Auditory Cue Effects on Gait-Phase-Dependent Electroencephalogram (EEG) Modulations during Overground and Treadmill Walking.

Walking rehabilitation following injury or disease involves voluntary gait modification, yet the specific brain signals underlying this process remains unclear. This aim of this study was to investigate the impact of an auditory cue on changes in brain activity when walking overground (O) and on a treadmill (T) using an electroencephalogram (EEG) with a 32-electrode montage. Employing a between-group repeated-measures design, 24 participants (age: 25.7 ± 3.8 years) were randomly allocated to either an O (n = 12) or T (n = 12) group to complete two walking conditions (self-selected speed control (sSC) and speed control (SC)). The differences in brain activities during the gait cycle were investigated using statistical non-parametric mapping (SnPM). The addition of an auditory cue did not modify cortical activity in any brain area during the gait cycle when walking overground (all p > 0.05). However, significant differences in EEG activity were observed in the delta frequency band (0.5-4 Hz) within the sSC condition between the O and T groups. These differences occurred at the central frontal (loading phase) and frontocentral (mid stance phase) brain areas (p < 0.05). Our data suggest auditory cueing has little impact on modifying cortical activity during overground walking. This may have practical implications in neuroprosthesis development for walking rehabilitation, sports performance optimization, and overall human quality-of-life improvement.

Comparison of Foot Kinematics Between Normal Arch and Flexible Flatfoot Using the Oxford Foot Model: A Matched Case-Control Study.

Background: Symptomatic flexible flatfoot causes alterations in gait, but exactly how this condition affects the intersegmental motion of the foot during the gait cycle remains unclear. Previous studies have examined the kinematics, yielding inconsistent findings. Therefore, the objective of this study was to investigate how flexible flatfoot deformity, defined as Johnson and Strom classification staging II, affects the intersegmental motion of the foot during fast walking based on a comparison with the matched control group. Methods: Eleven participants with symptomatic flexible flatfoot and 11 healthy matched control participants were recruited using a foot screening protocol incorporated through a foot physical examinations and radiographic measurements. All demographic characteristics exhibited comparable profiles between the groups. During controlled walking, kinematic outcomes pertaining to the hallux, hindfoot, forefoot, and tibia were collected using the multisegmental Oxford Foot Model. Results: All spatiotemporal parameters were comparable between the groups. In comparison to the control group, individuals with symptomatic flexible flatfoot demonstrated increased hallux valgus and plantarflexion, increased forefoot abduction, heightened hindfoot eversion, and internal rotation. Notably, no significant major differences were observed in the tibia motion segment. Further, significant correlations were identified between static foot measurements and the extent of the maximum deviation observed during dynamic kinematic assessments. Conclusion: Compared with age- and gender-matched controls, participants with symptomatic flexible flatfoot exhibited significant gait pattern deviations. A significant correlation also exists between static foot deformity measurements and dynamic kinematic deviations. Collectively, these findings have implications for developing targeted therapeutic interventions to address flexible flatfoot. Level of evidence: Level III, diagnostic study.

Spatiotemporal and kinematic adjustments in master runners may be associated with the relative physiological effort during running.

Master runners maintain a similar running economy to young runners, despite displaying biomechanical characteristics that are associated with a worse running economy. This apparent paradox may be explained by a greater physiological effort-i.e., percentage of maximal oxygen uptake (VO2-max)-that master runners perform at a given speed. Moreover, age-related responses to non-exhaustive sustained running are yet underexplored. The aims of this study were, therefore, to examine if biomechanical adjustments in master runners are physiological-effort dependent, and to explore the age-related biomechanical changes during a non-exhaustive sustained run. Young (23.9 ± 6; n = 12) and master (47.3 ± 6.9; n = 12) runners performed a sustained 30-minute treadmill run matched for relative physiological effort (70% VO2-max), while spatiotemporal and lower-limb kinematic characteristics were collected during the 1st and 30th minute. Group differences were observed in step/stride length, knee touch-down angle, and knee stiffness. However, both groups of runners had a similar step frequency, vertical center of mass oscillation, and knee range of motion. Age-related adjustment in these latter characteristics may thus not be an inevitable result of the aging process but rather a strategy to maintain running economy. The relative physiological effort of runners should, therefore, be considered when examining age-related adjustments in running biomechanics.

