Task-specific training for improving propulsion symmetry and gait speed in people in the chronic phase after stroke: a proof-of-concept study.

BACKGROUND: After stroke, some individuals have latent, propulsive capacity of the paretic leg, that can be elicited during task-specific gait training. The aim of this proof-of-concept study was to investigate the effect of five-week robotic gait training for improving propulsion symmetry by increasing paretic propulsion in chronic stroke survivors. METHODS: Twenty-nine individuals with chronic stroke and impaired paretic propulsion (≥ 8% difference in paretic vs. non-paretic propulsive impulse) were enrolled. Participants received ten 60-min sessions of individual robotic gait training targeting paretic propulsion (five weeks, twice a week), complemented with home exercises (15 min/day) focusing on increasing strength and practicing learned strategies in daily life. Propulsion measures, gait kinematics and kinetics, self-selected gait speed, performance of functional gait tasks, and daily-life mobility and physical activity were assessed five weeks (T0) and one week (T1) before the start of intervention, and one week (T2) and five weeks (T3) after the intervention period. RESULTS: Between T0 and T1, no significant differences in outcomes were observed, except for a marginal increase in gait speed (+ 2.9%). Following the intervention, propulsion symmetry (+ 7.9%) and paretic propulsive impulse had significantly improved (+ 8.1%), whereas non-paretic propulsive impulse remained unchanged. Larger gains in propulsion symmetry were associated with more asymmetrical propulsion at T0. In addition, following the intervention significantly greater paretic trailing limb angles (+ 6.6%) and ankle plantarflexion moments (+ 7.1%) were observed. Furthermore, gait speed (+ 7.2%), 6-Minute Walk Test (+ 6.4%), Functional Gait Assessment (+ 6.5%), and daily-life walking intensity (+ 6.9%) had increased following the intervention. At five-week follow-up (T3), gains in all outcomes were retained, and gait speed had further increased (+ 3.6%). CONCLUSIONS: The post-intervention gain in paretic propulsion did not only translate into improved propulsion symmetry and gait speed, but also pertained to performance of functional gait tasks and daily-life walking activity levels. These findings suggest that well-selected chronic stroke survivors may benefit from task-specific targeted training to utilize the residual propulsive capacity of the paretic leg. Future research is recommended to establish simple baseline measures for identification of individuals who may benefit from such training and confirm benefits of the used training concepts in a randomized controlled trial. TRIAL REGISTRATION: Registry number ClinicalTrials.gov ( www.clinicaltrials.gov ): NCT04650802, retrospectively registered 3 December 2020.

Effect of assist-as-needed robotic gait training on the gait pattern post stroke: a randomized controlled trial.

BACKGROUND: Regaining gait capacity is an important rehabilitation goal post stroke. Compared to clinically available robotic gait trainers, robots with an assist-as-needed approach and multiple degrees of freedom (AANmDOF) are expected to support motor learning, and might improve the post-stroke gait pattern. However, their benefits compared to conventional gait training have not yet been shown in a randomized controlled trial (RCT). The aim of this two-center, assessor-blinded, RCT was to compare the effect of AANmDOF robotic to conventional training on the gait pattern and functional gait tasks during post-stroke inpatient rehabilitation. METHODS: Thirty-four participants with unilateral, supratentorial stroke were enrolled (< 10 weeks post onset, Functional Ambulation Categories 3-5) and randomly assigned to six weeks of AANmDOF robotic (combination of training in LOPES-II and conventional gait training) or conventional gait training (30 min, 3-5 times a week), focused on pre-defined training goals. Randomization and allocation to training group were carried out by an independent researcher. External mechanical work (WEXT), spatiotemporal gait parameters, gait kinematics related to pre-defined training goals, and functional gait tasks were assessed before training (T0), after training (T1), and at 4-months follow-up (T2). RESULTS: Two participants, one in each group, were excluded from analysis because of discontinued participation after T0, leaving 32 participants (AANmDOF robotic n = 17; conventional n = 15) for intention-to-treat analysis. In both groups, WEXT had decreased at T1 and had become similar to baseline at T2, while gait speed had increased at both assessments. In both groups, most spatiotemporal gait parameters and functional gait tasks had improved at T1 and T2. Except for step width (T0-T1) and paretic step length (T0-T2), there were no significant group differences at T1 or T2 compared to T0. In participants with a pre-defined goal aimed at foot clearance, paretic knee flexion improved more in the AANmDOF robotic group compared to the conventional group (T0-T2). CONCLUSIONS: Generally, AANmDOF robotic training was not superior to conventional training for improving gait pattern in subacute stroke survivors. Both groups improved their mechanical gait efficiency. Yet, AANmDOF robotic training might be more effective to improve specific post-stroke gait abnormalities such as reduced knee flexion during swing. Trial registration Registry number Netherlands Trial Register ( www.trialregister.nl ): NTR5060. Registered 13 February 2015.

