Novel methods of instruction in ACL injury prevention programs, a systematic review

Response of Knee Joint Biomechanics to Landing Under Internal and External Focus of Attention in Female Volleyball Players

The aim of this study was to examine the effect of attentional focus instructions on the biomechanical variables associated with the risk of anterior cruciate ligament injury of the knee joint during a drop landing task using a time series analysis. Ten female volleyball players (age: 20.4 ± 0.8 years, height: 169.7 ± 7.1 cm, mass: 57.6 ± 3.1 kg, experience: 6.3 ± 0.8 years) performed landings from a 50 cm height under three different attentional focus conditions: (1) external focus (focus on landing as soft as possible), (2) internal focus (focus on bending your knees when you land), and (3) control (no-focus instruction). Statistical parameter mapping in the sagittal plane during the crucial first 30% of landing time showed a significant effect of attentional focus instructions. Despite the similarity in landing performance across foci instructions, adopting an external focus instruction promoted reduced vertical ground reaction force and lower sagittal flexion moment during the first 30% of execution time compared to internal focus, suggesting reduced knee loading. Therefore, adopting an external focus of attention was suggested to reduce most biomechanical risk variables in the sagittal plane associated with anterior cruciate ligament injuries, compared to internal focus and control condition. No significant differences were found in the frontal and horizontal planes between the conditions during this crucial interval.

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

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

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

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

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

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

Training interventions to reduce the risk of injury to the lower extremity joints during landing movements in adult athletes: a systematic review and meta-analysis

Objective

Aim of this systematic review was to summarise training interventions designed to reduce biomechanical risk factors associated with increased risk of lower extremity landing injuries and to evaluate their practical implications in amateur sports.

Design

Systematic review and meta-analysis.

Data sources

MEDLINE, Scopus and SPORTDiscus.

Eligibility criteria

Training intervention(s) aimed at reducing biomechanical risk factors and/or injury rates included the following: (1) prospective or (non-)randomised controlled study design; (2) risk factors that were measured with valid two-dimensional or three-dimensional motion analysis systems or Landing Error Scoring System during jump landings. In addition, meta-analyses were performed, and the risk of bias was assessed.

Results

Thirty-one studies met all inclusion criteria, capturing 11 different training interventions (eg, feedback and plyometrics) and 974 participants. A significantly medium effect of technique training (both instruction and feedback) and dynamic strengthening (ie, plyometrics with/without strengthening) on knee flexion angle (g=0.77; 95% CI 0.33 to 1.21) was shown. Only one-third of the studies had training interventions that required minimal training setup and additional coaching educations.

Conclusion

This systematic review highlights that amateur coaches can decrease relevant biomechanical risk factors by means of minimal training setup, for example, instructing to focus on a soft landing, even within only one training session of simple technique training. The meta-analysis emphasises implementing technique training as stand-alone or combined with dynamic strengthening into amateur sport training routine.

Using a target as external focus of attention results in a better jump-landing technique in patients after anterior cruciate ligament reconstruction - A cross-over study

BACKGROUND

Improving jump-landing technique during rehabilitation is important and may be achieved through different feedback techniques, i.e., internal focus of attention (IF) or external focus of attention using a target (EF). However, there is a lack of evidence on the most effective feedback technique after anterior cruciate ligament reconstruction (ACLR). The purpose of this study was to investigate the potential difference in jump-landing techniques between IF and EF instructions in patients after ACLR.

METHODS

Thirty patients (12 females, mean age 23.26 ± 4.91 years) participated after ACLR. Patients were randomly assigned into two groups that each followed a different testing sequence. Patients performed a drop vertical jump-landing test after receiving instructions with varying types of focus of attention. The Landing Error Scoring System (LESS) assessed the jump-landing technique.

RESULTS

EF was associated with a significantly better LESS score (P < 0.001) compared with IF. Only EF instructions led to improvements in jump-landing technique.

CONCLUSION

Using a target as EF resulted in a significantly better jump-landing technique than IF in patients after ACLR. This indicates that increased use of EF could or might result in a better treatment outcome during ACLR rehabilitation.

Videogestütztes Feedbacktraining als präventives Techniktraining – Eine exploratorische Studie

Hintergrund Im Sport wird angenommen, dass ein dynamischer Knievalgus bei einbeinigen Landungen einen relevanten Verletzungsmechanismus des vorderen Kreuzbands darstellt. Während bestehende effektive Präventionsprogramme zur Reduktion des Knievalgus primär auf die Verbesserung allgemeiner konditioneller und/oder koordinativer Einflussgrößen ausgerichtet sind, fokussiert ein Video-Feedback-Training die Korrektur individueller Defizite in der sportlichen Technik, um u. a. ein potenzielles Verletzungsrisiko zu reduzieren.

Ziel Evaluation der kurz- und insbesondere mittel- und langfristigen Wirksamkeit eines Video-Feedback-Trainings zur Veränderung des frontalen Kniewinkels bei einbeinigen Landungen.

Methode Im Rahmen einer exploratorischen Studie wurden 10 sportlich aktive Personen (Alter: 25 ± 5 Jahre, Größe: 170,8 ± 4,5 cm) getestet. Diese führten in Anlehnung an das Landing Error Scoring System (LESS-Test) einbeinige Drop-Jumps in einem Pretest, in einer Aneignungsphase mit Video-Feedback und 2 Retentionstests 2 und 6 Wochen nach der Aneignungsphase ohne Video-Feedback aus. Das Video-Feedback wurde in der Aneignungsphase bei jedem zweiten Sprung und zusätzlich selbstbestimmt auf Nachfrage über ein Expertenmodell mit neutraler Kniestellung im Overlay-Modus aus der Frontalperspektive gegeben.

Ergebnisse Die Ergebnisse wurden nach Sprung- und Nichtsprungbein der Proband*innen differenziert. Sie zeigen eine bedeutsame Verringerung des frontalen Kniewinkels für das Sprungbein (F1, 9 = 10,43, p = 0,01, η2 p = 0,54, 95 % CI [0,04; 0,74]) bei einbeinigen Landungen in der Aneignungsphase, jedoch keine statistisch bedeutsame Verringerung für das Nichtsprungbein (F1, 9 = 4,07, p = 0,08, η2 p = 0,31, 1-β = 0,44). Im Retentionstest nach 6 Wochen nähert sich der frontale Kniewinkel beidseitig dem Ausgangsniveau aus dem Pretest wieder an.

