Training affects knee kinematics and kinetics in cutting maneuvers in sport

Effect of a tailored exercise programme on kinematics and kinetic knee injury risk during different side-cutting

Despite the high incidence of knee injuries reported in non-professional sports, the implementation of specific training programmes aimed at mitigating the kinematic and kinetic factors associated with these injuries remains limited. To determine the effects of a tailored exercise programme on kinematic and kinetic variables during side-cutting activities. Fifty-seven physically active participants were randomised into control group (CG; n: 28) that received no intervention, and an experimental group (EG; n: 29), that performed an individualised exercise programme that included a combination of strength, neuromuscular, proprioceptive, eccentric training and whole-body vibration (WBV) exercises. Knee, hip and trunk angles, vertical ground reaction force (VGRF), force in the antero-posterior (AP) and medio-lateral (ML) axes, acceleration, contact time and impulse were assessed during three types of side-cutting, two open manoeuvres (30º and 45º - SC30 and SC45 -respectively) and one closed manoeuvre (45º - SC45cl-). After the 12-week intervention, EG participants had lower knee extension during all side-cuttings, shorter contact time and lower acceleration, VGRF and impulse compared to CG during side-cutting manoeuvres. A tailored exercise programme could be an effective neuromuscular and biomechanical strategy to reduce risk factors for knee injury in healthy, physically active young people.

Examining the Effects of Dynamic and Isometric Resistance Training on Knee Joint Kinetics During Unplanned Sidesteps in Elite Female Athletes

ABSTRACT

Kadlec, D, Jordan, MJ, Alderson, J, and Nimphius, S. Examining the effects of dynamic and isometric resistance training on knee joint kinetics during unplanned sidesteps in elite female athletes. J Strength Cond Res 38(12): 2079-2087, 2024-The purpose of this study was to examine the effects of a 4-week block of isometric (isometric RT ) and dynamic resistance training (dynamic RT ) on kinetic variables associated with anterior cruciate ligament (ACL) injury risk during unplanned sidesteps in elite female athletes. Twenty-one elite female athletes competing for a women's international rugby union team were recruited with 15 ( n = 15; age: 23.4 ± 4.7 years; 170.7 ± 8.4 cm; 84.4 ± 15.4 kg) completing assessment of knee flexion moment, knee valgus moment (KVM), knee internal rotation moment (KIRM), knee joint power during unplanned sidesteps, and lower limb strength before and after a 4-week intervention. Linear mixed effects models and one-dimensional statistical parametric mapping assessed the effect of the interventions. Statistical significance was set at α = 0.05. Postintervention the isometric RT group revealed reduced peak KVM during early stance ( p = 0.04) while the dynamic RT group decreased peak KIRM ( p < 0.01) and KIRM over 8.8-86.6% ( p < 0.01) and 96.9-98.5% ( p = 0.047). An exploratory combined group analysis revealed reductions in KVM over 7.9-21.8% ( p = 0.002) and in KIRM over 8.3-90.5% ( p < 0.01) and 96.2-98.5% ( p = 0.046). Most lower limb isometric and dynamic strength measures increased after both resistance training interventions. Overall, both groups increased lower-body maximum strength while reducing kinetic knee joint variables associated with ACL injury risk during unplanned sidesteps. These results highlight the importance of increasing single-joint and multijoint strength in female athletes to mitigate the mechanical knee joint demands during sidestepping.

The future of in-field sports biomechanics: wearables plus modelling compute real-time in vivo tissue loading to prevent and repair musculoskeletal injuries

This paper explores the use of biomechanics in identifying the mechanistic causes of musculoskeletal tissue injury and degeneration. It appraises how biomechanics has been used to develop training programmes aiming to maintain or recover tissue health. Tissue health depends on the functional mechanical environment experienced by tissues during daily and rehabilitation activities. These environments are the result of the interactions between tissue motion, loading, biology, and morphology. Maintaining health of and/or repairing musculoskeletal tissues requires targeting the "ideal" in vivo tissue mechanics (i.e., loading and deformation), which may be enabled by appropriate real-time biofeedback. Recent research shows that biofeedback technologies may increase their quality and effectiveness by integrating a personalised neuromusculoskeletal modelling driven by real-time motion capture and medical imaging. Model personalisation is crucial in obtaining physically and physiologically valid predictions of tissue biomechanics. Model real-time execution is crucial and achieved by code optimisation and artificial intelligence methods. Furthermore, recent work has also shown that laboratory-based motion capture biomechanical measurements and modelling can be performed outside the laboratory with wearable sensors and artificial intelligence. The next stage is to combine these technologies into well-designed easy to use products to guide training to maintain or recover tissue health in the real-world.

The effects of fatigue on knee kinematics during unanticipated change of direction in adolescent girl athletes: a comparison between dominant and non-dominant legs

This study was aimed to compare the knee kinematic parameters between dominant and non-dominant legs of adolescent female athletes during change of direction (CoD) in fatigued and unpredictable settings. Knee kinematic parameters on 49 athletes (mean± SD; age = 14.69 ± 0.14 years; mass = 49.05 ± 1.22 kg; height = 1.61 ± 0.08 m) during CoD before and after performing the Bruce protocol and also in predictable and unpredictable setting situations were collected. Kinematic data were recorded at a sampling rate of 200 Hz. The results showed that the dominant leg had significantly 18.7% more flexion (p = 0.001, η = 0.95), 7.1% less valgus (p = 0.001, η = 0.95) and 0.32% lower tibia rotation (p = 0.003, η = 0.16) compared to the non-dominant leg in predictable and pre-fatigue (p < 0.05) conditions. With unpredictable and post-fatigue conditions the dominant limb again demonstrated 17.4% (p = 0.001, η = 0.67), greater knee flexion, 6.8% (0.003,η = 0.97) lower knee valgus and 1.4% (p = 0.001, η = 0.71) less tibiarotation. In conclusion, there may be an increased risk of injury withthe non-dominant leg due to changes in kinematic parameters caused by fatigue and unpredictable CoD manoeuvres.

Effects of 16 weeks of plyometric training on knee biomechanics during the landing phase in athletes

This study investigated the effects of plyometric training on lower-limb muscle strength and knee biomechanical characteristics during the landing phase. Twenty-four male subjects were recruited for this study with a randomised controlled design. They were randomly divided into a plyometric training group and a traditional training group and underwent training for 16 weeks. Each subject was evaluated every 8 weeks for knee and hip isokinetic muscle strength as well as knee kinematics and kinetics during landing. The results indicated significant group and time interaction effects for knee extension strength (F = 74.942 and p = 0.001), hip extension strength (F = 99.763 and p = 0.000) and hip flexion strength (F = 182.922 and p = 0.000). For landing kinematics, there were significant group main effects for knee flexion angle range (F = 4.429 and p = 0.047), significant time main effects for valgus angle (F = 6.502 and p = 0.011) and significant group and time interaction effects for internal rotation angle range (F = 5.475 and p = 0.008). The group main effect for maximum knee flexion angle was significant (F = 7.534 and p = 0.012), and the group and time interaction effect for maximum internal rotation angle was significant (F = 15.737 and p = 0.001). For landing kinetics, the group main effect of the loading rate was significant (F = 4.576 and p = 0.044). Significant group and time interaction effects were observed for knee extension moment at the moment of maximum vertical ground reaction force (F = 5.095 and p = 0.010) and for abduction moment (F = 8.250 and p = 0.001). These findings suggest that plyometric training leads to greater improvements in hip and knee muscle strength and beneficial changes in knee biomechanics during landing compared to traditional training.