Effectiveness of rehabilitation interventions to improve paretic propulsion in individuals with stroke - A systematic review.

BACKGROUND: Stroke survivors often show reduced walking velocity and gait asymmetry. These gait abnormalities are associated with reduced propulsion of the paretic leg. This review aimed to provide an overview of the potential effectiveness of post-stroke rehabilitation interventions to improve paretic propulsion, ankle kinetics and walking velocity. METHODS: A systematic search was performed in Pubmed, Web of Science, Embase, and Pedro. Studies were eligible if they reported changes in propulsion measures (impulse, peak value and symmetry ratios) or ankle kinetics (moment and power) following intervention in stroke survivors (group size ≥10). Study selection, data extraction and quality assessment were performed independently by two authors. FINDINGS: A total of 28 studies were included, of which 25 studies applied exercise interventions, two studies focused on surgical interventions, and one on non-invasive brain stimulation. The number of high-quality trials was limited (N = 6; score Downs and Black scale ≥19). Propulsion measures were the primary outcome in eight studies. In general, mixed results were reported with 14 interventions yielding improvements in propulsion and ankle kinetics. In contrast, gains in walking velocity were observed in the vast majority of studies (N = 20 out of 23). INTERPRETATION: Interventions that yielded gains in propulsion appeared to have in common that they challenged and/or enabled the utilization of latent propulsive capacity of the paretic leg during walking. Walking speed generally increased, regardless of the observed change in propulsion, suggesting the use of compensatory mechanisms. Findings should, however, be interpreted with some caution, as the evidence base for this emerging focus of rehabilitation is limited.

Test-retest reliability of stability outcome measures during treadmill walking in patients with balance problems and healthy controls.

BACKGROUND: Improvement of balance control is an important rehabilitation goal for patients with motor and sensory impairments. To quantify balance control during walking, various stability outcome measures have described differences between healthy controls and patient groups with balance problems. To be useful for the evaluation of interventions or monitoring of individual patients, stability outcome measures need to be reliable. RESEARCH QUESTION: What is the test-retest reliability of six stability outcome measures during gait? METHODS: Patients with balance problems (n = 45) and healthy controls (n = 20) performed two times a two-minute walk test (2MWT). The intraclass correlation coefficient (ICC) and Bland-Altman analysis (coefficient of repeatability; CR) were used to evaluate the test-retest reliability of six stability outcome measures: dynamic stability margin (DSM), margin of stability (MoS), distance between the extrapolated centre of mass (XCoM) and centre of pressure (CoP) in anterior-posterior (XCoM-CoPAP) and medial-lateral (XCoM-CoPML) direction, and inclination angle between centre of mass (CoM) and CoP in anterior-posterior (CoM-CoPAP-angle) and medial-lateral (CoM-CoPML-angle) direction. A two way mixed ANOVA was performed to reveal measurement- and group-effects. RESULTS: The ICCs of all stability outcome measures ranged between 0.51 and 0.97. Significant differences between the measurements were found for the DSM (p = 0.017), XCoM-CoPAP (p = 0.008) and CoM-CoPAP-angle (p = 0.001). Significant differences between controls and patients were found for all stability outcome measures (p < 0.01) except for the MoS (p = 0.32). For the XCoM-CoP distances and CoM-CoP angles, the CRs were smaller than the difference between patients and controls. SIGNIFICANCE: Based on the ICCs, the reliability of all stability outcome measures was moderate to excellent. Since the XCoM-CoPML and CoM-CoPML-angle showed no differences between the measurements and smaller CRs than the differences between patients and controls, the XCoM-CoPML and CoM-CoPML-angle seem the most promising stability outcome measures to evaluate interventions and monitor individual patients.