Muscle Activation and Ground Reaction Force between Single-Leg Drop Landing and Jump Landing among Young Females during Weight-Acceptance Phase.

Single-leg drop landing (SLDL) and jump landing (SLJL) are frequently used as assessment tools for identifying potential high-risk movement patterns; thus, understanding differences in neuromuscular responses between these types of landings is essential. This study aimed to compare lower extremity neuromuscular responses between the SLDL and SLJL. Thirteen female participants performed an SLDL and SLJL from a 30-cm box height. Vertical ground reaction force (vGRF), time to peak vGRF, and surface electromyography (sEMG) data were collected. Continuous neuromuscular responses, peak vGRF, and time to peak vGRF were compared between the tasks. Statistical parametric mapping (SPM) analysis demonstrated that the SLJL had a significantly higher sEMG activity in the rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) within the first 10% of the landing phase compared with SLDL. At 20-30% of the landing phase, sEMGs in the RF and VL during the SLDL were significantly higher compared with SLJL (p < 0.05). A higher peak vGRF and shorter time to peak vGRF was observed during SLJL (p < 0.05). In conclusion, our findings highlight that SLJL exhibited greater RF, VL, and VM activities than SLDL at initial impact (10% landing), coinciding with a higher peak vGRF and shorter time to attain peak vGRF. Our findings support the role of the quadriceps as the primary energy dissipator during the SLJL.

Comparing the Efficacy of Long Spinal Board, Sked Stretcher, and Vacuum Mattress in Cervical Spine Immobilization; a Method-Oriented Experimental Study.

Introduction: Inadequate spinal motion restriction in patients suffering from spinal injuries could lead to further neurological damage, ultimately worsening their prognosis. This study aimed to investigate the efficacy of long spinal boards (LSB), ske stretcher, and vacuum mattress for cervical spine immobilization during transportation of patients by measuring the angular motion of the cervical spine following lifting, transferring, and tilting. Methods: We conducted an experimental study using a box of three randomizations and crossover designs without a washout period effect for the long spinal board, sked stretcher, and vacuum mattress. We concealed the randomization with sequentially numbered, opaque, sealed envelopes (SNOSE). Kinematic data were collected using eight optoelectronic cameras at 200 Hz (BTS Bioengineering, Milan, Italy) in triangular planes (lateral bending, flexion-extension, and axial rotation) while performing all three motions (static lift-hold, transfer, and 90° tilt). Results: 12 cases (7 males and 5 females) with the mean age of 20 ± 3.03 (range: 18-28) years were studied. The three highest angular motions were observed in the axial rotation plane during patient's tilting under immobilization on all devices (Vacuum mattress having the highest value of 99.01±8.93, followed by the LSB at 89.89±34.35 and the sked stretcher at 86.30±7.73 degrees). During patient lifting, a higher angular motion was observed with vacuum mattress immobilization in flexion extension (Coefficient = 4.45; 95%CI: 0.46 - 8.45; p =0.029) and axial rotation (Coefficient = 3.70; 95%CI: 0.58 - 6.81; p =0.020) planes. During patient transfer, a higher angular motion was observed with sked stretcher in the flexion-extension plane (Coefficient = 2.98; 95%CI: 0.11 - 5.84; p = 0.042). During patient tilting to 90 degrees, a higher angular motion was observed with vacuum mattress immobilization in lateral bending (Coefficient = -4.08; 95%CI: -7.68 - -0.48; p = 0.026) for the vacuum mattress. Conclusion: Based on the finding of the present study, patients on the vacuum mattress experience significantly higher angular motion in flexion extension and axial rotation during lifting, as well as lateral bending during 90-degree tilting. In addition, patients on the sked stretcher showed significantly higher angular motion in flexion-extension during the transferring. However, the predictive margins for immobilization across all devices did not demonstrate clinically significant differences among the three immobilization devices.

Scapular dyskinesis after treatment of proximal humerus fracture, a 3-dimensional motion analysis and clinical outcomes.