The effect of a suspension training on physical fitness, lower extremity biomechanical factors, and occupational health in Navy personnel: a randomized controlled trial

Optimal physical fitness is essential for military personnel to effectively meet their rigorous physical demands. This study aimed to investigate the effectiveness of a suspension training program on physical fitness, biomechanical risk factors for lower extremity injury, mental health, and work-related factors in Navy personnel. A total of 50 young men participated in a randomized controlled trial. The participants were randomly assigned to two groups (n = 25): the intervention group and the control group. The intervention group performed an eight-week suspension training session three times per week, while the control group maintained their daily duties. The primary outcome was physical performance. The secondary outcomes were determined biomechanical risk factors for lower extremity injuries, mental health, and work-related factors. The data were analyzed using the analysis of covariance (ANCOVA). Compared with the control group, the intervention group showed significant improvements in physical performance, biomechanical risk for lower extremity injuries, and work-related factors from baseline to follow-up (p ≤ 0.05). However, there was no improvement in mental health. Based on these findings, suspension training positively impacted physical fitness, reduced injury risk, and enhanced the work-related factors of Navy personnel. This study provides new insights for various related experts and military coaches because it is an easy-to-use and feasible method with minimal facilities.

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

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

Clinical Determinants of Knee Joint Loads While Sidestepping: An Exploratory Study With Male Rugby Union Athletes

Background

While several clinical factors have independently been linked to anterior cruciate ligament (ACL) injury risk factors, their collective impact on knee loading during the sidestep maneuver is unknown. To better understand these factors, we assessed the relationship between strength, balance, and sprint kinetics and external knee abduction moments during sidestepping on each leg.

Methods

Sixteen male academy-level rugby union athletes (age, 20 ± 3 years; body-height, 186 ± 9 cm; body-mass, 99 ± 14 kg) were bilaterally assessed in single-leg: isokinetic concentric and eccentric knee and concentric hip strength, balance at 2 difficulty levels, vertical and horizontal force production during maximal sprinting, and 3-dimensional motion capture while sidestepping on the preferred and non-preferred leg. A hierarchical multiple regression analysis based on this theoretical approach of the mechanics of ACL injury risk was performed.

Results

When sidestepping on the preferred leg, larger abduction moments were explained by less concentric hip extension strength and vertical force production during maximal sprinting (R 2 = 41%; ES = 0.64); when sidestepping on the non-preferred leg, larger abduction moments were explained by more concentric hip flexion strength (R 2 = 8%; ES = 0.29). Larger symmetry scores between the legs (representing greater abduction moments) were explained by more horizontal force production during maximal sprinting and less eccentric knee flexion strength (R 2 = 32%; ES = 0.56).

Conclusions

Independently, the preferred and non-preferred legs contribute to increased knee abduction moments via unique distributions of strength and/or sprint kinetics. The allocations of strength and sprint kinetics appear interrelated through weaker posterior muscular strength and may be modifiable through a targeted strength training approach.

Maintaining soldier musculoskeletal health using personalised digital humans, wearables and/or computer vision

OBJECTIVES

The physical demands of military service place soldiers at risk of musculoskeletal injuries and are major concerns for military capability. This paper outlines the development new training technologies to prevent and manage these injuries.

DESIGN

Narrative review.

METHODS

Technologies suitable for integration into next-generation training devices were examined. We considered the capability of technologies to target tissue level mechanics, provide appropriate real-time feedback, and their useability in-the-field.

RESULTS

Musculoskeletal tissues' health depends on their functional mechanical environment experienced in military activities, training and rehabilitation. These environments result from the interactions between tissue motion, loading, biology, and morphology. Maintaining health of and/or repairing joint tissues requires targeting the "ideal" in vivo tissue mechanics (i.e., loading and strain), which may be enabled by real-time biofeedback. Recent research has shown that these biofeedback technologies are possible by integrating a patient's personalised digital twin and wireless wearable devices. Personalised digital twins are personalised neuromusculoskeletal rigid body and finite element models that work in real-time by code optimisation and artificial intelligence. Model personalisation is crucial in obtaining physically and physiologically valid predictions.

CONCLUSIONS

Recent work has shown that laboratory-quality biomechanical measurements and modelling can be performed outside the laboratory with a small number of wearable sensors or computer vision methods. The next stage is to combine these technologies into well-designed easy to use products.

Effects of FIFA 11 + warm-up program on kinematics and proprioception in adolescent soccer players: a parallel‑group randomized control trial

This study aimed to compare the effects of 8 weeks 11 + warm-up injury prevention program on kinematics and proprioception in adolescent male and female soccer players. Forty adolescent soccer players (20 males, 20 females) aged between 14-16 years old were randomly assigned into four groups. The experimental group performed the 11 + program for 8 weeks and the control group did their warm-up program. The kinematic variable in a cutting maneuver was measured using VICON motion analysis and ankle and knees' proprioception by joint position sense (JPS) was measured using a digital inclinometer. For kinematic variables only significant differences in knee valgus among females 11 + compared with female and male control groups were found (P < 0.05). Moreover, there were significant improvements in joint position sense variables in 11 + groups compared to control groups (P < 0.05). In conclusion, the 11 + program was proven to be a useful warm-up protocol in improving knee valgus and JPS among female and male adolescent soccer players. We suggest adding more training elements to the 11 + program that aimed to enhance the proper alignment of lower extremities which may consequently improve joint kinematics.

The effectiveness of the comprehensive corrective exercise program on kinematics and strength of lower extremities in males with dynamic knee valgus: a parallel-group randomized wait-list controlled trial

Background

Dynamic knee valgus (DKV) is a prevalent movement impairment widely regarded as a risk factor for lower extremity disorders such as patellofemoral pain syndrome. The present study aimed to investigate the effectiveness of the comprehensive corrective exercise program (CCEP) on kinematics and strength of lower extremities in males with DKV.

Methods

Thirty asymptomatic young men with DKV between the ages of 18 and 28 years participated in this study. They were randomly assigned to the intervention (n = 15) and control groups (n = 15). The intervention group performed the CCEP for three sessions per week for eight weeks, while the control group only did activities of daily living. Hip external rotator and abductor muscle strength and three-dimensional lower extremity kinematics consisting of knee varus/valgus, femur adduction/abduction, femur medial/lateral rotation, and tibial medial/lateral rotation were measured at the baseline and post-test. The data were analyzed using the analysis of covariance (ANCOVA).

Results

There were significant improvements in all kinematics variables in the intervention group after the 8-week CCEP. Moreover, the strength of abductor and external rotator muscle improved in the intervention group (P < 0.05).

Conclusions

The CCEP led to substantial improvements in the selected variables of lower extremity kinematics and muscle strength in participants with DKV during a single-leg squat. These results imply that practitioners should adopt a comprehensive approach to pay simultaneous attention to both proximal and distal segments for improving DKV.

Trial registration

The protocol has been approved in the Registry of Clinical Trials (Registration N: IRCT20180821040843N1) on 2018-12-30.

The effectiveness of injury prevention programs that include core stability exercises in reducing the incidence of knee injury among soccer players: A systematic review and meta-analysis

BACKGROUND: The knee is one of the most common sites of injuries among soccer players. The incidence of knee injuries can be reduced by improving the neuromuscular control and core stability. OBJECTIVE: This study aimed to evaluate the effectiveness of injury prevention programs that include core stability exercises in reducing the incidence of knee injuries among soccer players. METHODS: Data were obtained from different databases (1985–2021). Only randomized controlled trials that used injury prevention programs that include core stability exercise to prevent knee injuries were included. The keywords used during the search were ‘knee injuries’, ‘core stability exercises’, ‘FIFA 11+’, ‘prevention of knee injuries’, ‘anterior cruciate ligament injury’ and variations of these search terms. RESULTS: The pooled results of 7828 soccer players and 863700 exposure h showed an overall injury reduction of 56% per 1000 h of exposure in the intervention group compared to the control group with an injury risk ratio of 0.44 (95% CI 0.321–0.619; P= 0.001). CONCLUSIONS: Injury prevention programs that include core stability exercises reduce knee injury rates among soccer players by 56% (46% in male and 65% in female soccer players).