Immediate after-effects of robot-assisted gait with pelvic support or pelvic constraint on overground walking in healthy subjects.

BACKGROUND: Recovery of walking is a primary rehabilitation goal of most stroke survivors. Control of pelvic movements is one of the essential determinants of gait, yet surprisingly, conventional robot-assisted gait trainers constrain pelvic movements. Novel robot-assisted gait trainers, such as LOPES II, are able to support pelvic movements during gait. The aim of this cross-over study was to investigate the immediate after-effects of pelvic support (PS) or pelvic constraint (PC) gait training with LOPES II on overground walking in healthy subjects. METHODS: Thirteen able-bodied subjects (22.8 ± 2.1 years) participated in two 20-min gait training sessions with LOPES II; one with PS and one with PC. During the PS-training, the LOPES II actively guided the lateral displacement of the pelvis, while pelvic rotations were free. During the PC-condition, both lateral displacement and pelvic rotations were constrained and reduced to a minimum. The training sessions were separated by a 30-min resting period. Lateral displacement of the pelvis, hip and knee kinematics, and spatiotemporal parameters during overground walking were determined at baseline and immediately following the training using 3D gait analysis. RESULTS: During the PS-condition in LOPES II the lateral pelvic displacement was significantly greater (105.6 ± 0 .5 mm) than during the PC-condition (10.8 ± 0 .7 mm; p < 0.001). Analysis of the first five steps of overground walking immediately following PC-condition showed significantly smaller lateral displacements of the pelvis (32.3 ± 12.0 mm) compared to PS-condition (40.1 ± 9 .8 mm; p < 0.01). During the first five steps, step width was significantly smaller after PC-condition (0.17 ± 0. 04 m) compared to PS-condition (0.20 ± 0.04 m; p = 0.01) and baseline (0.19 ± 0. 03 m; p = 0.01). Lateral displacement of the pelvis and step width post training returned to baseline levels within 10 steps. PC- nor PS-condition affected kinematics, gait velocity, cadence, stride length or stance time. CONCLUSIONS: In healthy subjects, robot-assisted gait training with pelvic constraint had immediate negative after-effects on the overground walking pattern, as compared to robot-assisted gait training with pelvic support. Gait training including support of the lateral displacement of the pelvis better resembles the natural gait pattern. It remains to be identified whether pelvic support during robot-assisted gait training is superior to pelvic constraint to promote gait recovery in individuals with neurological disorders.

Classifying trunk strength impairment according to the activity limitation caused in wheelchair rugby performance.

International Federations in Paralympic sports should develop evidence-based classification, based on the relative strength of association between impairment and activities that determine sport-specific performance. The purpose of the current study was to assess the relationship between trunk strength impairment and three activities that determine performance in wheelchair rugby, and to determine whether this relationship supports the concept of "natural classes." Trunk muscle strength and three determinants of performance were assessed in 27 athletes. The correlations between lateral trunk muscle strength and the determinant tilting the chair, and between forward trunk muscle strength and the determinants 1 m acceleration and sprint momentum were calculated. To group athletes based on impairment, K-means cluster analysis was used to group athletes according to how much trunk muscle strength affected the activities. There were significant, moderate to strong correlations between left-right strength and chair tilting (r=.50), between forward strength and 1 m acceleration (r=.59), and between forward strength and sprint momentum (r=.79). Cluster analysis indicated at least one cut-point in performance with a decrease in impairment in all three wheelchair activities, supporting the concept of "natural classes."

Estimating severity of sideways fall using a generic multi linear regression model based on kinematic input variables.

