under high-impact loads pertinent to sports activities. The study advocates for further research into different loading scenarios and the protective role of muscle co-activation in ACL injury prevention.

Comparison of physical therapy utilization, timing of return-to-sport test completion, and hop test performance by age and between sexes in youth athletes after anterior cruciate ligament reconstruction

OBJECTIVE

To compare physical therapy (PT) utilization, timing of return-to-sport (RTS) test and hop test performance by age and between sexes in youth after anterior cruciate ligament reconstruction (ACLR).

DESIGN

Multicenter retrospective cohort.

METHODS

A retrospective review of adolescents after primary ACLR was conducted. Participants completed return-to-sport (RTS) tests including single-legged hop testing. PT frequency, average weekly visits, and timing of RTS test were calculated. T-tests assessed the effect of age and sex on average weekly PT visits and multivariable logistic regressions assessed odds of passing hop tests.

RESULTS

289 participants were included (15.7 ± 1.9 years). There was no difference in average weekly PT visits (p = 0.321) or time to RTS test (p = 0.162) by age. There were significant differences in average weekly PT visits (p = 0.047) and mean time from surgery to RTS test (p = 0.048) between sexes with small effect sizes (d = 0.24 and d = 0.21, respectively). Age and sex had no effect on odds of passing hop tests (OR, 1.29; 95% CI, 0.71-2.35 and OR, 0.79; 95%CI, 0.43-1.45, respectively).

CONCLUSION

In a youth cohort, age and sex may have no clinically important effect on PT visit utilization, timing of RTS test or hop test performance.

Reported Anterior Cruciate Ligament Injury Incidence in Adolescent Athletes Is Greatest in Female Soccer Players and Athletes Participating in Club Sports: A Systematic Review and Meta-analysis

PURPOSE

To identify the risk of anterior cruciate ligament (ACL) injury in adolescent athletes based on sex, sport, and sport affiliation.

METHODS

A literature search was performed using 3 online databases (PubMed, Cochrane Library, and EMBASE) from database inception to November 2023 per the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies consisted of Level I or II studies reporting on ACL injury exposures in time (hours) or injuries per 1,000 athlete-exposures (AEs) (1 game or practice) in adolescent athletes. Exclusion criteria consisted of non-English studies, case reports, animal/cadaveric studies, and review articles. Methodological quality and bias assessment of the included studies was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. ACL injuries were analyzed and pooled to calculate incidence rates (IRs), per-season risk, and relative risk (RR) based on sex, sport, and sport affiliation (club sport participation vs school sport participation).

RESULTS

A total of 1,389 ACL injuries over 19,134,167 AEs were identified (IR, 0.075; 95% confidence interval [CI], 0.071-0.079). Of these, 670 ACL injuries were reported in female athletes over 7,549,892 AEs (IR, 0.089; 95% CI, 0.087-0.091) with 719 in males over 11,584,275 AEs (IR, 0.062; 95% CI, 0.058-0.067). The greatest RR for ACL injury in females was in soccer (RR, 3.12; 95% CI, 2.58-3.77) for AEs. The greatest per-season risk of ACL injuries reported in female athletes occurred in soccer (1.08%), basketball (1.03%), and gymnastics (1.01%). The greatest per-season risk of ACL injuries reported in male athletes occurred in football (0.82%), lacrosse (0.64%), and soccer (0.35%). Club sport participation, in both AEs (RR, 3.94; 95% CI, 3.19-4.87) and hours of exposure (RR, 1.57; 95% CI, 1.07-2.28), demonstrated an increased risk of ACL injury.

CONCLUSIONS

The risk of ACL injuries was 1.56-fold greater in adolescent female athletes compared with male athletes. The highest-risk sport for females was soccer. Participation in club sports possessed higher rates of injury compared with school sports.

LEVEL OF EVIDENCE

Level II; meta-analysis of Level I and II studies.

The 11+ injury prevention programme decreases rate of hamstring strain injuries in male collegiate soccer players

OBJECTIVES

To investigate if the 11+ injury prevention programme decreases the risk of hamstring injury and improves recovery time and determine whether compliance with the 11+ affects hamstring injury risk.

METHODS

This study is a secondary analysis from a prospective cluster randomised controlled trial that included 65 National Collegiate Athletic Association (NCAA) division I and II men's soccer teams over the fall 2012 season. Thirty-one teams were randomised to the intervention group that were using the 11+ as their warm-up and 35 teams to the control group that continued to use their traditional warm-up. Each certified athletic trainer (ATC) collected data on demographics, hamstring injury (HSI), mechanism of injury, position, playing surface, time lost due to injury and compliance to the 11+ programme.

RESULTS

The 11+ decreased the risk of HSI by 63% compared with the control group (RR=0.37, 95% CI 0.21 to 0.63). Difference in return to play after HSI between the control (9.4±11.2 days) and intervention groups (10.2±11.3 days) was not significant (p=0.8). High compliance (>2 or more doses on average per week) reduced the risk of HSI by 78% (RR=0.22, 95% CI 0.06 to 0.87) compared with low compliance (<1 dose on average per week), and moderate compliance (1 to <2 doses on average per week) decreased the risk of HSI by 67% (RR=0.33, 95% CI 0.11 to 0.97) compared with low compliance. There was no significant difference between high and moderate compliance.

CONCLUSION

The 11+ decreased the risk of HSI by 63% but did not improve recovery time. High to moderate compliance is essential and makes the programme more effective at reducing HSI.

Female Lower Body Muscle Forces: A Musculoskeletal Modeling Comparison of Back Squats, Split Squats and Good Mornings

The aim of this study was to analyze lower leg muscle forces during strength exercises such as back squats, good mornings and split squats, with a particular emphasis on females. By focusing on females, who are more vulnerable to anterior cruciate ligament injuries, we aimed to better understand muscle engagement and its role in injury prevention. Eight participants were monitored during exercises with a barbell load of 25% of body weight and, during the back squat, an additional 50% load. The analysis was conducted using personalized musculoskeletal models, electromyography (EMG) and Vicon motion capture systems to assess various muscle groups, including the m. gluteus maximus and m. gluteus medius, as well as the hamstring and quadriceps muscles. The back squat produced the highest forces for the quadriceps muscles, particularly the rectus femoris (>25 N/kg), as well as in the back leg during the split squat (>15 N/kg). The gluteal muscles were most active during good mornings and in the front leg of the split squat, especially the m. gluteus maximus medial part (>20 N/kg). The hamstrings generated the highest muscle forces in the front leg of the split squat, with the greatest forces observed in the m. semimembranosus. Our research highlights how musculoskeletal modeling helps us to understand the relationship among muscles, joint angles and anterior cruciate ligament injury risks, especially in strength training females. The results emphasize the need for personalized exercise guidance and customized models to make strength training safer and more effective.