Schlussfolgerung Ein Video-Feedback-Training bietet sich als einfach durchzuführendes, alternatives Verletzungspräventionsprogramm an. Eine fehlende mittel- und langfristige Veränderung und hohe Variabilität des frontalen Kniewinkels lassen eine mehrfache und/oder regelmäßige Durchführung eines Video-Feedback-Trainings sinnvoll erscheinen. In weiteren Studien mit Kontrollgruppendesign und unterschiedlichen Feedback-Prozeduren wird systematisch zu prüfen sein, ob eine längerfristige Reduktion eines potenziellen Verletzungsrisikos des vorderen Kreuzbands erreicht werden kann.

Focus of Attention During ACL Injury Prevention Exercises Affects Improvements in Jump-Landing Kinematics in Soccer Players: A Randomized Controlled Trial

ABSTRACT

Dalvandpour, N, Zareei, M, Abbasi, H, Abdoli, B, Mohammadian, MA, Rommers, N, and Rössler, R. Focus of attention during ACL injury prevention exercises affects improvements in jump-landing kinematics in soccer players: a randomized controlled trial. J Strength Cond Res 37(2): 337-342, 2023-Anterior cruciate ligament tears are severe and complex knee injuries that commonly occur in soccer. Prevent injuries enhance performance (PEP) is an exercise-based prevention program to effectively reduce anterior cruciate ligament injuries. It is, however, unclear how the delivery of the program contributes to its effectiveness. Therefore, we aimed to investigate the effect of the focus of attention that was emphasized during the delivery of the PEP program on jump-landing kinematics in male, elite-level, U21 soccer players. Forty-two players participated in this randomized controlled trial and were allocated to (a) the internal focus of attention (IF) group, receiving instructions focusing on the execution of the exercise (b), the external focus of attention (EF) group, receiving instructions focusing on the outcome of the exercise, or (c) the control group. Before and after the 8-week intervention, players performed a jump-landing task during which we measured hip and knee angles at the initial contact, peak knee flexion, and peak vertical ground reaction force using a 3-dimensional motion analyzer. A repeated-measures analysis of variance was used to compare groups over time. Significant time-by-group interaction effects with large effect sizes were found for hip flexion at all moments (p < 0.032; η2 > 0.15) and for the knee flexion angle at initial contact and maximum knee flexion (p < 0.001; η2 > 0.35), all in favor of the EF group. This shows that EF during PEP improves hip and knee joint kinematics in the sagittal plane more than IF. Therefore, EF during PEP instructions is preferred to increase the effectiveness of this injury prevention program.

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

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

Differences in strength and landing biomechanics between female jumpers and swimmers

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

Effect of six-week traditional resistance and functional training on functional performance in female netball players

Background

Improving the quality of functional movements in athletes generally requires additional training targeting specific functional deficiencies. However, well-rounded, traditional strength and conditioning program should also improve player’s movement quality. Therefore, the primary aim of this study was to compare the effect of two different six-week interventions on the functional score of female netball players.

Methods

In a randomized controlled study, players were divided into control and intervention group. Both groups completed identical six-week strength and conditioning program, with the intervention group also completing additional corrective exercises three sessions per week during the same period.

Results

The FMS® score was significantly higher in the intervention group after 6-week program (f = 9.85, p = 0.004). However, the differences in total score may be attributed mainly to differences between groups in active straight leg raise (p = 0.004) and trunk stability push-up test (p = 0.02), as other individual tests demonstrated similar time and group effect.

Conclusion

These results indicate that although FMS® based intervention may improve overall functional movement score, the athletes in both groups have demonstrated similar improvements in most of the individual tests. Hence, a well-rounded strength and conditioning program incorporating athlete-specific exercises based on limitations identified in the functional movement screen, may result in a balanced training strategy and reduce the need for supplementary functional training sessions.

Optimizing Rehabilitation and Return to Sport in Athletes With Anterior Knee Pain Using a Biomechanical Perspective

Anterior knee pain represents one of the most common athletic knee conditions and arguably also one of the most complex. The patellofemoral joint is at the center of several forces, and alterations in any of these force vectors due to muscular imbalance, soft-tissue tightness or laxity, and altered functional movement patterns can all combine to create a painful anterior knee. While typically anterior knee pain is not a surgical entity, the orthopaedic surgeon with an understanding of these biomechanical intricacies is best positioned to provide comprehensive evidence-based care for the patient with anterior knee pain.

Level of Evidence

V, expert opinion.

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

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

High compliance with the injury prevention exercise programme Knee Control is associated with a greater injury preventive effect in male, but not in female, youth floorball players

PURPOSE

Evaluate team and player compliance with the Knee Control injury prevention exercise programme, study the association between player compliance and injury rates, and compare coach demographics, baseline prevention expectancies, and programme utilisation between teams with high and low compliance.

METHODS

Prospective one-season cohort study based on a cluster randomised controlled trial on 301 (107 female) floorball players aged 12-17 years. Floorball exposure and injuries were self-reported weekly by players using the Oslo Sports Trauma Research Center questionnaire. Team and player compliance to Knee Control was reported monthly by coaches. Additionally, coaches answered pre- and post-season surveys. Teams were divided into a high (≥ 80%) or low (< 80%) compliance group based on their use of Knee Control during the season. Players were divided into three compliance groups based on their average weekly number of Knee Control sessions; high (≥ 2 sessions), intermediate (≥ 1 to < 2 sessions), and low dose (< 1 session).

RESULTS

Mean team compliance for the high and low compliance groups were 95% (range 82-100) and 50% (range 13-66), respectively. Mean ± SD weekly Knee Control dose in the three player compliance groups were 2.4 ± 0.3, 1.4 ± 0.3, and 0.7 ± 0.3 sessions, respectively. There were no differences in total injury incidence between the player compliance groups, but players in the high-dose group had a 35% lower prevalence of injuries overall [adjusted prevalence rate ratio (PRR) 0.65, 95% CI 0.48-0.89] and 60% lower prevalence of substantial injuries (adjusted PRR 0.40, 95% CI 0.26-0.61) compared with the low-dose group. Male players in the high-dose group had consistently lower injury incidence and prevalence, while no between compliance group differences were seen in female players. There were no differences in sex, years of coaching experience, or baseline prevention expectancies in general between coaches for teams in the high vs. low compliance groups, but teams in the high compliance group had a better utilisation fidelity.

