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Nowadays, the better assessment of low back pain (LBP) is an important challenge, as it is the leading musculoskeletal condition worldwide in terms of years of disability. The objective of this study was to evaluate the relevance of various machine learning (ML) algorithms and Sample Entropy (SampEn), which assesses the complexity of motion variability in identifying the condition of low back pain. Twenty chronic low-back pain (CLBP) patients and 20 healthy non-LBP participants performed 1-min repetitive bending (flexion) and return (extension) trunk movements. Analysis was performed using the time series recorded by three inertial sensors attached to the participants. It was found that SampEn was significantly lower in CLBP patients, indicating a loss of movement complexity due to LBP. Gaussian Naive Bayes ML proved to be the best of the various tested algorithms, achieving 79% accuracy in identifying CLBP patients. Angular velocity of flexion movement was the most discriminative feature in the ML analysis. This study demonstrated that: supervised ML and a complexity assessment of trunk movement variability are useful in the identification of CLBP condition, and that simple kinematic indicators are sensitive to this condition. Therefore, ML could be progressively adopted by clinicians in the assessment of CLBP patients.

Low back pain (LBP) obviously reduces the quality of life but is also the world's leading cause of years lived with disability. Alterations in motor response and changes in movement patterns are expected in LBP patients when compared to healthy people. Such changes in dynamics may be assessed by the nonlinear analysis of kinematical time series recorded from one patient's motion. Since sample entropy (SampEn) has emerged as a relevant index measuring the complexity of a given time series, we propose the development of a clinical test based on SampEn of a time series recorded by a wearable inertial measurement unit for repeated bending and returns (b and r) of the trunk. Twenty-three healthy participants were asked to perform, in random order, 50 repetitions of this movement by touching a stool and another 50 repetitions by touching a box on the floor. The angular amplitude of the b and r movement and the sample entropy of the three components of the angular velocity and acceleration were computed. We showed that the repetitive b and r "touch the stool" test could indeed be the basis of a clinical test for the evaluation of low-back-pain patients, with an optimal duration of 70 s, acceptable in daily clinical practice.

International audience; Introduction: Lower limb amputation impairs postural performance that could be characterized by biomechanical parameters. This study is to investigate postural performance of persons with transfemoral and transtibial amputation compared to controls without amputation.Methods: Eight transtibial, nine transfemoral and twelve able-bodied males participated in this study. Lower limb joints, pelvis and trunk angles were obtained from an optoelectronic motion analysis system to evaluate body posture parameters. The mean, range and speed of the center of pressure (CoP) in both antero-posterior and medio-lateral axes as well as the ellipse area covered by 90% of CoP and free moment were calculated using a single force-plate.Results and discussion: Differences in body posture were only noted between the non-amputee and the transtibial groups. Transtibial amputees leaned more forwardly their trunk by 3.5° compared to able-bodied (p = 0.028). The mean CoP position in transfemoral amputees was closer to the non-amputated side than transtibial amputees (p = 0.034) and as compared to the dominant side in non-amputees (p = 0.042). Factor analysis revealed three postural performance modalities. Non-amputees postural performance was characterized solely by body posture parameters. Transfemoral amputees exclusively favored a modality associated with standing balance parameters, whereas transtibial amputees exhibited a mixed modality comprising a combination of postural and balance parameters.Conclusion: These findings support that the level of amputation is characterized by postural performance modalities different from non-amputees. Clinicians could apply this knowledge as part of their routine rehabilitation program to enhance postural and standing balance assessments in unilateral transfemoral and transtibial amputees.

Background The equivalency of treadmill and overground walking has been investigated in a large number of studies. However, no systematic review has been performed on this topic. Research question The aim of this study was to compare the biomechanical, electromyographical and energy consumption outcomes of motorized treadmill and overground walking. Methods Five databases, ScienceDirect, SpringerLink, Web of Science, PubMed, and Scopus, were searched until January 13, 2021. Studies written in English comparing lower limb biomechanics, electromyography and energy consumption during treadmill and overground walking in healthy young adults (20-40 years) were included. Results Twenty-two studies (n=409 participants) were included and evaluated via the Cochrane Collaboration’s tool. These 22 studies showed that some kinematic (reduced pelvic ROM, maximum hip flexion angle for females, maximum knee flexion angle for males and cautious gait pattern), kinetic (sagittal plane joint moments: dorsiflexor moments, knee extensor moments and hip extensor moments and sagittal plane joint powers at the knee and hip joints, peak backwards, lateral and medial COP velocities and propulsive forces during late stance) and electromyographic (lower limbs muscles activities) outcome measures were significantly different for motorized treadmill and overground walking. Significance Spatiotemporal, kinematic, kinetic, electromyographic and energy consumption outcome measures were largely comparable for motorized treadmill and overground walking. However, the differences in kinematic, kinetic and electromyographic parameters should be taken into consideration by clinicians, trainers, and researchers when working on new protocols related to patient rehabilitation, fitness rooms or research as to be as close as possible to the outcome measures of overground walking. The protocol registration number is CRD42021236335 (PROSPERO International Prospective Register of Systematic Reviews).

