Augmented feedback reduces jump landing forces

Comparing the Effects of Virtual Reality Breathing Exercise and Incentive Spirometry Exercise on Improving Pulmonary Function in Children with Spastic Diplegic Cerebral Palsy

INTRODUCTION

Children with cerebral palsy (CP) have a higher incidence of respiratory dysfunction than healthy children. Virtual reality breathing therapy is an assistive technology that is becoming popular in the rehabilitation of children with CP.

METHODS

This experimental study included a total of 32 children with spastic diplegic CP who were divided into two groups: the virtual reality breathing training (VRBT) group and the incentive spirometry (IST) group. Individuals classified as levels I to III on the gross motor function classification system (GMFCS) were recruited using the simple random sampling method.

RESULT

The results of comparing the values of forced vital capacity (FVC), forced expiratory volume at one second (FEV1), and the ratio of FVC/FEV1 showed a significant difference between groups. A significant difference was found in the VRBT group compared to the IST group, except for the peak expiratory flow (PEF) values, which showed a nonsignificant difference between the groups.

CONCLUSION

There were significant differences in FVC and FEV1 between the VRBT and IST groups. It has been concluded that VRBT has additional benefits in improving pulmonary functions.

Models of Video Feedback for Youth Athletes Performing an American Football Tackle

CONTEXT

Video feedback is an expeditious method for improving athlete safety when performing activities with an inherent risk of injury. Providing appropriate and validated feedback during tackling training in American football may be a mechanism for athletes to learn safe tackling performance.

OBJECTIVE

To determine the effect of video feedback in the instruction of tackling form.

DESIGN

Controlled laboratory study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 32 youth football athletes (28 boys, 4 girls; age = 11.8 ± 0.8 years) participated in 1 day of training. Of those, 14 participants completed 2 additional days of training and a 48-hour retention and transfer test.

INTERVENTION(S)

Video feedback using self as model, expert as model, combined self and expert model, and oral feedback to promote safe tackling performance in a laboratory environment.

MAIN OUTCOME MEASURE(S)

Shoulder extension, cervical extension, trunk angle, pelvis height, and step length by training block and over time.

RESULTS

For the 1-day training group, main effects for time were observed for shoulder extension (P < .01), cervical extension (P = .01), pelvis height (P < .01), and step length (P < .01), with better performance for pelvis height and step length after combined feedback. For the 3-day training group, main effects of time were identified in pelvis height (P < .01) and step length (P < .01), with combined feedback showing better performance than other methods in shoulder extension and pelvis height. Combined feedback resulted in better performance compared with its component parts and oral feedback alone. In the combined model, participants viewed both their performance and the expert model, enabling them to see the difference between current and required performance.

CONCLUSIONS

Combined feedback may be superior to other forms of feedback in improving movement performance. This effect can be generalized across disciplines that provide instruction and feedback in movement.

The effect of types of sensory feedback on the acquisition and retention of squat performance: A randomized, double-blind, controlled trial

Various sensory feedback methods are considered important for motor learning, but the effect of each sensory feedback method on effective squat learning still needs to be clarified. This study aimed to investigate the effect of sensory feedback types on the acquisition and retention of a squat. A double-blinded, randomized controlled trial was carried out. Thirty-healthy people were recruited and randomly assigned to the visual feedback group (VFG = 10), tactile feedback group (TFG = 10), and control group (CG = 10). VFG received visual feedback through video data of the participant performing squats, and TFG received tactile feedback through manual contact with a physical therapist. Both groups received feedback on the movements that needed correction after each set was completed. CG maintained rest without receiving any feedback. The retro-reflexive marker, force plate, and electromyography were used to measure body angle, foot center of pressure (COP), and muscle activity. All assessments were measured to confirm a squat acquisition. VFG and TFG showed significant differences in neutral knee position (NKP), trunk forward lean (TFL), anterior knee displacement (AKD), and anteroposterior (AP) foot COP (p < 0.050). In addition, the acquisition was retained until 3 days later for NKP and a week later for TFL, AKD, and AP foot COP in VFG (p < 0.050), while the acquisition was not retained in TFG (p > 0.050). There was no statistically significant change in CG (p > 0.050). This study demonstrated that visual feedback positively affects the acquisition and retention of squats. Therefore, we recommend the use of visual feedback for squat acquisition and retention in exercise novices.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Vibrotactile feedback in virtual motor learning: A systematic review

Vibrotactile feedback can be effectively applied to motor (physical) learning in virtual environments, as it can provide task-intrinsic and augmented feedback to users, assisting them in enhancing their motor performance. This review investigates current uses of vibrotactile feedback systems in motor learning applications built upon virtual environments by systematically synthesizing 24 peer-reviewed studies. We aim to understand: (1) the current state of the science of using real-time vibrotactile feedback in virtual environments for aiding the acquisition (or improvement) of motor skills, (2) the effectiveness of using vibrotactile feedback in such applications, and (3) research gaps and opportunities in current technology. We used the Sensing-Analysis-Assessment-Intervention framework to assess the scientific literature in our review. The review identifies several research gaps in current studies, as well as potential design considerations that can improve vibrotactile feedback systems in virtual motor learning applications, including the selection and placement of feedback devices and feedback designs.

A Comprehensive Summary of Systematic Reviews on Sports Injury Prevention Strategies

Background

A large volume of systematic reviews and meta-analyses has been published on the effectiveness of sports injury prevention programs.

Purpose

To provide a qualitative summary of published systematic reviews and meta-analyses that have examined the effectiveness of sports injury prevention programs on reducing musculoskeletal injuries.

Study Design

Systematic review; Level of evidence, 4.

Methods

We searched the PubMed, CINAHL, EMBASE, and the Cochrane databases for systematic reviews and meta-analyses that evaluated the effectiveness of sports injury prevention programs. We excluded published abstracts, narrative reviews, articles not published in English, commentaries, studies that described sports injury prevention strategies but did not assess their effectiveness, studies that did not assess musculoskeletal injuries, and studies that did not assess sports-related injuries. The most relevant results were extracted and summarized. Levels of evidence were determined per the Oxford Centre for Evidence-Based Medicine, and methodological quality was assessed using the AMSTAR-2 (A MeaSurement Tool to Assess systematic Reviews, revised version).

Results

A total of 507 articles were retrieved, and 129 were included. Articles pertaining to all injuries were divided into 9 topics: sports and exercise in general (n = 20), soccer (n = 13), ice hockey (n = 1), dance (n = 1), volleyball (n = 1), basketball (n = 1), tackle collision sports (n = 1), climbing (n = 1), and youth athletes (n = 4). Articles on injuries by anatomic site were divided into 11 topics: general knee (n = 8), anterior cruciate ligament (n = 34), ankle (n = 14), hamstring (n = 11), lower extremity (n = 10), foot (n = 6), groin (n = 2), shoulder (n = 1), wrist (n = 2), and elbow (n = 1). Of the 129 studies, 45.7% were ranked as evidence level 1, and 55.0% were evidence level 2. Based on the AMSTAR-2, 58.9% of the reviews reported a priori review methods, 96.1% performed a comprehensive literature search, 47.3% thoroughly described excluded articles, 79.1% assessed risk of bias for individual studies, 48.8% reported a valid method for statistical combination of data (ie, meta-analysis), 45.0% examined the effect of risk of bias on pooled study results, and 19.4% examined the risk for publication bias.