CONCLUSION

There was a clear dose-response relationship between more frequent Knee Control use and lower injury rates in male floorball players, but not in female players. Teams with higher compliance also showed a better utilisation fidelity with the programme.

LEVEL OF EVIDENCE

Level II.

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

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

Effective Attentional Focus Strategies after Anterior Cruciate Ligament Reconstruction: A Commentary

Individuals after anterior cruciate ligament reconstruction (ACLR) have a high rate of reinjury upon return to competitive sports. Deficits in motor control may influence reinjury risk and can be addressed during rehabilitation with motor learning strategies. When instructing patients in performing motor tasks after ACLR, an external focus of attention directed to the intended movement effect has been shown to be more effective in reducing reinjury risk than an internal focus of attention on body movements. While this concept is mostly agreed upon, recent literature has made it clear that the interpretation and implementation of an external focus of attention within ACLR rehabilitation needs to be better described. The purpose of this commentary is to provide a clinical framework for the application of attentional focus strategies and guide clinicians towards effectively utilizing an external focus of attention in rehabilitation after ACLR.

LEVEL OF EVIDENCE

5.

Comprehensive Rehabilitation of the Athlete: A Specific and Purposeful Approach

There is a need to improve the quality of rehabilitation in sports medicine to return athletes to optimal function safely and quickly, reducing the risk of reinjury. This paper describes a planning paradigm to guide clinical reasoning during individual treatment sessions and a model for planning the rehabilitation program from acute injury to return to play. The design of a rehabilitation program should be a collaborative, team effort, and accounting for the specific needs of the athlete. As the athlete progresses from acute injury management all the way back to full competition, the rehabilitation professional emphasizes the components of pain management, motion, motor control, and force production in varying degrees based upon phases of tissue healing and the athlete's response. Utilizing high-value, evidence-based treatments maximize both the effectiveness and efficiency of rehabilitation to restore and improve upon preinjury levels of physical performance.

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.

Ankle Dorsiflexion Affects Hip and Knee Biomechanics During Landing

BACKGROUND

Restricted ankle dorsiflexion range of motion (DFROM) has been linked to lower extremity biomechanics that place an athlete at higher risk for injury. Whether reduced DFROM during dynamic movements is due to restrictions in joint motion or underutilization of available ankle DFROM motion is unclear.

HYPOTHESIS

We hypothesized that both lesser total ankle DFROM and underutilization of available motion would lead to high-risk biomechanics (ie, greater knee abduction, reduced knee flexion).

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Nineteen active female athletes (age, 20.0 ± 1.3 years; height, 1.61 ± 0.06 m; mass, 67.0 ± 10.7 kg) participated. Maximal ankle DFROM (clinical measure of ankle DFROM [DF-CLIN]) was measured in a weightbearing position with the knee flexed. Lower extremity biomechanics were measured during a drop vertical jump with 3-dimensional motion and force plate analysis. The percent of available DFROM used during landing (DF-%USED) was calculated as the peak DFROM observed during landing divided by DF-CLIN. Univariate linear regressions were performed to identify whether DF-CLIN or DF-%USED predicted knee and hip biomechanics commonly associated with injury risk.

RESULTS

For every 1.0° less of DF-CLIN, there was a 1.0° decrease in hip flexion excursion (r² = 0.21, P = 0.05), 1.2° decrease in peak knee flexion angles (r² = 0.37, P = 0.01), 0.9° decrease in knee flexion excursion (r² = 0.40, P = 0.004), 0.002 N·m·N^-1·cm^-1 decrease in hip extensor work (r² = 0.28, P = 0.02), and 0.001 N·m·N^-1·cm^-1 decrease in knee extensor work (r² = 0.21, P = 0.05). For every 10% less of DF-%USED, there was a 3.2° increase in peak knee abduction angles (r² = 0.26, P = 0.03) and 0.01 N·m·N^-1·cm^-1 lesser knee extensor work (r² = 0.25, P = 0.03).

CONCLUSION

Lower levels of both ankle DFROM and DF-%USED are associated with biomechanics that are considered to be associated with a higher risk of sustaining injury.

CLINICAL RELEVANCE

While total ankle DFROM can predict some aberrant movement patterns, underutilization of available ankle DFROM can also lead to higher risk movement strategies. In addition to joint specific mobility training, clinicians should incorporate biomechanical interventions and technique feedback to promote the utilization of available motion.

Incorporating Internal and External Training Load Measurements in Clinical Decision Making After ACL Reconstruction: A Clinical Commentary

BACKGROUND AND PURPOSE

Poor outcomes after anterior cruciate ligament reconstruction (ACLr), including the relatively high risk of suffering a subsequent ACL injury, suggest the need to optimize rehabilitation and return-to-sport testing. The purpose of this commentary is to introduce clinicians to the concept of monitoring training load during rehabilitation, to review methods of quantifying internal and external loads, and to suggest ways that these technologies can be incorporated into rehabilitation progressions and return-to-sport decisions after anterior ACLr.

DESCRIPTION OF TOPIC WITH RELATED EVIDENCE

Quantifying and identifying the effects of training load variables, external (distance, impacts, decelerations) and internal (heart rate, heart rate variability) workload, during rehabilitation can indicate both positive (improved physical, physiological, or psychological capacity) or negative (heightened risk for injury or illness) adaptations and allow for the ideal progression of exercise prescription. When used during return-to-sport testing, wearable technology can provide robust measures of movement quality, readiness, and asymmetry not identified during performance-based testing.

DISCUSSION / RELATION TO CLINICAL PRACTICE

Researchers have reported the actual in-game demands of men and women of various ages and competition levels during multi-directional sport. Wearable technology can provide similar variables during rehabilitation, home exercise programs, and during on-field transition back to sport to ensure patients have met the expected fitness capacity of their sport. Additionally, clinicians can use internal load measures to objectively monitor patient's physiological responses to rehabilitation progressions and recovery rather than relying on subjective patient-reported data.