BACKGROUND: The alteration of scapular kinematics can predispose patients to shoulder pathologies and dysfunction. Previous literature has associated various types of shoulder injuries with scapular dyskinesis, but there are limited studies regarding the effect that proximal humeral fractures (PHFs) have on scapular dyskinesis. This study aims to determine the change in scapulohumeral rhythm following treatment of a proximal humerus fracture as well as differences in shoulder motion and functional outcomes among patients who presented with or without scapular dyskinesis. We hypothesized that differences in scapular kinematics would be present following treatment of a proximal humerus fracture, and patients who presented with scapular dyskinesis would subsequently have inferior functional outcome scores. METHODS: Patients treated for a proximal humerus fracture from May 2018 to March 2021 were recruited for this study. The scapulohumeral rhythm and global shoulder motion were determined using a 3-dimensional motion analysis (3DMA) and the scapular dyskinesis test. Functional outcomes were then compared among patients with or without scapular dyskinesis, including the SICK (scapular malposition, inferomedial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement) Scapula Rating Scale, the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), the visual analog scale (VAS) for pain, and the EuroQol-5 Dimension 5-Level questionnaire (EQ-5D-5L). RESULTS: Twenty patients were included in this study with a mean age of 62.9 ± 11.8 years and follow-up time of 1.8 ± 0.2 years. Surgical fixation was performed in 9 of the patients (45%). Scapular dyskinesis was present in 50% of patients (n = 10). There was a significant increase in scapular protraction on the affected side of patients with scapular dyskinesis during abduction of the shoulder (P = .037). Additionally, patients with scapular dyskinesis demonstrated worse SICK scapula scores (2.4 ± 0.5 vs. 1.0 ± 0.4, P = .024) compared to those without scapular dyskinesis. The other functional outcome scores (ASES, VAS pain scores, and EQ-5D-5L) showed no significant differences among the 2 groups (P = .848, .713, and .268, respectively). CONCLUSIONS: Scapular dyskinesis affects a significant number of patients following treatment of their PHFs. Patients presenting with scapular dyskinesis exhibit inferior SICK scapula scores and have more scapular protraction during shoulder abduction compared to patients without scapular dyskinesis.

Integration of force and IMU sensors for developing low-cost portable gait measurement system in lower extremities.

Gait analysis is the method to accumulate walking data. It is useful in diagnosing diseases, follow-up of symptoms, and rehabilitation post-treatment. Several techniques have been developed to assess human gait. In the laboratory, gait parameters are analyzed by using a camera capture and a force plate. However, there are several limitations, such as high operating costs, the need for a laboratory and a specialist to operate the system, and long preparation time. This paper presents the development of a low-cost portable gait measurement system by using the integration of flexible force sensors and IMU sensors in outdoor applications for early detection of abnormal gait in daily living. The developed device is designed to measure ground reaction force, acceleration, angular velocity, and joint angles of the lower extremities. The commercialized device, including the motion capture system (Motive-OptiTrack) and force platform (MatScan), is used as the reference system to validate the performance of the developed system. The results of the system show that it has high accuracy in measuring gait parameters such as ground reaction force and joint angles in lower limbs. The developed device has a strong correlation coefficient compared with the commercialized system. The percent error of the motion sensor is below 8%, and the force sensor is lower than 3%. The low-cost portable device with a user interface was successfully developed to measure gait parameters for non-laboratory applications to support healthcare applications.

Validity and Reliability of Inertial Measurement Unit (IMU)-Derived 3D Joint Kinematics in Persons Wearing Transtibial Prosthesis.

BACKGROUND: A validity and reliability assessment of inertial measurement unit (IMU)-derived joint angular kinematics during walking is a necessary step for motion analysis in the lower extremity prosthesis user population. This study aimed to assess the accuracy and reliability of an inertial measurement unit (IMU) system compared to an optical motion capture (OMC) system in transtibial prosthesis (TTP) users. METHODS: Thirty TTP users were recruited and underwent simultaneous motion capture from IMU and OMC systems during walking. Reliability and validity were assessed using intra- and inter-subject variability with standard deviation (S.D.), average S.D., and intraclass correlation coefficient (ICC). RESULTS: The intra-subject S.D. for all rotations of the lower limb joints were less than 1° for both systems. The IMU system had a lower mean S.D. (o), as seen in inter-subject variability. The ICC revealed good to excellent agreement between the two systems for all sagittal kinematic parameters. CONCLUSION: All joint angular kinematic comparisons supported the IMU system's results as comparable to OMC. The IMU was capable of precise sagittal plane motion data and demonstrated validity and reliability to OMC. These findings evidence that when compared to OMC, an IMU system may serve well in evaluating the gait of lower limb prosthesis users.