Conclusion

This comprehensive review provides sports medicine providers with a single source of the most up-to-date publications in the literature on sports injury prevention.

Changes in landing mechanics using augmented feedback: 4-Week training and retention study

CONTEXT

Non-contact ACL injuries are common in female athletes during landing tasks. Post-trial performance-based feedback may be an effective method to reduce landing forces and knee valgus during landing. Information regarding the retention of these changes based on such training is generally lacking for weekly and monthly retention.

OBJECTIVE

To determine the effectiveness of post-trial feedback training to promote and retain changes in vertical ground reaction force (vGRF) and knee to ankle (K:A) ratio during a dual task drop landing in female collegiate athletes.

DESIGN

Repeated measures; SETTING: University campus.

PARTICIPANTS

22 female collegiate athletes.

MATERIALS AND METHODS

Dual task drop landings were performed over 4 successive weeks with immediate post trial feedback on peak vGRF, symmetry, and K:A ratio. K:A ratio was a surrogate measure for knee valgus in drop landing.

RESULTS

Significant decreases in vGRF and increases in K:A ratio were found within training sessions (p = .000). Both variables were retained each week over the 4 weeks.

CONCLUSION

Using a custom portable clinical feedback system may be an effective tool in reducing peak vGRFs and knee abduction angles during a drop landing over a 4-week period in female collegiate athletes.

Motor learning methods that induce high practice variability reduce kinematic and kinetic risk factors of non-contact ACL injury

The prevention of non-contact anterior cruciate ligament (ACL) injuries often involves movement training, but the effectiveness of different motor learning methods has not been fully investigated. The purpose of this study was therefore to examine the effects of linear pedagogy (LP), nonlinear pedagogy (NLP) and differential learning (DL) motor learning methods on changing kinetic and kinematic factors during expected sidestep cutting related to non-contact ACL injuries. These methods primarily differ in the amount and type of movement variability they induce during practice. Sixty-six beginner male soccer players (27.5 ± 2.7 years, 180.6 ± 4.9 cm, 78.2 ± 4.6 kg) were randomly allocated to a group that trained for 12 weeks with either a LP, NLP or DL type of motor learning methods. All participants completed a biomechanical evaluation of side-step cutting before and after the training period. Analysis of covariance was used to compare post-testing outcomes among the groups while accounting for group differences in baseline performance. Changes in all kinematic and kinetic variables in NLP and DL groups were significantly higher compared to the LP group. Most comparisons were also different between NLP and DL group with the exception of vertical ground reaction force, the knee extension/flexion, knee valgus, and ankle dorsiflexion moments. Our findings indicate that beginner male soccer players may benefit from training programs incorporating NLP or DL versus LP to lower biomechanical factors associated with non-contact ACL injury, most likely because of the associated increased execution variability during training. We discuss that practitioners should consider using the NLP or DL methods, and particular the NLP, during which variability is induced to guide search, when implementing training programs to prevent ACL injuries in soccer.

Females Decrease Vertical Ground Reaction Forces Following 4-Week Jump-Landing Feedback Intervention Without Negative Affect on Vertical Jump Performance

CONTEXT

High vertical ground reaction force (vGRF) when initiating ground contact during jump landing is one biomechanical factor that may increase risk of anterior cruciate ligament injury. Intervention programs have been developed to decrease vGRF to reduce injury risk, yet generating high forces is still critical for performing dynamic activities such as a vertical jump task.

OBJECTIVE

To evaluate if a jump-landing feedback intervention, cueing a decrease in vGRF, would impair vertical jump performance in a separate task (Vertmax).

DESIGN

Randomized controlled trial. Patients (or Other Participants): Forty-eight recreationally active females (feedback: n = 31; 19.63 [1.54] y, 1.6 [0.08] cm, 58.13 [7.84] kg and control: n = 15; 19.6 [1.68] y, 1.64 [0.05] cm, 60.11 [8.36] kg) participated in this study.

INTERVENTION

Peak vGRF during a jump landing and Vertmax were recorded at baseline and 4 weeks post. The feedback group participated in 12 sessions over the 4-week period consisting of feedback provided for 6 sets of 6 jumps off a 30-cm box. The control group was instructed to return to the lab 28 days following the baseline measurements.

MAIN OUTCOME MEASURES

Change scores (postbaseline) were calculated for peak vGRF and Vertmax. Group differences were evaluated for peak vGRF and Vertmax using a Mann-Whitney U test (P < .05).

RESULTS

There were no significant differences between groups at baseline (P > .05). The feedback group (-0.5 [0.3] N/kg) demonstrated a greater decrease in vGRF compared with the control group (0.01 [0.3] N/kg) (t(46) = -5.52, P < .001). There were no significant differences in change in Vertmax between groups (feedback = 0.9 [2.2] cm, control = 0.06 [2.1] cm; t(46) = 0.46, P = .64).

CONCLUSIONS

While the feedback intervention was effective in decreasing vGRF when landing from a jump, these participants did not demonstrate changes in vertical jump performance when assessed during a different task. Practitioners should consider implementing feedback intervention programs to reduce peak vGRF, without worry of diminished vertical jump performance.

Landing Error Scoring System scores change with knowledge of scoring criteria and prior performance

OBJECTIVE

To examine if the knowledge of scoring criteria and prior performance influence Landing Error Scoring System (LESS) outcomes.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Thirty individuals.

MAIN OUTCOME MEASURES

The LESS was tested at Baseline and one week later under two conditions: Pre and Post information. For the Post condition, LESS items were explained to participants, as were their individual Baseline scores. Mean LESS scores and number of individuals categorized at high and low risk were compared between Pre and Post using paired t-tests and McNemar's tests, respectively. McNemar's tests were also used to compare proportions of specific LESS errors between Pre and Post conditions.

RESULTS

Mean LESS Post scores (4.7 ± 1.2 errors) were significantly lower than Pre scores (6.6 ± 2.0 errors, p < 0.001) as was the number of individuals at high risk (25 vs 10 participants, p < 0.001). A significantly lower proportion of participants scored an error for the joint displacement item of LESS Post compared to Pre condition (p < 0.001).

CONCLUSION

When using the LESS, it is important that tested individuals have no knowledge of scoring criteria or previous errors for a valid assessment of innate jump-landing movement patterns and injury risk.