Optimizing Whole-Body Kinematics During Single-Leg Jump Landing to Reduce Peak Abduction/Adduction and Internal Rotation Knee Moments: Implications for Anterior Cruciate Ligament Injury Risk

Knee abduction/adduction moment and knee internal rotation moment are known surrogate measures of anterior cruciate ligament (ACL) load during tasks like sidestepping and single-leg landing. Previous experimental literature has shown that a variety of kinematic strategies are associated or correlated with ACL injury risk; however, the optimal kinematic strategies needed to reduce peak knee moments and ACL injury are not well understood. To understand the complex, multifaceted kinematic factors underpinning ACL injury risk and to optimize kinematics to prevent the ACL injury, a musculoskeletal modeling and simulation experimental design was used. A 14-segment, 37-degree-of-freedom, dynamically consistent skeletal model driven by force/torque actuators was used to simulate whole-body single-leg jump landing kinematics. Using the residual reduction algorithm in OpenSim, whole-body kinematics were optimized to reduce the peak knee abduction/adduction and internal/external rotation moments simultaneously. This optimization was repeated across 30 single-leg jump landing trials from 10 participants. The general optimal kinematic strategy was to bring the knee to a more neutral alignment in the transverse plane and frontal plane (featured by reduced hip adduction angle and increased knee adduction angle). This optimized whole-body kinematic strategy significantly reduced the peak knee abduction/adduction and internal rotation moments, transferring most of the knee load to the hip.

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.

Effect of the FIFA 11+ on Landing Patterns and Baseline Movement Errors in Elite Male Youth Soccer Players

CONTEXT

There is no evidence regarding the effect of the FIFA 11+ on landing kinematics in male soccer players, and few studies exist regarding the evaluating progress of interventions based on the initial biomechanical profile.

OBJECTIVE

To investigate the effect of the FIFA 11+ program on landing patterns in soccer players classified as at low or high risk for noncontact anterior cruciate ligament injuries.

DESIGN

Randomized controlled trial.

SETTING

Field-based functional movement screening performed at the soccer field.

PARTICIPANTS

A total of 24 elite male youth soccer players participated in this study.

INTERVENTION

The intervention group performed the FIFA 11+ program 3 times per week for 8 weeks, whereas the control group performed their regular warm-up program.

MAIN OUTCOME MEASURES

Before and after the intervention, all participants were assessed for landing mechanics using the Landing Error Scoring System. Pretraining Landing Error Scoring System scores were used to determine risk groups.

RESULTS

The FIFA 11+ group had greater improvement than the control group in terms of improving the landing pattern; there was a significant intergroup difference (F1,20 = 28.86, P < .001, ηp2=.591). Soccer players categorized as being at high risk displayed greater improvement from the FIFA 11+ program than those at low risk (P = .03). However, there was no significant difference in the proportion of risk category following the routine warm-up program (P = 1.000).

CONCLUSIONS

The present study provides evidence of the usefulness of the FIFA 11+ program for reducing risk factors associated with noncontact anterior cruciate ligament injuries. The authors' results also suggest that soccer players with the higher risk profile would benefit more than those with lower risk profiles and that targeting them may improve the efficacy of the FIFA 11+ program.

The effect of silicone ankle sleeves and lace-up ankle braces on neuromuscular control, joint torque, and cutting agility

Objective

To evaluate the effects of silicone ankle sleeves (SASs) and lace-up ankle braces (LABs) on neuromuscular control, net joint torques, and cutting agility in healthy, active individuals.

Design

Markerless motion-capture technology tracked subjects fitted with SASs, LABs, or no brace while they performed the movements: Y-excursion, left cutting, right cutting, single-leg drop vertical jump (SLDVJ), 45-degree bound, and single-leg squat (SLS).

Setting

University Laboratory.

Participants

Ten healthy, active individuals (5 males and 5 females, mean ± SD 23.60 ± 1.43 years of age).

Main outcome measures

Degrees of joint range of motion (ROM), Newton-meters of joint torque, time to perform a cutting maneuver.

Results

SASs and LABs resulted in significantly different knee and ankle ROM and hip internal rotation in the SLDVJ, SLS, Y-excursion, cutting maneuver, and 45-degree bound when compared to control (p < .05). Both ankle and knee torque were significantly reduced in the 45-degree bound and cutting movements with both types of PABs (p < .05). There were minimal differences between the SASs and LABs for all conditions. There were no statistically significant differences in cutting times for any of the 3 conditions.

Conclusion

Both SAS and LAB positively impacted neuromuscular control, reduced net joint torque, and neither impaired cutting agility when compared to control.

An individualised approach to assess the sidestep manoeuvre in male rugby union athletes

OBJECTIVES

This study aimed to (1) quantitatively assess external knee abduction moments between legs, and (2) qualitatively assess anterior cruciate ligament injury risk between group mean and individual athlete data during the sidestep manoeuvre.

DESIGN

Descriptive cross-sectional study.

METHODS

Sixteen male academy-level rugby union athletes (20.4±2.7yr; 186.3±9.1cm; 99.1±14.4kg) performed three maximal effort sidesteps (>6.0ms^-1) on each leg. Three-dimensional motion analysis was used to obtain external knee abduction moments, wherein the two legs were separated by the preferred and non-preferred kicking leg. Quantitative comparisons were made between legs, while qualitative comparisons were made been group mean and individual athlete data.

RESULTS

When sidestepping on the non-preferred leg, athletes produced 25% greater knee abduction moments (ES=0.43) and presented modified postural adjustments associated with injury risk (extended knee [ES=-0.26; -8%], more trunk lateral flexion [ES=0.42; 17%] and more distance between the centre-of-mass and ankle-joint-centre of the stance leg [ES=0.97; 11%]) compared to the preferred leg. Individually, only 9 out of 16 athletes presented a higher abduction moment in their non-preferred leg with individual asymmetries ranging between 2.2 and 47%.

CONCLUSIONS

Nearly half of the athletes assessed in this study showed the potential to "slip under the radar" when using the group mean for assessment. When assessing athletes for anterior cruciate ligament injury risk factors, individual athlete data should be examined in conjunction with the group mean for a more holistic view of the data.

The Effect of Training Interventions on Change of Direction Biomechanics Associated with Increased Anterior Cruciate Ligament Loading: A Scoping Review

Change of direction (COD) manoeuvres are associated with anterior cruciate ligament (ACL) injury risk due to the propensity to generate large multiplanar knee joint loads. Given the short- and long-term consequences of ACL injury, practitioners are interested in methods that reduce knee joint loads and subsequent ACL loading. An effective strategy to reduce ACL loading is modifying an athlete's movement mechanics to reduce knee joint loading. The purpose of this scoping review was to critically appraise and comprehensively synthesise the existing literature related to the effects of training interventions on COD biomechanics associated with increased knee joint loads and subsequent ACL loading, and identify gaps and recommend areas for future research. A review of the literature was conducted using Medline and Sport DISCUS databases. Inclusion criteria consisted of pre-post analysis of a COD task, a minimum 4-week training intervention, and assessments of biomechanical characteristics associated with increased ACL loading. Of the 1,027 articles identified, 22 were included in the scoping review. Based on current literature, balance training and COD technique modification are the most effective training modalities for reducing knee joint loading (small to moderate effect sizes). One study reported dynamic core stability training was effective in reducing knee joint loads, but further research is needed to definitively confirm the efficacy of this method. Perturbation-enhanced plyometric training, the F-MARC 11 + soccer specific warm-up, Oslo Neuromuscular warm-up, and resistance training are ineffective training modalities to reduce COD knee joint loads. Conflicting findings have been observed for the Core-Pac and mixed training programme. Consequently, practitioners should consider incorporating balance and COD technique modification drills into their athletes' training programmes to reduce potentially hazardous knee joint loads when changing direction. However, training intervention studies can be improved by investigating larger sample sizes (> 20), including a control group, acknowledging measurement error when interpreting their findings, and considering performance implications, to confirm the effectiveness of training interventions and improve adherence.

