Papers by Dario Liebermann
Scientific Reports, Dec 21, 2023
Frontiers in Human Neuroscience, Feb 24, 2022
Background: Instrumented gait analysis post-stroke is becoming increasingly more common in resear... more Background: Instrumented gait analysis post-stroke is becoming increasingly more common in research and clinics. Although overall standardized procedures are proposed, an almost infinite number of potential variables for kinematic analysis is generated and there remains a lack of consensus regarding which are the most important for sufficient evaluation. The current aim was to identify a discriminative core set of kinematic variables for gait post-stroke. Methods: We applied a three-step process of statistical analysis on commonly used kinematic gait variables comprising the whole body, derived from 3D motion data on 31 persons post-stroke and 41 non-disabled controls. The process of identifying relevant core sets involved: (1) exclusion of variables for which there were no significant group differences; (2) systematic investigation of one, or combinations of either two, three, or four significant variables whereby each core set was evaluated using a leave-one-out cross-validation combined with logistic regression to estimate a misclassification rate (MR). Results: The best MR for one single variable was shown for the Duration of singlesupport (MR 0.10) or Duration of 2nd double-support (MR 0.11) phase, corresponding to an 89-90% probability of correctly classifying a person as post-stroke/control. Adding Pelvis sagittal ROM to either of the variables Self-selected gait speed or Stride length, alternatively adding Ankle sagittal ROM to the Duration of single-stance phase, increased the probability of correctly classifying individuals to 93-94% (MR 0.06). Combining three variables decreased the MR further to 0.04, suggesting a probability of 96% for correct classification. These core sets contained: (1) a spatial (Stride/Step length) or a temporal variable (Self-selected gait speed/Stance time/Swing time or Duration of 2nd double-support), (2) Pelvis sagittal ROM or Ankle plantarflexion during push-off, and (3) Arm Posture Score or Cadence or a knee/shoulder joint angle variable. Adding a fourth variable did not further improve the MR.
American Journal of Sports Medicine, May 23, 2022
Background: An anterior cruciate ligament (ACL) rupture may result in poor sensorimotor knee cont... more Background: An anterior cruciate ligament (ACL) rupture may result in poor sensorimotor knee control and, consequentially, adapted movement strategies to help maintain knee stability. Whether patients display atypical lower limb mechanics during weight acceptance of stair descent at different time frames after ACL reconstruction (ACLR) is unknown. Purpose: To compare the presence of atypical lower limb mechanics during the weight acceptance phase of stair descent among athletes at early, middle, and late time frames after unilateral ACLR. Study Design: Controlled laboratory study. Methods: A total of 49 athletes with ACLR were classified into 3 groups according to time after ACLR—early (<6 months; n = 17), middle (6-18 months; n = 16), and late (>18 months; n = 16)—and compared with asymptomatic athletes (control; n = 18). Sagittal plane hip, knee, and ankle angles; angular velocities; moments; and powers were compared between the ACLR groups’ injured and noninjured legs and the control group as well as between legs within groups using functional data analysis methods. Results: All 3 ACLR groups showed greater knee flexion angles and moments than the control group for injured and noninjured legs. For the other outcomes, the early group had, compared with the control group, less hip power absorption, more knee power absorption, lower ankle plantarflexion angle, lower ankle dorsiflexion moment, and less ankle power absorption for the injured leg and more knee power absorption and higher vertical ground reaction force for the noninjured leg. In addition, the late group showed differences from the control group for the injured leg revealing more knee power absorption and lower ankle plantarflexion angle. Only the early group took a longer time than the control group to complete weight acceptance and demonstrated asymmetry for multiple outcomes. Conclusion: Athletes with different time frames after ACLR revealed atypically large knee angles and moments during weight acceptance of stair descent for both the injured and the noninjured legs. These findings may express a chronically adapted strategy to increase knee control. In contrast, atypical hip and ankle mechanics seem restricted to an early time frame after ACLR. Clinical Relevance: Rehabilitation after ACLR should include early training in controlling weight acceptance. Including a control group is essential when evaluating movement patterns after ACLR because both legs may be affected.
Routledge eBooks, Dec 9, 2019
Frontiers in Human Neuroscience
Essentials of Performance Analysis in Sport
... 53. Self, BP and Paine, D.(2001)'Ankle biomechanics during four landing techniqu... more ... 53. Self, BP and Paine, D.(2001)'Ankle biomechanics during four landing techniques', Med. Sci. Sports Exerc., 33: 13381344. 54. Sidaway, B., McNitt-Gray, J. and Davis, G.(1989)'Visual timing of muscle preactivation in preparation for landing', Ecol. Psych., 1: 253264. 55. ...