Children's Single-Leg Landing Movement Capability Analysis According to the Type of Sport Practiced

(1) Background: Understanding children's motor patterns in landing is important not only for sport performance but also to prevent lower limb injury. The purpose of this study was to analyze children's lower limb joint angles and impact force during single-leg landings (SLL) in different types of jumping sports using statistical parametric mapping (SPM). (2) Methods: Thirty children (53.33% girls, M = 10.16 years-old, standard deviation (SD) = 1.52) divided into three groups (gymnastics, volleyball and control) participated in the study. The participants were asked to do SLLs with the dominant lower limb (barefoot) on a force plate from a height of 25 cm. The vertical ground reaction force (GRF) and lower limb joint angles were assessed. SPM{F} one-way analysis of variance (ANOVA) and SPM{t} unpaired t-tests were performed during the landing and stability phases. (3) Results: A significant main effect was found in the landing phase of jumping sport practice in GRF and joint angles. During the stability phase, this effect was exhibited in ankle and knee joint angles. (4) Conclusions: Evidence was obtained of the influence of practicing a specific sport in childhood. Child volleyball players performed SLL with lower impact force and higher knee flexion than child gymnasts. Training in specific jumping sports (i.e., volleyball and gymnastics) could affect the individual capacity to adapt SLL execution.

Effects of 4-week impairment-based rehabilitation on jump-landing biomechanics in chronic ankle instability patients

OBJECTIVE

To determine effects of 4-weeks of impairment-based rehabilitation on lower extremity neuromechanics during jump-landing.

DESIGN

Descriptive laboratory study.

PARTICIPANTS

Twenty-six CAI subjects (age = 21.4 ± 3.1 sex=(M = 7,F = 19), height = 169.0 ± 8.8 cm, weight = 71.0 ± 13.8 kg) completed 15 jump-landing trials prior to and following 12 supervised rehabilitation sessions.

MAIN OUTCOME MEASURES

Frontal and sagittal lower extremity kinematics and kinetics and sEMG amplitudes (anterior tibialis, peroneus brevis, peroneus longus, and medial gastrocnemius). Means and 90% confidence intervals (CIs) were calculated for 100 ms prior to and 200 ms following ground contact. Areas where pre- and post-rehabilitation CIs did not overlap were considered significantly different. Kinematic and kinetic peaks and kinematic excursion were compared with paired t-test (P ≤ 0.05).

RESULTS

Following rehabilitation, CAI subjects exhibited less ankle (2.1° (0.8, 3.4), P < 0.01) and hip (2.0° (0.5, 3.7), P = 0.01) frontal plane excursion and lower peak hip abduction (2.5° (0.0, 5.0), P = 0.05). There was less ankle (5.0° (1.7, 8.3), P < 0.01) and knee (3.4° (0.8, 6.0), P = 0.01) sagittal plane excursion following rehabilitation. There was decreased peroneus longus activity from 9 ms to 135 ms post ground contact and decreased peak plantar flexion moment (0.08 N∗m/kg (0.01, 0.13), P = 0.02) following rehabilitation.

CONCLUSION

Progressive impairment-based rehabilitation resulted in reductions in kinematic excursion and peroneus longus muscle activity, suggesting a more efficient landing strategy.

Biofeedback flutter device for managing the symptoms of patients with COPD

BACKGROUND

Flutter is a device used in removing excess lung secretions. The conventional flutter lacks a biofeedback component to facilitate optimal use by the patients.

OBJECTIVE

The current research aims to compare the effects of biofeedback flutter devices with the conventional flutter in managing the symptoms of patients with chronic obstructive pulmonary diseases.

METHODS

One hundred and sixty-eight participants were randomly allocated into four groups: Group A (conventional), Group B (visual biofeedback), Group C (auditory biofeedback) and Group D (visual and auditory biofeedback). All groups were treated five days for 20 minutes. Outcome measures included wet sputum weight [during intervention (T1) and 1 hour after intervention (T2)], oxygen saturation and dyspnea score (before and after intervention) on all days.

RESULTS

The wet sputum expectorated (T2) by Group B was significantly higher than Group A (P< 0.001), Group C (P< 0.001) and Group D (P< 0.05). The dyspnea score for Group B (P< 0.05), Group C (P< 0.05) and Group D (P< 0.05) was significantly lower than Group A. The post-intervention oxygen saturation level was higher in Group D followed by Groups B, C and A.

CONCLUSION

The use of biofeedback flutter is effective in the removal of secretion, reducing dyspnea and improving oxygen saturation when compared to conventional flutter.

Loading Behaviors Do Not Match Loading Abilities Postanterior Cruciate Ligament Reconstruction

PURPOSE

Strategies that underload the surgical limb after anterior cruciate ligament reconstruction (ACLr) are observed in submaximal tasks. It is not known what underlies these strategies in early rehabilitation. The purpose of this study was to determine if underloading can be attributed to the inability to meet task demands with and without attention to limb loading or learned behavior.

METHODS

Twenty individuals (110.6 [18.1] days) post-ACLr and 20 healthy individuals (CTRL) participated in this study. Participants performed standing, sit-to-stand, and squat tasks under natural, instructed, and feedback conditions. Limb-loading symmetry was calculated as the between-limb ratio of vertical ground reaction force impulse during each task. General Linear Model repeated-measures analysis, 2 (group) × 3 (condition), determined the effects of group and condition on limb-loading symmetry for each task.

RESULTS

Significant interactions were observed for each task (all P < 0.001). Compared with CTRL, ACLr exhibited greater asymmetry during natural (deficits: standing, 10%, P = 0.001; sit-to-stand, 25%, P < 0.001; squat, 15%, P < 0.001) and instructed (deficits: sit-to-stand, 13%, P = 0.001; squat, 8%, P = 0.04), but not feedback conditions. The CTRL maintained symmetry across conditions and tasks. Anterior cruciate ligament reconstruction exhibited greater asymmetry in natural compared with instructed (deficits: standing, 11%, P < 0.001; sit-to-stand, 14%, P < 0.001; squat, 8%, P = 0.001) and feedback (deficits: standing, 10%, P = 0.001; sit-to-stand, 21%, P < 0.001; squat, 15%, P < 0.001) conditions.

CONCLUSIONS

The presence of loading asymmetries in natural but not feedback conditions indicates that individuals 3 months post-ACLr shift loading away from surgical limb despite the ability to meet task demands which may be suggestive of nonuse behavior. Even when instructed to load symmetrically, individuals continued to exhibit some degree of asymmetry.

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

CONTEXT

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

OBJECTIVE

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

DESIGN

Pretest and posttest control study.

SETTING

University research laboratory.

PARTICIPANTS

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

INTERVENTION

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSION

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

Task but not arm restriction influences lower extremity joint mechanics during bilateral landings

Box and jump landing tasks are commonly used to study lower extremity injury mechanisms, such as anterior cruciate ligament (ACL) injuries. Arm restriction during these tasks is typically determined via researcher preference. Therefore, the purpose of this study was to compare three-dimensional lower extremity kinematics and kinetics during bilateral box and jump landings, and to determine the effects of arm restriction. Twenty-eight participants (14 males, 14 females) completed three bilateral landings tasks: box landings with arms unrestricted (BLA), box landings with arms restricted against the trunk (BLNA) and jump landings (JL). Right leg joint kinematics and kinetics were collected and compared between landing tasks. No statistically significant differences were found between BLA and BLNA, therefore arm restriction did not appear to influence lower extremity variables during bilateral box landings. However, specific injury-related variables, such as peak knee adduction moment differed between box and jump landings (BLNA: 0.31 ± 0.3 Nm/(kg·m)); JL: 0.45 ± 0.3 Nm/(kg·m); p = 0.020). Our results suggest that based on study purpose, careful consideration is needed when determining what bilateral landing task to choose during data collection.