Brain&ndash, computer interfaces (BCIs) have been proven to be useful for stroke rehabilitation, but there are a number of factors that impede the use of this technology in rehabilitation clinics and in home-use, the major factors including the usability and costs of the BCI system. The aims of this study were to develop a cheap 3D-printed wrist exoskeleton that can be controlled by a cheap open source BCI (OpenViBE), and to determine if training with such a setup could induce neural plasticity. Eleven healthy volunteers imagined wrist extensions, which were detected from single-trial electroencephalography (EEG), and in response to this, the wrist exoskeleton replicated the intended movement. Motor-evoked potentials (MEPs) elicited using transcranial magnetic stimulation were measured before, immediately after, and 30 min after BCI training with the exoskeleton. The BCI system had a true positive rate of 86 &plusmn, 12% with 1.20 &plusmn, 0.57 false detections per minute. Compared to the measurement before the BCI training, the MEPs increased by 35 &plusmn, 60% immediately after and 67 &plusmn, 60% 30 min after the BCI training. There was no association between the BCI performance and the induction of plasticity. In conclusion, it is possible to detect imaginary movements using an open-source BCI setup and control a cheap 3D-printed exoskeleton that when combined with the BCI can induce neural plasticity. These findings may promote the availability of BCI technology for rehabilitation clinics and home-use. However, the usability must be improved, and further tests are needed with stroke patients.

International audience; Background: How Achilles tendon mechanics and plantar flexion strength and torque steadiness are altered in the intact leg of persons with trauma-related amputation is unknown. Understanding Achilles tendon mechanics following amputation will further inform rehabilitation approaches to enhance posture, balance, and force control.Objective: Conduct a pilot study to quantify plantar flexion maximal voluntary contraction torque, torque steadiness, and Achilles tendon mechanics in persons with unilateral trauma-related transfemoral amputation and controls without amputation.Study design: Cross-sectional study.Methods: Isometric plantar flexion maximal voluntary contractions were performed with the intact leg of ten males with transfemoral amputation (48 ± 14 years) and the dominant leg of age-matched male controls without amputation. Torque steadiness was calculated as the coefficient of variation in torque over 6 s during submaximal tracking tasks (5%, 10%, 25%, 50%, and 75% maximal voluntary contraction). Achilles tendon elongation and cross-sectional area were recorded with ultrasound to calculate strain, stress, and stiffness.Results: Maximal voluntary contraction and torque steadiness did not differ between persons with amputation (90.6 ± 31.6 N m, 3.7 ± 2.0%) and controls (95.8 ± 26.8 N m, 2.9 ± 1.2%; p > 0.05). Tendon stiffness (21.1 ± 18.2 N/mm) and strain (5.2 ± 1.3%) did not differ between groups (p > 0.05). Tendon cross-sectional area was 10% greater in persons with amputation leading to 29% lower stress (p = 0.021). Maximal voluntary contraction was a predictor of a lower coefficient of variation in torque (R2 = 0.11, p < 0.05).Conclusion: Persons with trauma-related transfemoral amputation do not differ in plantar flexion maximal voluntary contraction and torque steadiness of the intact leg compared with controls without amputation. Larger tendon cross-sectional area reduces stress and enables distribution of force across a greater area.