Do neoprene sleeves and prophylactic knee braces affect neuromuscular control and cutting agility?

OBJECTIVES

To evaluate the effects of neoprene sleeves (NSs) and prophylactic knee braces (PKBs) on neuromuscular control and cutting agility.

DESIGN

Markerless motion-capture technology tracked subjects (1) without a brace as a control (2) with NSs and (3) with PKBs during single-leg drop vertical jump (SLDVJ), single-leg squat (SLS), Y-excursion, and cutting movements. Movements were recorded five times per bracing condition in three different sessions.

SETTING

University laboratory.

PARTICIPANTS

Ten healthy, active subjects (5 male, 5 female; age range, 22-26 years).

MAIN OUTCOME MEASURES

Degrees of motion and time to completion.

RESULTS

Use of NSs and PKBs reduced subjects' hip internal rotation in the loading phase of SLDVJ (p = 0.026, 0.02) and SLS (p = 0.005, <0.001), reduced knee flexion in the loading phase of SLDVJ (p = 0.038, <0.001), and reduced knee frontal plane abduction (FPA) with SLS (p = 0.015, 0.024) and Y-excursion (p = 0.002, 0.005) compared to control. Use of PKBs decreased subjects' hip internal rotation in the Y-excursion (p = 0.024) and reduced knee FPA in the SLDVJ loading phase (p = 0.014) compared to control. There was no difference in cutting agility for either group (p = 0.145, 0.347).

CONCLUSION

Both NSs and PKBs positively impacted neuromuscular control without impacting cutting agility.

Influence of lateral pedal translation on muscle recruitment and kinematics in cyclists

Background/Objective

Current cycling pedals constrain the pedaling motion to the sagittal plane. This study aimed to evaluate novel pedal systems that allow lateral translation through the pedal stroke via frontal plane kinematics and muscle recruitment.

Methods

Sixteen cyclists were recruited to pedal on three pedal systems: standard pedals (STD), free lateral translation (LAT), and a guided lateral translation pedal (VL). Frontal plane kinematics were measured via markers on the hip, knee, and foot. EMG recordings were collected from 8 leg muscles and expressed as a percentage of functional threshold power activation levels.

Results

Knee and ankle range of movement was significantly more highly correlated in the VL pedals compared to STD (r = .46 ± .08, vs. .23 ± .05; p = .028). The rectus femoris was recruited significantly less in the VL vs. STD pedals (23.6 ± 7.7% lower, p = .008). The hip abductors were more highly recruited in VL vs. STD: gluteus medius (16.9 ± 7.2% higher, p = .033) and the tensor fascia latae (30.9 ± 8.5% lower, p = .003).

Conclusion

VL pedals may improve knee-to-ankle tracking through the pedal stroke and may allow cyclists to increase power output through the additional recruitment of hip abductors.

Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention

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

Effects of wobble board training on single-leg landing neuromechanics

Balance training programs have been shown to reduce ankle sprain injuries in sports, but little is known about the transfer from this training modality to motor coordination and ankle joint biomechanics in sport-specific movements. This study aimed to investigate the effects of wobble board training on motor coordination and ankle mechanics during early single-leg landing from a lateral jump. Twenty-two healthy men were randomly assigned to either a control or a training group, who engaged in 4 weeks of wobble board training. Full-body kinematics, ground reaction force, and surface electromyography (EMG) from 12 lower limb muscles were recorded during landing. Ankle joint work in the sagittal, frontal, and transverse plane was calculated from 0 to 100 ms after landing. Non-negative matrix factorization (NMF) was applied on the concatenated EMG Pre- and Post-intervention. Wobble board training increased the ankle joint eccentric work 1.2 times in the frontal (P < .01) and 4.4 times in the transverse plane (P < .01) for trained participants. Wobble board training modified the modular organization of muscle recruitment in the early landing phase by separating the activation of plantar flexors and mediolateral ankle stabilizers. Furthermore, the activation of secondary muscles across motor modules was reduced after training, refocusing the activation on the main muscles involved in the mechanical main subfunctions for each module. These results suggest that wobble board training may modify motor coordination when landing from a lateral jump, focusing on the recruitment of specific muscles/muscle groups that optimize ankle joint stability during early ground contact in single-leg landing.

National Athletic Trainers' Association Position Statement: Prevention of Anterior Cruciate Ligament Injury

OBJECTIVE

  To provide certified athletic trainers, physicians, and other health care and fitness professionals with recommendations based on current evidence regarding the prevention of noncontact and indirect-contact anterior cruciate ligament (ACL) injuries in athletes and physically active individuals.

BACKGROUND

  Preventing ACL injuries during sport and physical activity may dramatically decrease medical costs and long-term disability. Implementing ACL injury-prevention training programs may improve an individual's neuromuscular control and lower extremity biomechanics and thereby reduce the risk of injury. Recent evidence indicates that ACL injuries may be prevented through the use of multicomponent neuromuscular-training programs.

RECOMMENDATIONS

  Multicomponent injury-prevention training programs are recommended for reducing noncontact and indirect-contact ACL injuries and strongly recommended for reducing noncontact and indirect-contact knee injuries during physical activity. These programs are advocated for improving balance, lower extremity biomechanics, muscle activation, functional performance, strength, and power, as well as decreasing landing impact forces. A multicomponent injury-prevention training program should, at minimum, provide feedback on movement technique in at least 3 of the following exercise categories: strength, plyometrics, agility, balance, and flexibility. Further guidance on training dosage, intensity, and implementation recommendations is offered in this statement.

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.

Causes of motor system overload in step aerobics: Literature review

Many publications have indicated the positive impact of step aerobics on health. Although step aerobics aims to improve endur­ance and other health parameters, injuries incurred from overload happen to both instructors and participants. Values of vertical ground reaction force (vGRF) while stepping on and off the bench do not lead to overload on the motor system - they are simi­lar to the values obtained for walking or stair climbing. One reason for injuries may be the step workout technique. Overloads may be caused by incorrect technique of foot positioning on the bench, small knee angle during stepping off, and small angle of trunk flexion. This study presents an overview of current research on the load of the motor system in step aerobics.

ACL Injury Prevention Training Results in Modification of Hip and Knee Mechanics During a Drop-Landing Task

Background:

Injury prevention training has been shown to be effective in reducing the incidence of noncontact anterior cruciate ligament (ACL) injury; however, the underlying reason for the success of these training programs is unclear.

Purpose:

To investigate whether an ACL injury prevention program that has been shown to reduce the incidence of ACL injury alters sagittal plane hip and knee biomechanics during a drop-landing task.

Study Design:

Descriptive laboratory study.

