Publications of François Tubez
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See detailUpper limb field tests and tennis serve performance: which tests to choose?
Tooth, Camille ULiege; Forthomme, Bénédicte ULiege; Tubez, François ULiege et al

in Journal of Medicine and Science in Tennis (2021), 27(1),

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See detailDevelopment of a new fatigability jumping protocol : Effect of the test duration on reproducibility and performance
Paulus, Julien ULiege; Croisier, Jean-Louis ULiege; Kaux, Jean-François ULiege et al

in Science et Sports (2021), 36(3), 95-102

The Wingate Anaerobic Test (WAnT) and isokinetic fatigability protocols are mainly used to evaluate the anaerobic power of athletes for whom jumping is a predominant action in their sport. Nevertheless ... [more ▼]

The Wingate Anaerobic Test (WAnT) and isokinetic fatigability protocols are mainly used to evaluate the anaerobic power of athletes for whom jumping is a predominant action in their sport. Nevertheless, the testing protocol must be as close as possible to the activity pattern of the sport to be valid. Therefore, for these athletes, the test should consist of repetitions of jumps that are task-specific. Our aim was to propose a new jumping protocol allowing for specific assessment of fatigue, to examine its absolute and relative reliability and to determine its ideal duration. Twenty male volleyball performed fifty countermovement jumps (CMJ) at a rate of 33 jumps per minute on two occasions, with seven days recovery between each session. Jump height was computed for each CMJ using a 3D optoelectronic system, which was subsequently added to determine cumulative performance after 10, 15, 20, 25, 30, 35, 40, 45 and 50 repetitions. Reliability of the average jump height was not affected by the lengthening of the protocol and was high for all considered durations (ICC > 0.94; SEM < 5%). A decrease in performance was directly and proportionally related to the duration of the fatigability protocol. Measuring average jump height during a protocol involving 25 CMJ at the rate of 33 jumps per minute appears to represent the best compromise between reliability, induced fatigue and physiological considerations. Moreover, until 25 repetitions, the partial sums by five repetitions can and should be used to further explore the subject's performance during the test. [less ▲]

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See detailEvaluation de la mobilité lombairepar le test de Schober : revue narrative de la littérature
Jacquemin, Denis ULiege; Demoulin, Christophe ULiege; Tubez, François ULiege et al

in Mains Libres (2020), 2

Introduction : Deux tests cliniques sont majoritairement utilisés dans la littérature pour évaluer la mobilité du rachis lombaire : la double inclinométrie et le test de Schöber. Ce dernier dispose d’une ... [more ▼]

Introduction : Deux tests cliniques sont majoritairement utilisés dans la littérature pour évaluer la mobilité du rachis lombaire : la double inclinométrie et le test de Schöber. Ce dernier dispose d’une plus grande notoriété clinique et est plus facile à réaliser. L’existence de plusieurs variantes de ce test et des doutes concernant sa validité justifient la réalisation de cette revue de la littérature. Objectif : Synthétiser les connaissances sur le test de Schober et ses différentes variantes, en termes de consignes méthodologiques et de qualités métrologiques et en réaliser une analyse critique. Développement : Depuis le premier test, créé en 1937 par Schober, plusieurs modifications (test de Schober Modifié et Modifié‑Modifié) ont été apportées notamment au niveau du choix des repères. Ceci a amené une variabilité métho‑dologique et des interprétations différentes en fonction des études et donc une grande confusion scientifique et clinique.Discussion : La littérature décrit une grande hétérogé‑néité en termes de modalités pratiques et une absence de consensus concernant la méthode optimale pour réaliser le(s) test(s) de Schober. La variabilité et l’imprécision des repères inférieurs et supérieurs affectent la reproductibilité, l’interprétation et la validité de ce(s) test(s) par rapport aux clichés radiologiques. Les normes de mobilité ne tiennent pas compte des caractéristiques morphologiques, du genre ni de l’âge des sujets étudiés. Or, ces paramètres paraissent influencer la mobilité lombaire. Conclusion : Cette revue de la littérature remet en question la pertinence du test de Schober, ainsi que de ses différentes versions et met en évidence l’utilité de mener des études afin de développer un nouvel outil clinique capable d’évaluer la mobilité lombaire. [less ▲]