Relationship Between Shoulder Pain and Joint Reaction Forces and Muscle Moments During 2 Speeds of Wheelchair Propulsion.

The purpose of this study was to determine shoulder joint reaction forces and muscle moments during 2 speeds (1.3 and 2.2 m/s) of wheelchair propulsion and to investigate the relationship between joints reaction forces, muscle moments, and shoulder pain. The measurements were obtained from 20 manual wheelchair users. A JR3 6-channel load sensor (±1% error) and a Qualisys system were used to record 3-dimensional pushrim kinetics and kinematics. A 3-dimensional inverse dynamic model was generated to compute joint kinetics. The results demonstrated significant differences in shoulder joint forces and moments (P < .01) between the 2 speeds of wheelchair propulsion. The greatest peak shoulder joint forces during the drive phase were anterior directed (Fy, 184.69 N), and the greatest joint moment was the shoulder flexion direction (flexion moment, 35.79 N·m) at 2.2 m/s. All the shoulder joint reaction forces and flexion moment were significantly (P < .05) related to shoulder pain index. The forces combined in superior and anterior direction found at the shoulder joint may contribute to the compression of subacromial structure and predispose manual wheelchair users to potential rotator cuff impingement syndrome.

The Effect of Arm Dominance on Knee Joint Biomechanics During Basketball Block Shot Single-Leg Landing.

Single arm blocking is a key component of successful basketball defence. The player uses either their dominant or non-dominant arm to block the ball landing on a common leg. Understanding how the bio-physical loads of the landing leg change as a function of the blocking arm will provide insights into potential injury risk of the lower limb. The aim of this study was to investigate the effects of arm dominance on the biomechanical variables of injury risk of the lower limb, specifically the knee joint during the single-leg landing in female basketball players. Kinematic and kinetic data were collected from fourteen female basketball athletes (20.85 ± 1.35 years, 1.69 ± 0.06 m, 60.37 ± 7.75 kg), each performing three trials of a dominant arm and non-dominant block jump landing on the dominant leg. The results showed significantly higher anterior and medial ground reaction force, knee joint flexion and abduction and lateral knee force during the dominant arm landing (p < 0.05). These findings highlight potential injury risk and the need for the player to be more proficient at dominant arm block-shot landing. The player should aim to develop a larger landscape of technique to meet the demands of the game and facilitate a more effective and safer landing strategy.

Predictive validity of the Stopping Elderly Accidents, Deaths & Injuries (STEADI) program fall risk screening algorithms among community-dwelling Thai elderly.

BACKGROUND: Fall risk screening using multiple methods was strongly advised as the initial step for preventing fall. Currently, there is only one such tool which was proposed by the U.S. Centers for Disease Control and Prevention (CDC) for use in its Stopping Elderly Accidents, Death & Injuries (STEADI) program. Its predictive validity outside the US context, however, has never been investigated. The purpose of this study was to determine the predictive validity (area under the receiver operating characteristic curve: AUC), sensitivity, and specificity of the two-step sequential fall-risk screening algorithm of the STEADI program for Thai elderly in the community. METHODS: A 1-year prospective cohort study was conducted during October 2018-December 2019. Study population consisted of 480 individuals aged 65 years or older living in Nakhon Ratchasima Province, Thailand. The fall risk screening algorithm composed of two serial steps. Step 1 is a screening by the clinician's 3 key questions or the Thai Stay Independent brochure (Thai-SIB) 12 questions. Step 2 is a screening by 3 physical fitness testing tools including Time Up and Go test (TUG), 30-s Chair Stand, and 4-stage balance test. Participants were then followed for their fall incidents. Statistical analyses were conducted by using Cox proportional hazard model. The AUC, sensitivity, specificity, and other relevant predictive validity indices were then estimated. RESULTS: The average age of the participants was 73.3 ± 6.51 years (range 65-95 years), and 52.5% of them were female. The screening based on the clinician's 3 key questions in Step 1 had a high AUC (0.845), with the sensitivity and specificity of 93.9% (95% CI 88.8, 92.7) and 75.0% (95% CI 70.0, 79.6), respectively. Appropriate risk categorization however differed slightly from the original STEADI program. CONCLUSIONS: With some modification, the fall risk screening algorithm based on the STEADI program was applicable in Thai context.