Introduction This study investigated self-paced voluntary oscillations of scoliotic and non-scoliotic girls. Temporal variables and frequency coherence were calculated for the overall, low and high frequency bandwidths of the center of pressure excursions and free-moment to identify which variables best describe sway balance modalities in both groups. Methods Twenty-three girls with adolescent idiopathic moderate scoliosis (spinal curves to the right) formed the scoliotic group and 19 matched able-bodied girls formed the non-scoliotic group. Each girl performed self-paced voluntary medio-lateral and antero-posterior sways while standing on a force platform. Center of pressure displacements, out of plane deviation and free-moment were measured and their frequency content calculated. The magnitude of the coherence was calculated for each signal pairs for three frequency ranges. Results In both sway conditions, the center of pressure excursion parameters were on average 28% higher for the scoliotic group. Factor analysis revealed that balance modalities were essentially based on frequency coherence pair interactions whereas temporal parameters play a secondary role. However, these balance modalities were altered in the scoliotic group. They relied essentially on 2 additional principal components and 3 additional variables reflecting a fine tuning of the control mechanism to maintain dynamic balance. Interpretation Scoliotic girls appear to be performing a wide ellipsoidal trajectory when performing whole body oscillations. Superfluous variables could be related to the difficulty in preserving balance during body sway tasks and could parasitize the scoliotic dynamic control balance modalities. Self-paced voluntary sways could be an appropriate complementary balance test for untreated scoliotic girls.

Background Generally, scoliotic girls have a tendency to lean further back than a comparable group of non-scoliotic girls. To date, no study has addressed how standing balance in untreated scoliotic girls is affected by a natural backwardly or forwardly inclined trunk. Methods 27 able-bodied young girls and 27 young girls with a right thoracic curve were classified as leaning forward or backward according to the median of their trunk sagittal inclination. Participants stood upright barefoot. Trunk and pelvis orientations were calculated from 8 bony landmarks. Upright standing balance was assessed by 9 parameters calculated from the excursion of the center of pressure and the free moment. Findings In the anterior-posterior direction, backward scoliotic girls had a greater center of pressure range (P = 0.036) and speed (P = 0.015) by 10.4 mm and 2.8 mm/s respectively than the forward scoliotic group. Compared to their matching non-scoliotic group, the backward scoliotic girls stood more on their heels by 14.6 mm (P = 0.017) and display greater center of pressure speed by 2.5 mm/s (P = 0.028). Medio-lateral center of pressure range (P = 0.018) and speed (P = 0.008) were statistically higher by 8.7 mm and 3.6 mm/s for the backward group. Only the free moment RMS was significantly larger (P = 0.045) for the backward scoliotic group when compared to the forwardly inclined scoliotic group. Interpretation Only those with a backward lean displayed statistically significant differences from both forward scoliotic girls and non-scoliotic girls. Untreated scoliotic girls with an exaggerated back extension could profit more from postural rehabilitation to improve their standing balance.

Resume Objectifs L’objectif de cette revue etait d’examiner, chez les enfants, l’influence des chaussures minimalistes sur la biomecanique de course et d’etablir une analyse theorique de l’influence de ce type de chaussure sur le risque de blessure. Actualites Entre 8 et 15 ans, les stress repetes induits par la pratique sportive reguliere et les poussees de croissance que connaissent les enfants sportifs les rendent enclins aux blessures de sur-sollicitation. Les plus communes pour le membre inferieur sont les maladies d’Osgood-Schlatter et de Sever. Le premier lien entre le corps et le sol etant la chaussure, cette derniere peut etre de premiere importance concernant le risque d’apparition de ces pathologies. Il est suggere que l’utilisation de chaussures minimalistes modifierait la biomecanique de course et donc potentiellement le risque de blessure. Perspectives et projets De futures investigations sont necessaires pour identifier, au cours du temps, si les enfants adaptent ou non leur motricite a l’utilisation de chaussures minimalistes et si le port de ces dernieres influence le risque de blessure de sur-sollicitation. Conclusion Par rapport aux chaussures conventionnelles, l’utilisation de chaussures minimalistes induit generalement un placement du pied plus a plat avec une cheville plus en flexion plantaire lors de l’impact avec le sol et une flexion du genou moins importante pendant la phase d’appui. Il semble que ces modifications conduisent a une reduction des forces de tension au niveau du genou et qu’elles pourraient diminuer le risque de maladie d’Osgood-Schlatter. Concernant la maladie de Sever, l’analyse biomecanique n’est pas concluante a cause de la complexite de sa patho-mecanique. Le port de chaussures minimalistes devrait diminuer les forces compressives sous le talon par une redistribution de la pression sur l’ensemble de la face plantaire ou sous l’avant-pied mais pourrait en contrepartie augmenter les forces de tension au niveau de l’insertion du tendon d’Achille sur le calcaneum.