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See detailInfluence of scapular dyskinesis, kinesiotaping and fatigue on tennis serve performance
Tooth, Camille ULiege; Schwartz, Cédric ULiege; Fransolet, Charlotte ULiege et al

in International Journal of Performance Analysis in Sport (2020)

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See detailEvaluation de la mobilité lombaire: Schober or not Schober?
Jacquemin, Denis ULiege; Demoulin, Christophe ULiege; Botton, Anne-Sophie et al

in Kinesitherapie, La Revue (2019, February), 19(206), 82-83

The aim of this study was to verify the validity of the Modified Schober test by checking the real positioning of its benchmarks regarding the spinal skeleton. Study performed on a sample of 42 patients ... [more ▼]

The aim of this study was to verify the validity of the Modified Schober test by checking the real positioning of its benchmarks regarding the spinal skeleton. Study performed on a sample of 42 patients with low back pain via CT or MRI. In 64.3% of cases, the upper marker was below L1, at an average distance of 2.15 cm. Our study therefore questions the validity of the modified Schober test to identify the upper end of the lumbar spine. [less ▲]

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See detailLa position trophée au service en tennis
Tubez, François ULiege; Forthomme, Bénédicte ULiege; Croisier, Jean-Louis ULiege et al

Conference (2019, February)

Introduction : Le service est un des coups les plus importants du tennis. De nombreux outils technologiques permettent d'étudier ce geste de façon précise. C'est le cas des systèmes d'analyse ... [more ▼]

Introduction : Le service est un des coups les plus importants du tennis. De nombreux outils technologiques permettent d'étudier ce geste de façon précise. C'est le cas des systèmes d'analyse tridimensionnelle. L'intérêt de ces outils est de faire évoluer les joueurs vers un geste "optimal" pour effectuer le service le plus performant et le moins traumatisant possible. L'objectif de cette étude est d'observer la séquence des actions réalisées autour de la "position trophée" et de déterminer un potentiel meilleur moment pour la décrire. Nous avons également observé l'évolution de cette position au cours du développement du joueur. Matériel, population et méthode : Une analyse cinématique 3D en laboratoire a été réalisée sur 8 joueurs adultes professionnels, 8 joueurs adolescents espoirs et 8 jeunes enfants joueurs nationaux. (Tableau 1) Les tests réalisés dans cette étude sont effectués au Laboratoire d’Analyse du Mouvement Humain de l’Université de Liège. Le laboratoire est aménagé afin de correspondre le plus possible aux dimensions et aux caractéristiques d’un terrain de tennis. Le système Codamotion est un système d’analyse tridimensionnelle qui utilise des marqueurs actifs. Il est constitué de quatre unités CX1 et de 28 marqueurs Nous avons utilisé 28 marqueurs branchés à 7 boitiers (4 marqueurs par boitier). Ceux-ci sont placés selon des repères anatomiques qui respectent les recommandations de l’International Society of Biomechanics (ISB). Résultats : Les instants de flexion maximale des genoux, de position basse du bassin, de flexion du coude à 90° et de position basse du coude semblent être ceux se rapprochant le plus de la position trophée observée chez le joueur élite. (Tableau 2) L'analyse statistique met en évidence des différences significatives entre les groupes lors de cette position trophée. Conclusion ou discussion: La séquence des actions chez les adultes commence par une flexion des membres inférieurs et se poursuit par le placement de la raquette en position haute. Cette séquence est inversée chez les enfants. Le timing des différentes phases du service est différent entre les groupes: une phase de préparation plus longue et une phase d'accélération plus courte sont observées chez les adultes. Il est désormais possible de décrire plus précisément la position trophée et ses caractéristiques, ce qui n'avait jusqu'à présent jamais été fait. Il serait intéressant pour l’entraîneur de réaliser des séances de travail spécifiques pour cette position trophée afin d'améliorer son apprentissage depuis le plus jeunes âge. [less ▲]