Effects of a neuromuscular training program on the performance and inter-limb asymmetries in highly trained junior male tennis players

Background

The objective of this study was to assess the effectiveness of neuromuscular training on the performance of highly trainer junior tennis players.

Methods

Twelve male tennis players (age: 13.4 ± 0.36 years; weight: 50.2 ± 6.29 kg; height: 163 ± 4.41 cm) participated and were randomly divided into two groups. The experimental group (EG) performed neuromuscular training that included exercises for speed, strength, throws, agility, jumps and coordination twice a week for a duration of 10 weeks. Performance was evaluated using various variables, including bilateral and unilateral countermovement jump, 30 cm drop jump and horizontal jump, 505 change of direction test conducted with both the right and left legs, 20-m sprint, and overhead 3 kg medicine ball throw. Asymmetries were also evaluated during the unilateral tests. The impact of the training was assessed through the utilization of ANCOVA tests and effect size measurements.

Results

The results indicated a significant enhancement in the EG, specifically in bilateral vertical jump and horizontal jump, as well as explosive strength and speed. Conversely, the control group (CG) did not display similar advancements. Furthermore, there was no increase in asymmetries.

Conclusion

This suggests that the implementation of a neuromuscular training program could prove to be an effective approach in enhancing explosive power in the lower limbs among young competitive tennis players. Finally, this training program could contribute to the enhancement of their physical attributes in lower body of young tennis players.

The inter-laboratory equivalence for lower limb kinematics and kinetics during unplanned sidestepping

Much inter-intra-tester kinematic and kinetic repeatability research exists, with a paucity investigating inter-laboratory equivalence. The objective of this research was to evaluate the inter-laboratory equivalence between time varying unplanned kinematics and moments of unplanned sidestepping (UnSS). Eight elite female athletes completed an established UnSS procedure motion capture laboratories in the UK and Australia. Three dimensional time varying unplanned sidestepping joint kinematics and moments were compared. Discrete variables were change of direction angles and velocity. Waveform data were compared using mean differences, 1D 95%CI and RMSE. Discrete variables were compared using 0D 95% CI. The mean differences and 95%CI for UnSS kinematics broadly supported equivalence between laboratories (RMSE≤5.1°). Excluding hip flexion/extension moments (RMSE = 1.04 Nm/kg), equivalence was also supported for time varying joint moments between laboratories (RMSE≤0.40 Nm/kg). Dependent variables typically used to characterise UnSS were also equivalent. When consistent experimental and modelling procedures are employed, consistent time varying UnSS lower limb joint kinematic and moment estimates between laboratories can be obtained. We therefore interpret these results as a support of equivalence, yet highlight the challenges of establishing between-laboratory experiments or data sharing, as well as establishing appropriate ranges of acceptable uncertainty. These findings are important for data sharing and multi-centre trials.

Influence of Torsional Stiffness in Badminton Footwear on Lower Limb Biomechanics

Torsional stiffness of athletic footwear plays a crucial role in preventing injury and improving sports performance. Yet, there is a lack of research focused on the biomechanical effect of torsional stiffness in badminton shoes. This study aimed to comprehensively investigate the influence of three different levels of torsional stiffness in badminton shoes on biomechanical characteristics, sports performance, and injury risk in badminton players. Fifteen male players, aged 22.8 ± 1.96 years, participated in the study, performing badminton-specific tasks, including forehand clear stroke [left foot (FCL) and right foot (FCR)], 45-degree sidestep cutting (45C), and consecutive vertical jumps (CVJ). The tasks were conducted wearing badminton shoes of torsional stiffness measured with Shore D hardness 50, 60, and 70 (referred to as 50D, 60D, and 70D, respectively). The primary biomechanical parameters included ankle, knee, and MTP joint kinematics, ankle and knee joint moments, peak ground reaction forces, joint range of motion (ROM), and stance time. A one-way repeated measures ANOVA was employed for normally distributed data and Friedman tests for non-normally distributed data. The 70D shoe exhibited the highest ankle dorsiflexion and lowest ankle inversion peak angles during 45C task. The 60D shoe showed significantly lower knee abduction angle and coronal motions compared to the 50D and 70D shoes. Increased torsional stiffness reduced stance time in the FCR task. No significant differences were observed in anterior-posterior and medial-lateral ground reaction forces (GRF). However, the 70D shoe demonstrated higher vertical GRF than the 50D shoe while performing the FCR task, particularly during 70% - 75% of stance. Findings from this study revealed the significant role of torsional stiffness in reducing injury risk and optimizing performance during badminton tasks, indicating that shoes with an intermediate level of stiffness (60D) could provide a beneficial balance between flexibility and stability. These findings may provide practical references in guiding future badminton shoe research and development. Further research is necessary to explore the long-term effects of altering stiffness, considering factors such as athletic levels and foot morphology, to understand of the influence of torsional stiffness on motion biomechanics and injury prevalence in badminton-specific tasks.

Telerehabilitation to Address the Rehabilitation Gap in Anterior Cruciate Ligament Care: Survey of Physical Therapists/Care Providers

Background

While the importance of structured rehabilitation following anterior cruciate ligament reconstruction (ACLR), particularly in the return-to-sport phase, is known, for most patients, supervised physical therapy is often completed before this time point. The recent emergence of telerehabilitation and other digital health interventions has the potential to address this "rehabilitation gap."

Methods

The study was conducted as a cross-section, online survey collecting qualitative and quantitative data from open and closed questions. Inclusion criteria included local qualified physical therapists or other professionals working with ACLR patients.