The sonic instructor: A music-based biofeedback system for improving weightlifting technique

In this study, we assumed that correct functional movements for weightlifting can be learned with the help of a music-based biofeedback system. We compared musical feedback with verbal feedback from experienced trainers using two independent groups. The focus was on one specific movement called deadlift. Physical parameters under considerations were the spine (i.e. loss of midline stability resulting in flexion) and the forward displacement of the barbell during the repetitions relative to the mid-foot. We recruited 31 recreational weight lifters (21-42 years of age). Results revealed that both feedback types are effective in improving the movements for deadlift. No significant differences were found across the two feedback types, neither in terms of movement, nor in terms of clarity and motivation. The results suggest that the proposed feedback system is a valid tool for technology-aided training and self-training practices.

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

CONTEXT: 

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

OBJECTIVE: 

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

DATA SOURCES: 

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

DATA EXTRACTION: 

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

DATA SYNTHESIS: 

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

CONCLUSIONS: 

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

Effect of Posttrial Visual Feedback and Fatigue During Drop Landings on Patellofemoral Joint Stress in Healthy Female Adults

Patellofemoral pain (PFP) is common in females. Patellofemoral joint stress (PFJS) may be important in the development of PFP. Ground reaction force (GRF) during landing activities may impact PFJS. Our purpose was to determine how healthy females alter their landing mechanics using visual posttrial feedback on their GRF and assess how PFJS changes. Seventeen participants performed a series of drop landings during 3 conditions: baseline, feedback, and postfatigue feedback. The fatigue protocol used repetitive jump squats. Quadriceps force was estimated through inverse-dynamics-based static optimization approach. Then, PFJS was calculated using a musculoskeletal model. Multivariate differences were shown across conditions (P = .01). Univariate tests revealed differences in PFJS (P = .014), knee range of motion (P = .001), and GRF (P = .005). There were no differences in quadriceps force (P = .125). PFJS and GRF decreased from baseline to feedback (P = .002, P = .007, respectively), while PFJS increased from feedback to postfatigue feedback (P = .03). Knee range of motion increased from baseline to feedback (P = .043), then decreased from feedback to postfatigue feedback (P < .001). Visual feedback of GRF may reduce PFJS, but may not effectively transfer to a fatigued state.

Positive Effects of Augmented Feedback to Reduce Time on Ground in Well-Trained Runners

CONTEXT

Successful elite sprint to long-distance runners are known to have shorter ground-contact time (GCT) than their less successful counterparts.

PURPOSE

To investigate whether augmented feedback (aF) about GCT can reduce the time on ground (TOG) per minute in long-distance runners and, if so, whether this reduction improves running performance.

METHODS

Thirty well-trained runners were allocated to 3 groups. The intervention group (IG) received visual aF about their GCT during 8 high-intensity interval sessions in the 4-wk training period and were instructed to minimize GCT. The 1st control group (CG1) trained with the IG but was not given any feedback. The 2nd control group (CG2) followed their own training routine. Data were obtained pre- and postintervention for all 3 groups. The dependent variable was TOG per minute, computed from step frequency and GCT.

RESULTS

The IG significantly reduced TOG (P = .043, -1.7%, 90%CL -3.1;-0.3) and improved their mean 10 × 400-m performance time (P < .001, -1.5%, 90%CL -1.9;-1.1). In contrast, the 2 control groups revealed unchanged values, indicating that normal high-intensity training and an individualized routine without aF were not able to reduce TOG. The fact that CG1 received the same instructions and participated in the same training sessions as the IG underlined that aF was crucial to reduce TOG.

CONCLUSIONS

The provision of aF about GCT seems to be a promising approach that should be considered during training practice of well-trained runners.

Verbal augmented feedback in the rehabilitation of lower extremity musculoskeletal dysfunctions: a systematic review

Background

Verbal augmented feedback (VAF) is commonly used in physiotherapy rehabilitation of individuals with lower extremity musculoskeletal dysfunction or to induce motor learning for injury prevention. Its effectiveness for acquisition, retention and transfer of learning of new skills in this population is unknown.

Objectives

First, to investigate the effect of VAF for rehabilitation and prevention of lower extremity musculoskeletal dysfunction. Second, to determine its effect on motor learning and the stages of acquisition, retention and transfer in this population.

Design

Systematic review designed in accordance with the Centre for Reviews and Dissemination and reported in line with Preferred Reporting Items for Systematic Review and Meta-analysis.

Method

MEDLINE, Embase, PubMed and five additional databases were searched to identify primary studies with a focus on VAF for prevention and rehabilitation of lower extremity musculoskeletal dysfunction. One reviewer screened the titles and abstracts. Two reviewers retrieved full text articles for final inclusion. The first reviewer extracted data, whereas the second reviewer audited. Two reviewers independently assessed risk of bias and quality of evidence using Cochrane Collaboration’s tool and Grading of Recommendations Assessment, Development and Evaluation, respectively.

Results

Six studies were included, with a total sample of 304 participants. Participants included patients with lateral ankle sprain (n=76), postoperative ACL reconstruction (n=16) and healthy individuals in injury prevention (n=212). All six studies included acquisition, whereas retention was found in five studies. Only one study examined transfer of the achieved motor learning (n=36). VAF was found to be effective for improving lower extremity biomechanics and postural control with moderate evidence from five studies.

Conclusion

VAF should be considered in the rehabilitation of lower extremity musculoskeletal dysfunctions. However, it cannot be unequivocally confirmed that VAF is effective in this population, owing to study heterogeneity and a lack of high-quality evidence. Nevertheless, positive effects on lower extremity biomechanics and postural control have been identified. This suggests that further research into this topic is warranted where an investigation of long-term effects of interventions is required. All stages (acquisition, retention and transfer) should be evaluated.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

I.

Association of Quadriceps Strength and Psychosocial Factors With Single-Leg Hop Performance in Patients With Meniscectomy

Background:

Clinicians use the single-leg hop test to assess readiness for return to sports after knee injury. Few studies have reported the results of single-leg hop testing after meniscectomy. Additionally, the contributions of impairments in quadriceps strength and psychosocial factors to single-leg hop performance are unknown.

Purpose:

To compare single-leg hop performance (distance and landing mechanics) between limbs and to examine the association of single-leg hop performance with quadriceps strength and psychosocial factors in patients with meniscectomy.

Study Design:

Descriptive laboratory study.

Methods:

A total of 22 subjects who underwent meniscectomy for traumatic meniscal tears received either standard rehabilitation alone or with additional quadriceps strengthening. Testing was conducted immediately postrehabilitation and at 1 year postsurgery. A single-leg hop test was performed bilaterally, and hop distance was used to create a hop symmetry index. Landing mechanics (peak knee flexion angle, knee extension moment, and peak vertical ground-reaction force) were analyzed with a motion-capture system and a force plate. An isokinetic dynamometer (60 deg/s) assessed knee extensor peak torque and rate of torque development (RTD_0-200ms and RTD_{0–peak torque}). Questionnaires assessed fear of reinjury (Tampa Scale for Kinesiophobia [TSK-11]) and self-efficacy (Knee Activity Self-Efficacy [KASE]).