LEVEL OF EVIDENCE

5.

Visual Perturbation to Enhance Return to Sport Rehabilitation after Anterior Cruciate Ligament Injury: A Clinical Commentary

Anterior cruciate ligament (ACL) tears are common traumatic knee injuries causing joint instability, quadriceps muscle weakness and impaired motor coordination. The neuromuscular consequences of injury are not limited to the joint and surrounding musculature, but may modulate central nervous system reorganization. Neuroimaging data suggest patients with ACL injuries may require greater levels of visual-motor and neurocognitive processing activity to sustain lower limb control relative to healthy matched counterparts. Therapy currently fails to adequately address these nuanced consequences of ACL injury, which likely contributes to impaired neuromuscular control when visually or cognitively challenged and high rates of re-injury. This gap in rehabilitation may be filled by visual perturbation training, which may reweight sensory neural processing toward proprioception and reduce the dependency on vision to perform lower extremity motor tasks and/or increase visuomotor processing efficiency. This clinical commentary details a novel approach to supplement the current standard of care for ACL injury by incorporating stroboscopic glasses with key motor learning principles customized to target visual and cognitive dependence for motor control after ACL injury.

LEVEL OF EVIDENCE

5.

Restricting ankle dorsiflexion does not mitigate the benefits of external focus of attention on landing biomechanics in healthy females

PURPOSE

Restricted ankle dorsiflexion can promote aberrant biomechanics associated with risk for knee injury during dynamic activities. Attentionally focused instructions have been used to improve high-risk knee biomechanics during landing tasks. Yet, it is unknown whether attentionally focused instruction can effectively improve landing patterns in the presence of a mechanical restriction on the ankle. Therefore, our purpose was to determine whether restricting ankle dorsiflexion by use of bracing mitigated the effects of attentional foci on landing biomechanics in healthy females.

METHODS

We used a crossover design to investigate lower extremity biomechanics in 19 healthy females between the ages of 18-35 during a series of jump-landing tasks. Participants completed 6 blocks of 3 jump-landings on separate force platforms in a randomized order based on brace condition (brace, no brace) and mode of attentional foci (neutral, internal focus [IF], external focus [EF]). Attentionally focused instructions were provided immediately prior to 3 practice jump-landings, followed by 5 test jump-landings with self-controlled feedback only.

RESULTS

Ankle bracing decreased peak dorsiflexion and sagittal range of motion (ROM) (mean difference: 5.7-5.8°), and peak inversion and frontal ROM (mean difference: 2.4-3.0°). However, hip flexion ROM (mean difference: 1.8°) increased compared to the no brace condition. Regardless of ankle bracing, EF instruction increased peak hip flexion (mean difference: 4.9°) and hip flexion range of motion (mean difference: 3.8-4.6°), while decreasing peak knee valgus (mean difference: 0.8-1.0°) and knee valgus moment (mean difference: 0.04 Nm/kg). Additionally, EF instruction increased peak hip abduction to a similar degree when braced (mean difference: 3.6-4.0°) and not braced (mean difference: 2.1-2.5°). Lastly, EF instruction increased hip abduction ROM only when braced (mean difference: 2.3-2.4°), but decreased peak knee valgus power only when not braced (mean difference: 0.18 W/kg).

CONCLUSIONS

Our findings indicate that mechanically restricting ankle dorsiflexion does not mitigate the ability of EF instruction to enhance jump-landing performance by means of improving hip and knee biomechanics in healthy females. However, our findings suggest an improved ability to control the rate of knee valgus loading when not braced. Therefore, we conclude that EF instruction remains a viable clinical strategy to improve landing patterns in the presence of restricted ankle dorsiflexion, yet this approach may be ineffective to reduce the rate of knee joint loading.

Measurement of Quasi-Static 3-D Knee Joint Movement Based on the Registration From CT to US

The measurement of quasi-static 3-D knee joint movement is an important basis for studying the mechanism of knee joint injury. Most of the existing measurement methods make use of computed tomography (CT) and nuclear magnetic resonance (MR) imaging technology and hence have the disadvantages of invasiveness, ionizing radiation, low accuracy, and high cost. To overcome those drawbacks, this article innovatively proposes a 3-D motion measurement system for the knee joint based on the registration of CT images to ultrasound (US) images. More specifically, the lower limbs of a subject were first scanned once to acquire the CT images. A portable handheld device was designed to control a US probe for mechanically scanning the subject's lower limbs in a linear trajectory. During the movement of the subject's lower limbs, the US scanning was performed quasi-statically. The acquired US images were then registered to the CT images, and the 3-D motions of the lower limb bones could be recreated with the bones scanned in CT images. To guarantee the registration accuracy and efficiency, we used the H-shaped multiview slice assembly as the structural image content for the registration process. The experimental results show that our approach can accurately measure the 3-D motion of the knee joint and meet the needs of 3-D motion analysis of knee joint in practice.

The Effects of Cognitive Loading on Motor Behavior in Injured Individuals: A Systematic Review

BACKGROUND

Research suggests that individuals with musculoskeletal injury may have difficulty negotiating physical tasks when they are combined with cognitive loads.

OBJECTIVE

Our objective was to conduct a systematic review to understand the effects of increased cognitive demand on movement patterns among individuals with musculoskeletal injuries.

METHODS

A comprehensive search of PubMed, MEDLINE, the Cumulative Index for Nursing and Allied Health Literature (CINAHL), and SPORTDiscus was conducted to find research reports that included a population that had previously experienced an ankle, knee, or low back injury, included an uninjured control group, and assessed a dual-task paradigm.

RESULTS

Forty-five full-text research reports were assessed, of which 28 studies (six ankle injury, nine knee injury, and 13 low back pain studies) were included in the review. Included studies were assessed for methodological quality and the study design extracted for analysis including the participants, cognitive and physical tasks performed, as well as outcome measures (e.g., three-dimensional kinematics, center of pressure, etc.). All studies included were cross-sectional or case-control with methodological quality scores of 17.8 ± 2.2 out of a possible 22. Twenty-five of the 28 studies found changes in motor performance with dual-task conditions compared with single tasks. Furthermore, 54% of studies reported a significant group by task interaction effect, reporting at least one alteration in injured groups' motor performance under dual-task conditions when compared with an uninjured group.