Results

Eighty-three percent of respondents experienced a "rehabilitation gap" with their ACLR patients. Few reported currently utilizing apps or websites (9.74%). The majority (41/58) reported experience with telerehabilitation, and 84% felt that there was a role for digital rehabilitation strategies to address the "rehabilitation gap." The vast majority (94.74%) of participants felt that standard commercial insurance did not permit sufficient rehabilitation.

Discussion

While the majority of our respondents acknowledged the existence of a "rehabilitation gap," as well as familiarity with and confidence in telerehabilitation, few were using this technique at the time of our survey. This suggests an opportunity for development in this space.

An 8-week injury prevention exercise program combined with change-of-direction technique training limits movement patterns associated with anterior cruciate ligament injury risk

Knee ligament sprains are common during change-of-direction (COD) maneuvers in multidirectional team sports. This study aimed to compare the effects of an 8-week injury prevention exercise program containing COD-specific exercises and a similar program containing linear sprint exercises on injury- and performance-related variables during a 135° COD task. We hypothesized that the COD-specific training would lead to (H1) stronger reductions in biomechanical variables associated with anterior cruciate ligament (ACL) injury risk during COD, i.e. knee abduction moment and angle, hip internal rotation angle and lateral trunk lean, and (H2) more effective improvements in COD performance according to the COD completion time, executed angle, ground contact time, and approach speed. Twenty-two sports science students (40% female) completed biomechanical assessments of COD movement strategies before and after participating in two supervised 25-min training sessions per week over 8 weeks. We observed significant 'training x group' interaction effects in support of H1: the COD-specific training but not the linear sprint training led to reduced peak knee abduction moments (interaction, p = 0.027), initial knee abduction (interaction, p < 0.001), and initial lateral trunk lean angles (interaction, p < 0.001) compared to baseline. Although the COD-specific training resulted in sharper executed angles (interaction, p < 0.001), the sprint-specific training group showed reduced COD completion (interaction, p = 0.037) and ground contact times (interaction, p < 0.001). In conclusion, a combination of generic and COD-specific injury prevention training resulted in COD technique adaptations that can help to avoid ACL injury-prone COD movements but may negatively affect COD speed.

Is a Maximal Strength-Training Program Effective on Physical Fitness, Injury Incidence, and Injury Burden in Semi-Professional Soccer Players? A Randomized Controlled Trial

The aims of the study were to analyze the effects of a 12-week maximal strength- training program on injury incidence, injury burden, and physical fitness in semi-professional soccer players and to compare the perceived exertion load and well-being state between injured and non-injured soccer players. Twenty semi-professional male soccer players participated in this study. Participants were randomly allocated to an experimental group (EG, n = 10 players), who performed a maximal strength-training program, or to a control group (CG, n = 10 players), who only performed their regular soccer training. Physical fitness was measured at baseline and after the training program. In addition, the injury incidence, burden, training/match load, and the state of well-being of the players were recorded. The EG showed significant improvements in vertical jumps, change in direction ability, linear sprints, repeated sprint ability, isometric strength (p < 0.003; effect size = 1.78-11.86), and quadriceps-hamstring imbalance in both legs (p < 0.001; effect size = 2.37-3.71) in comparison to the CG. In addition, the EG players showed a significantly (p < 0.05) lower injury burden (p < 0.001, relative risk = 5.05, 95% confidence interval = 3.27-7.79). This study demonstrated the beneficial effects of a 12-week maximal strength-training program on physical fitness attributes and injury burden in semi-professional soccer players.

Hamstring-to-quadriceps activation ratio during lower-limb strengthening exercises

Multiple exercises included in strength training involve greater activation of the quadriceps compared to hamstring muscles, which may lead to knee joint imbalances. The aim of this study was to examine the ratio of surface electromyography (sEMG) activity hamstring and quadriceps muscle groups (hamstring-to-quadriceps activation ratio; H:Q EMG), as well as lateral to medial hamstring activation ratio (LH:MH) in parallel squat, Romanian deadlift, hip thrust, lying leg curl and seated knee extension. The H:Q EMG was greater during lying leg curl compared to other exercises during both the concentric and eccentric phase, however the Romanian deadlift and hip thrust also resulted in relatively high H:Q EMG. Pairwise comparisons revealed that LH:MH was greater in the parallel squat compared to the Romanian deadlift and hip thrust in the concentric phase, and compared to the Romanian deadlift and hip thrust during the eccentric phase. Our data suggests that the lying leg curl promotes the greatest hamstring activation and H:Q EMG, amongst the exercises investigated, while also providing relatively homogenous LH:MH. The lying leg curl should be considered as a primary exercise in rehabilitation and training programmes, aiming to proportionally activate LH:MH and increase H:Q EMG, which may improve knee muscle balance.

How robust are clinical trials in primary and secondary ankle sprain prevention?

OBJECTIVES

Determine the statistical stability of RCTs examining primary and secondary prevention of ankle sprains.

METHODS

Databases were searched to August 2023. We included parallel design RCTs, using conservative interventions for preventing ankle sprain, reporting dichotomous injury event outcomes. Statistical stability was quantified using Fragility Index (FI) and Fragility Quotient (FQ). Subgroup analyses were undertaken to test if FI varied based on by study objective, original approach to analysis (frequency vs time to event), follow-up duration, and pre-registration.

RESULTS

3559 studies were screened with 45 RCTs included. The median number of events required to change the statistical significance (FI) was 4 (IQR 1-6). FI was similar regardless of study objective, original analysis, follow-up duration, and pre-registration status. Median (IQR) FQ was 0.015 (0.005-0.046), therefore reversing events <2 patients/100 would alter significance. In 80% of studies the number of patients lost to follow-up was greater than the FI.

CONCLUSION

RCTs informing primary and secondary prevention of ankle sprain are fragile. Only a small percentage of outcome event reversals would reverse study significance, and this is often exceeded by the number of drop outs. Robust reporting of dichotomous outcomes requires the use P values and key metrics such as FI or FQ.

A multicomponent neuromuscular warm-up program reduces lower-extremity injuries in trained basketball players: a cluster randomized controlled trial

OBJECTIVE

To assess the effects of a novel multicomponent neuromuscular warm-up program on lower-extremity injury incidence in basketball players competing at the regional level.