Disability and Rehabilitation: Assistive Technology, 2020
Purpose: Motor recovery of the upper limb (UL) is related to exercise intensity, defined as movem... more Purpose: Motor recovery of the upper limb (UL) is related to exercise intensity, defined as movement repetitions divided by minutes in active therapy, and task difficulty. However, the degree to which UL training in virtual reality (VR) applications deliver intense and challenging exercise and whether these factors are considered in different centres for people with different sensorimotor impairment levels is not evidenced. We determined if (1) a VR programme can deliver high UL exercise intensity in people with sub-acute stroke across different environments and (2) exercise intensity and difficulty differed among patients with different levels of UL sensorimotor impairment. Methods: Participants with sub-acute stroke (<6 months) with Fugl-Meyer scores ranging from 14 to 57, completed 10 $ 50-min UL training sessions using three unilateral and one bilateral VR activity over 2 weeks in centres located in three countries. Training time, number of movement repetitions, and success rates were extracted from game activity logs. Exercise intensity was calculated for each participant, related to UL impairment, and compared between centres. Results: Exercise intensity was high and was progressed similarly in all centres. Participants had most difficulty with bilateral and lateral reaching activities. Exercise intensity was not, while success rate of only one unilateral activity was related to UL severity. Conclusion: The level of intensity attained with this VR exercise programme was higher than that reported in current stroke therapy practice. Although progression through different activity levels was similar between centres, clearer guidelines for exercise progression should be provided by the VR application. ä IMPLICATIONS FOR REHABILITATION VR rehabilitation systems can be used to deliver intensive exercise programmes. VR rehabilitation systems need to be designed with measurable progressions through difficulty levels.
Annals of Physical and Rehabilitation Medicine, 2018
Introduction/Background Recent advances in the augmented reality (AR) technology have significant... more Introduction/Background Recent advances in the augmented reality (AR) technology have significantly extended to the clinical rehabilitation in patients with stroke. The aim of this study is to investigate the therapeutic potentials of the home-based exercise program with the AR system to improve balance in stroke patients. Material and method The home-based exercise program with AR system was designed as prospective, randomized controlled study with blind observer. We analyzed interim data of total 30 stroke patients who completed functional assessment immediately after the intervention for 4 weeks. In the experimental group (n = 15), we provided the home-based exercise program with the AR system (Uincare ®), which was composed with the task-specific game-based system. In the control group (n = 15), the written home-based exercise pogrom was provided. All participants were recommended the home-based exercise with 30 minutes a day for 4 weeks. Functional assessments with Timed Up and Go test, Tinetti Performance Oriented Mobility Assessment, and Berg Balance scale were performed before and after the intervention for 4 weeks. Results There was no significant difference in general and functional characteristics before the intervention. There was no serious adverse effect in both groups. In each group, there was a significant improvement on balance after the home-based exercise for 4 weeks (P < 0.05). However, there was no significant difference in balance after the intervention between the two groups. Conclusion This study was the first clinical trials to use the homebased exercise program with AR system in stroke patients. In addition, the results of present study revealed that a therapeutic potential of the home-based exercise program with the AR system to improve balance in stroke patients. Further study with larger number of patients will be needed to clarify the effects of the homebased exercise program with the AR system. Keywords Home-based exercise program; Augmented reality (AR) technology; Stroke Disclosure of interest The authors have not supplied their declaration of competing interest.
Annals of Physical and Rehabilitation Medicine, 2018
Neurorehabilitation and Neural Repair, 2019
Background. Spasticity is common in patients with stroke, yet current quantification methods are ... more Background. Spasticity is common in patients with stroke, yet current quantification methods are insufficient for determining the relationship between spasticity and voluntary movement deficits. This is partly a result of the effects of spasticity on spatiotemporal characteristics of movement and the variability of voluntary movement. These can be captured by Gaussian mixture models (GMMs). Objectives. To determine the influence of spasticity on upper-limb voluntary motion, as assessed by the bidirectional Kullback-Liebler divergence (BKLD) between motion GMMs. Methods. A total of 16 individuals with subacute stroke and 13 healthy aged-equivalent controls reached to grasp 4 targets (near-center, contralateral, far-center, and ipsilateral). Two-dimensional GMMs (angle and time) were estimated for elbow extension motion. BKLD was computed for each individual and target, within the control group and between the control and stroke groups. Movement time, final elbow angle, average elbow ...