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See detailEvolution of the trophy position along the tennis serve player’s development
Tubez, François ULiege; Schwartz, Cédric ULiege; Croisier, Jean-Louis ULiege et al

in Sports Biomechanics (2019)

The trophy position is a coaching cue for the tennis serve that usually corresponds to the racquet high point (RHP) during the preparatory action for the stroke. Mastering this position and its time of ... [more ▼]

The trophy position is a coaching cue for the tennis serve that usually corresponds to the racquet high point (RHP) during the preparatory action for the stroke. Mastering this position and its time of occurrence seems essential in overarm movements like in the tennis serve. Clinicians and coaches have a real interest in understanding the trophy position and its evolution during the development of the elite players at different ages. A 3D motion system was used to measure the kinematics of the serve. A group of high-level tennis players were selected for three different age groups: 8 adults (ITN 1), 8 teenagers (ITN 3) and 8 children (ITN 5–6). Results show a modified pattern sequence of the tennis serve between children and adult players. RHP appears earlier relative to impact for children (−0.54 ± 0.10 s) than for adults (−0.36 ± 0.11 s) and teenagers (−0.33 ± 0.05 s) (p = 0.007). At RHP, children present lower trunk transverse plane rotation (p < 0.003) and higher shoulder external rotation (p < 0.003). These positions for the child players may represent an increased risk of shoulder and trunk injury than for older players and contribute to a lower racquet resultant velocity at impact. [less ▲]

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See detailInter-Session Reliability of the Tennis Serve and Influence of the Laboratory Context
Tubez, François ULiege; Forthomme, Bénédicte ULiege; Croisier, Jean-Louis ULiege et al

in Journal of Human Kinetics (2019), 66(1), 57-67

To meet the demand of a player's entourage (e.g., coaches and medical staff), it is important for the biomechanics specialist to perform repeatable measures. To the best of our knowledge, to date, it has ... [more ▼]

To meet the demand of a player's entourage (e.g., coaches and medical staff), it is important for the biomechanics specialist to perform repeatable measures. To the best of our knowledge, to date, it has not been demonstrated whether similar results are obtained between two sessions of testing or between laboratory and field sport kinematic protocols with regard to the tennis serve. This study had two primary aims. First, the inter-session repeatability of biomechanical variables of a tennis serve was evaluated. Second, the differences between laboratory and field evaluations were studied. Thirteen national tennis players (ITN 3) performed the same 28 markers' set laboratory test twice two weeks apart, and other thirteen national players (ITN 3) performed two 4 markers' set tests both in the laboratory and on an official tennis court one week apart. A 3D motion system was used to measure lower-limb, pelvis, trunk, dominant arm and racket kinematics. A force plate was used to evaluate kinetics of legs' drive in the laboratory. A personal method based on a point scoring system was developed to evaluate the ball landing location accuracy. We observed that the majority of the studied variables were acceptable for excellent relative reliability for the inter-session analysis. We also showed that the impact of the laboratory versus field context on the player's serve was limited © 2019 2019 François Tubez, Bénédicte Forthomme, Jean-Louis Croisier, Olivier Brüls, Vincent Denoël, Julien Paulus, Cédric Schwartz, published by Sciendo. [less ▲]

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See detailDoes the landmarks used in the modified schober test cover the entire lumbar spine? Proposal for a new procedure
Jacquemin, Denis ULiege; Demoulin, Christophe ULiege; Georges, Mathilde et al

Poster (2018, December 01)

Introduction Although the Modified Schöber Test (McRae and Wright version) has been widely used to measure the flexibility of the lumbar spine, its validity remains controversial Purpose The aim of this ... [more ▼]