Results:

Rehabilitation groups did not significantly differ in single-leg hop performance; therefore, groups were combined for further analyses. The mean hop symmetry index was 88.6% and 98.9% at postrehabilitation and 1 year postsurgery, respectively. Compared with the nonsurgical limb, the surgical limb showed decreased peak knee flexion angle at postrehabilitation and decreased knee extension moment at 1 year postsurgery. The hop symmetry index was positively associated with peak torque, RTD_0-200ms, and the KASE score at postrehabilitation. Moreover, at postrehabilitation, the peak knee flexion angle was positively associated with peak torque and RTD_0-200ms, and the knee extension moment was positively associated with RTD_0-200ms. At 1 year postsurgery, peak knee flexion angle and knee extension moment were both positively associated with peak torque, RTD_0-200ms, and RTD_{0–peak torque}.

Conclusion:

Although the hop symmetry index could be considered satisfactory for returning to sports, asymmetries in landing mechanics still exist in the first year postmeniscectomy. Greater quadriceps strength was associated with greater single-leg hop distance and better landing mechanics at both postrehabilitation and 1 year postsurgery. Knee activity self-efficacy was the only psychosocial factor associated with single-leg hop performance and isolated to a positive association with single-leg hop distance at postrehabilitation.

Clinical Relevance:

Rate of development is not typically measured in the clinic but can be an additional quadriceps measure to monitor for single-leg hop performance. Quadriceps strength and psychosocial factors appear to have separate influence on single-leg hop performance after meniscectomy, which has implications for developing appropriate interventions for optimal single-leg hop performance.

A Method for Evaluating Timeliness and Accuracy of Volitional Motor Responses to Vibrotactile Stimuli

Artificial sensory feedback (ASF) systems can be used to compensate for lost proprioception in individuals with lower-limb impairments. Effective design of these ASF systems requires an in-depth understanding of how the parameters of specific feedback mechanism affect user perception and reaction to stimuli. This article presents a method for applying vibrotactile stimuli to human participants and measuring their response. Rotating mass vibratory motors are placed at pre-defined locations on the participant's thigh, and controlled through custom hardware and software. The speed and accuracy of participants' volitional responses to vibrotactile stimuli are measured for researcher-specified combinations of motor placement and vibration frequency. While the protocol described here uses push-buttons to collect a simple binary response to the vibrotactile stimuli, the technique can be extended to other response mechanisms using inertial measurement units or pressure sensors to measure joint angle and weight bearing ratios, respectively. Similarly, the application of vibrotactile stimuli can be explored for body segments other than the thigh.

Motion Analysis and the Anterior Cruciate Ligament: Classification of Injury Risk

Anterior cruciate ligament (ACL) injuries are common, catastrophic events that incur large expense and lead to degradation of the knee. As such, various motion capture techniques have been applied to identify athletes who are at increased risk for suffering ACL injuries. The objective of this clinical commentary was to synthesize information related to how motion capture analyses contribute to the identification of risk factors that may predict relative injury risk within a population. Individuals employ both active and passive mechanisms to constrain knee joint articulation during motion. There is strong evidence to indicate that athletes who consistently classify as high-risk loaders during landing suffer from combined joint stability deficits in both the active and passive knee restraints. Implementation of prophylactic neuromuscular interventions and biofeedback can effectively compensate for some of the deficiencies that result from poor control of the active knee stabilizers and reduce the incidence of ACL injuries.

Jump-landing biomechanics following a 4-week real-time feedback intervention and retention

BACKGROUND

Poor neuromuscular control can increase the risk of anterior cruciate ligament (ACL) injury. Landing with decreased knee and hip flexion may increase the risk of lower extremity injury. Feedback interventions have demonstrated changes in jump-landing biomechanics. Traditional feedback (TF), provided after task completion, includes critical factors to focus on during jump-landing. Real-time feedback (RTF), provided while completing the task, may be superior for improving jump-landing biomechanics. This investigation evaluated the effect of RTF+TF compared to TF and a control group in changing lower extremity jump-landing biomechanics following a 4-week feedback intervention and a 1-week no feedback retention.

METHODS

Participants completed 12 feedback sessions over 4 weeks. At each session, participants performed 6 sets of 6 jumps off a 30 cm box. Participants were provided TF or RTF+TF following each set of jumps. Participants were tested at baseline, immediately following the 4-week intervention and following a 1-week retention. The control group was tested at two time points 4 weeks apart.

FINDINGS

Acquisition analysis: RTF+TF and TF groups demonstrated greater change in peak hip flexion angles and peak knee flexion angles compared to the control group following the intervention. TF and RTF+TF groups demonstrated a greater decrease in peak vertical ground reaction force compared to the control group. No significant differences were observed between groups in the retention analysis.

INTERPRETATION

This study provides evidence of acquisition of biomechanical changes following a 4-week feedback intervention. Future research should further investigate the retention of biomechanical changes, the optimal length of feedback interventions and transfer of learned biomechanics to similar athletic tasks.

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.

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

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

Landing Technique and Performance in Youth Athletes After a Single Injury-Prevention Program Session

CONTEXT

Injury-prevention programs (IPPs) performed as season-long warm-ups improve injury rates, performance outcomes, and jump-landing technique. However, concerns regarding program adoption exist. Identifying the acute benefits of using an IPP compared with other warm-ups may encourage IPP adoption.

OBJECTIVE

To examine the immediate effects of 3 warm-up protocols (IPP, static warm-up [SWU], or dynamic warm-up [DWU]) on jump-landing technique and performance measures in youth athletes.

DESIGN

Randomized controlled clinical trial.

SETTING

Gymnasiums.

PATIENTS OR OTHER PARTICIPANTS

Sixty male and 29 female athletes (age = 13 ± 2 years, height = 162.8 ± 12.6 cm, mass = 37.1 ± 13.5 kg) volunteered to participate in a single session.

INTERVENTION(S)

Participants were stratified by age, sex, and sport and then were randomized into 1 protocol: IPP, SWU, or DWU. The IPP consisted of dynamic flexibility, strengthening, plyometric, and balance exercises and emphasized proper technique. The SWU consisted of jogging and lower extremity static stretching. The DWU consisted of dynamic lower extremity flexibility exercises. Participants were assessed for landing technique and performance measures immediately before (PRE) and after (POST) completing their warm-ups.

MAIN OUTCOME MEASURE(S)

One rater graded each jump-landing trial using the Landing Error Scoring System. Participants performed a vertical jump, long jump, shuttle run, and jump-landing task in randomized order. The averages of all jump-landing trials and performance variables were used to calculate 1 composite score for each variable at PRE and POST. Change scores were calculated (POST - PRE) for all measures. Separate 1-way (group) analyses of variance were conducted for each dependent variable (α < .05).