Methods:

Thirty female club soccer players (age range, 11-17 years) with no history of knee injury participated in this study. Kinematics and ground-reaction forces were collected while each participant performed a drop-landing task prior to and immediately after participation in a 12-week ACL injury prevention training program.

Results:

After ACL injury prevention training, participants demonstrated decreased knee extensor moments (P = .03), increased energy absorption at the hip (P = .04), decreased knee-to-hip extensor moment ratios (P = .05), and decreased knee-to-hip energy absorption ratios (P = .03).

Conclusion:

Participation in an ACL injury prevention training program decreased reliance on the knee extensor muscles and improved use of the hip extensor muscles, which may explain the protective effect of this type of training program on ACL injury.

Clinical Relevance:

Based on these findings, clinicians can better understand how ACL injury prevention training, such as the Prevent Injury and Enhance Performance (PEP) Program, may change movement behavior at both the hip and knee. Furthermore, the study findings may support the implementation of the PEP Program, or a similar program, for clinicians aiming to improve use of the hip in an effort to reduce knee loading and consequent injuries.

Postural Stability During Single-Leg Stance: A Preliminary Evaluation of Noncontact Lower Extremity Injury Risk

Study Design Controlled laboratory study with a prospective cohort design. Background Postural stability deficits during single-leg stance have been reported in persons with anterior cruciate ligament (ACL) injury, ACL reconstruction, and chronic ankle instability. It remains unclear whether impaired postural stability is a consequence or cause of these injuries. Objectives To prospectively investigate whether postural stability deficits during single-leg stance predict noncontact lower extremity injuries. Methods Fifty injury-free female athletes performed a transition task from double-leg stance to single-leg stance with eyes closed. Center-of-pressure displacement, the main outcome variable, was measured during the first 3 seconds after the time to a new stability point was reached during single-leg stance. Noncontact lower extremity injuries were recorded at a 1-year follow-up. Results Six participants sustained a noncontact ACL injury or ankle sprain. Center-of-pressure displacement during the first 3 seconds after the time to a new stability point was significantly increased in the injured (P = .030) and noninjured legs (P = .009) of the injured group compared to the respective matched legs of the noninjured group. The area under the receiver operating characteristic curve (AUC) analysis revealed significant discriminative accuracy between groups for the center-of-pressure displacement during the first 3 seconds after the time to a new stability point of the injured (AUC = 0.814, P = .015) and noninjured legs (AUC = 0.897, P = .004) of the injured group compared to the matched legs of the noninjured group. Conclusion This preliminary study suggests that postural stability measurements during the single-leg stance phase of the double- to single-leg stance transition task may be a useful predictor of increased risk of noncontact lower extremity injury. Further research is indicated. Level of Evidence Prognosis, level 4. J Orthop Sports PhysTher 2016;46(8):650-657. Epub 3 Jul 2016. doi:10.2519/jospt.2016.6278.

The Effectiveness of Injury Prevention Programs to Modify Risk Factors for Non-Contact Anterior Cruciate Ligament and Hamstring Injuries in Uninjured Team Sports Athletes: A Systematic Review

BACKGROUND

Hamstring strain and anterior cruciate ligament injuries are, respectively, the most prevalent and serious non-contact occurring injuries in team sports. Specific biomechanical and neuromuscular variables have been used to estimate the risk of incurring a non-contact injury in athletes.

OBJECTIVE

The aim of this study was to systematically review the evidences for the effectiveness of injury prevention protocols to modify biomechanical and neuromuscular anterior cruciate and/or hamstring injuries associated risk factors in uninjured team sport athletes.

DATA SOURCES

PubMed, Science Direct, Web of Science, Cochrane Libraries, U.S. National Institutes of Health clinicaltrials.gov, Sport Discuss and Google Scholar databases were searched for relevant journal articles published until March 2015. A manual review of relevant articles, authors, and journals, including bibliographies was performed from identified articles.

MAIN RESULTS

Nineteen studies were included in this review. Four assessment categories: i) landing, ii) side cutting, iii) stop-jump, and iv) muscle strength outcomes, were used to analyze the effectiveness of the preventive protocols. Eight studies using multifaceted interventions supported by video and/or technical feedback showed improvement in landing and/or stop-jump biomechanics, while no effects were observed on side-cutting maneuver. Additionally, multifaceted programs including hamstring eccentric exercises increased hamstring strength, hamstring to quadriceps functional ratio and/or promoted a shift of optimal knee flexion peak torque toward a more open angle position.

CONCLUSIONS

Multifaceted programs, supported by proper video and/or technical feedback, including eccentric hamstring exercises would positively modify the biomechanical and or neuromuscular anterior cruciate and/or hamstring injury risk factors.

ACL injury in football: a literature overview of the prevention programs

BACKGROUND

The ACL prevention programs are addressed to the control and/or modification of the so-called "modifiable risk factors". All these programs focus on different intervention strategies aimed to decrease the ACL injury risk, particularly in female athletes population.

PURPOSE

To furnish an overview of the most used ACL injury prevention program through a narrative review.

CONCLUSION

In literature there are many reports on prevention programs whose common denominator is the proper alignment of the lower limb joints and proper motor control during movements that are considered at risk for ACL integrity, as the landing phase after a jump. Nevertheless, some programs would appear more effective than others. In any cases a major problem remains the lack of sufficient compliance in respect of prevention programs. Finally, it is important to remember that the ethiology of ACL injuries is multifactorial. For this reason a prevention program able to prevent all the risk situations is utopian.

STUDY DESIGN

Narrative review.

Biomechanical and neuromuscular characteristics of male athletes: implications for the development of anterior cruciate ligament injury prevention programs

Prevention of anterior cruciate ligament (ACL) injury is likely the most effective strategy to reduce undesired health consequences including reconstruction surgery, long-term rehabilitation, and pre-mature osteoarthritis occurrence. A thorough understanding of mechanisms and risk factors of ACL injury is crucial to develop effective prevention programs, especially for biomechanical and neuromuscular modifiable risk factors. Historically, the available evidence regarding ACL risk factors has mainly involved female athletes or has compared male and female athletes without an intra-group comparison for male athletes. Therefore, the principal purpose of this article was to review existing evidence regarding the investigation of biomechanical and neuromuscular characteristics that may imply aberrant knee kinematics and kinetics that would place the male athlete at risk of ACL injury. Biomechanical evidence related to knee kinematics and kinetics was reviewed by different planes (sagittal and frontal/coronal), tasks (single-leg landing and cutting), situation (anticipated and unanticipated), foot positioning, playing surface, and fatigued status. Neuromuscular evidence potentially related to ACL injury was reviewed. Recommendations for prevention programs for ACL injuries in male athletes were developed based on the synthesis of the biomechanical and neuromuscular characteristics. The recommendations suggest performing exercises with multi-plane biomechanical components including single-leg maneuvers in dynamic movements, reaction to and decision making in unexpected situations, appropriate foot positioning, and consideration of playing surface condition, as well as enhancing neuromuscular aspects such as fatigue, proprioception, muscle activation, and inter-joint coordination.

The efficacy of a movement control exercise programme to reduce injuries in youth rugby: a cluster randomised controlled trial

Background

Injuries to youth rugby players have become an increasingly prominent health concern, highlighting the importance of developing and implementing appropriate preventive strategies. A growing body of evidence from other youth sports has demonstrated the efficacy of targeted exercise regimens to reduce injury risk. However, studies have yet to investigate the effect of such interventions in youth contact sport populations like rugby union.

Objective

To determine the efficacy of an evidence-based movement control exercise programme compared with a sham exercise programme to reduce injury risk in youth rugby players. Exercise programme compliance between trial arms and the effect of coach attitudes on compliance will also be evaluated.

