Divided attention during cutting influences lower extremity mechanics in female athletes

Relationships between Patient-Reported Outcomes and Predictors of Second ACL Injuries during Unanticipated Jump Landings

BACKGROUND

Reactive and external visual-cognitive demands are prevalent in sport and likely contribute to anterior cruciate ligament (ACL) injury scenarios. However, these demands are absent in common return-to-sport assessments. This disconnect leaves a blind spot for determining when an athlete can return to sport with mitigated re-injury risk.

PURPOSE

To characterize relationships between patient-reported outcome measures (PROMs) and cognitive-task interference (i.e., cognitive demands exacerbating neuromuscular impairments) for biomechanical predictors of second ACL injuries during jump landings that involved rapid unanticipated decision making.

METHODS

Thirty-six persons following primary ACL reconstruction (ACLR; 26 females/10 males, 19.8 ± 1.8 yr; 1.71 ± 0.1 m; 69.6 ± 12.8 kg, 1.5 ± 0.6 yr post-ACLR; Tegner: 6.8 ± 1.8) participated. PROMs of ACL-RSI and the Forgotten Joint Score-12 Knee (FJS-12) were selected to assess altered psychological state (e.g., confidence, attention toward knee). Jumping tasks under anticipated and unanticipated secondary jump directions were performed. Biomechanical variables were dual-task changes (unanticipated - anticipated) in 1) uninvolved limb hip rotator impulse (DTC_Uni-HRot_Imp), 2) asymmetry of knee extensor moment at initial contact (DTC_KEM_Asym), and 3) range of involved knee abduction angle (DTC_KAbA_Range). Regression models tested for relationships between PROMs and the dual-task change in biomechanical variables.

RESULTS

ACL-RSI (DTC_Uni-HRot_Imp ( P < 0.001)) and FJS-12 (DTC_KAbA_Range ( P = 0.001)) had significant relationships with dual-task change in the opposite direction as expected (worse PROM ➔ less dual-task change). A follow-up analysis indicated that dual-task change was inversely correlated with the baseline estimates for kinetic biomechanical variables (less risky single-task biomechanics ➔ greater dual-task change for Uni-HRot_Imp and KEM_Asym).

CONCLUSIONS

The collective results are consistent with higher functioning participants (better PROMs) who also demonstrate desirable biomechanics during single-task conditions being prone to demonstrating the greatest risk-associated DTC in unanticipated scenarios.

Neurophysiology of ACL Injury

The neurophysiology of ACL injury extends beyond the mechanical rupture of the ligament to encompass profound alterations in the central and peripheral nervous systems, impacting sensorimotor integration and neuromuscular control. The ACL, densely populated with mechanoreceptors, plays a critical role in joint proprioception, dynamically regulating knee stability through complex neural circuits that connect to the spinal cord and brain. When disrupted by injury, these neural pathways contribute to delayed muscular activation, altered motor planning, and compromised joint stability. Such neuromechanical deficits increase the likelihood of reinjury and highlight the need for comprehensive neuroplastic rehabilitation. Neuroplastic therapy, employing tools like external focus strategies, stroboscopic glasses, smartboards, and virtual reality, aims to restore and enhance neural connectivity, sensory integration, and motor coordination. These advanced tools target distinct phases of motor learning, promoting automaticity and resilience in movement patterns. By integrating visual-cognitive, proprioceptive, and reflexive controls, this therapeutic approach not only accelerates recovery but also optimizes performance and reduces the risk of re-injury, representing a paradigm shift in ACL rehabilitation.

Relationship between Cognitive Demands and Biomechanical Indicators Associated with Anterior Cruciate Ligament Injury: A Systematic Review

BACKGROUND

Anterior cruciate ligament (ACL) injury during contact sports has a high incidence that has not been reduced despite the immense resources devoted to understanding its aetiology. A neurocognitive approach could increase knowledge of the mechanisms contributing to ACL injury enabling practitioners to address and minimise future risk.

OBJECTIVE

To systematically review the influence of manipulating cognitive demands during motor tasks (i.e. degree of uncertainty) on biomechanical variables associated with ACL injury risk.

METHODS

A systematic review was performed according to the Cochrane Handbook for Systematic Reviews of Interventions by searching the major sporting electronic databases. The search strategy included four groups of terms and was conducted by two authors independently. All studies were screened using unique inclusion criteria, with the included studies assessed for risk of bias.

RESULTS

Twenty-five studies were identified from 2031 records and included into the review process. During the experimental conditions where cognitive demands were higher, most biomechanical indicators associated with a greater risk of ACL injury during landing and cutting tasks were significantly enhanced compared with conditions with low or no cognitive demands.

CONCLUSIONS

An increase in task complexity through cognitive load significantly leads to changes in mechanisms associated with ACL injury during single-leg landings and cutting movements. Consequently, coaches and exercise professionals should consider inclusion of dual-task paradigms or uncertainty during injury risk assessment scenarios and injury prevention programs to help identify athletes at risk of ACL injury and reduce ACL injury frequency.

REGISTRATION

This protocol was registered in the PROSPERO database ( https://www.crd.york.ac.uk/PROSPERO ) in May 2022, with the registration number CRD42022315795.