Many research groups have studied fall impact mechanics to understand how fall severity can be reduced to prevent hip fractures. Yet, direct impact force measurements with force plates are restricted to a very limited repertoire of experimental falls. The purpose of this study was to develop a generic model for estimating hip impact forces (i.e. fall severity) in in vivo sideways falls without the use of force plates. Twelve experienced judokas performed sideways Martial Arts (MA) and Block ('natural') falls on a force plate, both with and without a mat on top. Data were analyzed to determine the hip impact force and to derive 11 selected (subject-specific and kinematic) variables. Falls from kneeling height were used to perform a stepwise regression procedure to assess the effects of these input variables and build the model. The final model includes four input variables, involving one subject-specific measure and three kinematic variables: maximum upper body deceleration, body mass, shoulder angle at the instant of 'maximum impact' and maximum hip deceleration. The results showed that estimated and measured hip impact forces were linearly related (explained variances ranging from 46 to 63%). Hip impact forces of MA falls onto the mat from a standing position (3650±916N) estimated by the final model were comparable with measured values (3698±689N), even though these data were not used for training the model. In conclusion, a generic linear regression model was developed that enables the assessment of fall severity through kinematic measures of sideways falls, without using force plates.

The impact of trunk impairment on performance-determining activities in wheelchair rugby.

In Paralympic sport, classification of impairment is needed to prevent a one-sided and predictable outcome of competition, in which the least impaired athlete has the best chance to win. To develop evidence-based classification in wheelchair rugby, the impact of trunk impairment, measured by the Trunk Impairment Classification (TIC), on performance-determining activities was assessed. Arm impairment was analyzed as a covariant. Fifty-five athletes, 21 with TIC score 0, 13 with TIC score 0.5, 11 with TIC score 1.0, and 10 with TIC score 1.5 performed standardized sport-specific activities. A multiple step forward regression analysis was performed for all activities to assess the relative impact of trunk and arm impairment on performance. Trunk impairment was the most important factor for tilting the chair and acceleration in the first 2 m. The explained variance of the performance by trunk and arm impairment ranged from 23% for acceleration in the first meter, to 37% for sprint momentum, the tilt test left, and the time to cover 3 and 4 m. This study shows that athletes with limited trunk impairment are more proficient in wheelchair rugby than athletes with severe trunk impairment.

Can mastication in children with cerebral palsy be analyzed by clinical observation, dynamic ultrasound and 3D kinematics?

The aim of this study was to explore the feasibility of the Mastication Observation and Evaluation (MOE) instrument, dynamic ultrasound and 3D kinematic measurements to describe mastication in children with spastic cerebral palsy and typically developing children. Masticatory movements during five trials of eating a biscuit were assessed in 8 children with cerebral palsy, spastic type (mean age 9.08years) and 14 typically developing children (mean age 9.01years). Differences between trials were tested (t-test) and the mastication of individual children with cerebral palsy was analyzed. MOE scores ranged from 17 to 31 (median 24) for the children with cerebral palsy and from 28 to 32 (median 31) for the typically developing children. There was an increased chewing cycle duration, a smaller left-right and up-down tongue displacement and larger anterior mandible movements for the trials (n=40) of cerebral palsy children (p<0.000 for all comparisons) compared to the trials of typically developing children (n=70). The MOE captures differences in mastication between individual children with cerebral palsy. The MOE items 'jaw movement' and 'fluency and coordination' showed the most similarity with the objective measurements. Objective measurements of dynamic ultrasound and 3D kinematics complemented data from the MOE instrument.

Incorporating in vivo fall assessments in the simulation of femoral fractures with finite element models.

Femoral fractures are a major health issue. Most experimental and finite element (FE) fracture studies use polymethylmethacrylate cups on the greater trochanter (GT) to simulate fall impact loads. However, in vivo fall studies showed that the femur is loaded distally from the GT. Our objective was to incorporate in vivo fall data in FE models to determine the effects of loading position and direction, and size of simulated impact site on the fracture load and fracture type for a healthy and an osteoporotic femur. Twelve sets of loading position and angles were applied through 'near point loads' on the models. Additional simulations were performed with 'cup loads' on the GT, similar to the literature. The results showed no significant difference between fracture loads from simulations with near point loads distally from the GT and those with cup loads on the GT. However, simulated fracture types differed, as near point loads distally from the GT generally resulted in various neck fractures, whilst cup load simulations predicted superior neck and trochanteric fractures only. This study showed that incorporating in vivo fall assessments in FE models by loading the models distally from the GT results in prediction of realistic fracture loads and fracture types.