Setting

School rugby coaches in England will be the target of the researcher intervention, with the effects of the injury prevention programmes being measured in male youth players aged 14–18 years in school rugby programmes over the 2015–2016 school winter term.

Methods

A cluster-randomised controlled trial with schools randomly allocated to either a movement control exercise programme or a sham exercise programme, both of which are coach-delivered. Injury measures will derive from field-based injury surveillance, with match and training exposure and compliance recorded. A questionnaire will be used to evaluate coach attitudes, knowledge, beliefs and behaviours both prior to and on the conclusion of the study period.

Outcome measures

Summary injury measures (incidence, severity and burden) will be compared between trial arms, as will the influence of coach attitudes on compliance and injury burden. Additionally, changes in these outcomes through using the exercise programmes will be evaluated.

Trial registration number

ISRTCNN13422001.

Preventing Australian football injuries with a targeted neuromuscular control exercise programme: comparative injury rates from a training intervention delivered in a clustered randomised controlled trial

BACKGROUND

Exercise-based training programmes are commonly used to prevent sports injuries but programme effectiveness within community men's team sport is largely unknown.

OBJECTIVE

To present the intention-to-treat analysis of injury outcomes from a clustered randomised controlled trial in community Australian football.

METHODS

Players from 18 male, non-elite, community Australian football clubs across two states were randomly allocated to either a neuromuscular control (NMC) (intervention n=679 players) or standard-practice (control n=885 players) exercise training programme delivered as part of regular team training sessions (2× weekly for 8-week preseason and 18-week regular-season). All game-related injuries and hours of game participation were recorded. Generalised estimating equations, adjusted for clustering (club unit), were used to compute injury incidence rates (IIRs) for all injuries, lower limb injuries (LLIs) and knee injuries sustained during games. The IIRs were compared across groups with cluster-adjusted Injury Rate Ratios (IRRs).

RESULTS

Overall, 773 game injuries were recorded. The lower limb was the most frequent body region injured, accounting for 50% of injuries overall, 96 (12%) of which were knee injuries. The NMC players had a reduced LLI rate compared with control players (IRR: 0.78 (95% CI 0.56 to 1.08), p=0.14.) The knee IIR was also reduced for NMC compared with control players (IRR: 0.50 (95% CI 0.24 to 1.05), p=0.07).

CONCLUSIONS

These intention-to-treat results indicate that positive outcomes can be achieved from targeted training programmes for reducing knee and LLI injury rates in men's community sport. While not statistically significant, reducing the knee injury rate by 50% and the LLI rate by 22% is still a clinically important outcome. Further injury reductions could be achieved with improved training attendance and participation in the programme.

Effects of two different injury prevention resistance exercise protocols on the hamstring torque-angle relationship: a randomized controlled trial

The effects of two different 6-week lower body injury prevention programmes on knee muscle torque-angle relationship were examined in soccer players. Thirty-two men were randomly assigned to three groups: hamstring-eccentric (ECC) (n = 11), unstable-squatting (UNS) (n = 11), and control (n = 10). Intervention groups performed three training sessions per week using only three ECC or UNS exercises, respectively. Maximal peak knee flexion torque was measured at 35°, 45°, 60°, 80°, 90°, and 100°, pre- and post-intervention. Peak torque increased at 35° (P = 0.034, Cohen's d = 0.67) and 45° (P = 0.004, Cohen's d = 0.96) in the ECC group, and at 60° (P = 0.024, Cohen's d = 1.16), 80° (P = 0.018, Cohen's d = 1.21), and 90° (P = 0.001, Cohen's d = 1.38) in the UNS group. As these specific modifications might respectively and differentially protect athletes against hamstring and knee-joint injuries, the integration of both types of exercises should be considered when designing injury prevention programmes for soccer players.

Knee mechanics during planned and unplanned sidestepping: a systematic review and meta-analysis

BACKGROUND

Knee joint mechanics during sidestepping are associated with anterior cruciate ligament injury. Unplanned sidestepping more closely emulates game scenarios when compared with planned sidestepping by limiting decision time, increasing knee loading and challenging the integrity of soft-tissue structures in the knee. It is important to quantify the loads that may challenge the integrity of the knee during planned and unplanned sidestepping.

OBJECTIVE

Our objective was to review literature on knee mechanics during planned and unplanned phases of sidestepping.

DATA SOURCES

PubMed, CINAHL, MEDLINE (EBSCO), SPORTDiscus and Web of Science were searched using the terms knee mechanics OR knee kine*, AND plan*, unplan*, anticipat*, unanticipat*, side*, cut* or chang*.

STUDY SELECTION

A systematic approach was used to evaluate 4,629 records. Records were excluded when not available in English, only available in abstract of conference proceedings, not involving a change-of-direction sidestep, not comparing planned and unplanned or maintaining a running velocity greater than 2 m s(−1).

DATA EXTRACTION

Included studies were evaluated independently by two authors using a custom-designed methodological quality assessment derived from the Physiotherapy Evidence Database (PEDro) scale and then confirmed by a third author.

DATA SYNTHESIS

Only six studies met the inclusion criteria and were retained for meta-analysis. Magnitude-based inferences were used to assess the standardised effect of the differences between planned and unplanned sidestepping. Knee angles and knee moments were extracted and reported for flexion/extension, abduction/adduction and internal/external rotation for initial contact, weight acceptance, peak push-off and final push-off phases of sidestepping.

RESULTS

For kinematic variables, unplanned sidestepping produced a wide range of small to large increases in knee extension angles, small and moderate increases in knee abduction angles and a small increase in internal rotation angle relative to planned sidestepping during the sidestepping manoeuvre. For kinetic variables, unplanned sidestepping produced mostly small (small to large) increases in knee flexor moments, small to moderate increases in knee abductor moments and mostly moderate (small to large) increases in internal rotator moments relative to planned sidestepping.

LIMITATIONS

Approach velocity constraints during the sidestepping manoeuvre were lifted due to the low number of eligible studies. The varying approach velocities included (ranging from 3.0 to 5.5 m s(−1)) may impact the kinematic and kinetic variables examined in this review.

CONCLUSIONS

Differences in knee mechanics between planned and unplanned sidestepping exist. The most substantial effects occurred during the weight acceptance phase of sidestepping. It seems that biomechanical factors commonly associated with anterior cruciate ligament injury risk are affected the most during the loading phase compared with peak push-off; made evident in the coronal (abductor) and transverse (internal rotator) knee kinetic data presented in this review. The authors of this review propose a rationale for the incorporation of unplanned sport tasks in the development of anterior cruciate ligament injury screening and in prophylactic training programmes.

Unstable Surface Improves Quadriceps:Hamstring Co-contraction for Anterior Cruciate Ligament Injury Prevention Strategies

Background:

Increasing quadriceps:hamstring muscular co-contraction at the knee may reduce the risk of anterior cruciate ligament (ACL) injury. The purpose of this investigation was to examine muscle activation in the quadriceps and hamstrings and peak kinematics of the knee, hip, and trunk when performing a single-leg drop (SLD) on to a Bosu ball (unstable surface) compared with on to the floor (stable surface).

Hypotheses:

(1) The SLD on an unstable surface would lower the quadriceps to hamstrings electromyographic (EMG) activation ratio (Q:H EMG activation ratio) compared with being performed on the floor. (2) Lower Q:H EMG activation ratio would be caused by a relative increase in hamstring activation, with no significant change in quadriceps activation.

Study Design:

Controlled laboratory study.