International audience; Background: This study test if the frequency coherence calculated for the overall, low and high frequency bandwidths of the center of pressure excursions and free-moment calculated during standing balance are similar between scoliotic and non-scoliotic girls and if the coherence values within each frequency band are comparable for a given group of girls.Methods: Twenty-nine girls with adolescent idiopathic scoliosis formed the scoliotic group and 22 able-bodied girls formed the non-scoliotic group. Each girl maintained a quiet upright stance on a force plate. Three trials were performed at a sampling frequency of 64 Hz for 64 s. Mean anterio-posterior, medio-lateral center of pressure positions and free-moment were measured and their frequency content calculated. The magnitude of the coherence was calculated for each signal pairs for three frequency ranges.Results: The magnitude of the medio-lateral center of pressure/free-moment coherence in the low and high frequency bands was significantly different between the groups. Within each group, the magnitude of the medio-lateral center of pressure/free-moment coherence was significantly higher than the other two coherence pairs at low frequencies (P < 0.001). Factor analysis revealed that able-bodied girls exhibited a mixed standing balance modality consisting of posture (center of pressure) and proprioceptive information (free-moment). Scoliotic girls adopted an adaptive modality mostly based on proprioception information to maintain their standing balance.Interpretation: Scoliotic girls systematically depend on the free-moment to modulate their antero-posterior center of pressure displacements. These results suggest a postural reeducation program aimed at improving proprioception while repositioning the mean center of pressure by postural corrections.

IF=3.077; International audience; ObjectiveTo investigate ankle torque and steadiness in the intact leg of transtibial and transfemoral unilateral amputees.DesignComparative study.SettingMedical rehabilitation centers.ParticipantsFifteen persons with a unilateral transfemoral amputation, 8 persons with a transtibial amputation, and 14 able-bodied male participants volunteered to participate in this study (N=37).InterventionsNot applicable.Main Outcomes MeasuresMaximal isometric torque performed during ankle plantarflexion and dorsiflexion in the intact limb of amputees and in the dominant limb of able-bodied persons. The coefficient of variation (CV) of the plantarflexion torque was calculated over 5 seconds during a submaximal isometric contraction (15%) in order to assess torque steadiness. Furthermore, electromyographic activity (the root mean square amplitude) of the gastrocnemius medialis and tibialis anterior muscles was analyzed.ResultsPlantarflexion maximal torque was significantly higher for the able-bodied group (115±39 Nm) than for the group with a transfemoral amputation (77±34 Nm) (P

International audience; During isometric contractions, the net joint torque stability is modulated with the force production phases, i.e., increasing (IFP), holding (HFP), and decreasing force (DFP) phases. It was hypothesized that this modulation results from an altered cortical control of agonist and antagonist muscle activations. Eleven healthy participants performed 50 submaximal isometric ankle plantar flexion contractions. The force production phase effect (IFP, HFP and DFP) was assessed on the net joint torque stability, agonist and antagonist muscles activations, cortical activation, and corticomuscular coherence (CMC) with agonist and antagonist muscles. In comparison to HFP, the net joint torque stability, the agonist muscles activation and the CMC with agonist muscles were lower during IFP and even more during DFP. Antagonist muscle activations, cortical activations and CMC with antagonist muscles were higher during HFP than during IFP only. Increased CMC with agonist and antagonist muscles appeared to enhance the fine motor control. At a cortical level, agonist and antagonist muscle activations seemed to be controlled independently according to their muscle function and the phase of force production. Results revealed that CMC was an adequate measure to investigate the cortical regulation of agonist and antagonist muscle activations. This may have potential applications for patients with altered muscle activations.

International audience; While muscle contraction in voluntary efforts has been widely investigated, little is known about contraction during neuromuscular electrical stimulation (NMES). The aim of this study was to quantify in vivo muscle architecture of agonist and antagonist muscles at the ankle joint during NMES. Muscle fascicle lengths and pennation angles of the tibialis anterior (TA) and lateral gastrocnemius muscles were assessed via ultrasonography in 8 healthy young males. Measures were obtained during maximal NMES and torque-matched voluntary dorsiflexion contractions. In the TA, NMES induced a shorter fascicle length (67.2 ± 8.1 mm vs 74.6 ± 11.4 mm; p = 0.04) and a greater pennation angle (11.0 ± 2.4° vs 9.3 ± 2.5°; p = 0.03) compared with voluntary torque-matched dorsiflexion contractions. Architectural responses in the antagonist lateral gastrocnemius muscle did not significantly differ from rest or between voluntary and electrically induced contractions (p > 0.05). Contraction of the antagonist muscle was not a contributing factor to a greater fascicle shortening and increased pennation angle in the TA during NMES. TA architectural response during NMES likely arose from the contribution of muscle synergists during voluntary contractions coupled with a potentially localized contractile activity under the stimulation electrodes during NMES induced contractions.