Increased Visual Attentional Demands Alter Lower Extremity Sidestep Cutting Kinematics in Male Basketball Players

Background

In basketball, changing direction is one of the primary mechanisms of anterior cruciate ligament (ACL) injury, often occurring within complex game situations with high cognitive demands. It is unknown how visual attention affects sidestep cutting kinematics during the entire energy absorption phase of the cut in an ecologically valid environment.

Purpose

The purpose of this research was to study the effect of added cognitive load, in the form of increased visual attentional demands, on sidestep cutting kinematics during the energy absorption phase of the cut in an ecologically valid environment.

Study Design

Crossover Study.

Methods

Fifteen male basketball players (aged 22.1 ± 2.3) performed ten sidestep cutting movements without (BASE) and with (VIS) a visual attention dual task. 3D kinematics of the hip, knee and ankle were recorded utilizing Xsens IMU motion capture. Temporal kinematics were analyzed using Statistical Parametric Mapping. Discrete time point kinematics were additionally analyzed at initial contact (IC) and at peak knee flexion utilizing paired t-tests. Effect sizes were calculated.

Results

Hip flexion was significantly reduced in the VIS condition compared to the BASE condition (p<0.01), including at IC (VIS 35.0° ± 7.2°, BASE 40.7° ± 4.9°, p=0.02, d=0.92) and peak (VIS 37.8° ± 9.7°, BASE 45.5° ± 6.9°, p=0.001, d=0.90). Knee flexion was significantly reduced in the VIS condition, in comparison to the BASE condition (p<0.01), at peak (VIS 59.9° ± 7.5°, BASE 64.1° ± 7.4°, p=0.001, d=0.55).

Conclusion

The addition of visual attention during sidestep cutting altered lower limb kinematics, which may increase ACL injury risk. It is suggested that ACL injury risk screening and prevention should include sidestep cutting with visual attentional demands, in order to mimic the cognitive demands of the sports environment.

Level of Evidence

3.

Think fast, stay healthy? A narrative review of neurocognitive performance and lower extremity injury

BACKGROUND

Lower extremity (LE) injury has been problematic in athletic populations. While previous research has identified biomechanical and neuromuscular risk factors, more recent efforts have determined that neurocognitive performance (NP) may influence LE injury risk.

OBJECTIVES

To describe the present findings pertaining to the relationship between NP and LE injury. This review described potential cerebral neural mechanisms underpinning LE injury with a particular emphasis on the role of vision in sensorimotor integration. Lastly, newer technology such as stroboscopic eyewear, smartboards, and virtual/augmented reality were discussed for their utility in assessing and training NP.

METHODS

Narrative review that described NP and LE injury, as well as plausible mechanisms and training interventions.

RESULTS

NP appears to influence both LE biomechanics and LE injury risk. Athletes with worse NP demonstrated decreased knee flexion and increased frontal plane knee loading compared to better performing athletes. Most studies determined an association between NP and LE injury risk. Visual motor reaction time, processing speed, and working memory appear to be useful NP measures for identifying athletes at risk for LE injury. Various brain regions including the precuneus and lingual gyrus may be implicated as neural signatures for LE injury. While recently developed technology offer promise, far-transfer effects to LE injury risk reduction have yet to be substantially investigated.

CONCLUSIONS

NP should be considered an important component for identifying LE injury risk. Sports scientists and clinicians may consider a variety of assessments and interventions to quantify and train NP in conjunction with previously established protocols.

Neurocognitive & Ecological Motor Learning Considerations for the 11+ ACL Injury Prevention Program: A Commentary

The 11+ is a structured warm-up program designed to prevent injuries in soccer players, but has proven efficacy in many populations, settings and sports. It consists of 15 exercises that target the most common injury sites, such as the knee, ankle, and groin. However, the implementation and adherence of the 11+ remain suboptimal, and recent compelling data indicates underlying mechanisms of injury risk related to neural control of movement may not be adequately targeted. Updates to the 11+ considering practical implications of neurocognitive and ecological motor learning may be warranted for coaches and practitioners. We review the evidence on how an updated 11+ may influence the cognitive and perceptual processes involved in motor control and learning, such as attention, anticipation, decision making, and feedback. How the 11+ can be adapted to the ecological constraints and affordances of the football (soccer) environment is also discussed, including the task, the individual, and the context. By considering these factors, the 11+ can be more effective, engaging, and enjoyable for the players, and thus improve its adoption and compliance. The 11+ has the capability to not only a physical warm-up, but also a neurocognitive and ecological preparation for the game. Therefore, the purpose of this manuscript is to describe the conceptual design of a new ecological neurocognitively enriched 11+, that builds on the strong foundation of the original intervention with considerations for the newly discovered potential neural control of movement risk factors.