Landing Error Scoring System: Data from Youth Volleyball Players.

The Landing Error Scoring system (LESS) is a reliable screening tool for Anterior Cruciate Ligament (ACL) injury. The test is focused on biomechanical errors of landing motion and is used to evaluate the risk of knee injuries in several sports, such as football and basketball, which involve repeated jumping demands. Presently, available LESS data from youth volleyball players is limited, thus screening for injury risk has not been comprehensively undertaken in this cohort. The LESS is typically performed by jumping from a box while video motion in 2 sagittal and frontal planes is recorded, with the jump landing rated against 17-items. A total of 233 players performed three jump landing trials resulting in a total of 1398 videos being recorded. Each LESS score item was rated by two physical therapists and one sports scientist and the data were separated into four separate LESS score categories: excellent (≤4), good (4 - 5), moderate (5 - 6), and poor (>6). Descriptive analysis (percentage) was employed to describe the data, with scores subdivided by gender. The data may be applied to identify youth volleyball players at potential risk of sustaining a lower body injury from poor landing biomechanics.

Neuromuscular control of the ankle during pre-landing in athletes with chronic ankle instability: Insights from statistical parametric mapping and muscle co-contraction analysis.

OBJECTIVE: The present study aimed to compare the neuromuscular control of the muscles around the ankle between athletes with CAI and without history of any ankle sprain (Non-CAI) by using statistic parametric mapping (SPM) and co-contraction analyses. DESIGN: Cross-sectional study; Setting: Laboratory; Participants: 40 athletes (20 CAI, 20 Non-CAI) were pair-matched for age and gender. MAIN OUTCOME MEASURES: Neuromuscular control was examined using surface electromyography (EMG) amplitude and muscle co-contraction 200 ms before foot-contact with the ground during a jump-landing task. RESULTS: The EMG amplitude of tibialis anterior, peroneus longus, and gastrocnemius medialis were analyzed using statistic parametric mapping. The CAI group exhibited decreased EMG amplitude of peroneus longus during preparation for foot-contact. There were no significant co-contraction differences between groups. CONCLUSIONS: Our findings demonstrate that SPM combined with the co-contraction provides a comprehensive EMG analysis to detect the differences of neuromuscular control between athletes with and without chronic ankle instability. Additionally, this finding indicates that CAI contributed to altered neuromuscular control during the pre-landing phase, which may contribute to re-injury mechanisms.

The Stay Independent Brochure as a Screening Evaluation for Fall Risk in an Elderly Thai Population.

INTRODUCTION: The Stay Independent Brochure (SIB) is a widely used fall-risk self-assessment tool, which is part of the Stopping Elderly Accident, Deaths & Injuries (STEADI) program in the US. However, the validity and reliability of the SIB have not been established in an elderly Thai population. OBJECTIVE: To construct a fall risk screening tool based on the SIB in a Thai elderly population and investigate its psychometric effect in a community context. METHODS: A total of 480 elderly participants volunteered to take part in this study from the Nakhon Ratchasima province. In the first part of the study, the original version of the SIB was translated into Thai (total 12 questions) and adapted into a modified version (total 18 questions). The translated SIBs were cross-culturally adapted and tested for content validity, test-retest reliability, inter-rater reliability, construct validity and internal consistency. In the second part of the study, the psychometric properties of the translated SIBs were assessed using test-retest and inter-rater reliability and content and construct validity. RESULTS: The SIBs had good content validity (IOC: 0.80 to 1.00), and the interclass correlation coefficient (ICC) of test-retest and inter-rater reliability was excellent for both SIB versions (ICC 0.89-0.95). The construct validity of 18 questions was tested by principal component factor analysis with varimax rotation and using factor loading greater than 0.4, and yielded 6 factors that explained 59.1% of the variance in fall risk (more than 12 questions). The coefficient alpha was higher than the usually recommended value of 0.70 for the total score of both SIB versions. The convergent validity between the TUG and BBS tests was statistically significant (p<0.001). CONCLUSION: Based on psychometric properties, it is recommended that the two Thai versions of the SIB are an appropriate initial screening tool for the multi-steps fall risk assessment algorithm in predicting falls in an elderly Thai community.