RESULTS

No differences were observed among groups for any performance measures (P > .05). The Landing Error Scoring System scores improved after the IPP (change = -0.40 ± 1.24 errors) compared with the DWU (0.27 ± 1.09 errors) and SWU (0.43 ± 1.35 errors; P = .04).

CONCLUSIONS

An IPP did not impair sport performance and may have reduced injury risk, which supports the use of these programs before sport activity.

The Effects of Game-Based Breathing Exercise on Pulmonary Function in Stroke Patients: A Preliminary Study

Background

Reduction of respiratory function along with hemiparesis leads to decreased endurance, dyspnea, and increased sedentary behavior, as well as to an increased risk of stroke. The main purpose of this study was to investigate the preliminary effects of game-based breathing exercise (GBE) on pulmonary function in stroke patients.

Material/Methods

Thirty-eight in-patients with stroke (22 men, 16 women) were recruited for the study. Participants were randomly allocated into 2 groups: patients assigned to the GBE group (n=19), and the control group (n=19). The GBE group participated in a GBE program for 25 minutes a day, 3 days a week, during a 5 week period. For the same period, both groups participated in a conventional stroke rehabilitation program. Forced vital capacity (FVC), forced expiratory volume at 1 second (FEV₁), FEV₁/FVC, and maximum voluntary ventilation (MVV) were measured by a spirometer in pre- and post-testing.

Results

The GBE group had significantly improved FVC, FEV_1, and MVV values compared with the control group (p<0.05), although there was no significant difference in FEV₁/FVC value between groups. Significant short-term effects of the GBE program on pulmonary function in stroke patients were recorded in this study.

Conclusions

These findings gave some indications that it may be feasible to include GBE in rehabilitation interventions with this population.

Optimization of the anterior cruciate ligament injury prevention paradigm: novel feedback techniques to enhance motor learning and reduce injury risk

Primary anterior cruciate ligament (ACL) injury prevention programs effectively reduce ACL injury risk in the short term. Despite these programs, ACL injury incidence is still high, making it imperative to continue to improve current prevention strategies. A potential limitation of current ACL injury prevention training may be a deficit in the transfer of conscious, optimal movement strategies rehearsed during training sessions to automatic movements required for athletic activities and unanticipated events on the field. Instructional strategies with an internal focus of attention have traditionally been utilized, but may not be optimal for the acquisition of the control of complex motor skills required for sports. Conversely, external-focus instructional strategies may enhance skill acquisition more efficiently and increase the transfer of improved motor skills to sports activities. The current article will present insights gained from the motor-learning domain that may enhance neuromuscular training programs via improved skill development and increased retention and transfer to sports activities, which may reduce ACL injury incidence in the long term.

The effects of 2 landing techniques on knee kinematics, kinetics, and performance during stop-jump and side-cutting tasks

BACKGROUND

Anterior cruciate ligament injuries (ACL) commonly occur during jump landing and cutting tasks. Attempts to land softly and land with greater knee flexion are associated with decreased ACL loading. However, their effects on performance are unclear.

HYPOTHESIS

Attempts to land softly will decrease peak posterior ground-reaction force (PPGRF) and knee extension moment at PPGRF compared with a natural landing during stop-jump and side-cutting tasks. Attempts to land with greater knee flexion at initial ground contact will increase knee flexion at PPGRF compared with a natural landing during both tasks. In addition, both landing techniques will increase stance time and lower extremity mechanical work as well as decrease jump height and movement speed compared with a natural landing during both tasks.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 18 male and 18 female recreational athletes participated in the study. Three-dimensional kinematic and kinetic data were collected during stop-jump and side-cutting tasks under 3 conditions: natural landing, soft landing, and landing with greater knee flexion at initial ground contact.

RESULTS

Attempts to land softly decreased PPGRF and knee extension moment at PPGRF compared with a natural landing during stop-jump tasks. Attempts to land softly decreased PPGRF compared with a natural landing during side-cutting tasks. Attempts to land with greater knee flexion at initial ground contact increased knee flexion angle at PPGRF compared with a natural landing during both stop-jump and side-cutting tasks. Attempts to land softly and land with greater knee flexion at initial ground contact increased stance time and lower extremity mechanical work, as well as decreased jump height and movement speed during both stop-jump and side-cutting tasks.

CONCLUSION

Although landing softly and landing with greater knee flexion at initial ground contact may reduce ACL loading during stop-jump and side-cutting tasks, the performance of these tasks decreased, as indicated by increased stance time and mechanical work as well as decreased jump height and movement speed.

CLINICAL RELEVANCE

Training effects tested in laboratory environments with the focus on reducing ACL loading may be reduced in actual competition environments when the focus is on athlete performance. The effects of training programs for ACL injury prevention on lower extremity biomechanics in athletic tasks may need to be evaluated in laboratories as well as in actual competitions.

The effect of videotape augmented feedback on drop jump landing strategy: Implications for anterior cruciate ligament and patellofemoral joint injury prevention

BACKGROUND

Modification of high-risk movement strategies such as dynamic knee valgus is key to the reduction of anterior cruciate ligament (ACL) and patellofemoral joint (PFJ) injuries. Augmented feedback, which includes video and verbal feedback, could offer a quick, simple and effective alternative to training programs for altering high-risk movement patterns. It is not clear whether feedback can reduce dynamic knee valgus measured using frontal plane projection angle (FPPA).

METHODS

Vertical ground reaction force (vGRF), two-dimensional FPPA of the knee, contact time and jump height of 20 recreationally active university students were measured during a drop jump task pre- and post- an augmented feedback intervention. A control group of eight recreationally active university students were also studied at baseline and repeat test.

RESULTS

There was a significant reduction in vGRF (p=0.033), FPPA (p<0.001) and jump height (p<0.001) and an increase in contact time (p<0.001) post feedback in the intervention group. No changes were evident in the control group.

CONCLUSION

Augmented feedback leads to significant decreases in vGRF, FPPA and contact time which may help to reduce ACL and PFJ injury risk. However, these changes may result in decreased performance.

CLINICAL RELEVANCE

Augmented feedback reduces dynamic knee valgus, as measured via FPPA, and forces experienced during the drop jump task and therefore could be used as a tool for helping decrease ACL and PFJ injury risk prior to, or as part of, the implementation of injury prevention training programs.

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

Anterior cruciate ligament (ACL) injury prevention programs have been successful in the short term. Motor learning strategies with an internal focus (IF) to body movements have traditionally been utilized, but may be less suitable than an external focus (EF) for the acquisition and control of complex motor skills required for sport. To investigate the available literature and provide an overview of the effect of IF and EF instructions on jump landing technique. Systematic searches were conducted in PubMed (1966 to May 2014), CINAHL (1981 to May 2014) and PsycInfo (1989 to May 2014). A priori defined inclusion criteria were: (i) full text; (ii) published in English, German or Dutch; (iii) healthy adult subjects (mean age ≥18 years); (iv) jump and landing performance tested and (v) study used comparison between an EF and IF. Performance (jump height and distance) and technique (kinematics and kinetics) were the primary outcome variables of interest. Nine papers were included. Significant better motor performance and movement technique was found with an EF compared to an IF. Considering the beneficial results in the included studies when utilizing an EF, it is suggested to implement these strategies into ACL injury prevention programs.