METHODS

A cluster randomized controlled experimental design was adopted to compare injury incidence between players exposed to the injury prevention warm-up program and those exposed to a typical warm-up program across an entire basketball season. Four teams consisting of 57 players (male: n = 42; female: n = 15) were allocated to the intervention group (age: 21.6 ± 2.5 years; height: 186.2 ± 8.8 cm; body mass: 80.0 ± 10.4 kg) and four teams consisting of 55 players (male: n = 43; female: n = 12) were allocated to the control group (age: 21.6 ± 2.6 years; height: 186.9 ± 9.1 cm; body mass: 81.5 ± 10.9 kg). The novel warm-up combined running exercises with active stretching, plyometrics, balance, strength, and agility drills. Coaching and medical staff provided details on injury incidence each week. Data analyses included the use of poisson regression analyses and the incidence rate ratio (IRR) with 95% confidence intervals (CI).

RESULTS

The intervention group experienced a significantly lower ankle sprain incidence rate (IRR = 0.26, 95% CI = 0.05, 0.98, p = 0.02) and a tendency toward a lower knee injury incidence rate (IRR = 0.32, 95% CI = 0.03, 1.78, p = 0.07) compared to the control group. Considering only non-contact lower-extremity injuries of any type, the intervention group experienced a significantly lower incidence rate compared to the control group (IRR = 0.26, 95% CI = 0.05, 0.98, p < 0.001).

CONCLUSION

This multi-team study demonstrated a novel multicomponent warm-up program resulted in less lower-extremity injuries, particularly ankle sprains and knee injuries, compared to a typical warm-up program in regional-level male and female basketball players.

The Use of Elastic Resistance Bands to Reduce Dynamic Knee Valgus in Squat-Based Movements: A Narrative Review

An elastic band wrapped around the distal thighs has recently been proposed as a method for reducing dynamic knee valgus (medial movement of the knee joint in the frontal/coronal plane) while performing squats. The rationale behind this technique is that, by using an external force to pull the knees into further knee valgus, the band both exaggerates the pre-existing movement and provides additional local proprioceptive input, cueing individuals to adjust their knee alignment. If these mechanisms are true, then elastic bands might indeed reduce dynamic knee valgus, which could be promising for use in injury prevention as excessive knee valgus may be associated with a greater risk of sustaining an ACL rupture and/or other knee injuries. Due to this possibility, certain athletic populations have already adopted the use of elastic bands for training and/or rehab, despite a limited number of studies showing beneficial findings. The purpose of this narrative review is to examine current literature that has assessed lower limb muscle activity and/or lower limb kinematics performance on squat-based movements with or without an elastic band(s). Importantly, this paper will also discuss the key limitations that exist in this area, propose suggestions for future research directions, and provide recommendations for training implementations.

Level of Evidence

5.

Effect of Whole Body Parameters on Knee Joint Biomechanics: Implications for ACL Injury Prevention During Single-Leg Landings

BACKGROUND

Previous studies have examined the effect of whole body (WB) parameters on anterior cruciate ligament (ACL) strain and loads, as well as knee joint kinetics and kinematics. However, articular cartilage damage occurs in relation to ACL failure, and the effect of WB parameters on ACL strain and articular cartilage biomechanics during dynamic tasks is unclear.

PURPOSES

(1) To investigate the effect of WB parameters on ACL strain, as well as articular cartilage stress and contact force, during a single-leg cross drop (SLCD) and single-leg drop (SLD). (2) To identify WB parameters predictive of high ACL strain during these tasks.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Three-dimensional motion analysis data from 14 physically active men and women were recorded during an SLCD and SLD. OpenSim was used to obtain their kinematics, kinetics, and muscle forces for the WB model. Using these data in kinetically driven finite element simulations of the knee joint produced outputs of ACL strains and articular cartilage stresses and contact forces. Spearman correlation coefficients were used to assess relationships between WB parameters and ACL strain and cartilage biomechanics. Moreover, receiver operating characteristic curve analyses and multivariate binary logistic regressions were used to find the WB parameters that could discriminate high from low ACL strain trials.

RESULTS

Correlations showed that more lumbar rotation away from the stance limb at peak ACL strain had the strongest overall association (ρ = 0.877) with peak ACL strain. Higher knee anterior shear force (ρ = 0.895) and lower gluteus maximus muscle force (ρ = 0.89) at peak ACL strain demonstrated the strongest associations with peak articular cartilage stress or contact force in ≥1 of the analyzed tasks. The regression model that used muscle forces to predict high ACL strain trials during the dominant limb SLD yielded the highest accuracy (93.5%), sensitivity (0.881), and specificity (0.952) among all regression models.

CONCLUSION

WB parameters that were most consistently associated with and predictive of high ACL strain and poor articular cartilage biomechanics during the SLCD and SLD tasks included greater knee abduction angle at initial contact and higher anterior shear force at peak ACL strain, as well as lower gracilis, gluteus maximus, and medial gastrocnemius muscle forces.

CLINICAL RELEVANCE

Knowledge of which landing postures create a high risk for ACL or cartilage injury may help reduce injuries in athletes by avoiding those postures and practicing the tasks with reduced high-risk motions, as well as by strengthening the muscles that protect the knee during single-leg landings.

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

Background and Purpose

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

Study Design

Observational cohort, repeated measures reliability study.

Methods

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

Results

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

Conclusion

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

Level of evidence

3b.

Differences in Lower Extremity Coordination Patterns as a Function of Sports Specialization

The practice of early sport specialization, defined as intense year-round training in a single sport at the exclusion of others, is increasing in youth athletics. Despite potential benefits, sport specialization may be detrimental to the health of young athletes, as specialization may increase the risk of musculoskeletal injuries-particularly overuse injuries. However, there remains limited knowledge about how sports specialization uniquely alters underlying sports-related motor behavior. The purpose of this study was to compare the variability of movement patterns exhibited by highly sports specialized youth athletes to that of nonspecialized athletes during performance of a sport-specific, virtual reality based cutting task. It was hypothesized that highly specialized athletes would display different patterns of movement coordination compared to nonspecialized athletes during both the run-up phase and cut-and-decelerate phase. In support of the hypothesis, specialized athletes exhibited both intra- and inter-limb coordination that were significantly different than unspecialized athletes. Overall, the results indicate that the highly specialized athletes tended to exhibit greater degrees of coordination but also the ability to break the coordinated patterns of joint angle changes to execute a cutting maneuver, which requires asymmetric demands on the lower extremities while planting on one leg and changing direction.

Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention

The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This guideline focuses on the exercise-based prevention of knee injuries and provides an update on the 2018 guideline, J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303 J Orthop Sports Phys Ther. 2023;53(1):CPG1-CPG34. doi:10.2519/jospt.2023.0301.

Higher Adherence to Anterior Cruciate Ligament Injury Prevention Programs Is Associated With Lower Injury Rates: A Meta-Analysis and Meta-Regression

Background: Athletes who participate in sports that involve cutting and pivoting movements are particularly susceptible to anterior cruciate ligament (ACL) injury. Preventing this injury is the best way to combat its health consequences and costs. There may be a dose-response relationship between adherence and injury reduction. Purpose: We sought to examine whether athletes’ adherence to injury prevention programs (IPPs) is associated with reductions in ACL and lower extremity (LE) injuries. Methods: We conducted a systematic review of the PubMed, EMBASE, and Cochrane Library databases, searching for studies published between 2011 and 2021. Studies were included if they reported on the use of an ACL IPP compared with a control group and recorded the rate of injuries to calculate a rate ratio, as well as adherence to the program as a percentage of sessions performed. For the meta-analysis, the rate ratios were pooled using the DerSimonian-Laird random-effects model. Results: For the 15 studies included (11 randomized controlled trials and 4 cohort studies), the random-effects model grouped athletes’ adherence to an IPP as high (76% or more of the sessions), moderate (51%–75% of the sessions), and low (50% or fewer of the sessions). We found that athletes with the highest level of IPP adherence had a significantly lower incidence of ACL injury. The rate ratios for moderate and low adherence did not demonstrate a reduced incidence of ACL injury. Injury prevention program participation was also associated with a decrease in LE injury rates. Conclusion: This systematic review and meta-analysis found that athletes with high adherence to IPPs had reduced rates of ACL and LE injuries. Our findings suggest that educating coaches and athletes on the dose-dependent benefits of IPPs may promote the routine incorporation of these programs into warm-up sessions to decrease the risk of ACL and LE injuries.

Kinetic time-curves can classify individuals in distinct levels of drop jump performance

This study examined whether analysing kinetic features of drop jumps (DJ) as one-dimensional biomechanical curves can reveal specific patterns that are consistent and can cluster DJ performance. Hierarchical clustering analysis on DJ from 40 cm data performed by 128 physically active male participants (23.0 ± 4.5 yrs, 1.84 ± 0.07 m, 79.1 ± 10.8 kg) was performed on the derived time-normalised force, power and vertical stiffness curves to unmask the underlying patterns and to explore the dissimilarities identified from the subgroup (cluster) analysis. Results revealed poor, average and top DJ performers. Top performers exhibited larger peak force, power and vertical stiffness compared to the other two groups, and the poor performers had lower values compared to the average performers (p < .05). The time curves of force, power and vertical stiffness exhibited between cluster dissimilarities from ~25% to ~70%, and ~20% to 40% plus ~55% to 70% from the beginning of the ground contact, respectively. The force and power time-curves distinguished DJ ability similarly since they shared 69% of the cases in the top performers' cluster. The content of cases (membership) for vertical stiffness was different from the membership for the force and power time-curve clusters. In conclusion, stiffness should be considered during plyometric training, but does not distinctly define DJ performance.

Mode-specific effects of concentric and eccentric isokinetic training of the hamstring muscle at slow angular velocity on the functional hamstrings-to-quadriceps ratio-a randomized trial

Background

Previous studies have examined the mode specificity of eccentric and concentric isokinetic training, but have reported conflicting results. Few studies have reported that eccentric and concentric isokinetic training are mode-specific, i.e., they will increase only the eccentric or concentric strength, respectively. Other studies have reported that mode specificity does not exist. Therefore, this study aimed to assess the mode-specific effects of eccentric and concentric isokinetic training of the hamstring muscle at slow angular velocity on eccentric peak torque of the hamstring (PT_ecc), concentric peak torque of the quadriceps (PT_con), acceleration time of the hamstring (AT_hams) and quadriceps (AT_quad), deceleration time of the hamstring (DT_hams) and quadriceps (DT_quad), time to peak torque of the hamstring (TPT_hams) and quadriceps (TPT_quad), and functional Hamstring-to-Quadriceps ratio (PT_ecc/PT_con).

Subjects

A total of 30 participants were randomly divided into eccentric and concentric groups.

Methods

Two groups pre-test-post-test experimental design was used. In the eccentric and concentric groups, eccentric and concentric isokinetic training of hamstring muscle was performed respectively, at an angular velocity of 60°/s for 6 weeks duration. PT_ecc, PT_con, AT_hams, AT_quad, DT_hams, DT_quad, TPT_hams, TPT_quad, and PT_ecc/PT_con were measured before and after the completion of training.

Results

In the eccentric group, a significant difference (p < 0.05) was observed in PT_ecc (increased by 21.55%), AT_hams (decreased by 42.33%), AT_quad (decreased by 28.74%), and PT_ecc/PT_con (increased by 17.59%). No significant difference (p > 0.05) was observed in PT_con, TPT_hams, TPT_quad, DThams, and DT_quad. In the concentric group, a significant difference (p < 0.05) was observed in PT_ecc (increased by 12.95%), AT_hams (decreased by 27.38%) AT_quad (decreased by 22.08%), DT_quad (decreased by 26.86%), and PT_ecc/PT_con (increased by 8.35%). No significant difference (p > 0.05) was observed in PT_quad, TPT_hams, TPTquad, and DT_hams. Between-group analysis revealed a significant difference (p < 0.05) only in TPT_quad; otherwise, in the rest of the parameters, no significant difference (p > 0.05) was observed.

Conclusions

Both eccentric and concentric isokinetic training of the hamstring for 6 weeks increased PT_ecc, PT_ecc/PT_con, and decreased AT_hams and AT_quad. The effects of eccentric and concentric isokinetic training of the hamstring on PT_ecc, PT_ecc/PT_con, AT_hams, and AT_quad were not mode specific.