Immediate effect of ACL kinesio taping technique on knee joint biomechanics during a drop vertical jump: a randomized crossover controlled trial.

BACKGROUND: The purpose of this study was to investigate the effect of an ACL Kinesio Taping technique (ACL-KT) on knee joint biomechanics during a drop vertical jump (DVJ). METHODS: Twenty healthy male participants (age 21.1±0.3 years; mass 64.2±4.3 kg; height 174.2±5.5 cm) participated in this study. The participants performed a DVJ and landed onto 2 adjacent force platforms under both ACL-KT and placebo (PT) conditions. All data were collected with 3-D motion analysis and comparison peak knee joint angles and moments, and knee joint angle at initial contact (IC) between conditions analyzed using a paired sample t-test. Statistical parametric mapping (SPM) was selected to assess difference between groups for the entire three-component knee trajectory during the contact phase. RESULTS: ACL-KT had a significant effect on decreasing knee abduction angle at IC (1.43±2.12 deg.) compared with the PT (-1.24±2.42 deg.) (p=0.04). A significant difference in knee abduction angle between the taping conditions was found between 100 ms before IC, at IC and 100 ms after IC (p<0.05). There were no significant differences (p>0.05) found between conditions in any of the other variables. CONCLUSION: This result confirmed that the application of ACL-KT is useful to reduce knee abduction angle at IC during a DVJ in healthy participants. Therefore, ACL-KT may be an acceptable intervention to reduce ACL injury risk. TRIAL REGISTRATION: Retrospective registered on 25 September 2018. Trial number: TCTR20180926005.

Decreased supraspinal control and neuromuscular function controlling the ankle joint in athletes with chronic ankle instability.

PURPOSE: Chronic ankle instability (CAI) alters lower extremity neuromuscular function, associated with a change in corticomotor excitability. The aim of this study was to compare corticomotor excitability and neuromuscular function of the muscles around the ankle between athletes with CAI and without CAI (non-CAI). METHODS: Nineteen CAI athletes (15 men and 4 women) and 19 non-CAI athletes (15 men and 4 women) participated (age- and sex-matched). Corticomotor excitability was measured by transcranial magnetic stimulation for the following muscles: the tibialis anterior (TA), peroneus longus (PL) and gastrocnemius medialis (GM). The resting motor threshold (rMT), motor evoked potential (MEP), and latency (Lat) were subsequently measured. Neuromuscular function was assessed with a jump test, using the EMG activity before foot contact, peak torque, and joint position sense. RESULTS: The corticomotor excitability in CAI showed a lower normalized MEP in the TA (p = 0.026) and PL (p = 0.003), and longer latency in the TA (p = 0.049) and GM (p = 0.027) compared with non-CAI. The neuromuscular assessment showed CAI had less EMG activity of the PL (p < 0.001), less peak torque of the dorsiflexor (p = 0.019) muscle compared with non-CAI. CONCLUSION: Athletes with CAI had lower corticomotor excitability in the TA and PL and a longer latency in the TA and GM muscles. Additionally, CAI demonstrated functional neuromuscular deficits by decreasing EMG activity of the PL muscle and strength of the dorsiflexor muscle. Our findings indicated maladaptation at both cortical and peripheral levels among athletes with CAI.

The effect of virtual reality-based balance training on motor learning and postural control in healthy adults: a randomized preliminary study.