Biomechanic Differences Between Anticipated and Unanticipated Volleyball Block Jump: Implications for Lower Limb Injury Risk

Volleyball is a high-intensity sport characterized by repetitive jumping, sudden directional changes, and overhead movements, all of which significantly increase the risk of injuries, particularly to the shoulders, knees, and ankles. Despite the frequency of injuries caused by actions like blocking and spiking, there has been limited research focused on the specific biomechanical risk factors unique to volleyball. This study aimed to investigate the lower limb biomechanics during block jumps in both the dominant and non-dominant directions, under both anticipated and unanticipated conditions, in fifteen elite male volleyball players. Kinematic and kinetic data from the ankle, knee, and hip joints were recorded. Our results revealed statistically significant differences between the dominant and non-dominant directions at the ankle, knee, and hip joints. The non-dominant direction exhibited a greater ankle dorsiflexion angle and velocity, as well as higher knee flexion angle, velocity, moment, power, and abduction moment, along with increased hip flexion angle and power. Additionally, unanticipated movements led to increases in vertical ground reaction force (vGRF), hip extension moment, and flexion power, while ankle dorsiflexion plantarflexion velocity and knee flexion power decreased. It appears that movements in the dominant direction were stiffer and less cushioned, potentially increasing the risk of injury. While the non-dominant direction provided better shock absorption, it also elevated the knee valgus moment, which could increase the load on the knee. Furthermore, in unanticipated situations, athletes with short reaction times, unable to quickly adjust their automated movement patterns, faced a higher risk of limb overuse, thereby increasing the likelihood of injury. In practice, coaches should consider differences in limb coordination and movement direction, incorporating unilateral preventive exercises to reduce the risk of injury.

An ecological dynamics approach to ACL injury risk research: a current opinion

Research of non-contact anterior cruciate ligament (ACL) injury risk aims to identify modifiable risk factors that are linked to the mechanisms of injury. Information from these studies is then used in the development of injury prevention programmes. However, ACL injury risk research often leans towards methods with three limitations: 1) a poor preservation of the athlete-environment relationship that limits the generalisability of results, 2) the use of a strictly biomechanical approach to injury causation that is incomplete for the description of injury mechanisms, 3) and a reductionist analysis that neglects profound information regarding human movement. This current opinion proposes three principles from an ecological dynamics perspective that address these limitations. First, it is argued that, to improve the generalisability of findings, research requires a well-preserved athlete-environment relationship. Second, the merit of including behaviour and the playing situation in the model of injury causation is presented. Third, this paper advocates that research benefits from conducting non-reductionist analysis (i.e., more holistic) that provides profound information regarding human movement. Together, these principles facilitate an ecological dynamics approach to injury risk research that helps to expand our understanding of injury mechanisms and thus contributes to the development of preventative measures.

Neuromuscular fatigue and cognitive constraints independently modify lower extremity landing biomechanics in healthy and chronic ankle instability individuals

The purpose was to determine the impact of both cognitive constraint and neuromuscular fatigue on landing biomechanics in healthy and chronic ankle instability (CAI) participants. Twenty-three male volunteers (13 Control and 10 CAI) performed a single-leg landing task before and immediately after a fatiguing exercise with and without cognitive constraints. Ground Reaction Force (GRF) and Time to Stabilization (TTS) were determined at landing in vertical, anteroposterior (ap) and mediolateral (ml) axes using a force plate. Three-dimensional movements of the hip, knee and ankle were recorded during landing using a motion capture system. Exercise-induced fatigue decreased ankle plantar flexion and inversion and increased knee flexion. Neuromuscular fatigue decreased vertical GRF and increased ml GRF and ap TTS. Cognitive constraint decreased ankle internal rotation and increased knee and hip flexion during the flight phase of landing. Cognitive constraint increased ml GRF and TTS in all three axes. No interaction between factors (group, fatigue, cognitive) were observed. Fatigue and cognitive constraint induced greater knee and hip flexion, revealing higher proximal control during landing. Ankle kinematic suggests a protective strategy in response to fatigue and cognitive constraints. Finally, these two constraints impair dynamic stability that could increase the risk of ankle sprain.

Neurocognitive Errors and Noncontact Anterior Cruciate Ligament Injuries in Professional Male Soccer Players

CONTEXT

Evidence is emerging that core neurocognitive functions such as working memory and inhibitory control (ie, motor-response and attentional inhibition) are linked to the anterior cruciate ligament (ACL) injury risk. Research has been conducted in laboratory settings, but the contribution of neurocognition to actual ACL injuries under real-world conditions is unknown.

OBJECTIVE

To describe the possible neurocognitive errors involved in noncontact ACL injury mechanisms.

DESIGN

Case series.

SETTING

Soccer matches.

PATIENTS OR OTHER PARTICIPANTS

A total of 47 professional male soccer players.

MAIN OUTCOME MEASURE(S)

Three independent reviewers evaluated 47 videos of players sustaining noncontact ACL injuries. Neurocognitive errors in inhibitory control were operationalized as follows: (1) motor-response inhibition was scored when a player demonstrated poor decision-making and approached the opponent with high speed that reduced the ability to stop or change the intended action and (2) an attentional error was scored when a player shifted his selective attention away from the relevant task to irrelevant stimuli.