CONCLUSION

The results of this systematic review indicate that motor performance is further impaired by placing a cognitive load on individuals in populations with musculoskeletal injury. More demanding tasks such as gait appear to be more affected in injured individuals than simple balance tasks. Future investigators may want to consider the difficulty of the tasks included as well as the impact of dual-task paradigms on rehabilitation programs.

Principles of Motor Learning to Support Neuroplasticity After ACL Injury: Implications for Optimizing Performance and Reducing Risk of Second ACL Injury

Athletes who wish to resume high-level activities after an injury to the anterior cruciate ligament (ACL) are often advised to undergo surgical reconstruction. Nevertheless, ACL reconstruction (ACLR) does not equate to normal function of the knee or reduced risk of subsequent injuries. In fact, recent evidence has shown that only around half of post-ACLR patients can expect to return to competitive level of sports. A rising concern is the high rate of second ACL injuries, particularly in young athletes, with up to 20% of those returning to sport in the first year from surgery experiencing a second ACL rupture. Aside from the increased risk of second injury, patients after ACLR have an increased risk of developing early onset of osteoarthritis. Given the recent findings, it is imperative that rehabilitation after ACLR is scrutinized so the second injury preventative strategies can be optimized. Unfortunately, current ACLR rehabilitation programs may not be optimally effective in addressing deficits related to the initial injury and the subsequent surgical intervention. Motor learning to (re-)acquire motor skills and neuroplastic capacities are not sufficiently incorporated during traditional rehabilitation, attesting to the high re-injury rates. The purpose of this article is to present novel clinically integrated motor learning principles to support neuroplasticity that can improve patient functional performance and reduce the risk of second ACL injury. The following key concepts to enhance rehabilitation and prepare the patient for re-integration to sports after an ACL injury that is as safe as possible are presented: (1) external focus of attention, (2) implicit learning, (3) differential learning, (4) self-controlled learning and contextual interference. The novel motor learning principles presented in this manuscript may optimize future rehabilitation programs to reduce second ACL injury risk and early development of osteoarthritis by targeting changes in neural networks.

The Effects of Instruction Exercises on Performance and Kinetic Factors Associated With Lower-Extremity Injury in Landing After Volleyball Blocks

CONTEXT

Female volleyball players are more predisposed to anterior cruciate ligament injury in comparison with their male counterparts. Recent research on anterior cruciate ligament injury prevention strategies has shown the positive results of adopting the external focus (EF) of attention in sports.

OBJECTIVE

To determine the effect of 6-week EF instruction exercises on performance and kinetic factors associated with lower-extremity injury in landing after the volleyball blocks of female athletes.

DESIGN

Pretest and posttest control study.

SETTING

University research laboratory.

PARTICIPANTS

Thirty-two female volleyball players (18-24 y old) from the same team randomly divided into experimental (n = 16) and control (n = 16) groups.

INTERVENTION

The experimental group performed a 6-week exercise program with EF instructions. The control group continued its regular volleyball team schedule.

MAIN OUTCOME MEASURES

To assess function, single-leg triple hop test for distance was used. A force plate was used to evaluate kinetic variables including vertical ground reaction forces, the rate of loading, and dynamic postural stability index. All data were assessed at baseline and after the intervention.

RESULTS

There was a significant increase in single-leg triple hop test (P < .05) and in the first and second peak ground reaction force, rate of loadings, dynamic postural stability index (P < .05).

CONCLUSION

According to the results of this study, anterior cruciate ligament injury prevention programs should incorporate EF instruction exercises to enhance the kinetics and to increase athletes' functional performance.

Unanticipated jump-landing after anterior cruciate ligament reconstruction: Does unanticipated jump-landing testing deliver additional return to sport information to traditional jump performance tests?

BACKGROUND

We aimed to delineate if unanticipated jump-landing assessments delivers complementary information to those of commonly used hop and jump tests after anterior cruciate ligament reconstruction.

METHODS

Eleven participants (5 males) performed a series of unanticipated jump-landings and traditional hop and jump performance tests (single leg hops for distance, triple crossover hops for distance and drop jumps). The number of mistrials, time to stabilization and peak ground reaction force (pGRF) at landing and jump/hop distance were measured. Pearson correlations to find potential associations between the unanticipated jump-landing-values and the traditional jump/hop performance tests were calculated twice: once for the affected and once for the unaffected legs. t-Tests for dependent samples were used to detect differences between affected and unaffected leg within each test condition.

FINDINGS

The pGRF at unanticipated landing significantly correlated to the pGRF at drop jump landing (r = 0.68) and the hopping distance after the triple crossover hops (r = 0.71, each p < .05). No other significant correlation occurred (p > .05). Hopping distance after single leg hops (mean: 110.2 cm vs. 95.5 cm) and triple crossover hops for distance (mean: 315.3 cm vs. 294.2 cm) showed significant differences between the unaffected and the reconstructed leg (p < .05). Other parameters showed no significant between-legs differences (p > .05).

INTERPRETATION

Both, the reconstructed and the contralateral leg seems to be affected. Unanticipated jump landing tasks deliver information beyond those of commonly used jump and hop tests, the thereby assessed abilities may thus be a complementary aspect of dynamic knee function than those assessed with classic tests.

Sex differences in sagittal plane control emerge during adolescent growth: a prospective investigation

PURPOSE

Females athletes have a higher incidence of non-contact knee joint injuries compared to their male counterparts. This may be attributable to sex-specific differences in neuromuscular control, which arise during the pubertal growth spurt. The purpose of this longitudinal study was to assess the development of landing kinematics of adolescent male and female athletes during the adolescent growth-spurt.

METHODS

One hundred and eighty-four adolescent athletes (55% male, 45% female; mean age = 13 ± 0.3 years) participated. Testing was undertaken at baseline and then repeated at 6, 12, 18 and 24 months. Participants performed three drop vertical jump (DVJ) trials from a 31 cm box. Frontal and sagittal plane knee joint angles were recorded. The average measurement of the three jumps was used for analysis at each time point. To assess maturation status, participants were categorised according to their age from peak height velocity at baseline. Pre-initial contact knee flexion (pre-IC), peak knee flexion and knee valgus displacement were the dependant variables. The categorical independent variables were sex (male versus female) and time.