International audience

Worldwide, tennis is practiced by millions of children, several thousands being intensive players. The participation in high-performance training programmes and competition places them at risk to e...

International audience; Athletic children are prone to overuse injuries, especially at the heel and knee. Since footwear is an extrinsic factor of lower limb injury risk, the aim of this study was to assess the influence of shoe aging on children running biomechanics. Fourteen children active in sports participated in a laboratory biomechanical evaluation. A new pair of shoes was provided to each participant at an inclusion visit. Four months later, the participants performed a running task and their kinematics and kinetics were assessed both with their used shoes and with a new pair of shoes identical to the first. Furthermore, mechanical cushioning properties of shoes were evaluated before and after in-vivo aging. After 4 months of use, the sole stiffness increased by 16% and the energy loss capacity decreased by 18% (p < 0.001). No ankle or knee kinematic adjustment was found at foot strike in used shoes but changes were observed later during stance. Running with used shoes produced a higher loading rate of the vertical ground reaction force (+ 23%, p = 0.016), suggesting higher compressive forces under the heel and placing children at risk to experience impact-related injuries. Nevertheless, the decreased peak ankle and knee power absorption in used shoes (-11%, p = 0.010 and -12%, p = 0.029, respectively) suggests a lower ankle and knee joints loading during the absorption phase that may be beneficial regarding stretch-related injuries.

International audience; Compared to traditional tennis shoes, using 0-drop shoes was shown to induce an immediate switch from rear- to forefoot strike pattern to perform an open stance tennis forehand for 30% of children tennis players. The purpose of the study was to examine the long-term effects of a gradual reduction in the shoe drop on the biomechanics of children tennis players performing open stance forehands. Thirty children tennis players participated in 2 laboratory biomechanical test sessions (intermediate: +4 months and final: +8 months) after an inclusion visit where they were randomly assigned to control (CON) or experimental (EXP) group. CON received 12-mm-drop shoes twice, whereas EXP received 8mm then 4-mm-drop shoes. Strike index indicated that all CON were rearfoot strikers in intermediate and final test sessions. All EXP were rearfoot strikers in intermediate test session, but half the group switched towards a forefoot strike pattern in final test session. This switch resulted in a decreased loading rate of the ground reaction force (-73%, p=.005) but increased peak ankle plantarflexors moment (+47%, p=.050) and peak ankle power absorption (+107%, p=.005) for these participants compared with CON. Biomechanical changes associated with the long-term use of partial minimalist shoes suggest a reduction in heel compressive forces but an increase in Achilles tendon tensile forces.

IF=3.23; International audience; IntroductionLa terminaison de la marche, planifiée (Roeing et al., 2015) ou non (Jung et al., 2016), peut être utilisée afin de perturber la stabilité posturale d’une personne. L’objectif de cette étude est de présenter une méthode pour évaluer l’impact d’un arrêt soudain lors de l’initiation de la marche sur les moments articulaires générés au niveau du membre inférieur d’appui.Matériel et méthodesVingt et un jeunes adultes ont participé à cette étude. Le participant, filmé par un système optoélectronique, était en position debout, chaque pied sur une plateforme de forces, regard fixé sur un écran placé à 6m face à lui. À l’apparition d’un carré vert à l’écran, le participant devait initier sa marche (condition Go), en ligne droite et à vitesse spontanée. Aléatoirement, un carré rouge, déclenché à partir de l’activité électromyographique du muscle jambier antérieur, pouvait venir remplacer le carré vert, requérant alors un arrêt soudain et inattendu de l’initiation de la marche (condition Go & Stop). Pour ces 2 conditions, les moments articulaires générés au niveau des différentes articulations du membre inférieur d’appui ont été analysés.RésultatsUne différence significative entre les conditions n’a été observée qu’au niveau du pic du moment fléchisseur plantaire : 1,48±0,41 Nm/kg, 1,12±0,38 Nm/kg, respectivement (p

IF=1.55; International audience; This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p=.004) and the ankle was less dorsiflexed at foot strike (p=.037). In D0 compared with D12, the peak impact force was reduced by 17% (p=.049), the ankle was less dorsiflexed at foot strike (p=.045) and the knee was more flexed at foot strike (p=.007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p=.658) or the peak ankle plantarflexor moment (p=.071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.