RESULTS

Of 47 noncontact ACL injuries, 26 (55%) were related to a pressing-type injury, 19 (73%) of which involved a deceiving action made by the opponent, suggesting poor inhibitory control of the defender. Of the remaining 21 noncontact ACL injuries (45%), 16 (76%) could be attributed to attentional errors. Agreement among the 3 raters was very good for all items except poor decision-making, which showed fair to good agreement (Fleiss κ = 0.71). Interrater reliability was excellent (intraclass correlation coefficient = 0.99-1.00).

CONCLUSIONS

Errors in motor-response inhibitory control and attentional inhibition were common during noncontact ACL injury events in professional male soccer players. The interrater agreement in detecting neurocognitive errors in general was very good.

The Effects of Various Cognitive Tasks Including Working Memory, Visuospatial, and Executive Function on Postural Control in Patients With Anterior Cruciate Ligament Injury

Anterior cruciate ligament (ACL) rupture can impair balance performance, particularly during cognitive motor dual-tasks. This study aimed to determine the effects of various modalities of cognitive load (working memory, and visuospatial and executive function) on postural control parameters in individuals with ACL injury. Twenty-seven ACL-injured and 27 healthy participants were evaluated doing different cognitive tasks (silent backward counting, Benton's judgment of line orientation, and Stroop color-word test) while standing on a rigid surface or a foam. Each task was repeated three times and then averaged. Center of pressure variables used to measure postural performance included sway area and sway velocity in anterior-posterior and medial-lateral directions. Cognitive performance was also assessed by calculating errors and the score of cognitive tasks. A mixed model analysis of variance for center of pressure parameters indicated that patients had more sways than the healthy group. The interaction of group by postural difficulty by cognitive tasks was statistically significant for cognitive errors (p < .01), and patients with ACL injury indicated more cognitive errors compared to healthy controls while standing on the foam. The main effect of cognitive task was statistically significant for all postural parameters, representing reduced postural sways in both groups with all cognitive tasks. However, ACL-injured patients showed more cognitive errors in difficult postural conditions, suggesting that individuals with ACL injury may prioritize postural control over cognitive task accuracy and adopt the posture-first strategy to maintain balance under dual-task conditions.

Dual tasking increases kinematic and kinetic risk factors of ACL injury

ACL injuries are common among athletes playing team sports. The impact of divided attention during team sports on landing mechanics is unclear. Twenty-one healthy females jumped at a 60° angle to their right and performed a second jump to their right or left at a 60° angle. The direction of the second jump was shown before movement (baseline) or mid-flight of the first jump (dual task). The signal for the dual-task conditions showed five arrows and the middle one indicated the jump direction (Flanker paradigm). The other arrows pointed in the same (congruent) or the opposite (incongruent) direction as the middle arrow. Results indicated larger initial and peak knee flexion angles, smaller peak knee valgus moments, and smaller vertical and posterior GRFs during baseline right jumps compared to other conditions. Peak posterior GRF was increased in the incongruent condition compared to the congruent condition during left jumps. Performance was decreased with longer stance times for the dual task compared to the baseline in both jump directions. Further, the incongruent condition had a longer stance time than the congruent condition during left jumps. More research focusing on decision-making with more challenging visual stimuli mimicking dynamic team sports is merited.

Do Differences Exist in Impact Test Domains between Youth Athletes with and without an Anterior Cruciate Ligament Injury?

Poor baseline reaction time, as measured via the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT), has been associated with anterior cruciate ligament (ACL) injury risk in adult athletes. Our study sought to determine whether the reaction time and impulse control ImPACT test domains differed between ACL injured and uninjured pediatric athletes. A total of 140 high-school aged athletes comprising 70 athletes who went on to sustain an ACL injury between 2012 and 2018 and 70 age- and sex-matched uninjured controls were included in the study. Mean reaction times were similar for the injured (0.67 s) and uninjured (0.66 s) athletes (p = 0.432), and the impulse control scores were also similar for those with (5.67) and without (6.07) an ACL injury (p = 0.611). Therefore, neurocognitive risk factors for sustaining an ACL injury in adults cannot necessarily be extrapolated to adolescent athletes. Further research is needed to understand why differences exist between injury risk in youth and adult athletes.

The effect of dual-task on jump landing kinematics and kinetics in female athletes with or without dynamic knee valgus

It has been indicated that dual tasks may multiply the possibility of injuries due to divided attention. This study aimed to investigate the effect of dual-task on kinematics and kinetics of jump landing in female athletes with and without dynamic knee valgus. In this study, 32 recreational athletes between 18 and 30 years old were recruited and divided into with (n = 17) and without (n = 15) dynamic knee valgus groups. The 3-D positions of retroreflective markers were recorded at 200 Hz using a 8-camera Kestrel system (Motion Analysis Corporation, Santa Rosa, CA), while ground reaction forces were synchronously recorded at 1000 Hz using 2 adjacent force plates (FP4060-NC; Bertec Corporation, Columbus, OH). Kinematics and kinetics of jump landing were recorded while counting backward digits as a dual task, and also without counting backward digits as a single task. One-way repeated measures of variance were used to analyse data at the significant level of 95% (α < 0.05). The study found that the dual-task affected the angles and moments of hip, knee, and ankle joints (P < 0.05) in both groups. Additionally, the effect of the dual-task differed significantly between the two groups in the angles hip flexion (P < 0.001), knee abduction (P < 0.001), and ankle internal rotation (P = 0.001), as well as the moments hip flexion (P < 0.001), hip abduction (P = 0.011), knee flexion (P = 0.017), knee internal rotation (P < 0.001), ankle dorsiflexion (P = 0.046), ankle eversion (P < 0.001), and ankle internal rotation (P = 0.046). Athletes with dynamic knee valgus may have been less able to protect themselves during the landing and are more prone to lower extremities injuries. As a result, using kinematics and kinetics in athletes with dynamic knee valgus during landing may help identify potential mechanisms associated with risk factors of lower extremity injuries and ACL injuries as well.