Methods:

Thirty-nine Division I National Collegiate Athletic Association (NCAA) female athletes performed 3 SLDs per leg onto a Bosu ball and onto the floor. Muscle activity of the vastus lateralis and lateral hamstrings were used to estimate peak quadriceps and hamstring activation, along with the Q:H EMG activation ratio. Kinematic measures at the knee, hip, and trunk were also estimated. Differences between landings were assessed using a 2-level analysis of variance (limb and surface).

Results:

The maximum Q:H EMG activation ratio was significantly reduced when athletes performed an SLD onto the Bosu ball (20%, P < 0.001) compared with the floor. Peak hamstring activity was higher when athletes landed on a Bosu ball (18% higher, P = 0.029) compared with when they landed on the floor.

Conclusion:

Compared with landing on the floor (a stable surface), landing on a Bosu ball (unstable surface) changed the athlete’s co-contraction at the knee and increased hamstring activity. However, landing on a Bosu ball also decreased the athlete’s knee flexion, which was an undesired effect.

Clinical Relevance:

These findings highlight the potential utility of unstable surfaces as a training tool to reduce the risk of ACL injury in female athletes.

Bridging the gap between content and context: establishing expert consensus on the content of an exercise training program to prevent lower-limb injuries

OBJECTIVE

To achieve expert consensus on the content of an exercise training program (known as FootyFirst) to prevent lower-limb injuries.

DESIGN

Three-round online Delphi consultation process.

SETTING

Community Australian Football (AF).

PARTICIPANTS

Members of the Australian Football Leagues' Medical Officers (n = 94), physiotherapists (n = 50), and Sports Science (n = 19) Associations were invited to participate through e-mail. Five people with more general expertise in sports-related lower-limb injury prevention were also invited to participate.

MAIN OUTCOME MEASURES

The primary outcome measure was the level of agreement on the appropriateness of the proposed exercises and progressions for inclusion in FootyFirst. Consensus was reached when ≥75% of experts who responded to each item agreed and strongly agreed, or disagreed and strongly disagreed, that an exercise or its progressions were appropriate to include in FootyFirst.

RESULTS

Fifty-five experts participated in at least 1 Delphi round. In round 1, consensus was achieved that the proposed warm-up (run through and dynamic stretches) and the exercises and progressions for hamstring strength and for balance, landing, and changing direction were appropriate to include in FootyFirst. There was also consensus in round 1 that progressions for hip/core strength should be included in FootyFirst. Consensus was reached in round 2 that the revised groin strength and hip strength exercises should be included in FootyFirst. Consensus was reached for the progression of the groin strength exercises in round 3.

CONCLUSIONS

The formal consensus development process has resulted in an evidence-informed, researcher-developed, exercise-based sports injury prevention program that is expert endorsed and specific to the context of AF.

CLINICAL RELEVANCE

Lower-limb injuries are common in running, kicking, and contact sports like AF. These injuries are often costly to treat, and many have high rates of recurrence, making them challenging to treat clinically. Reducing these injuries is a high priority for players, teams, and medical staff. Exercise programs provide a method for primary prevention of lower-limb injuries, but they have to be evidence based, have currency with sports practitioners/clinicians, and utility for the context in which they are to be used. However, the comprehensive methods and clinical engagement processes used to develop injury prevention exercise programs have not previously been described in detail. This study describes the results of engaging clinicians and sport scientists in the development of a lower-limb sports injury prevention program for community AF, enabling the development of a program that is both evidence informed and considerate of expert clinical opinion.

Postural stability deficits during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects

The goal of this study was to evaluate postural stability during the transition from double-leg stance (DLS) to single-leg stance (SLS) in anterior cruciate ligament reconstructed (ACLR) (n=20) and non-injured control subjects (n=20). All ACLR subjects had fully returned to their pre-injury sport participation. Both groups were similar for age, gender, height, weight, body mass index and activity level. Spatiotemporal center of pressure outcomes of both legs of each subject were measured during the transition from DLS to SLS in eyes open and eyes closed conditions. Movement speed was standardized. The center of pressure displacement after a new stability point was reached during the SLS phase was significantly increased in the ACLR group compared to the control group in the eyes closed condition (P=.001). No significant different postural stability outcomes were found between the operated and non-operated legs. In conclusion, the ACLR group showed postural stability deficits, indicating that these persons may have a decreased ability to stabilize their body after the internal postural perturbation created by the transition from DLS to SLS. The non-operated leg may not be the best reference when evaluating postural stability of the operated leg after ACLR, as no differences were found between legs.

Validation of a virtual reality balance module for use in clinical concussion assessment and management

OBJECTIVE

To determine the criterion and content validity of a virtual reality (VR) balance module for use in clinical practice.

DESIGN

Retrospective, VR balance module completed by participants during concussion baseline or assessment testing session.

SETTING

A Pennsylvania State University research laboratory.

PARTICIPANTS

A total of 60 control and 28 concussed students and athletes from the Pennsylvania State University.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

This study examined: (1) the relationship between VR composite balance scores (final, stationary, yaw, pitch, and roll) and area of the center-of-pressure (eyes open and closed) scores and (2) group differences (normal volunteers and concussed student-athletes) on VR composite balance scores.

RESULTS

With the exception of the stationary composite score, all other VR balance composite scores were significantly correlated with the center of pressure data obtained from a force platform. Significant correlations ranged from r = -0.273 to -0.704 for the eyes open conditions and from r = -0.353 to -0.876 for the eyes closed condition. When examining group differences on the VR balance composite modules, the concussed group did significantly (P < 0.01) worse on all measures compared with the control group.

CONCLUSIONS

The VR balance module met or exceeded the criterion and content validity standard set by the current balance tools and may be appropriate for use in a clinical concussion setting.

CLINICAL RELEVANCE

Virtual reality balance module is a valid tool for concussion assessment in clinical settings. This novel type of balance assessment may be more sensitive to concussion diagnoses, especially later (7-10 days) in the recovery phase than current clinical balance tools.

What is normal? Female lower limb kinematic profiles during athletic tasks used to examine anterior cruciate ligament injury risk: a systematic review

BACKGROUND

It has been proposed that the performance of athletic tasks where normal motion is exceeded has the potential to damage the anterior cruciate ligament (ACL). Determining the expected or 'normal' kinematic profile of athletic tasks commonly used to assess ACL injury risk can provide an evidence base for the identification of abnormal or anomalous task performances in a laboratory setting.

OBJECTIVE

The objective was to conduct a systematic review of studies examining lower limb kinematics of females during drop landing, drop vertical jump, and side-step cutting tasks, to determine 'normal' ranges for hip and knee joint kinematic variables.

DATA SOURCES

An electronic database search was conducted on the SPORTDiscus(TM), MEDLINE, AMED and CINAHL (January 1980-August 2013) databases using a combination of relevant keywords.

STUDY SELECTION

Studies identified as potentially relevant were independently examined by two reviewers for inclusion. Where consensus could not be reached, a third reviewer was consulted. Original research articles that examined three-dimensional hip and knee kinematics of female subjects during the athletic tasks of interest were included for review. Articles were excluded if subjects had a history of lower back or lower limb joint injury or isolated data from the female cohort could not be extracted.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two reviewers independently assessed the quality of included studies. Data on subject characteristics, the athletic task performed, and kinematic data were extracted from included studies. Studies were categorised according to the athletic task being examined and each study allocated a weight within categories based on the number of subjects assessed. Extracted data were used to calculate the weighted means and standard deviations for hip and knee kinematics (initial contact and peak values). 'Normal' motion was classified as the weighted mean plus/minus one standard deviation.