Reliability of the revised wheelchair rugby trunk impairment classification system.

STUDY DESIGN: Observational, cross-sectional. OBJECTIVES: A new classification system for trunk impairment in wheelchair rugby was introduced in 2010. It consists of 10 tests, arranged in an algorithm, to assign four different trunk scores (0, 0.5, 1.0 or 1.5) to athletes. The purpose of this study was to assess the inter-rater reliability of this classification system. SETTING: National competition for wheelchair rugby and wheelchair basketball in the Netherlands and Belgium. METHODS: Three experienced wheelchair rugby classifiers independently assigned trunk scores to wheelchair rugby and wheelchair basketball athletes in two sessions. After each session, test descriptions were adjusted. The inter-rater reliability was evaluated by determining the agreement and Fleiss Kappa. RESULTS: In the first session, all classifiers agreed on the trunk score in 13 out of 16 athletes; the overall Kappa was 0.76 (P<0.001). The Kappa per trunk score ranged from 0.29 to 1. Four test descriptions were adjusted after the first session. In the second session, there was an agreement in trunk score between the classifiers in 15 out of 21 athletes. The overall Kappa was 0.75 (P<0.0001), and the Kappa per trunk scores ranged from 0.58 to 0.92. After the second session, two test descriptions were improved. CONCLUSION: The revised classification system for trunk impairment in wheelchair rugby showed a adequate inter-rater reliability for the allocation of trunk scores.

Double-leg stance and dynamic balance in individuals with functional ankle instability.

To investigate whether double-leg stance could reveal balance deficits in subjects with functional ankle instability (FAI) and whether such an assessment of static balance would be correlated with measures of dynamic instability, 16 individuals with FAI and 16 healthy controls participated in this study. Static postural control was tested using double-leg stance (either with the eyes open (EO) or closed (EC)) on a dual-plate force platform. Dynamic balance was evaluated using the Multiple Hop Test (MHT) and a weight-shifting task. FAI subjects were significantly less stable in the anteroposterior direction during double-leg stance (as assessed by velocity of centre of pressure, VCP), both for the EO and EC condition. In the mediolateral direction the VCP values were also higher in FAI, but significance was only found for the EC condition (p=.02). FAI subjects made significantly more balance errors compared to healthy controls (p<.001) on both the affected and less affected leg during MHT. There were no significant differences between FAI and healthy subjects during the weight-shifting task. No relationship was found between double-leg stance and MHT measures (all correlations (rs) less than .30). This study suggests that static postural control during double-leg stance is impaired in FAI subjects. Although dynamic balance during MHT is also affected, no significant relationship was found between static and dynamic measurements, which indicate that they are most probably related to different aspects of postural control.

Assessment of mastication in healthy children and children with cerebral palsy: a validity and consistency study.

The aim of this study was to develop the Mastication Observation and Evaluation instrument for observing and assessing the chewing ability of children eating solid and lumpy foods. This study describes the process of item definition and item selection and reports the content validity, reproducibility and consistency of the instrument. In the developmental phase, 15 experienced speech therapists assessed item relevance and descriptions over three Delphi rounds. Potential items were selected based on the results from a literature review. At the initial Delphi round, 17 potential items were included. After three Delphi rounds, 14 items that regarded as providing distinctive value in assessment of mastication (consensus >75%) were included in the Mastication Observation and Evaluation instrument. To test item reproducibility and consistency, two experts and five students evaluated video recordings of 20 children (10 children with cerebral palsy aged 29-65 months and 10 healthy children aged 11-42 months) eating bread and a biscuit. Reproducibility was estimated by means of the intraclass correlation coefficient (ICC). With the exception of one item concerning chewing duration, all items showed good to excellent intra-observer agreement (ICC students: 0.73-1.0). With the exception of chewing duration and number of swallows, inter-observer agreement was fair to excellent for all items (ICC experts: 0.68-1.0 and ICC students: 0.42-1.0). Results indicate that this tool is a feasible instrument and could be used in clinical practice after further research is completed on the reliability of the tool.

Can martial arts techniques reduce fall severity? An in vivo study of femoral loading configurations in sideways falls.