RESULTS

There was a significant sex*time interaction for pre-IC knee flexion, with males increasing knee flexion with time to a greater extent than females. There was no significant sex*time interaction for knee valgus displacement; although females displayed greater knee valgus displacement across all time points.

CONCLUSIONS

Adolescent male and female athletes display differing kinematic profiles across growth and development. This has clinical relevance for emphasising increased knee flexion, as well as decreasing abnormal frontal plane displacement in injury prevention programmes for adolescent females.

LEVEL OF EVIDENCE

II.

The Use of Augmented Information for Reducing Anterior Cruciate Ligament Injury Risk During Jump Landings: A Systematic Review

CONTEXT: 

A comprehensive systematic review of the literature on the use of augmented information in anterior cruciate ligament (ACL) injury-prevention programs to improve jump-landing technique was conducted. The use of motor-learning concepts could provide more robust means of preventing ACL injuries.

OBJECTIVE: 

To systematically summarize the effectiveness of augmented information in improving the biomechanical factors associated with an increased risk for ACL injury.

DATA SOURCES: 

Articles were retrieved using the electronic databases of PubMed, MEDLINE, CINAHL, and Google Scholar and 3 lines of truncated search words: (a) lower extremity, knee, ACL, and anterior cruciate ligament; (b) prevention, injury prevention, and prehab; and (c) augmented information, augmented feedback, feedback, cue, and instruction. We also performed a hand search of the reference lists of the screened articles.

DATA EXTRACTION: 

We independently assessed the methodologic quality using the Cochrane Group on Screening and Diagnostic Test Methods list. Articles were placed in 1 of 3 augmented-information categories: prescriptive, feedback, or transition. Articles were also categorized based on whether the information likely encouraged an internal or external focus of attention.

DATA SYNTHESIS: 

The searches identified a total of 353 studies, of which 18 were included. Most researchers found that augmented information could lead to technique changes to reduce the biomechanical risk factors associated with ACL injury. The average methodologic quality of the studies was 11.8 out of 17, with a range from 8 to 15. The authors of only 7 studies examined retention of the improved techniques.

CONCLUSIONS: 

The evidence suggests that augmented information can be used to significantly improve the biomechanical indicators associated with ACL injury and to enhance current ACL injury-prevention programs. Combined prescriptive and feedback information that encouraged both internal and external foci led to the largest retention effect sizes.

Does implicit motor learning lead to greater automatization of motor skills compared to explicit motor learning? A systematic review

Background

Implicit motor learning is considered to be particularly effective for learning sports-related motor skills. It should foster movement automaticity and thereby facilitate performance in multitasking and high-pressure environments. To scrutinize this hypothesis, we systematically reviewed all studies that compared the degree of automatization achieved (as indicated by dual-task performance) after implicit compared to explicit interventions for sports-related motor tasks.

Methods

For this systematic review (CRD42016038249) conventional (MEDLINE, CENTRAL, Embase, PsycINFO, SportDiscus, Web of Science) and grey literature were searched. Two reviewers independently screened reports, extracted data, and performed risk of bias assessment. Implicit interventions of interest were analogy-, errorless-, dual-task-, and external focus learning. Data analysis involved descriptive synthesis of group comparisons on absolute motor dual-task (DT) performance, and motor DT performance relative to single-task motor performance (motor DTCs).

Results

Of the 4125 reports identified, we included 25 controlled trials that described 39 implicit-explicit group comparisons. Risk of bias was unclear across trials. Most comparisons did not show group differences. Some comparisons showed superior absolute motor DT performance (N = 2), superior motor DTCs (N = 4), or both (N = 3) for the implicit compared to the explicit group. The explicit group showed superior absolute motor DT performance in two comparisons.

Conclusions

Most comparisons did not show group differences in automaticity. The remaining comparisons leaned more toward a greater degree of movement automaticity after implicit learning than explicit learning. However, due to an overall unclear risk of bias the strength of the evidence is level 3. Motor learning-specific guidelines for design and especially reporting are warranted to further strengthen the evidence and facilitate low-risk-of-bias trials.

Application of motor learning in neurorehabilitation: a framework for health-care professionals

Learning motor skills is an essential part of most rehabilitation processes. Facilitating and supporting motor learning is particularly challenging in neurological rehabilitation: patients who suffer from neurological diseases experience both physical limitations and difficulties of cognition and communication that affect and/or complicate the motor learning process. Therapists (e.g. physiotherapists and occupational therapists) who work in neurorehabilitation are therefore continuously searching for the best way to facilitate patients during these intensive learning processes. To support therapists in the application of motor learning, a framework was developed, integrating knowledge from the literature and the opinions and experiences of international experts. This article presents the framework, illustrated by cases from daily practice. The framework may assist therapists working in neurorehabilitation in making choices, implementing motor learning in routine practice, and supporting communication of knowledge and experiences about motor learning with colleagues and students. The article discusses the framework and offers suggestions and conditions given for its use in daily practice.

A novel approach to enhance ACL injury prevention programs

Efficacy studies have demonstrated decreased anterior cruciate ligament (ACL) injury rates for athletes participating in injury prevention programs. Typically, ACL injury prevention programs entail a combination of plyometrics, strength training, agility and balance exercises. Unfortunately, improvements of movement patterns are not sustained over time. The reason may be related to the type of instructions given during training. Encouraging athletes to consciously control knee movements during exercises may not be optimal for the acquisition of complex motor skills as needed in complex sports environments. In the motor learning domain, these types of instructions are defined as an internal attentional focus. An internal focus, on one's own movements results in a more conscious type of control that may hamper motor learning. It has been established in numerous studies that an external focus of attention facilitates motor learning more effectively due to the utilization of automatic motor control. Subsequently, the athlete has more recourses available to anticipate on situations on the field and take appropriate feed forward directed actions. The purpose of this manuscript was to present methods to optimize motor skill acquisition of athletes and elaborate on athletes' behavior.