IF=1.56; International audience; Footwear comfort is essential and pressure distribution on the foot was shown as a relevant objective measurement to assess it. However, asperities on the foot sides, especially the metatarsals and the instep, make its evaluation difficult with available equipment. Thus, a sock equipped with textile pressure sensors was designed. Results from the mechanical tests showed a high linearity of the sensor response under incremental loadings and allowed to determine the regression equation to convert voltage values into pressure measurements. The sensor response was also highly repeatable and the creep under constant loading was low. Pressure measurements on human feet associated with a perception questionnaire exhibited that significant relationships existed between pressure and comfort perceived on the first, the third and the fifth metatarsals and top of the instep. Practitioner Summary: A sock equipped with textile sensors was validated for measuring the pressure on the foot top, medial and lateral sides to evaluate footwear comfort. This device may be relevant to help individuals with low sensitivity, such as children, elderly or neuropathic, to choose the shoes that fit the best.

IF=2.34; International audience; The effect of visual feedback on enhancing isometric maximal voluntary contractions (MVC) was evaluated. Twelve adults performed plantar-flexion and dorsi-flexion MVCs in 3 conditions (no visual feedback, visual feedback, and visual feedback with target). There was no significant effect of visual conditions on dorsi-flexion MVC but there was an effect on plantar-flexion. Irrespective of whether a target was evident, visual feedback increased plantar-flexion MVC by ∼15%. This study highlights the importance of optimal feedback to enhance MVC.

IF=1.866; International audience; The purpose of this study was to determine the optimal inner-shoe volume for children tennis players. Sixteen participants, aged from 8 to 12 years old assessed comfort of 6 shoes, which were a combination of 3 lasts (thin, medium and wide) and 2 upper constructions (flexible and stiff), while a sock equipped with textile sensors was measuring the pressure applied on their foot. The thin last was based on the proportion of an adult last. The widest shoes produced the lowest pressure on the 1st and 5th metatarsal heads, the medial midfoot and the medial and lateral heel (p < 0.05), whilst they were perceived the most comfortable for the 3rd and 5th metatarsal heads, the 5th metatarsal base and the medial and lateral heel (p < 0.05). These outcomes indicated that footwear manufacturers should design wider shoes for children than for adults

IF=2.75; International audience; The purpose of this study was to quantitatively and qualitatively assess dynamic balance with accuracy in individuals with chronic ankle instability (CAI). To this aim, a motion capture system was used while participants performed the Star Excursion Balance Test (SEBT). Reached distances for the 8 points of the star were automatically computed, thereby excluding any dependence to the experimenter. In addition, new relevant variables were also computed, such as absolute time needed to reach each distance, lower limb ranges of motion during unipodal stance, as well as absolute error of pointing. Velocity of the center of pressure and range of variation of ground reaction forces have also been assessed during the unipodal phase of the SEBT thanks to force plates. CAI group exhibited smaller reached distances and greater absolute error of pointing than the control group (p

IF=2.3; International audience; Purpose: Many studies have focused on maximum torque exerted by ankle joint muscles during plantar flexion. While strength parameters are typically measured with isokinetic or isolated ankle dynamometers, these devices often present substantial limitations for the measurement of torque because they account for force in only 1 dimension (1D), and the device often constrains the body in a position that augments torque through counter movements. The purposes of this study were to determine the contribution of body position to ankle plantar-flexion torque and to assess the use of 1D and 3D torque sensors.Methods: A custom designed 'Booted, Open-Unit, Three dimension, Transportable, Ergometer' (B.O.T.T.E.) was used to quantify plantar flexion in two conditions: (1) when the participant was restrained within the unit (locked-unit) and (2) when the participant's position was independent of the ankle dynamometer (open-unit). Ten young males performed maximal voluntary isometric plantar-flexion contractions using the B.O.T.T.E. in open and locked-unit mechanical configurations.Results: The B.O.T.T.E. was reliable with ICC higher than 0.90, and CV lower than 7 %. The plantar-flexion maximal resultant torque was significantly higher in the locked-unit compared with open-unit configuration (P < 0.001; +61 to +157 %) due to the addition of forces from the body being constrained within the testing device. A 1D compared with 3D torque sensor significantly underestimated the proper capacity of plantar-flexion torque production (P < 0.001; -37 to -60 %).Conclusions: Assessment of plantar-flexion torque should be performed with an open-unit dynamometer mounted with a 3D sensor that is exclusive of accessory muscles but inclusive of all ankle joint movements.