Background: After shoulder surgery for joint stabilization, patients often report that shoulder f... more Background: After shoulder surgery for joint stabilization, patients often report that shoulder function improves and positive signs in the ‘apprehension test’ disappear. However, objective validation of the outcomes of shoulder surgery has never been provided. We inquired first about the characteristics of arm movements in healthy individuals and found that in the literature that healthy 2D motion of the arm (e.g., movements performed on table) tend to be smooth and follow shortest amplitude paths with symmetric and unimodal tangential velocity profiles (Minimum Jerk model; Flash and Hogan 1985). In this study, we assumed that such smoothness criterion could be used as an objective indicator of healthy arm movements also in 3D, and thus, we compared the motor outcome before and after different but common surgical procedures for shoulder stabilization (arthroscopy versus open surgery). Methods: Data were obtained from 3 consecutive point-to-point arm movement trials carried out in each of 3 speed conditions (fast, preferred, slow) and 4 different targets locations towards one central target above the head (Speeds and Movement Directions were repeated measures while Groups were the between-subjects factor). Trials were collected from 14 healthy control subjects (group C), 11 patients before surgery (group B), 3 patients after arthroscopy for stabilization of the shoulder (group A) and 10 patients that underwent open surgery (group D). 3D data were captured by a motion tracking system at a rate of 100 Hz from reflective markers attached to the right arm (acromion and the distal end of the humerus). The kinematic data were pre-processed using MatLab routines. Statistical analyses were based on the following objective measures of smoothness: Time-to-peak speed (TT P), peak-to-mean amplitude ratio (PAR), speed similarity index (SSI) and number of peaks in the tangential velocity of the arm (NO P). Descriptive statistics and multiple 2-way ANO VAs were carried out using these dependent variables (p Results: Significant effects of the Group factor were observed in the ANOVAs using TT P, PAR and NOP as dependent variables, but not SSI. Post hoc comparisons showed that Group A differed significantly from all others. Patients in group D did not significantly differed from healthy subjects (group C), but patients before surgery (group B) differed from all others. Notably, patients after arthroscopy were also closer to the maximal smoothness scores predicted by the minimum jerk model than even healthy subjects. Discussion: The results show that kinematics measures may be used to objectively assess the success of one surgical procedure over another. The maximal smoothness criterion seems to be a sensitive measure describing shoulder performance, and thus, parameters derived from this assumption allow for a discrimination of healthy motion from pathological motion. As it stems from the current study, arthroscopy seems to be the preferable intervention since objective measures of smoothness showed that these patients outperform others after surgery. A test of based on slow movement may enhance these differences among procedures because slow movements may rely more on proprioceptive input.
Scientific Reports
Hemiparesis and spasticity are common co-occurring manifestations of hemispheric stroke. The rela... more Hemiparesis and spasticity are common co-occurring manifestations of hemispheric stroke. The relationship between impaired precision and force in voluntary movement (hemiparesis) and the increment in muscle tone that stems from dysregulated activity of the stretch reflex (spasticity) is far from clear. Here we aimed to elucidate whether variation in lesion topography affects hemiparesis and spasticity in a similar or dis-similar manner. Voxel-based lesion-symptom mapping (VLSM) was used to assess the impact of lesion topography on (a) upper limb paresis, as reflected by the Fugl-Meyer Assessment scale for the upper limb and (b) elbow flexor spasticity, as reflected by the Tonic Stretch Reflex Threshold, in 41 patients with first-ever stroke. Hemiparesis and spasticity were affected by damage to peri-Sylvian cortical and subcortical regions and the putamen. Hemiparesis (but not spasticity) was affected by damage to the corticospinal tract at corona-radiata and capsular levels, and by...
Journal of NeuroEngineering and Rehabilitation, 2021
BackgroundHemiparesis following stroke is often accompanied by spasticity. Spasticity is one fact... more BackgroundHemiparesis following stroke is often accompanied by spasticity. Spasticity is one factor among the multiple components of the upper motor neuron syndrome that contributes to movement impairment. However, the specific contribution of spasticity is difficult to isolate and quantify. We propose a new method of quantification and evaluation of the impact of spasticity on the quality of movement following stroke.MethodsSpasticity was assessed using the Tonic Stretch Reflex Threshold (TSRT). TSRT was analyzed in relation to stochastic models of motion to quantify the deviation of the hemiparetic upper limb motion from the normal motion patterns during a reaching task. Specifically, we assessed the impact of spasticity in the elbow flexors on reaching motion patterns using two distinct measures of the ‘distance’ between pathological and normal movement, (a) the bidirectional Kullback–Liebler divergence (BKLD) and (b) Hellinger’s distance (HD). These measures differ in their sens...
Medicine & Science in Sports & Exercise, 2002
SPIRIT 2013 Checklist: recommended items to address in a clinical trial protocol and related docu... more SPIRIT 2013 Checklist: recommended items to address in a clinical trial protocol and related documents. (PDF 152Â kb)
Isokinetics and Exercise Science, 2002
This study was aimed to explore the relationship between lower limb extension power measured by i... more This study was aimed to explore the relationship between lower limb extension power measured by isokinetic knee extensions (IK) and vertical jumps performed on a force plate (VJ) and speed skating (SS) sprint power measured by a laser device. Methods: Twenty elite short-and long-track speed skaters performed 100 m sprints followed by VJ and IK trials. Power-time curves were calculated off-line. Pearson correlation coefficients were used to determine the degree of association between the variables.
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Papers by Dario Liebermann