Introduction Although the Modified Schöber Test (McRae and Wright version) has been widely used to measure the flexibility of the lumbar spine, its validity remains controversial Purpose The aim of this study was to compare the validity of the Modified Schöber Test (MST) to a new test based on different cutaneous marks by investigating (by means of MRI) if the distance between these landmarks cover the complete lumbar spine Method 80 Patients with low back pain having a lumbosacral MRI prescription were included in the study. Radiopaque markers were placed 10 cm above (superior point) of the lumbosacral junction, identified by palpation, and 5 cm below (inferior point) for the MST (n = 80/80) and, for the New Test (n = 52/80), at a point 5 cm below (inferior point) of the line passing through the posterior superior iliac spines (PSIS-5) as well as at a point (superior point) corresponding to 30% of the distance between this inferior point and C7. The subsequent imaging examination was performed in a supine position Results For the MST participants, the superior point was on (41,25%), above (8,75%) or below (50%) L1. For the new test, 100% of the skin markers were on (53,85%) or above (46,15%) L1 Conclusion The new test presented in the present study might be more valid than the traditional MST to reflect the coverage of the full lumbar spine and therefore its mobility [less ▲]

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See detailDO THE LANDMARKS USED IN THE MODIFIED SCHOBER TEST COVER THE ENTIRE LUMBAR SPINE? PROPOSAL FOR A NEW MARKING PROCEDURE
Jacquemin, Denis ULiege; Demoulin, Christophe ULiege; Georges, M. et al

in Abstract Book of th 9th Biennial Congress of the Belgian Back Society (2018, December)

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See detailInfluence of fatigue on sprint acceleration mechanics: is there a connection with hamstring injury?
Paulus, Julien ULiege; Schwartz, Cédric ULiege; Kaux, Jean-François ULiege et al

Poster (2018, July 09)

Introduction The relationship between hamstring injury and their capacity to produce a force are no longer to demonstrate: decreased ability to produce strength after muscle injury [1], increased risk of ... [more ▼]