IF=3.23; International audience; During maximal contractions, the sum of forces exerted by homonymous muscles unilaterally is typically higher than the sum of forces exerted by the same muscles bilaterally. However, the underlying mechanism(s) of this phenomenon, which is known as the bilateral strength deficit, remain equivocal. One potential factor that has received minimal attention is the contribution of body adjustments to bilateral and unilateral force production. The purpose of this study was to evaluate the plantar-flexors in an innovative dynamometer that permitted the influence of torque from body adjustments to be adapted. Participants were identically positioned between two setup configurations where torques generated from body adjustments were included within the net ankle torque (locked-unit) or independent of the ankle (open-unit). Twenty healthy adult males performed unilateral and bilateral maximal voluntary isometric plantar-flexion contractions using the dynamometer in the open and locked-unit mechanical configurations. While there was a significant bilateral strength deficit in the locked-unit (p = 0.01), it was not evident in the open-unit (p = 0.07). In the locked-unit, unilateral torque was greater than in the open-unit (p0.05). This study revealed that the mechanical configuration of the dynamometer and then the body adjustments caused the observation of a bilateral strength deficit

During an isometric contraction, the force generated is not constant but fluctuates around a target value. Force steadiness can influence the individual's functional ability in activities of daily ...

International audience; Background.– Chronic ankle instability (CAI), characterized by recurrent episodes of lateral instability [3], is a complication of lateral ankle sprain which is the most common injury in sport activities [1]. Static balance can be evaluated in bipodal and unipodal conditions, and dynamic balance with Star Excursion Balance Test (SEBT) [2].Objective.– The aim of this study is to note if static and/or dynamic balance can characterize CAI.Methods.– Sixteen healthy subjects (CTRL) and 20 subjects with CAI (CAI) realize unipodal and bipodal balance tests, with eyes opened (EO) and closed (EC).Results.–In static conditions, no difference between CAI and CTRL is shown. During bipodal balance tests, significant increases (P < 0.05) are observed for centre of pressure displacement and velocity for CAI between EO and EC conditions. Reached distances at SEBT are significantly shorter (P < 0.05) for CAI people.Discussion.– Characterization by static balance seems difficult, contrary to what has previously been found by other authors [4]. Differences between EO and EC conditions in bipodal balance tests suggest proprioceptive alteration [3]. Dynamic balance seems to be relevant to characterize CAI through SEBT [4].

This Ph.D. thesis aims to evaluate the standing posture modalities and the ankle joint torque in the intact limb in unilateral lower limb amputees. A first study shows the presence of three posture modalities: the non-amputee group relied on standing erect, the transfemoral amputees’ stance depended on balance control and the transtibial amputees exhibited a mixed modality of simultaneously maintaining an upright stance and standing balance. Since the ankle muscles have a functional importance in standing posture modalities, it is imperative to investigate the ankle joint torque in the intact limb. However, the current devices used to assess the ankle joint present substantial limitations for the measurement. Thus, a second study was designed to develop and to validate a new ankle ergometer B.O.T.T.E. Moreover, a third study was achieved in order to estimate the effect of visual feedback on enhancing isometric maximal voluntary contractions. A fourth study was realized to investigate the ankle joint torque in the intact leg of unilateral lower limb amputees. The results show that transfemoral amputees produce less torque and are less steady compared to transtibial amputees and able-bodied individuals. Overall, the present findings of this Ph.D. thesis could have implications for clinical practice and for rehabilitation of patients with a lower limb amputation., L’objectif de ce travail de thèse est de caractériser, chez les amputés unilatéraux du membre inférieur, les modalités posturales qui interviennent dans la régulation de l’équilibre orthostatique et d’étudier l’impact de l’amputation sur la production de force à la cheville physiologique. Une première étude a révélé la présence de trois modalités posturales afin de réguler le contrôle postural : les amputés transfémoraux adoptent une modalité posturale basée sur les paramètres de stabilité, les amputés transtibiaux optent pour une modalité posturale mixte et les non amputés se réfèrent aux paramètres de l’attitude posturale. Etant donné que l’articulation de la cheville joue un rôle essentiel dans la régulation de l’équilibre postural, il était alors pertinent d’investiguer la production de force à la cheville physiologique. Toutefois, les ergomètres permettant d’étudier l’articulation de la cheville présentent des biais de mesure majeurs. Dans ce cadre, une deuxième étude a été menée afin de développer et valider un nouvel ergomètre pour cheville : le B.O.T.T.E. Parallèlement, la mise en place d’une méthode de mesure basée sur le retour visuel permettant une quantification fiable du couple de force a fait l’objet d’une troisième étude. Ensuite, une quatrième étude visait à utiliser le B.O.T.T.E. pour investiguer l’impact de l’amputation sur la production de force à la cheville physiologique. Les résultats de cette étude confirment la présence d’un déficit au niveau du couple de force généré en flexion plantaire (conditions maximale et sous maximale) chez les amputés transfémoraux. Enfin, ce travail de thèse vise à aider les rééducateurs et les cliniciens à optimiser la prise en charge des patients amputés.