Positive effects of augmented verbal feedback on power production in NCAA Division I collegiate athletes

The purpose of this study was to determine how augmented verbal feedback, specifically knowledge of performance during a countermovement vertical jump (CMVJ) protocol, would affect acute power output. Each subject (N = 14 [9 men and 5 women], 21.4 ± 0.8 years, 179.6 ± 6.1 cm, 87.5 ± 14.8 kg) completed the CMVJ protocol twice in a balanced randomized order, one trial with feedback and one without feedback. At least 48 hours were allowed between sessions for resting. Student-athletes were used because of their trained state and their familiarity with plyometrics and receiving and processing feedback during training. Each testing session began with a 10-minute warm-up consisting of a combination of dynamic stretching and submaximal jumps (no proprioceptive neuromuscular facilitation or static stretching). After completion of the warm-up, the subjects then began the CMVJ protocol. The CMVJ protocol consisted of 3 sets of 5 jumps on a calibrated force plate set to read at 200 Hz (Accupower). Subjects were instructed at the start of the protocol to give maximal effort on each jump. The standard set and repetition scheme for this protocol was 3 sets of 5 maximal repetitions with 3 minutes rest between sets. This was used to mimic the practice of training for maximal power. Before each jump, the subject was told the jump number and given a verbal start cue before the jump's initiation. The verbal performance feedback given consisted of the full kinetic numerical value of the peak power output in watts of the last completed jump. Significance in this study was set at p ≤ 0.05. There was a significant difference between mean power outputs (4,335 ± 366 W to 4,108 ± 345 W, p = 0.003) and the peak power outputs (4,567 ± 381 W to 4,319 ± 371 W, p = 0.018) when comparing feedback to no feedback, respectively. There was a significant difference in peak power output between the feedback and no feedback trials during set 2 (mean difference 361 ± 161 W, p = 0.043) and set 3 (mean difference 283 ± 109 W, p = 0.022). Also, there was a significant difference in mean power output between feedback and no feedback trials during set 2 (mean difference 240 ± 66 W, p = 0.003) and set 3 (mean difference 299 ± 93 W, p = 0.007). When training for maximal power in a plyometric training protocol, verbal feedback can be used as both a simple and effective aid in producing optimal power outputs.

The effects of a home-based instructional program aimed at improving frontal plane knee biomechanics during a jump-landing task

STUDY DESIGN

Randomized controlled trial.

OBJECTIVES

To determine the effects of instruction to improve frontal plane knee biomechanics during a jump-landing task.

BACKGROUND

Technique training is a common component of knee injury-prevention programs. In developing programs that minimize time commitment and increase the likelihood of adoption by target groups, there is a need to evaluate individual program components.

METHODS

A total of 26 female recreational athletes (average age, 21.2 years), who presented with medial knee displacement during a jump-landing task, completed the study protocol. Participants were randomly placed into 1 of 2 groups, an experimental or control group. The experimental group received instructions aimed at improving knee abduction during jump landings. The control group received a sham training. Prior to training, baseline kinematics and kinetics (peak knee abduction angle, peak internal knee adductor moment, knee flexion excursion, peak internal knee extensor moment, and peak vertical ground reaction force) were obtained from participants while performing a basketball rebound task. Immediate (5 minutes postinstruction) and delayed (15-20 minutes postinstruction) retention tests were performed within the instructional session. Two additional retention tests were performed following home-based training (1 and 2 weeks following the initial training).

RESULTS

The initial instructional session resulted in greater knee flexion excursion (9°) and a 20% reduction in the peak internal knee adductor moment in the experimental group. Following home-based training, the experimental group continued to exhibit increased knee flexion excursion, along with decreased peak vertical ground reaction forces. No biomechanical changes were observed in the control group for any of the retention tests when compared to baseline.

CONCLUSION

The jump-training instructions employed in the current study resulted in kinematic and kinetic changes in the sagittal plane as opposed to the frontal plane.

LEVEL OF EVIDENCE

Prevention, level 2b-.

Different Sagittal Angles and Moments of Lower Extremity Joints during Single-leg Jump Landing among Various Directions in Basketball and Volleyball Athletes

[Purpose] The purpose of this study was to assess the sagittal angles and moments of lower extremity joints during single-leg jump landing in various directions. [Subjects] Eighteen male athletes participated in the study. [Methods] Participants were asked to perform single-leg jump-landing tests in four directions. Angles and net joint moments of lower extremity joints in the sagittal plane were investigated during jump-landing tests from a 30-cm-high platform with a Vicon™ motion system. The data were analyzed with one-way repeated measures ANOVA. [Results] The results showed that knee joint flexion increased and hip joint flexion decreased at foot contact. In peak angle during landing, increasing ankle dorsiflexion and decreasing hip flexion were noted. In addition, an increase in ankle plantarflexor moment occurred. [Conclusion] Adjusting the dorsiflexion angle and plantarflexor moment during landing might be the dominant strategy of athletes responding to different directions of jump landing. Decreasing hip flexion during landing is associated with a stiff landing. Sport clinicians and athletes should focus on increasing knee and hip flexion angles, a soft landing technique, in diagonal and lateral directions to reduce risk of injury.

Biofeedback in rehabilitation

This paper reviews the literature relating to the biofeedback used in physical rehabilitation. The biofeedback methods used in rehabilitation are based on biomechanical measurements and measurements of the physiological systems of the body. The physiological systems of the body which can be measured to provide biofeedback are the neuromuscular system, the respiratory system and the cardiovascular system. Neuromuscular biofeedback methods include electromyography (EMG) biofeedback and real-time ultrasound imaging (RTUS) biofeedback. EMG biofeedback is the most widely investigated method of biofeedback and appears to be effective in the treatment of many musculoskeletal conditions and in post cardiovascular accident (CVA) rehabilitation. RTUS biofeedback has been demonstrated effective in the treatment of low back pain (LBP) and pelvic floor muscle dysfunction. Cardiovascular biofeedback methods have been shown to be effective in the treatment of a number of health conditions such as hypertension, heart failure, asthma, fibromyalgia and even psychological disorders however a systematic review in this field has yet to be conducted. Similarly, the number of large scale studies examining the use of respiratory biofeedback in rehabilitation is limited. Measurements of movement, postural control and force output can be made using a number of different devices and used to deliver biomechanical biofeedback. Inertial based sensing biofeedback is the most widely researched biomechanical biofeedback method, with a number of studies showing it to be effective in improving measures of balance in a number of populations. Other types of biomechanical biofeedback include force plate systems, electrogoniometry, pressure biofeedback and camera based systems however the evidence for these is limited. Biofeedback is generally delivered using visual displays, acoustic or haptic signals, however more recently virtual reality (VR) or exergaming technology have been used as biofeedback signals. VR and exergaming technology have been primarily investigated in post-CVA rehabilitation, however, more recent work has shown this type of biofeedback to be effective in improving exercise technique in musculoskeletal populations. While a number of studies in this area have been conducted, further large scale studies and reviews investigating different biofeedback applications in different clinical populations are required.