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

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

Effect of combining eight weeks of neuromuscular training with dual cognitive tasks on landing mechanics in futsal players with knee ligament dominance defect: a randomized controlled trial

BACKGROUND

The performing of jump and landing in futsal simultaneous with divided attention is one of the most common mechanisms of non-contact anterior cruciate ligament (ACL) injury. Neuromuscular training has effectively reduced the risk of ACL injury, but the effect of neurocognitive training has received less attention. This study investigated the effect of combining 8 weeks of neuromuscular training with dual cognitive tasks on the landing mechanics of futsal players with knee ligament dominance defects.

METHODS

Thirty male futsal players (mean ± SD: age: 21.86 ± 3.27 years) with knee ligament dominance defects were purposefully identified by the tuck jump test and were randomly divided into the intervention and the control group. The intervention group performed dual task (DT) training for three weekly sessions for 8 weeks and 60 min each, while the control group only did activities of daily living. During the drop vertical jump test, 2D landing kinematics in two moments of initial contact (IC) and full flexion (FF) were assessed. Data were analyzed by means of 2 × 2 repeated measures ANOVA followed by post hoc comparison (Bonferroni) at the significance level of (α ≤ 0.05).

RESULTS

A significant improvement was observed in the intervention group compared to the control group for the dynamic knee valgus at IC (F1,28 = 6.33; P = 0.02, ES = 0.31) and FF (F1,28 = 13.47; P = 0.003, ES = 0.49), knee flexion at IC (F1,28 = 20.08; P = 0.001, ES = 0.41) and FF (F1,28 = 13.67; P = 0.001, ES = 0.32), ankle dorsiflexion at IC (F1,28 = 37.17; P = 0.001, ES = 0.72) and FF (F1,28 = 14.52; P = 0.002, ES = 0.50), and trunk flexion at FF (F1,28 = 20.48; P = 0.001, ES = 0.59) angles. Changes in the trunk flexion at IC (F1,28 = 0.54; P = 0.47, ES = 0.03) and trunk lateral flexion at IC (F1,28 = 0.006; P = 0.93, ES = 0.00) and FF (F1,28 = 2.44; P = 0.141, ES = 0.148) angles were not statistically significant.

CONCLUSIONS

DT training compared to the control group improved landing mechanics in futsal players with knee ligament dominance defects.

TRIAL REGISTRATION

Current Controlled Trials using the IRCT website with ID number IRCT20210602051477N1 prospectively registered on 20/06/2021.

Effects of perceptual-cognitive tasks on inter-joint coordination of soccer players and ordinary college students

Perceptual-cognitive tasks play a pivotal role in performing voluntary movements, which is crucial for good performances among soccer players. This study explored the effect of perceptual-cognitive tasks on the inter-joint coordination of soccer players and college students during landing. The classic multiple objective tracking (MOT) task was used to simulate the perceptual-cognitive task under a sports environment. Fifteen soccer players (age: 20.1 ± 1.5 year, height: 181.4 ± 7.4 cm, weight: 75.4 ± 10.7 kg) and twenty ordinary college students (age: 20.0 ± 2.3 years, height: 177.9 ± 4.9 cm, weight: 71.6 ± 9.9 kg) were enrolled to the study. Participants in the two groups were subjected to a single task (landing task) and dual-task (MOT task and landing task). Coordination and variability indicators were recorded using a Vicon infrared motion capture system and a force measuring platform. The results showed that the mean absolute relative phase of hip and knee joint (MARP_hip-knee), deviation phase of hip and knee joint (DP_hip-knee), and deviation phase of knee and ankle joint (DP_knee-ankle) of the two groups under the dual-task were significantly different compared with the parameters when participants were subjected to the single task. The dual-task had higher effect size on DP_hip-Knee and MARP_hip-knee, indicating that dual-task had a greater impact on coordination of the hip and knee joints. DP_hip-knee and DP_knee-ankle of ordinary students were more extensive relative to those of the soccer players, and hip joint stiffness (K_hip) for ordinary students was lower than that of the soccer players under the different tasks. These findings implied that the perceptual-cognitive task markedly affected the inter-joint coordination of soccer players and college students, mainly by impairing the hip and knee coordination. Although there is less variability in lower extremity coordination patterns of soccer players compared to college students, the MOT task still affects their coordination ability.