Sideways falls onto the hip are a major cause of femoral fractures in the elderly. Martial arts (MA) fall techniques decrease hip impact forces in sideways falls. The femoral fracture risk, however, also depends on the femoral loading configuration (direction and point of application of the force). The purpose of this study was to determine the effect of fall techniques, landing surface and fall height on the impact force and the loading configuration in sideways falls. Twelve experienced judokas performed sideways MA and Block ('natural') falls on a force plate, both with and without a judo mat on top. Kinematic and force data were analysed to determine the hip impact force and the loading configuration. In falls from a kneeling position, the MA technique reduced the impact force by 27%, but did not change the loading configuration. The use of the mat did not change the loading configuration. Falling from a standing changed the force direction. In all conditions, the point of application was distal and posterior to the greater trochanter, but it was less distal and more posterior in falls from standing than from kneeling position. The present decrease in hip impact force with an unchanged loading configuration indicates the potential protective effect of the MA technique on the femoral fracture risk. The change in loading configuration with an increased fall height warrant further studies to examine the effect of MA techniques on fall severity under more natural fall circumstances.

Sensitivity of the OLGA and VCM models to erroneous marker placement: effects on 3D-gait kinematics.

Gait data need to be reliable to be valuable for clinical decision-making. To reduce the impact of marker placement errors, the Optimized Lower Limb Gait Analysis (OLGA) model was developed. The purpose of this study was to assess the sensitivity of the kinematic gait data to a standard marker displacement of the OLGA model compared with the standard Vicon Clinical Manager (VCM) model and to determine whether OLGA reduces the errors due to the most critical marker displacements. Healthy adults performed six gait sessions. The first session was a standard gait session. For the following sessions, 10mm marker displacements were applied. Kinematic data were collected for both models. The root mean squares of the differences (RMS) were calculated for the kinematics of the displacement sessions with respect to the first session. The results showed that the RMS values were generally larger than the stride-to-stride variation except for the pelvic kinematics. For the ankle, knee and hip kinematics, OLGA significantly reduced the averaged RMS values for most planes. The shank, knee and thigh anterior-posterior marker displacements resulted in RMS values exceeding 10°. OLGA reduced the errors due to the knee and thigh marker displacements, but not the errors due to the ankle marker displacements. In conclusion, OLGA reduces the effect of erroneous marker placement, but does not fully compensate all effects, indicating that accurate marker placement remains of crucial importance for adequate 3D-gait analysis and subsequent clinical decision-making.

Martial arts fall training to prevent hip fractures in the elderly.

UNLABELLED: Hip fractures are a common and serious consequence of falls. Training of proper fall techniques may be useful to prevent hip fractures in the elderly. The results suggested that martial arts fall techniques may be trainable in older individuals. Better performance resulted in a reduced impact force. INTRODUCTION: Hip fractures are a common and serious consequence of falls. Fall training may be useful to prevent hip fractures in the elderly. This pilot study determined whether older individuals could learn martial arts (MA) fall techniques and whether this resulted in a reduced hip impact force during a sideways fall. METHODS: Six male and nineteen female healthy older individuals completed a five-session MA fall training. Before and after training, force and kinematic data were collected during volitional sideways falls from kneeling position. Two MA experts evaluated the fall performance. Fear of falling was measured with a visual analog scale (VAS). RESULTS: After fall training, fall performance from a kneeling position was improved by a mean increase of 1.6 on a ten-point scale (P < 0.001). Hip impact force was reduced by a mean of 8% (0.20 N/N, P = 0.016). Fear of falling was reduced by 0.88 on a VAS scale (P = 0.005). CONCLUSION: MA techniques may be trainable in older individuals, and a better performance may reduce the hip impact force in a volitional sideways fall from a kneeling position. The additional reduction of fear of falling might result in the prevention of falls and related injuries.

The effects of time pressure and experience on the performance of fall techniques during a fall.