Impact differences in ground reaction force and center of mass between the first and second landing phases of a drop vertical jump and their implications for injury risk assessment

The drop vertical jump (DVJ) task is commonly used to assess biomechanical performance measures that are associated with ACL injury risk in athletes. Previous investigations have solely assessed the first landing phase. We examined the first and second landings of a DVJ for differences in the magnitude of vertical ground reaction force (vGRF) and position of center of mass (CoM). A cohort of 239 adolescent female basketball athletes completed a series of DVJ tasks from an initial box height of 31 cm. Dual force platforms and a three dimensional motion capture system recorded force and positional data for each trial. There was no difference in peak vGRF between landings (p=0.445), but side-to-side differences increased from the first to second landing (p=0.007). Participants demonstrated a lower minimum CoM during stance in the first landing than the second landing (p<0.001). The results have important implications for the future assessment of ACL injury risk behaviors in adolescent female athletes. Greater side-to-side asymmetry in vGRF and higher CoM during impact indicate the second landing of a DVJ may exhibit greater perturbation and better represent in-game mechanics associated with ACL injury risk.

Different modes of feedback and peak vertical ground reaction force during jump landing: a systematic review

CONTEXT

Excessive ground reaction force when landing from a jump may result in lower extremity injuries. It is important to better understand how feedback can influence ground reaction force (GRF) and potentially reduce injury risk.

OBJECTIVE

To determine the effect of expert-provided (EP), self-analysis (SA), and combination EP and SA (combo) feedback on reducing peak vertical GRF during a jump-landing task.

DATA SOURCES

We searched the Web of Science database on July 1, 2011; using the search terms ground reaction force, landing biomechanics, and feedback elicited 731 initial hits.

STUDY SELECTION

Of the 731 initial hits, our final analysis included 7 studies that incorporated 32 separate data comparisons.

DATA EXTRACTION

Standardized effect sizes and 95% confidence intervals (CIs) were calculated between pretest and posttest scores for each feedback condition.

DATA SYNTHESIS

We found a homogeneous beneficial effect for combo feedback, indicating a reduction in GRF with no CIs crossing zero. We also found a homogeneous beneficial effect for EP feedback, but the CIs from 4 of the 10 data comparisons crossed zero. The SA feedback showed strong, definitive effects when the intervention included a videotape SA, with no CIs crossing zero.

CONCLUSIONS

Of the 7 studies reviewed, combo feedback seemed to produce the greatest decrease in peak vertical GRF during a jump-landing task.

Augmented feedback supports skill transfer and reduces high-risk injury landing mechanics: a double-blind, randomized controlled laboratory study

BACKGROUND

There is a current need to produce a simple, yet effective method for screening and targeting possible deficiencies related to increased anterior cruciate ligament (ACL) injury risk.

HYPOTHESIS

Frontal plane knee angle (FPKA) during a drop vertical jump will decrease upon implementing augmented feedback into a standardized sport training program.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-seven female participants (mean ± SD: age, 14.7 ± 1.5 years; height, 160.9 ± 6.8 cm; weight, 54.5 ± 7.2 kg) were trained over 8 weeks. During each session, each participant received standardized training consisting of strength training, plyometrics, and conditioning. They were also videotaped running on a treadmill at a standardized speed and performing a repeated tuck jump for 10 seconds. Study participants were randomized into 2 groups and received augmented feedback on either their jumping (AF) or sprinting (CTRL) form. Average (mean of 3 trials) and most extreme (trial with greatest knee abduction) FPKA were calculated from 2-dimensional video captured during performance of the drop vertical jump.

RESULTS

After testing, a main effect of time was noted, with the AF group reducing their FPKA average by 37.9% over the 3 trials while the CTRL group demonstrated a 26.7% reduction average across the 3 trials (P < .05). Conversely, in the most extreme drop vertical jump trial, a significant time-by-group interaction was noted (P < .05). The AF group reduced their most extreme FPKA by 6.9° (pretest, 18.4° ± 12.3°; posttest, 11.4° ± 10.1°) on their right leg and 6.5° (pretest, 16.3° ± 14.5°; posttest, 9.8° ± 10.7°) on their left leg, which represented a 37.7% and 40.1% reduction in FPKA, respectively. In the CTRL group, no similar changes were noted in the right (pretest, 16.9° ± 14.3°; posttest, 14.0° ± 12.3°) or left leg (pretest, 9.8° ± 11.1°; posttest, 7.2° ± 9.2°) after training.

CONCLUSION

Providing athletes with augmented feedback on deficits identified by the tuck jump assessment has a positive effect on their biomechanics during a different drop vertical jump task that is related to increased ACL injury risk. The ability of the augmented feedback to support the transfer of skills and injury risk factor reductions across different tasks provides exciting new evidence related to how neuromuscular training may ultimately cross over into retained biomechanics that reduce ACL injuries during sport.

CLINICAL RELEVANCE

The tuck jump assessment's ease of use makes it a timely and economically favorable method to support ACL prevention strategies in young girls.

Instruction and jump-landing kinematics in college-aged female athletes over time

CONTEXT

Instruction can be used to alter the biomechanical movement patterns associated with anterior cruciate ligament (ACL) injuries.

OBJECTIVE

To determine the effects of instruction through combination (self and expert) feedback or self-feedback on lower extremity kinematics during the box-drop-jump task, running-stop-jump task, and sidestep-cutting maneuver over time in college-aged female athletes.

DESIGN

Randomized controlled clinical trial.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Forty-three physically active women (age = 21.47 ± 1.55 years, height = 1.65 ± 0.08 m, mass = 63.78 ± 12.00 kg) with no history of ACL or lower extremity injuries or surgery in the 2 months before the study were assigned randomly to 3 groups: self-feedback (SE), combination feedback (CB), or control (CT).

INTERVENTION(S)

Participants performed a box-drop-jump task for the pretest and then received feedback about their landing mechanics. After the intervention, they performed an immediate posttest of the box-drop-jump task and a running-stop-jump transfer test. Participants returned 1 month later for a retention test of each task and a sidestep-cutting maneuver. Kinematic data were collected with an 8-camera system sampled at 500 Hz.

MAIN OUTCOME MEASURE(S)

The independent variables were feedback group (3), test time (3), and task (3). The dependent variables were knee- and hip-flexion, knee-valgus, and hip- abduction kinematics at initial contact and at peak knee flexion.

RESULTS

For the box-drop-jump task, knee- and hip-flexion angles at initial contact were greater at the posttest than at the retention test (P < .001). At peak knee flexion, hip flexion was greater at the posttest than at the pretest (P = .003) and was greater at the retention test than at the pretest (P = .04); knee valgus was greater at the retention test than at the pretest (P = .03) and posttest (P = .02). Peak knee flexion was greater for the CB than the SE group (P = .03) during the box-drop-jump task at posttest. For the running-stop-jump task at the posttest, the CB group had greater peak knee flexion than the SE and CT (P ≤ .05).

CONCLUSIONS

Our results suggest that feedback involving a combination of self-feedback and expert video feedback with oral instruction effectively improved lower extremity kinematics during jump-landing tasks.