Analysis of Functional Arch Support Insoles on the Biomechanics and Performance in Right-Forward Lunging Step of Badminton Players

The purpose of this study was to examine the differences in biomechanical parameters and sports-specific performance of lower limbs between arch support insoles (ASI) and flat insoles (FLI) when performing net strides. After installing the MVN IMU system, 18 college badminton team members were asked to take the following tests: (1) Consecutive net stride tests; (2) Six-point footwork tests; (3) Retrieve/stroke the ball at the left and right net; (4) Smash and retrieve/stroke the ball at the net; (5) Smash at the front and back crossover step. The joint angle of the lower limbs and ground reaction force during the support phase was collected. The results demonstrated that the peak right hip flexion angle was significantly greater with ASI than FLI (63.09 ± 10.70; 60.08 ± 13.82; p = 0.028), while the peak right foot inversion angle was significantly smaller with ASI than FLI (20.68 ± 7.87; 23.85 ± 8.11; p = 0.013). The principal conclusion was that the arch support insole avoids the decrease in the hip flexion angle and the increase in the foot inversion angle during the net stride tests.

The effects of visual cognitive tasks on landing stability and lower extremity injury risk in high-level soccer players

BACKGROUND

Visual cognition plays a pivotal role in sports. It is widely recognized that there is an intriguing coupling that they could affect each other through interaction between visual cognition and motor control, but few studies linked the effects of visual cognitive tasks on landing stability to postural control and injury risk.

RESEARCH QUESTION

Whether visual cognitive tasks affect the landing stability and lower limb injury risk of professional soccer players?

METHODS

The current study used a three-dimensional Multiple Object Tracking (MOT) task to simulate visual cognitive difficulties experienced in soccer matches. Fifteen male high-level soccer athletes (height: 181.43 ± 7.36 cm, weight: 75.37 ± 10.67 kg, training years: 10.07 ± 2.98 yr) from our school team were recruited and completed a landing action from a high platform with and without MOT tasks. Vicon infrared high-speed motion capture system and three-dimensional force measuring platform were used to collect various outcomes simultaneously.

RESULTS

The Time to Stabilization (TTS) during landing was significantly prolonged, while the Medial-Lateral Stability Index (MLSI), Anterior-Posterior Stability (APSI), Dynamic Postural Index Stability Index (DPSI), the trajectory lengths, and envelope area of COP during landing were also increased during MOT dual-task.

DISCUSSION

The decline of these indicators reflected the deterioration in postural stability and greater requirements for maintaining balance which could increase the risk of injury in soccer athletes. We advocate that adequate visual attention and visual information processing might play critical roles in maintaining dynamic balance through the supraspinal neural network.

The Effects of Increasing Cognitive Load on Support Limb Kicking Mechanics in Male Futsal Players

Our objective was to examine the effects of cognitive load on support limb mechanics during a futsal kicking task. Twenty-one male futsal players completed kicks of a stationary ball without a secondary task (baseline), as well as kicks where cognitive load was increased by including a secondary cognitive task (dual-task) and requiring tracking of ball movement before the kick (pass). The athletes demonstrated less hip and knee flexion, higher loading rates, greater frontal and sagittal plane knee loading, and greater knee abduction for the dual-task condition, vs. baseline. They also demonstrated less knee flexion, higher loading rates, greater sagittal plane knee loading, and greater knee abduction for the pass condition, vs. baseline. It appears that cognitive load influences kicking mechanics.

Effect of unplanned athletic movement on knee mechanics: a systematic review with multilevel meta-analysis

OBJECTIVE

To compare the effects of pre-planned and unplanned movement tasks on knee biomechanics in uninjured individuals.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

Five databases (PubMed, Google Scholar, Cochrane Library, ScienceDirect and Web of Science) were searched from inception to November 2020. Cross-sectional, (randomised) controlled/non-controlled trials comparing knee angles/moments of pre-planned and unplanned single-leg landings/cuttings were included. Quality of evidence was assessed using the tool of the Grading of Recommendations Assessment, Development and Evaluation working group.

METHODS

A multilevel meta-analysis with a robust random-effects meta-regression model was used to pool the standardised mean differences (SMD) of knee mechanics between pre-planned and unplanned tasks. The influence of possible effect modifiers (eg, competitive performance level) was examined in a moderator analysis.

RESULTS

Twenty-five trials (485 participants) with good methodological quality (Downs and Black) were identified. Quality of evidence was downgraded due to potential risk of bias (eg, confounding). Moderate-quality evidence indicates that unplanned tasks evoked significantly higher external knee abduction (SMD: 0.34, 95% CI: 0.16 to 0.51, 14 studies) and tibial internal rotation moments (SMD: 0.51, 95% CI: 0.23 to 0.79, 11 studies). No significant between-condition differences were detected for sagittal plane mechanics (p>0.05). According to the moderator analysis, increased abduction moments particularly occurred in non-professional athletes (SMD: 0.55, 95% CI: 0.14 to 0.95, 5 studies).

CONCLUSION

Unplanned movement entails higher knee abduction and tibial internal rotation moments, which could predispose for knee injury. Exercise professionals designing injury-prevention protocols, especially for non-elite athletes, should consider the implementation of assessments and exercises requiring time-constrained decision-making.