Exploring individual adaptations to an anterior cruciate ligament injury prevention programme

BACKGROUND

Individual responses to anterior cruciate ligament injury prevention programmes (ACL IPPs) have received little attention. This study examined the effects of an ACL IPP on neuromuscular control and lower limb biomechanics during landing at the group and individual levels.

METHODS

Sixteen female athletes were randomly allocated to training (n=8) or control (n=8) groups. Electromyography, and three-dimensional kinematic and kinetic data were collected during landing at two testing sessions. Repeated measures ANOVA and effect sizes (Cohen's d) examined the effect of the IPP at the group and individual levels. A sub-group analysis comparing the effect of the IPP on 'high-' (i.e. large peak knee abduction moment at baseline) versus 'low-risk' individuals was also conducted.

RESULTS

At the group level; the IPP increased activation of the medial hamstrings prior to landing (p<0.001; d=0.264) and the medial gastrocnemius at landing (p<0.001; d=0.426), and increased hip external rotation early after initial contact (p<0.001; d=0.476). Variable adaptations were seen across individuals within the training group for all variables (p<0.001). The IPP had a large effect in reducing frontal plane knee moments for 'high-risk' individuals (d>0.91), however these results did not reach statistical significance (p>0.05).

CONCLUSIONS

The IPP induced adaptations during landing, however, individual data revealed dissimilar responses to the programme. Individuals displaying a pre-existing high-risk strategy may incur greater benefits from IPPs, yet only if the programme targets the relevant high-risk strategy.

Video Feedback and 2-Dimensional Landing Kinematics in Elite Female Handball Players

CONTEXT

  In team handball, an anterior cruciate ligament injury often occurs during landing after a jump shot. Many intervention programs try to reduce the injury rate by instructing athletes to land more safely. Video is an effective way to provide feedback, but little is known about its influence on landing technique in sport-specific situations.

OBJECTIVE

  To test the effectiveness of a video-overlay feedback method on landing technique in elite handball players.

DESIGN

  Controlled laboratory study.

SETTING

  Laboratory.

PATIENTS OR OTHER PARTICIPANTS

  A total of 16 elite female handball players assigned to a control group (n = 8; age = 17.61 ± 1.34 years, height = 1.73 ± 0.06 m, mass = 69.55 ± 4.29 kg) or video group (n = 8; age = 17.81 ± 0.86 years, height = 1.71 ± 0.03 m, mass = 64.28 ± 6.29 kg).

INTERVENTION(S)

  Both groups performed jump shots in a pretest, 2 training sessions, and a posttest. The video group received video feedback of an expert model with an overlay of their own jump shots in training sessions 1 and 2, whereas the control group did not.

MAIN OUTCOME MEASURE(S)

  We measured ankle, knee, and hip angles in the sagittal plane at initial contact and peak flexion; range of motion; and Landing Error Scoring System (LESS) scores. One 2 × 4 repeated-measures analysis of variance was conducted to analyze the group, time, and interaction effects of all kinematic outcome measures and the LESS score.

RESULTS

  The video group improved knee and hip flexion at initial contact and peak flexion and range of motion. In addition, the group's average peak ankle flexion (12.0° at pretest to 21.8° at posttest) and LESS score (8.1 pretest to 4.0 posttest) improved. When we considered performance variables, no differences between groups were found in shot accuracy or vertical jump height, whereas horizontal jump distance in the video group increased over time.

CONCLUSIONS

  Overlay visual feedback is an effective method for improving landing kinematics during a sport-specific jump shot. Further research is warranted to determine the long-term effects and transfer to training and game situations.

Osteoarthritis action alliance consensus opinion - best practice features of anterior cruciate ligament and lower limb injury prevention programs

AIM

To identify best practice features of an anterior cruciate ligament (ACL) and lower limb injury prevention programs (IPPs) to reduce osteoarthritis (OA).

METHODS

This consensus statement started with us performing a systematic literature search for all relevant articles from 1960 through January 2017 in PubMed, Web of Science and CINAHL. The search strategy combined the Medical Subject Heading (MeSH) and keywords for terms: (1) ACL OR “knee injury” OR “anterior cruciate ligament”; (2) “prevention and control” OR “risk reduction” OR “injury prevention” OR “neuromuscular training”; and (3) meta-analysis OR “systematic review” OR “cohort study” OR randomized. We found 166 different titles. The abstracts were reviewed for pertinent papers. The papers were reviewed by at least two authors and consensus of best practice for IPP to prevent OA was obtained by conference calls and e-mail discussions. All authors participated in the discussion.

RESULTS

The best practice features of an IPP have the following six components: (1) lower extremity and core strengthening; (2) plyometrics; (3) continual feedback to athletes regarding proper technique; (4) sufficient dosage; (5) minimal-to-no additional equipment; and (6) balance training to help prevent injuries. Exercises focused on preventing ankle sprains, hamstring injuries and lateral trunk movements are important. Plyometric exercises should focus on correcting knee valgus movement. Exercises should focus on optimizing the hamstring to quadriceps strength ratio. In order for IPP to be successful, there should be increased education and verbal feedback along with increased athletic compliance. Additional equipment is not necessary. Balance training alone does not significantly reduce injuries, but is beneficial with other exercises. Not enough evidence to recommend stretching and agility exercises, with no ill effects identified. Therefore, we suggest making these optional features.

CONCLUSION

Best practice features for ACL and lower limb IPPs to help prevent OA contain six key components along with two optional.

Motor learning strategies in basketball players and its implications for ACL injury prevention: a randomized controlled trial

PURPOSE

Adding external focus of attention (EF, focus on the movement effect) may optimize current anterior cruciate ligament (ACL) injury prevention programmes. The purpose of the current study was to investigate the effects of an EF, by a visual stimulus and an internal focus, by a verbal stimulus during unexpected sidestep cutting in female and male athletes and how these effects remained over time.

METHODS

Ninety experienced basketball athletes performed sidestep cutting manoeuvres in three sessions (S1, S2 and S3). In this randomized controlled trial, athletes were allocated to three groups: visual (VIS), verbal (VER) and control (CTRL). Kinematics and kinetics were collected at the time of peak knee frontal plane moment.