Consensus Delphi study on guidelines for the assessment of anterior cruciate ligament injuries in children

Background: Knee examination guidelines in minors are intended to aid decision-making in the management of knee instability. Clinical question: A Delphi study was conducted with a formal consensus process using a validated methodology with sufficient scientific evidence. A group consensus meeting was held to develop recommendations and practical guidelines for use in the assessment of instability injuries in children. Key findings: there is a lack of evidence to analyse anterior cruciate ligament injuries in children and their subsequent surgical management if necessary. Diagnostic guidelines and clinical assessment of the patient based on a thorough examination of the knee are performed and a guide to anterior cruciate ligament exploration in children is developed. Clinical application: In the absence of a strong evidence base, these established guidelines are intended to assist in that decision-making process to help the clinician decide on the most optimal treatment with the aim of benefiting the patient as much as possible. Following this expert consensus, surgical treatment is advised when the patient has a subjective sensation of instability accompanied by a pivot shift test ++, and may include an anterior drawer test + and a Lachman test +. If these conditions are not present, the conservative approach should be chosen, as the anatomical and functional development of children, together with a physiotherapy programme, may improve the evolution of the injury.

What are gender differences in lower limb muscle activity during jump-landing tasks? A systematic review and meta-analysis

Background

Gender differences in muscle activity during landing have been proposed as a possible contributing factor to the greater incidence of anterior cruciate ligament injuries in women. Conflicting results among a few studies in this regard makes it impossible to reach correct conclusions.

Objectives

The aim of this study was systematic review and the meta-analysis of previous studies which have compared the electromyographic activity of lower limb muscles in gluteus muscles (maximus and medius), quadriceps (rectus femoris, vastus medialis and lateralis), hamstrings (biceps femoris and semimembranosus), and gastrocnemius in men and women in jump–landing task.

Methods

A systematic search of the PubMed, SCOPUS, Science Direct databases was performed for eligible articles in October 2020. Cross-sectional studies that compared the muscle activity of male and female athletes without a history of previous injury in the jump–landing task were included. Unisex and non-athlete's studies were extracted from the included studies. The data were synthesized using a fixed and random effects model.

Results

Eight studies involving 145 participants were included. All participants were people who participated in regular exercises. The meta-analysis of timing and muscle activity was performed in the feedforward (pre contact) and feedback (post contact) stages. There were no significant differences in the muscle activity of biceps femoris (MD = −12.01; 95% CI − 51.49 to 27.47; p = 0.55; I² = 87%), vastus medialis (MD = −53.46; 95% CI − 129.73 to 22.81; p = 0.17; I² = 91%), semimembranosus (MD = 1.81; 95% CI − 6.44 to 10.07; p = 0.67; I² = 0%), gluteus medius (MD = −3.14; 95% CI − 14.24 to 7.96; p = 0.58; I² = 48%), and rectus femoris (MD = −5.83; 95% CI − 14.57 to 2.92; p = 0.19; I² = 87%) in the pre contact phase between two sexes. There was a significant difference between men and women in the activity of vastus lateralis muscle in the post contact phase (MD = −34.90; 95% CI − 48.23 to − 21.57). No significant difference was observed between the men and women in the timing of semimembranosus (MD = 23.53; 95% CI − 14.49 to 61.54; p = 0.23; I² = 56%) and biceps femoris muscle activity (MD = −46.84; 95% CI − 97.50 to 3.83; p = 0.07; I² = 82%).

Conclusion

The results showed that in all lower limb muscles except vastus lateralis there were no significant differences between muscle activity and muscle contraction timing in both sexes before and after foot contact. Therefore, it can be concluded that the reason for the greater susceptibility of ACL injuries in women than men is maybe related to other factors such as biomechanical and hormonal. Additional good quality research in this regard is required to strengthen these conclusions.

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.

Identification of Sex Differences within Lunge Decelerations via Lower Extremity Support Movements; Implications for ACL Injury Disparity, Prevention, and Rehabilitation

Loading characteristics and lower extremity injury mechanisms, such as the non-contact mechanism of cruciate ligament injury, differ between sexes. The Limb Support Moment (LSM) quantifies hip, knee, and ankle moment contribution to the net moment required to prevent limb collapse during deceleration tasks. In total, 10 males and 10 females performed single limb deceleration landings within three knee flexion ranges: 0–25°, 25–50°, and 50–75°. Lower extremity joint moments and LSMs were calculated for all planes at initial contact (IC) through 50 ms. A two-way multivariate ANOVA compared LSMs and joint moments between sexes for all planes. Female LSMs were significantly greater at IC in the sagittal and transverse planes due to the generation of hip and ankle extensor moments and larger hip, knee, and ankle internal rotation moments. Males demonstrated significantly greater LSMs in the frontal plane due to the generation of hip abductor moments. Results suggest that females have a more rigid lower limb than males at landing, with less shock absorption capacity and greater potential for frontal plane collapse due to an unsupportive hip adductor moment. Quantifying the contribution of joint moments to limb support via LSMs suggests that there are landing characteristic sex differences, which may provide insight into injury disparity while guiding injury prevention/rehabilitation methodology.

Mechanism of non-contact ACL injury: OREF Clinical Research Award 2021

Anterior cruciate ligament (ACL) ruptures significantly impact athletes in terms of return to play and loss of long-term quality of life. Before the onset of this study, understanding the mechanism of ACL injury was limited. Thus, the primary focus of this manuscript is to describe our multi-faceted approach to uncovering the mechanism of noncontact ACL injury (NC-ACLI) with the goal of developing preventive strategies. The initial qualitative analysis of ACL injury events revealed most (70%) injuries involve minimal to no contact and occurr during landing or deceleration maneuvers in team sports with a minor perturbation before the injury that may disrupt the neuromuscular system leading to poor body dynamics. A series of quantitative videotape studies demonstrated differences in leg and trunk positions at the time of NC-ACLI in comparison to control subjects. Analysis of the faulty dynamics provoking NC-ACLI, especially the flat-footed landing component, supports the theory that an axial compressive force is the critical factor responsible for NC-ACLI. Our magnetic resonance imaging study demonstrated the NC-ACLI position was associated with a higher tibial slope, and joint contact occurring on the flat, anterior portion of the lateral femoral condyle versus the round, posterior aspect. Both anatomic conditions favor sliding (pivot shift) over rolling in the presence of an axial compressive force. Subsequent cadaveric studies supported axial compressive forces as the primary component of NC-ACLI. Both a strong eccentric quadriceps contraction and knee abduction moments may increase the compressive force at the joint thereby lowering the axial threshold to injury. This manuscript summarizes the NC-ACLI mechanism portion of the 2021 OREF Clinical Research Award.