PROSPERO REGISTRATION NUMBER

CRD42019140331.

Neurocognitive and Neurophysiological Functions Related to ACL Injury: A Framework for Neurocognitive Approaches in Rehabilitation and Return-to-Sports Tests

Context:

Only 55% of the athletes return to competitive sports after an anterior cruciate ligament (ACL) injury. Athletes younger than 25 years who return to sports have a second injury rate of 23%. There may be a mismatch between rehabilitation contents and the demands an athlete faces after returning to sports. Current return-to-sports (RTS) tests utilize closed and predictable motor skills; however, demands on the field are different. Neurocognitive functions are essential to manage dynamic sport situations and may fluctuate after peripheral injuries. Most RTS and rehabilitation paradigms appear to lack this aspect, which might be linked to increased risk of second injury.

Objective:

This systematic and scoping review aims to map existing evidence about neurocognitive and neurophysiological functions in athletes, which could be linked to ACL injury in an integrated fashion and bring an extensive perspective to assessment and rehabilitation approaches.

Data Sources:

PubMed and Cochrane databases were searched to identify relevant studies published between 2005 and 2020 using the keywords ACL, brain, cortical, neuroplasticity, cognitive, cognition, neurocognition, and athletes.

Study Selection:

Studies investigating either neurocognitive or neurophysiological functions in athletes and linking these to ACL injury regardless of their design and technique were included.

Study Design:

Systematic review.

Level of Evidence:

Level 3.

Data Extraction:

The demographic, temporal, neurological, and behavioral data revealing possible injury-related aspects were extracted and summarized.

Results:

A total of 16 studies were included in this review. Deficits in different neurocognitive domains and changes in neurophysiological functions could be a predisposing risk factor for, or a consequence caused by, ACL injuries.

Conclusion:

Clinicians should view ACL injuries not only as a musculoskeletal but also as a neural lesion with neurocognitive and neurophysiological aspects. Rehabilitation and RTS paradigms should consider these changes for assessment and interventions after injury.

The influence of decision making and divided attention on lower limb biomechanics associated with anterior cruciate ligament injury: a narrative review

Cognitive loads have been shown to influence anterior cruciate ligament (ACL) injury risk. Two main sources of cognitive loads that athletes experience are decision making and dividing attention between multiple tasks. The aim of this paper was to review previous studies examining the effects of decision making and divided attention on lower limb biomechanics during landing and cutting. Previous research has shown decision making to significantly influence a number of biomechanical variables associated with increased risk of ACL injury, such as reduced knee flexion at initial contact, increased knee valgus angles, increased knee extension moment and increased knee valgus moment in decision-making tasks compared to pre-planned tasks. Furthermore, dividing attention between multiple tasks has been shown to result in reduced knee flexion at initial contact, increased vertical ground reaction force, and reduced stability during landing/cutting. The changes in lower limb biomechanics observed as a result of both decision making and dividing attention are likely due to a reduced ability to anticipate ground contact and implement protective movement patterns associated with reduced ACL loading. Collectively, these findings emphasise the need for tasks that incorporate decision making and divided attention when investigating ACL injury mechanisms and developing ACL injury risk screening assessments.

Trunk motion and anterior cruciate ligament injuries: a narrative review of injury videos and controlled jump-landing and cutting tasks

The aims of this narrative review were to summarise trunk motion and external trunk perturbation observed in anterior cruciate ligament (ACL) injury videos and to review the association between trunk motion and ACL loading variables in controlled jump-landing and cutting tasks in non-injured populations. Video analyses have shown limited trunk flexion and increased trunk lateral bending towards the injured leg are associated with increased risk of ACL injuries, while trunk axial rotation away from the injured leg is more frequent than rotation towards the injured leg. Contact with the trunk before and at the time of the injury is common and might increase the risk of ACL injury. Controlled jump-landing and cutting studies have shown that limited trunk flexion and increased trunk lateral bending are associated with increased ACL loading. However, the findings of trunk axial rotation are not consistent with most video analyses. Mid-flight external trunk perturbation could increase ACL loading variables for one leg and is consistent with the videos of trunk-contact ACL injuries. These findings may help understand the role of trunk motion on primary ACL injury mechanisms and improve ACL injury screening tasks and ACL injury prevention strategies with the consideration of trunk motion.

DUAL-TASK ASSESSMENT IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY: A SYSTEMATIC REVIEW

Background

Several systematic reviews have evaluated the role of dual-task assessment in individuals with concussion. However, no systematic reviews to date have investigated dual-task protocols with implications for individuals with anterior cruciate ligament (ACL) injury or ACL reconstruction (ACLR).

Purpose

To systematically review the evidence on dual-task assessment practices applicable to those with ACL deficiency/ACLR, specifically with the aim to identify motor-cognitive performance costs.

Study Design

Systematic review.