Although the practice of fall techniques has been introduced in fall prevention programs, it is not clear whether people can apply acquired techniques during a real-life fall. It would be helpful to know the time it takes to initiate and to successfully execute such techniques, as well as the effect of experience on the execution of these techniques. In this study we investigated the neuromuscular control of voluntary fall techniques in five seasoned judokas and nine non-judokas. After they had started falling from a kneeling position, they received an auditory cue prompting either a lateral natural fall arrest (block) or a martial arts (MA) fall. EMG data of shoulder and trunk muscles were collected. The requested technique was successfully applied in 85% of the falls. Following the cue, EMG amplitudes of the fall techniques started to diverge after 180-190 ms. EMG amplitudes were generally similar in both groups, but experience-related differences could be demonstrated in the pectoralis and trapezius. In conclusion, voluntary motor control is possible within the duration of a fall, even in inexperienced fallers. Differences in EMG activity might suggest that experienced fallers changed their reaction to possible falls from a preparation for arm abduction into a preparation for trunk rotation.

The relation between hip impact velocity and hip impact force differs between sideways fall techniques.

Fall techniques that reduce fall severity may decrease the risk of hip fractures. A fundamental variable for fall severity is impact force, but impact velocity is also used. The purpose of the study was to determine whether impact velocity is valid to determine differences in fall severity between different techniques. Five young adults with martial arts (MA) experience performed sideways falls from kneeling height using three techniques: Block with arm (Block) and MA techniques with and without use of the arm to break the fall. In addition, one subject also performed MA falls from standing height. Linear regression analysis showed a moderate relation between hip impact velocity and force, which was depended on technique. In falls with comparable impact velocities, forces in MA falls were lower than forces in Block falls. Hence, differences in impact force could not be predicted by velocity. In conclusion, hip impact velocity may be useful to make an approximate prediction of impact force within fall techniques. However, to determine differences between techniques it was not always a valid predictor. When direct impact force measurements are not possible, methods combining impact velocity with energy estimates before and after impact might be more valid.

Martial arts fall techniques reduce hip impact forces in naive subjects after a brief period of training.

Hip fractures are among the most serious consequences of falls in the elderly. Martial arts (MA) fall techniques may reduce hip fracture risk, as they are known to reduce hip impact forces by approximately 30% in experienced fallers. The purpose of this study was to investigate whether hip impact forces and velocities in MA falls would be smaller than in a 'natural' fall arrest strategy (Block) in young adults (without any prior experience) after a 30-min training session in sideways MA fall techniques. Ten subjects fell sideways from kneeling height. In order to identify experience-related differences, additional EMG data of both fall types were collected in inexperienced (n=10) and experienced fallers (n=5). Compared to Block falls, MA falls had significantly smaller hip impact forces (-17%) and velocities (-7%). EMG results revealed experience-related differences in the execution of the MA fall, indicative of less pronounced trunk rotation in the inexperienced fallers. This may explain their smaller reduction of impact forces compared to experienced fallers. In conclusion, the finding that a substantial reduction in impact forces can be achieved after a short training in MA techniques is very promising with respect to their use in interventions to prevent fall injuries.

Martial arts fall techniques decrease the impact forces at the hip during sideways falling.

Falls to the side and those with impact on the hip are risky for hip fractures in the elderly. A previous study has indicated that martial arts (MA) fall techniques can reduce hip impact force, but the underlying mechanism is unknown. Furthermore, the high impact forces at the hand used to break the fall have raised concerns because of the risk for wrist fractures. The purpose of the study was to get insight into the role of hand impact, impact velocity, and trunk orientation in the reduction of hip impact force in MA techniques. Six experienced judokas performed sideways falls from kneeling height using three fall techniques: block with arm technique (control), MA technique with use of the arm to break the fall (MA-a), and MA technique without use of the arm (MA-na). The results showed that the MA-a and MA-na technique reduced the impact force by 27.5% and 30%, respectively. Impact velocity was significantly reduced in the MA falls. Trunk orientation was significantly less vertical in the MA-a falls. No significant differences were found between the MA techniques. It was concluded that the reduction in hip impact force was associated with a lower impact velocity and less vertical trunk orientation. Rolling after impact, which is characteristic for MA falls, is likely to contribute to the reduction of impact forces, as well. Using the arm to break the fall was not essential for the MA technique to reduce hip impact force. These findings provided support for the incorporation of MA fall techniques in fall prevention programs for elderly.