Maternal Pre-Pregnancy Nutritional Status and Physical Activity Levels and a Sports Injury Reported in Children: A Seven-Year Follow-Up Study

Objective: Our aim was to analyze dose–response associations between maternal pre-pregnancy body mass index and physical activity levels with childhood sports injury rates. Methods: Participants included pre-pregnant mothers (n = 4811) and their children at the age of 7 years (n = 3311). Maternal anthropometry (height, weight, and body mass index), time spent in physical activity, and education level were recorded. All sports injuries were defined as injuries reported in the past year by the children at the age of 7 years. Results: Children whose mothers were overweight/obese in the pre-pregnancy period were 2.04 (OR = 2.04, 95% CI = 1.12–3.71) times more likely to report a sports injury at the age of 7 years. Underweight mothers exhibited a 74% decrease in the odds of their children reporting a sports injury at follow-up (OR = 0.26, 95% CI = 0.10–0.68). Finally, an increase in maternal physical activity across the last three quartiles was associated with a lower odds of sports injuries. Conclusions: The risk of reporting a sports injury was greater for children whose mothers were overweight/obese in the pre-pregnancy period. However, there was a lower risk with both maternal underweight status and increasing minutes of physical activity.

Drop Jumping on Sand Is Characterized by Lower Power, Higher Rate of Force Development and Larger Knee Joint Range of Motion

Plyometric training on sand is suggested to result in advanced performance in vertical jumping. However, limited information exists concerning the biomechanics of drop jumps (DJ) on sand. The purpose of the study was to compare the biomechanical parameters of DJs executed on rigid (RIGID) and sand (SAND) surface. Sixteen high level male beach-volleyball players executed DJ from 40 cm on RIGID and SAND. Force- and video-recordings were analyzed to extract the kinetic and kinematic parameters of the DJ. Results of paired-samples t-tests revealed that DJ on SAND had significantly (p < 0.05) lower jumping height, peak vertical ground reaction force, power, peak leg stiffness and peak ankle flexion angular velocity than RIGID. In addition, DJ on SAND was characterized by significantly (p < 0.05) larger rate of force development and knee joint flexion in the downward phase. No differences (p > 0.05) were observed for the temporal parameters. The compliance of SAND decreases the efficiency of the mechanisms involved in the optimization of DJ performance. Nevertheless, SAND comprises an exercise surface with less loading during the eccentric phase of the DJ, thus it can be considered as a surface that can offer injury prevention under demands for large energy expenditure.

Determining a preventive strategy for ankle sprain injury through a questionnaire survey of coaches of junior high school basketball teams

[Purpose] The purpose of this study was to determine a preventive strategy for ankle sprain injury through a questionnaire survey of coaches of junior high school basketball teams. [Participants and Methods] The questionnaire comprised questions concerning coaches’ characteristics, prevention-related content, and collaboration with medical staff. We distributed the questionnaire to 108 coaches, of which 48 (41.7%) responded. [Results] The results revealed that none of the participant coaches had ever collaborated with medical staff. [Conclusion] Additional effort from medical staff is needed to hold seminars and contact coaches of junior high school teams in order to conduct an injury prevention program.

Effects of Lower-limb Muscle Fatigue, Cardiopulmonary Fatigue, and Brain FatigueTasks on One-legged Landing Motion

OBJECTIVE

Anterior cruciate ligament (ACL) injury is one of the most frequent sportsinjuries, and previous studies have shown that fatigue is a risk factor for sports injuries.This study aimed to inform prevention of ACL injury by investigating how exercise and desk tasks affect trunk and lower limb alignment and ground reaction force (GRF) during one-legged landing movements.

METHODS

The study subjects were 12 men who performed a one-legged landing movement from a 30-cm platform before and after fatigue tasks, including lower-limb muscle fatigue, cardiopulmonary fatigue, and brain fatigue tasks. For the measurement of joint angles and moments and GRF, a three-dimensional motion analysis device and a floor reaction-force meter were used. Statistics were performed using Wilcoxon's signed rank sum test as a multiple comparison test with Bonferroni adjustment to compare the difference in effects.

RESULTS

The maximum trunk flexion angle during landing on one leg was significantly lower in the brain fatigue group than in the control group. The time to peak vertical GRF (pGRF) was significantly shorter in the leg-muscle fatigue group than in the control group.

CONCLUSION

Brain fatigue may have altered the postural strategy before and after landing, resulting in a decrease in trunk flexion angle. Time to pVGRF was shortened in the leg muscle fatigue group, suggesting that there may be an increased risk of ACL injury. Time to pVGRF during lower extremity muscle fatigue and trunk flexion angle during brain fatigue may be more pronounced during actual sports activities.

Hip and ankle strength and range of motion in female soccer players with dynamic knee valgus

BACKGROUND: Dynamic knee valgus (DKV) is a known risk factor for acute and chronic knee injuries and is more frequently diagnosed in females. A real-time single-leg squat test (SLST) could screen for DKV to prevent injuries. OBJECTIVE: To compare the differences in lower extremity strength and range of motion (ROM) in female soccer athletes with and without DKV during an SLST. METHODS: Eighteen subjects with DKV (DKV group) and 18 subjects without DKV (control group) during a single-leg squat were included. Hip strength (flexion, extension, abduction, adduction, internal rotation, and external rotation) was measured with a hand-held dynamometer. Hip ROM (internal and external rotation), and ankle ROM (dorsiflexion with the knee flexed and extended) were measured. Independent t-test was used to compare the averages of the groups. RESULTS: There were significant differences in hip abduction to adduction strength ratio (DKV: 1.48 ± 0.3, control: 1.22 ± 0.26, p< 0.01) and ankle dorsiflexion with knee flexed (DKV: 17.22 ± 6.82, control: 21.22 ± 4.55, p< 0.05) and extended (DKV: 10.14 ± 4.23, control: 14.75 ± 3.40, p< 0.001) between the groups. CONCLUSION: The hip abduction to adduction strength ratio and gastrocnemius and soleus flexibility may be associated factors in dynamic knee valgus and therefore should be assessed and treated, if indicated, as a possible preventive measure in female athletes with this variation.