Methods

A systematic literature review was undertaken on those with ACL-deficient or ACL-reconstructed knees performing dual-task activities. The following databases were searched from inception to June 8, 2018 including CINAHL, PsychInfo, PubMed, SPORTDiscus, Web of Science, and gray literature. Three primary search categories (knee, cognition, and motor task) were included. Only one reviewer independently performed the database search, data extraction, and scored each article for quality. All studies were assessed for quality and pertinent data were extracted, examined and synthesized.

Results

Ten studies were included for analysis, all of which were published within the prior ten years. Performance deficits were identified in those with either ACL deficiency or ACLR while dual-tasking, such as prioritization of postural control at the expense of cognitive performance, impaired postural control in single limb stance, greater number of cognitive errors, and increased step width coefficient of variation while walking. No studies examined those with prior ACL injury or ACLR during tasks that mimicked ACL injury mechanisms such as jump-landing or single-leg cutting.

Conclusion

The results of the current systematic review suggests that postural control, gait, and/or cognitive deficits exist when evaluated under a dual-task paradigm in those with ACL deficiency or ACLR. This systematic review highlights the need for future research on dual-task assessment for individuals who have sustained an ACL injury or undergone ACLR, specifically utilizing more difficult athletic movements.

Level of Evidence

Level 3a.

Increased visual distraction can impair landing biomechanics

Failed jump landings represent a key mechanism of musculoskeletal trauma. It has been speculated that cognitive dual-task loading during the flight phase may moderate the injury risk. This study aimed to explore whether increased visual distraction can compromise landing biomechanics. Twenty-one healthy, physically active participants (15 females, 25.8 ± 0.4 years) completed a series of 30 counter-movement jumps (CMJ) onto a capacitive pressure platform. In addition to safely landing on one leg, they were required to memorize either one, two or three jersey numbers shown during the flight phase (randomly selected and equally balanced over all jumps). Outcomes included the number of recall errors as well as landing errors and three variables of landing kinetics (time to stabilization/TTS, peak ground reaction force/pGRF, length of the centre of pressure trace/COPT). Differences between the conditions were calculated using the Friedman test and the post hoc Bonferroni-Holm corrected Wilcoxon test. Regardless of the condition, landing errors remained unchanged (p = .46). In contrast, increased visual distraction resulted in a higher number of recall errors (chi² = 13.3, p = .001). Higher cognitive loading, furthermore, appeared to negatively impact mediolateral COPT (p < .05). Time to stabilization (p = .84) and pGRF (p = .78) were unaffected. A simple visual distraction in a controlled experimental setting is sufficient to adversely affect landing stability and task-related short-term memory during CMJ. The ability to precisely perceive the environment during movement under time constraints may, hence, represent a new injury risk factor and should be investigated in a prospective trial.

The Effects of a Cognitive Dual Task on Jump-landing Movement Quality

Investigations on movement quality deficits associated with jump landing are numerous, however, these studies are often performed in laboratories with little distraction to the participant. This is contrary to how injury typically occurs secondary to sport-specific distraction where the athlete is cognitively loaded during motor performance. Thus, the purpose of this study was to determine the effect of a cognitive load on jump-landing movement quality. A dual-task design was used to determine the effects of a dual-task on tuck jump movement quality in 20 participants. There were three cognitive conditions (no cognitive task, easy-cognitive task, and difficult-cognitive task). The dual task elicited statistically significant changes in overall tuck jump score (movement quality) across the conditions with tuck jump score increasing from 3.52±1.64 baseline to 4.37±1.25 with the easy-cognitive task to 4.67±1.24 with the difficult-cognitive task. The findings of this study may be useful to screen for individuals at risk of lower extremity injury utilizing the tuck jump when paired with a cognitive task. The screening would then identify individuals who may have poor neuromuscular control when cognitively loaded.

Change of Direction Assessment Following Anterior Cruciate Ligament Reconstruction: A Review of Current Practice and Considerations to Enhance Practical Application

Change of direction (CoD) has been indicated as a key mechanism in the occurrence of anterior cruciate ligament (ACL) injury during invasion sports. Despite these associations, assessments of knee function in athletic populations at the time of return to sport following ACL reconstruction (ACLr) have often focused on strength and single-leg hop tests, with a paucity of evidence to describe the CoD characteristics. Therefore, the aim of this narrative review was to describe the movement strategies exhibited following ACLr during CoD tasks and to critically analyze the range of tests that have been used. Specifically, we examined their ability to identify between-limb deficits and individuals who display a heightened risk of secondary injury and/or reductions in their level of pre-injury performance. MEDLINE, PubMed and SPORT Discuss databases were used and 13 articles were identified that met the inclusion criteria. Examination of the available literature indicates that current field-based practices are not representative of relevant sport demands and are unable to effectively assess knee function following ACLr. Laboratory-based studies have identified residual deficits and altered movement strategies at the time of return to sport, and this in part may be related to risk of re-injury. However, these assessments exhibit inherent limitations and are not practically viable for monitoring progress during rehabilitation. Consequently, alternative solutions that are more-aligned with the multitude of factors occurring during CoD maneuvers in chaotic sports environments are warranted to allow practitioners to 'bridge the gap' between the laboratory and the sports field/court. This approach may facilitate a more informed decision-making process with the end goal being, a heightened 'return to performance' and a lower risk of re-injury.