RESULTS

Males in the VIS group showed a larger vertical ground reaction force (S1: 25.4 ± 3.1 N/kg, S2: 25.8 ± 2.9 N/kg, S3: 25.2 ± 3.2 N/kg) and knee flexion moments (S1: -3.8 ± 0.9 Nm/kg, S2: -4.0 ± 1.2 Nm/kg, S3: -3.9 ± 1.3 Nm/kg) compared to the males in the VER and CTRL groups and to the females in the VIS group (p < 0.05). Additionally, the males in the VIS group reduced knee valgus moment and the females in the VER group reduced knee varus moment over time (n.s.).

CONCLUSION

Male subjects clearly benefit from visual feedback. Females may need different feedback modes to learn a correct movement pattern. Sex-specific learning preferences may have to be acknowledged in day by day practice. Adding video instruction or feedback to regular training regimens when teaching athletes safe movement patterns and providing individual feedback might target suboptimal long-term results and optimize ACL injury prevention programmes.

LEVEL OF EVIDENCE

I.

Immersive virtual reality improves movement patterns in patients after ACL reconstruction: implications for enhanced criteria-based return-to-sport rehabilitation

PURPOSE

The purpose of this study was to evaluate the influence of immersion in a virtual reality environment on knee biomechanics in patients after ACL reconstruction (ACLR). It was hypothesized that virtual reality techniques aimed to change attentional focus would influence altered knee flexion angle, knee extension moment and peak vertical ground reaction force (vGRF) in patients following ACLR.

METHODS

Twenty athletes following ACLR and 20 healthy controls (CTRL) performed a step-down task in both a non-virtual reality environment and a virtual reality environment displaying a pedestrian traffic scene. A motion analysis system and force plates were used to measure kinematics and kinetics during a step-down task to analyse each single-leg landing.

RESULTS

A significant main effect was found for environment for knee flexion excursion (P = n.s.). Significant interaction differences were found between environment and groups for vGRF (P = 0.004), knee moment (P < 0.001), knee angle at peak vGRF (P = 0.01) and knee flexion excursion (P = 0.03). There was larger effect of virtual reality environment on knee biomechanics in patients after ACLR compared with controls.

CONCLUSION

Patients after ACLR immersed in virtual reality environment demonstrated knee joint biomechanics that approximate those of CTRL. The results of this study indicate that a realistic virtual reality scenario may distract patients after ACLR from conscious motor control. Application of clinically available technology may aid in current rehabilitation programmes to target altered movement patterns after ACLR.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

A Systematic Summary of Systematic Reviews on the Topic of the Anterior Cruciate Ligament

BACKGROUND

There has been a substantial increase in the amount of systematic reviews and meta-analyses published on the anterior cruciate ligament (ACL).

PURPOSE

To quantify the number of systematic reviews and meta-analyses published on the ACL in the past decade and to provide an overall summary of this literature.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review of all ACL-related systematic reviews and meta-analyses published between January 2004 and September 2014 was performed using PubMed, MEDLINE, and the Cochrane Database. Narrative reviews and non-English articles were excluded.

RESULTS

A total of 1031 articles were found, of which 240 met the inclusion criteria. Included articles were summarized and divided into 17 topics: anatomy, epidemiology, prevention, associated injuries, diagnosis, operative versus nonoperative management, graft choice, surgical technique, fixation methods, computer-assisted surgery, platelet-rich plasma, rehabilitation, return to play, outcomes assessment, arthritis, complications, and miscellaneous.

CONCLUSION

A summary of systematic reviews on the ACL can supply the surgeon with a single source for the most up-to-date synthesis of the literature.

Enhanced retention of drop vertical jump landing technique: A randomized controlled trial

External focus instructions have been shown to result in superior motor performance compared to internal focus instructions. Using an EF may help to optimize current anterior cruciate ligament (ACL) injury prevention programs. The purpose of the current study was to investigate the effects of instructions on landing technique and performance by comparing an external focus (EF), internal focus (IF), video (VI) and control (CTRL) group. Subjects (age 22.50±1.62years, height 179.70±10.43cm, mass 73.98±12.68kg) were randomly assigned to IF (n=10), EF (n=10), VI (n=10) or CTRL group (n=10). Landing was assessed from a drop vertical jump (DVJ) in five sessions: pretest, two training blocks (TR1 and TR2) and directly after the training sessions (post test) and retention test 1week later. Group specific instructions were offered in TR1 and TR2. Landing technique was assessed with the Landing Error Scoring System (LESS) and jump height was taken as performance measure. The results show that males in the VI group and females both in the VI and EF groups significantly improved jump-landing technique. Retention was achieved and jump height was maintained for males in the VI group and females both in the VI and EF groups. It is therefore concluded that EF and VI instructions have great potential in ACL injury prevention.

Can two-dimensional video analysis during single-leg drop vertical jumps help identify non-contact knee injury risk? A one-year prospective study

BACKGROUND

Previous studies showed that the amount of hip flexion and the combination of knee valgus and lateral trunk motion, measured with two-dimensional video analysis, were related to three-dimensional measured knee joint moments during single-leg drop vertical jumps, but it remains unclear whether these measurements can be used to identify non-contact knee injury risk.

METHODS

Fifty injury-free female athletes participated in the study. Two-dimensional video analysis was used to measure hip flexion, knee valgus and lateral trunk motion angles during single-leg drop vertical jumps. Time loss non-contact knee injuries were registered during a one-year follow-up. Independent t-tests and receiver operating characteristic analysis were used to analyze the predictive ability of the two-dimensional angles.

FINDINGS

Seven participants sustained a time loss non-contact knee injury. Hip flexion was not significantly different between groups (P>.05). The combination of knee valgus and lateral trunk motion was significantly smaller in the injured (P=.036) and non-injured legs (P=.009) of the future injured group compared with the respective matched leg of the non-injured group. The receiver operating characteristic analysis showed a significant discriminative accuracy between groups for the combination of knee valgus and lateral trunk motion of the uninjured leg of the future injured group with the matched leg of the non-injured group (area under curve=0.803; P=.012).

INTERPRETATION

The measurement of a combination of increased knee valgus and ipsilateral trunk motion during the single-leg drop vertical jump with two-dimensional video analysis can be used to help identify female athletes with increased non-contact knee injury risk.