Intra- and Interrater Reliability of the Directional Balance and Reach Tests With and Without Rotation

This study investigated whether the directional balance and reach with and without rotation is a reliable screening tool to measure dynamic balance and ability to control motion in three planes. Twenty healthy, collegiate athletes participated. The directional balance and reach exhibited good to excellent levels of intra- and interrater reliability (intraclass correlation coefficient = .77–.99). The directional balance and reach provides clinicians with a reliable method that requires minimum financial, spatial, and temporal costs to administer in small and large screening, training, and evaluation programs to recognize asymmetries and deficits in assessing dynamic balance in all three planes of motion.

Unique Considerations for the Pediatric Athlete During Rehabilitation and Return to Sport After Anterior Cruciate Ligament Reconstruction

Level of Evidence

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.

A Systematic Review and Meta-Analysis: Biomechanical Evaluation of the Effectiveness of Strength and Conditioning Training Programs on Front Crawl Swimming Performance

The objectives of this systematic review were to summarize and evaluate the effectiveness of strength and conditioning trainings on front crawl swimming, starts and turns performance with relevant biomechanical parameters. Four online databases including PudMed, ESCSOhost, Web of Science and SPORTDiscus were searched according to different combination of keywords. 954 articles were extracted from databases, and ultimately 15 articles were included in this study after removal of duplicate and articles screening according to inclusion and exclusion criteria. Meta-analyses were adopted when appropriate and Egger's regression symmetry was adopted to assess the publication bias and the results were presented with forest plots and funnel plots respectively. Fifteen articles studied the effects of strength and resistance, core, and plyometric trainings. The quality of the investigation was assessed by the checklist developed by Downs and Black. Most of the investigations found out that training programs were beneficial to front crawl sprinting swimming performance, stroke biomechanics, force, and muscle strength. First, strength and resistance trainings and core trainings were effective on sprinting performance enhancement. Second, resistance trainings were found to have positive effects on stroke rate. Plyometric trainings were beneficial to start performance, while there was no sufficient evidence for confirming the positive improvement on turn biomechanical, also overall swimming performance, after weeks of plyometric trainings. Strength and Conditioning trainings are suggested to implement in regular training regime regarding to the positive effects on swimming performance, including starts, turns and front crawl swim, and relevant biomechanical parameters, instead of swimming training only. Further research with higher quality is recommended to conduct and more investigations on the training effects to other stroke styles are also suggested.

Factors Associated With the Mechanism of ACL Tears in the National Football League: A Video-Based Analysis

Background

The factors associated with anterior cruciate ligament (ACL) injury mechanism in professional American football players are not well-understood.

Hypothesis

It was hypothesized that football-related and player-specific factors, such as position and body mass index (BMI), are associated with ACL injury mechanism in these athletes.

Study Design

Descriptive epidemiology study.

Methods

Videos of ACL tears occurring in National Football League (NFL) games over 6 consecutive seasons from 2014 to 2019 were reviewed by 2 orthopaedic surgeons who specialize in sports medicine. For each injury, the role of contact (direct contact [contact to the injured knee/lower extremity], indirect contact [contact not involving the injured knee/lower extremity], or no contact) as well as playing situation and lower extremity position were recorded. Additional player characteristics, timing of injury, and surface information were obtained from NFL game-day and injury database statistics.

Results

Of the 140 ACL tears, a minority occurred via direct contact to the injured lower extremity (30%), although this varied by position. Just over two-thirds (70%) of ACL tears in offensive linemen occurred via direct contact to the injured lower extremity, while wide receivers had no direct contact ACL tears. Elevated BMI was associated with a greater likelihood of ACL tears occurring via direct contact (53% in players with BMI ≥35 kg/m² vs 24% in players with BMI <35 kg/m²; P = <.01). Rookies had the lowest percentage of direct contact ACL tears (18%; P = .22). ACL tears that occurred during the middle 8 weeks of the regular season resulted more often from direct contact (38%; P = .06). ACL tears that occurred in the third quarter were the most likely to occur via direct contact (44%), while those that occurred in the fourth quarter were the least likely to occur via direct contact (13%; P < .01).

Conclusion

Although most NFL players sustained ACL tears via a noncontact mechanism (ie, through indirect or no contact), players with an elevated BMI, especially on the offensive line, were more likely to injure their ACL through direct contact. Position-dependent variance in injury mechanism may help guide injury prevention efforts in these athletes.

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.

Knee Biomechanical Deficits During a Single-Leg Landing Task Are Addressed With Neuromuscular Training in Anterior Cruciate Ligament-Reconstructed Athletes

OBJECTIVE

Faulty neuromuscular and biomechanical deficits of the knee are nearly ubiquitous in athletes after anterior cruciate ligament (ACL) reconstruction (ACLR). Knee biomechanical deficits are directly associated with an increased risk of second ACL injury, which typically occurs during a sports-related movement on a single limb. To date, the biomechanical effects of a neuromuscular training (NMT) program on knee biomechanics during a single-leg landing task have not been investigated.

DESIGN

Prospective Cohort Study.

SETTING

Controlled laboratory setting.

PARTICIPANTS

Eighteen ACLR and 10 control athletes.

INTERVENTIONS

Neuromuscular training.

MAIN OUTCOME MEASURES

Knee kinematics and kinetics.

RESULTS

There were no significant interactions of session and limb (P > 0.05) for the athletes with ACLR after training. However, there were several significant main effects of session (P < 0.05) for knee kinematics and kinetics during the single-leg landing task. After training, the athletes with ACLR landed with greater knee flexion angles, decreased knee abduction angles, increased knee flexion range of motion, and decreased knee excursion. Also, the ACLR athletes landed with lower knee flexion moments, greater knee adduction moments, and lower peak vertical ground reaction force. Post-training comparison of the ACLR and control cohorts found no significant interactions of group and limb (P > 0.05) and only a significant main effect of group (P < 0.05) for frontal plane knee angle at initial contact. The athletes with ACLR landed with greater knee adduction angles than the control group.

CONCLUSIONS

Deficits in knee biomechanics that are associated with an increased risk of ACL injury are attenuated after completion of this NMT program.