BACKGROUND: Adults with sedentary lifestyles seem to face a higher risk of falling in their later years. Several causes, such as impairment of strength, coordination, and cognitive function, influence worsening health conditions, including balancing ability. Many modalities can be applied to improve the balance function and prevent falling. Several studies have also recorded the effects of balance training in elderly adults for fall prevention. Accordingly, the aim of this study is to define the effect of virtual reality-based balance training on motor learning and postural control abilities in healthy adults. METHODS: For this study, ten subjects were randomly allocated into either the conventional exercise (CON) or the virtual reality (VR) group. The CON group underwent physical balance training, while the VR group used the virtual reality system 4 weeks. In the VR group, the scores from three game modes were utilized to describe the effect of motor learning and define the learning curves that were derived with the power law function. Wilcoxon Signed Ranks Test was performed to analyze the postural control in five standing tasks, and data were collected with the help of a force plate. RESULTS: The average score was used to describe the effect of motor learning by deriving the mathematical models for determining the learning curve. Additionally, the models were classified into two exponential functions that relied on the aim and requirement skills. A negative exponential function was observed in the game mode, which requires the cognitive-motor function. In contrast, a positive exponential function was found in the game with use of only the motor skill. Moreover, this curve and its model were also used to describe the effect of learning in the long term and the ratio of difficulty in each game. In the balance performance, there was a significant decrease in the center of pressure parameters in the VR group, while in the CON group, there was a significant increase in the parameters during some foot placements, especially in the medio-lateral direction. CONCLUSION: The proposed VR-based training relies on the effect of motor learning in long-term training though different kinds of task training. In postural analysis, both exercise programs are emphasized to improve the balance ability in healthy adults. However, the virtual reality system can promote better outcomes to improve postural control post exercising. Trial registration Retrospectively registered on 25 April 2018. Trial number TCTR20180430005.

Can segmental model reductions quantify whole-body balance accurately during dynamic activities?

When investigating whole-body balance in dynamic tasks, adequately tracking the whole-body centre of mass (CoM) or derivatives such as the extrapolated centre of mass (XCoM) can be crucial but add considerable measurement efforts. The aim of this study was to investigate whether reduced kinematic models can still provide adequate CoM and XCoM representations during dynamic sporting tasks. Seventeen healthy recreationally active subjects (14 males and 3 females; age, 24.9±3.2years; height, 177.3±6.9cm; body mass 72.6±7.0kg) participated in this study. Participants completed three dynamic movements, jumping, kicking, and overarm throwing. Marker-based kinematic data were collected with 10 optoelectronic cameras at 250Hz (Oqus Qualisys, Gothenburg, Sweden). The differences between (X)CoM from a full-body model (gold standard) and (X)CoM representations based on six selected model reductions were evaluated using a Bland-Altman approach. A threshold difference was set at ±2cm to help the reader interpret which model can still provide an acceptable (X)CoM representation. Antero-posterior and medio-lateral displacement profiles of the CoM representation based on lower limbs, trunk and upper limbs showed strong agreement, slightly reduced for lower limbs and trunk only. Representations based on lower limbs only showed less strong agreement, particularly for XCoM in kicking. Overall, our results provide justification of the use of certain model reductions for specific needs, saving measurement effort whilst limiting the error of tracking (X)CoM trajectories in the context of whole-body balance investigation.

Knee Muscular Control During Jump Landing in Multidirections.

BACKGROUND: Jump landing is a complex movement in sports. While competing and practicing, athletes frequently perform multi-planar jump landing. Anticipatory muscle activity could influence the amount of knee flexion and prepare the knee for dynamic weight bearing such as landing tasks. OBJECTIVES: The aim of the present study was to examine knee muscle function and knee flexion excursion as athletes naturally performed multi-direction jump landing. MATERIALS AND METHODS: Eighteen male athletes performed the jump-landing test in four directions: forward (0°), 30° diagonal, 60° diagonal, and lateral (90°). Muscles tested were vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), semitendinosus (ST), and biceps femoris (BF). A Vicon(TM) 612 workstation collected the kinematic data. An electromyography was synchronized with the Vicon(TM) Motion system to quantify dynamic muscle function. Repeated measure ANOVA was used to analyze the data. RESULTS: Jump-landing direction significantly influenced (P < 0.05) muscle activities of VL, RF, and ST and knee flexion excursion. Jumpers landed with a trend of decreasing knee flexion excursion and ST muscle activity 100 ms before foot contact progressively from forward to lateral directions of jump landing. CONCLUSIONS: A higher risk of knee injury might occur during lateral jump landing than forward and diagonal directions. Athletes should have more practice in jump landing in lateral direction to avoid injury. Landing technique with high knee flexion in multi-directions should be taught to jumpers for knee injury prevention.