RESULTS

Of 2,920 citations, a total of 159 articles were identified as potentially relevant, with 29 meeting all inclusion/exclusion criteria. Due to the limited number of studies available examining double-leg drop landings and single-leg drop vertical jumps, insufficient data was available to include these tasks in the review. Therefore, a total of 25 articles were included. From the included studies, 'normal' ranges were calculated for the kinematic variables of interest across the athletic tasks examined.

LIMITATIONS

Joint forces and other additional elements play a role in ACL injuries, therefore, focusing solely on lower limb kinematics in classifying injury risk may not encapsulate all relevant factors. Insufficient data resulted in no normal ranges being calculated for double-leg drop land and single-leg drop vertical jump tasks. No included study examined hip internal/external rotation during single-leg drop landings, therefore ranges for this kinematic variable could not be determined. Variation in data between studies resulted in wide normal ranges being observed across certain kinematic variables.

CONCLUSIONS

The ranges calculated in this review provide evidence-based values that can be used to identify abnormal or anomalous athletic task performances on a multi-planar scale. This may be useful in identifying neuromuscular factors or specific muscular recruitment strategies that contribute to ACL injury risk.

Do exercises used in injury prevention programmes modify cutting task biomechanics? A systematic review with meta-analysis

OBJECTIVE

Some injury prevention programmes aim to reduce the risk of ACL rupture. Although the most common athletic task leading to ACL rupture is cutting, there is currently no consensus on how injury prevention programmes influence cutting task biomechanics. To systematically review and synthesise the scientific literature regarding the influence of injury prevention programme exercises on cutting task biomechanics.

DESIGN

The three largest databases (Medline, EMBASE and CINAHL) were searched for studies that investigated the effect of injury prevention programmes on cutting task biomechanics. When possible meta-analyses were performed.

RESULTS

Seven studies met the inclusion criteria. Across all studies, a total of 100 participants received exercises that are part of ACL injury prevention programmes and 76 participants served in control groups. Most studies evaluated variables associated with the quadriceps dominance theory. The meta-analysis revealed decreased lateral hamstrings electromyography activity (p ≤ 0.05) while single studies revealed decreased quadriceps and increased medial hamstrings activity and decreased peak knee flexion moment. Findings from single studies reported that ACL injury prevention exercises reduce neuromuscular deficits (knee valgus moment, lateral trunk leaning) associated with the ligament and trunk dominance theories, respectively. The programmes we analysed appear most effective when they emphasise individualised biomechanical technique correction and target postpubertal women.

CONCLUSIONS

The exercises used in injury prevention programmes have the potential to improve cutting task biomechanics by ameliorating neuromuscular deficits linked to ACL rupture, especially when they emphasise individualised biomechanical technique correction and target postpubertal female athletes.

The effects of isolated ankle strengthening and functional balance training on strength, running mechanics, postural control and injury prevention in novice runners: design of a randomized controlled trial

BACKGROUND

Risk factors have been proposed for running injuries including (a) reduced muscular strength, (b) excessive joint movements and (c) excessive joint moments in the frontal and transverse planes. To date, many running injury prevention programs have focused on a "top down" approach to strengthen the hip musculature in the attempt to reduce movements and moments at the hip, knee, and/or ankle joints. However, running mechanics did not change when hip muscle strength increased. It could be speculated that emphasis should be placed on increasing the strength of the ankle joint for a "ground up" approach. Strengthening of the large and small muscles crossing the ankle joint is assumed to change the force distribution for these muscles and to increase the use of smaller muscles. This would be associated with a reduction of joint and insertion forces, which could have a beneficial effect on injury prevention. However, training of the ankle joint as an injury prevention strategy has not been studied. Ankle strengthening techniques include isolated strengthening or movement-related strengthening such as functional balance training. There is little knowledge about the efficacy of such training programs on strength alteration, gait or injury reduction.

METHODS/DESIGN

Novice runners will be randomly assigned to one of three groups: an isolated ankle strengthening group (strength, n = 40), a functional balance training group (balance, n = 40) or an activity-matched control group (control, n = 40). Isokinetic strength will be measured using a Biodex System 3 dynamometer. Running kinematics and kinetics will be assessed using 3D motion analysis and a force platform. Postural control will be assessed by quantifying the magnitude and temporal structure of the center of pressure trace during single leg stance on a force platform. The change pre- and post-training in isokinetic strength, running mechanics, and postural control variables will be compared following the interventions. Injuries rates will be compared between groups over 6 months.

DISCUSSION

Avoiding injury will allow individuals to enjoy the benefits of participating in aerobic activities and reduce the healthcare costs associated with running injuries.

TRIAL REGISTRATION

Current Controlled Trial NCT01900262.

Effects of different visual stimuli on postures and knee moments during sidestepping

PURPOSE

Evasive sidestepping during sports commonly results in noncontact anterior cruciate ligament injuries. Sidestepping in response to different simple visual stimuli has been studied previously but never investigated using quasi-game-realistic visual conditions. We compared the biomechanics of high-level and low-level soccer players when sidestepping in response to projected, three-dimensional defender(s) and the traditionally used planned and unplanned arrow stimuli.

METHODS

A three-dimensional motion analysis system captured the trunk and lower limb kinematics and ground reaction forces of 15 high-level and 15 low-level soccer players sidestepping in response to a one-defender scenario (1DS), two-defender scenario (2DS), arrow-planned condition (AP), and arrow-unplanned condition (AUNP). The temporal constraints imposed by the stimuli conditions resulted in increasing difficulty from AP, 1DS, 2DS, to AUNP. Selected joint kinematics and three-dimensional knee moments during the weight-acceptance phase of sidestepping were analyzed.

RESULTS

Hip external rotation at initial foot contact was smaller when participants sidestepped in response to the projected defenders versus arrow conditions. Hip abduction was smallest in the AP, moderate in the defender scenarios, and largest in the AUNP. Peak knee valgus moments were 25% larger in the defender scenarios and 70% larger in the AUNP compared with the AP. High-level players exhibited decreased hip abduction and knee valgus moments in the 2DS compared with the low-level players.

CONCLUSIONS

Compared with the arrow conditions, sidestepping in response to the defender(s) resulted in different postures and knee moments, which further differentiated between high-level and low-level players in the complex 2DS. These findings highlight the effects of stimuli realism and complexity on the visual-perceptual-motor skill of sidestepping, which has implications for anterior cruciate ligament injury prevention.

The reach and adoption of a coach-led exercise training programme in community football

OBJECTIVE

To determine the reach and adoption of a coach-led exercise training programme for lower limb injury prevention.

DESIGN

Secondary analysis of data from a group-clustered randomised controlled trial.

SETTING

A periodised exercise training warm-up programme was delivered to players during training sessions over an 8-week preseason (weeks 1-8) and 18-week playing season.

PARTICIPANTS

1564 community Australian football players.

MAIN OUTCOME MEASUREMENTS

Reach, measured weekly, was the number of players who attended training sessions. Adoption was the number of attending players who completed the programme in full, partially or not at all. Reasons for partial or non-participation were recorded.

RESULTS

In week 1, 599 players entered the programme; 55% attended 1 training session and 45% attended > 1 session. By week 12, 1540 players were recruited but training attendance (reach) decreased to <50%. When players attended training, the majority adopted the full programme-ranging from 96% (week 1) to above 80% until week 20. The most common reasons for low adoption were players being injured, too sore, being late for training or choosing their own warm-up.

CONCLUSIONS

The training programme's reach was highest preseason and halved at the playing season's end. However, when players attended training sessions, their adoption was high and remained close to 70% by season end. For sports injury prevention programmes to be fully effective across a season, attention also needs to be given to (1) encouraging players to attend formal training sessions and (2) considering the possibility of some form of programme delivery outside of formal training.