Thèse sous confidentialité du jury jusqu’au 18/05/2021 puis sous embargo illimité de l’auteur. Pour les membres de la communauté universitaire (hors UPHF), ce document est accessible via le Prêt entre bibliothèques (s’adresser à votre bibliothèque universitaire).; Nowadays, most of tennis footwear manufacturers propose children tennis shoes that are scaled-down from adult shoes. However, children are not adult-miniature and have specific needs. Between 8 and 12 years old, children experience growth spurts that decrease the lower limb flexibility and increase the tensile forces on tendons insertion sites onto bones. In addition, the practice of tennis in high-intensity, with the repetition of accelerations and decelerations, places high tensile forces at the Achilles tendon insertion site onto the calcaneus and large compressive forces under the calcaneus. The combination of these 2 factors increase the risk to experience one of the main overuse injuries in children: Sever’s disease. Therefore, the aim of this thesis work was to define the features of a suitable footwear for children tennis players in terms of fitting comfort and limitation of injuries. Firstly, a sock equipped with textile pressure sensors was designed and its measurement reliability was validated. Then, this innovative device was used to correlate pressure measurement and comfort perception on 8 foot locations, allowing to determine the optimal inner-shoe volume for children tennis players. Secondly, the acute effects of shoe drop on the biomechanics of children tennis players were examined and it was shown that reducing from 12 mm to 6 mm allowed to reduce ground reaction forces and thus potentially impact-related injuries. Finally, the long-term influence of shoe drop reduction on the biomechanics and heel pain reported by children tennis players was investigated. The gradual reduction in shoe drop induced a switch from a rear- to forefoot strike pattern in half of the participants and allowed to remove heel pain for them. Future studies are needed to examine the lower-limb structural adaptations linked to the use of partial minimalist shoes.; De nos jours, la plupart des fabriquants de chaussures proposent des chaussures pour les jeunes joueurs de tennis qui sont des modèles réduits de celles des adultes. Cependant, les enfants ne sont pas des adultes-miniatures et ont des besoins spécifiques. Entre 8 et 12 ans, les enfants sont sujets à des poussées de croissance qui diminuent la flexibilité du membre inférieur et augmentent les forces de tension sur les sites d’insertions des tendons sur les os. De plus, la pratique du tennis à haute intensité, avec la répétition d’accélérations et décélérations, place d’importantes forces de tension au niveau de l’insertion du tendon d’Achille sur le calcaneus et d’importantes forces de compression sous le calcaneus. La combinaison de ces 2 facteurs augmente le risque de subir l’une des principales blessures de sursollicitaton chez les enfants : la maladie de Sever. Par conséquent, l’objectif de ce travail de thèse était de définir les caractéristiques d’un chaussant adapté au joueur de tennis enfant en terme de volume chaussant confortable et de limitation des blessures. Premièrement, une chaussette équipée de capteurs de pressions textiles a été conçue et la fiabilité de sa mesure a été validée. Ensuite, cet outil innovant a été utilisé afin de corréler la mesure de pression et la perception du confort sur 8 zones du pied, permettant ainsi de déterminer le volume intérieur de la chaussure optimal pour le joueur de tennis enfant. Deuxièmement, les effets aigus du drop de la chaussure sur la biomécanique des joueurs de tennis enfants ont été examinés et il a été montré que la réduction de 12 mm à 6 mm permettait de réduire les forces de réaction du sol et donc potentiellement les blessures liées à l’impact. Enfin, l’influence à long-terme de la réduction du drop de la chaussure sur la biomécanique et les douleurs au talon reportées par les jeunes joueurs de tennis a été investiguée. La réduction progressive du drop de la chaussure a induit un changement de patron de pose du pied, arrière vers avant-pied, pour la moitié des participants et a permis de supprimer leurs douleurs au talon. De futures études sont nécessaires pour examiner les adaptations structurelles du membre inférieur liées à l’utilisation de chaussures partiellement minimalistes.