Introduction The relationship between hamstring injury and their capacity to produce a force are no longer to demonstrate: decreased ability to produce strength after muscle injury [1], increased risk of injury in case of weakness and/or isokinetic imbalance [2-4], eccentric strength weakness increasing the risk of muscle damage [5-7],… Several studies have also highlighted the fact that fatigue induced by sports activities would increase the risk of hamstring injuries [8, 9]. During a sprint, the ability to orient the forces horizontally, telltale of the effectiveness of the foot strikes [10], is related to the force production capacity of the hamstrings [11]. Moreover, two studies, a case report [12] and a preliminary study [13], seem to indicate that an alteration in horizontal force production during sprint occurs before and after hamstring injury. Is a progressive induction of fatigue lead to a decrease in the athlete's ability to produce horizontally oriented forces during a sprint and in this case could increase the risk of injury? Methods Seven amateur soccer player (22.7 ± 1.3 years, 179.3 ± 5.5 cm, 75.4 ± 4.6 kg) realized the Soccer-specific Aerobic Field Test (SAFT90) [9, 14] with three maximal 50m sprints before, one every each 15 minutes during and three after the protocol. The force- and power-velocity relationships and mechanical effectiveness of force application during sprint running are calculated from anthropometric and spatio-temporal data acquired with a Stalker ATS II radar [15]. Results The Repeated Measures ANOVA reveals a significant (p < 0.001) time dependent decrease in theoretical maximal velocity (v0) (-11.0%), in maximal velocity reached at the end of the acceleration (vHmax) (-10.2%) and in ratio of the net horizontal force (RF0) (-10.5%). Conversely, there's no time dependent modification in theoretical maximal force (F0) (-9.8%), in acceleration time constant (τ) (-18.2%) and in resultant ground reaction forces (GRF) (-3.3%). Discussion Our results, time dependent decrease in RF0, revealed that the fatigue, induced by SAFT90, impacts particularly the hip extensors since at the same time the GRF, resultant ground reaction forces, isn't significantly reduced by the induction of fatigue. Based on previous studies [12, 13], these findings about decreased strength production capacity of hamstring refine our knowledge of the relationships between exhaustion, decreased performance and increased predisposition to hamstring strain injury as the soccer game progresses. Indeed, this is the first time, at our knowledge, that the strength production capabilities of hip extensors are measured accurately during the sprint, the pattern responsible for the greatest number of hamstring injuries in football [16]. Acknowledgements The authors wish to thank the Wallonia-Brussels Federation for their assistance in this study. References 1. Maniar, N., et al., Hamstring strength and flexibility after hamstring strain injury: A systematic review and meta-analysis. British Journal of Sports Medicine, 2016. 2. Croisier, J.L., et al., Strength imbalances and prevention of hamstring injury in professional soccer players: A prospective study. Am J Sports Med, 2008. 36(8): p. 1469-75. 3. van Dyk, N., et al., Hamstring and quadriceps isokinetic strength deficits are weak risk factors for hamstring strain injuries: A 4-year cohort study. Am J Sports Med, 2016. 44(7): p. 1789-95. 4. Yeung, S.S., A.M. Suen, and E.W. Yeung, A prospective cohort study of hamstring injuries in competitive sprinters: Preseason muscle imbalance as a possible risk factor. Br J Sports Med, 2009. 43(8): p. 589-94. 5. Bourne, M.N., et al., Eccentric knee flexor strength and risk of hamstring injuries in rugby union: A prospective study. Am J Sports Med, 2015. 43(11): p. 2663-70. 6. Opar, D.A., et al., Eccentric hamstring strength and hamstring injury risk in Australian footballers. Med Sci Sports Exerc, 2015. 47(4): p. 857-65. 7. Timmins, R.G., et al., Short biceps femoris fascicles and eccentric knee flexor weakness increase the risk of hamstring injury in elite football (soccer): A prospective cohort study. British Journal of Sports Medicine, 2015. 8. Greig, M. and J.C. Siegler, Soccer-specific fatigue and eccentric hamstrings muscle strength. Journal of Athletic Training, 2009. 44(2): p. 180-184. 9. Small, K., et al., Soccer fatigue, sprinting and hamstring injury risk. Int J Sports Med, 2009. 30(8): p. 573-8. 10. Morin, J.B., et al., Mechanical determinants of 100-m sprint running performance. Eur J Appl Physiol, 2012. 112(11): p. 3921-30. 11. Morin, J.-B., et al., Sprint acceleration mechanics: The major role of hamstrings in horizontal force production. Frontiers in Physiology, 2015. 6: p. 404. 12. Mendiguchia, J., et al., Field monitoring of sprinting power-force-velocity profile before, during and after hamstring injury: two case reports. J Sports Sci, 2016. 34(6): p. 535-41. 13. Edouard, P. and J.-B. Morin, Preventing hamstring muscle injuries by sprint acceleration performance evaluation: What? How? When?, in IOC World Conference on Prevention of Injury & Illness in sport. 2017: Monaco. 14. Lovell, R., B. Knapper, and K. Small, Physiological responses to SAFT90: A new soccer-specific match simulation. Coaching and Sports Science, 2008. 3: p. 46-67. 15. Samozino, P., et al., A simple method for measuring power, force, velocity properties, and mechanical effectiveness in sprint running. Scand J Med Sci Sports, 2016. 26(6): p. 648-58. 16. Ekstrand, J., M. Hagglund, and M. Walden, Epidemiology of muscle injuries in professional football (soccer). Am J Sports Med, 2011. 39(6): p. 1226-32. [less ▲]

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See detailContribution à l’évaluation biomécanique du service au tennis. Une analyse de la « trophy position »
Tubez, François ULiege

Doctoral thesis (2018)

The serve play an important role in high level tennis game. A well-mastered serve is a substantial advantage for the players. Numerous actors can contribute to the player's serve development from the ... [more ▼]

The serve play an important role in high level tennis game. A well-mastered serve is a substantial advantage for the players. Numerous actors can contribute to the player's serve development from the first steps of learning to the full physical and technical maturity : coach, doctor, physiotherapist, physical trainer, biomechanist, psychologist, etc. The first part of this thesis contributes to the establishment of a tennis serve evaluation protocol. To evaluate this movement in terms of biomechanics, it is important to use appropriate tools. We have identified those used in the literature to evaluate this movement and described their advantages and disadvantages. This review of the literature highlights the diversity of tools and protocols used by researchers in this field of study. Currently, the most relevant ones used for the biomechanical study of the serve are 3D analysis tools with markers (kinematics) and force platforms (kinetics). The radar is also useful in quantifying ball speed. Next, we analyzed the evaluation procedures (protocols) of this gesture and we proposed a personal protocol adapted to our tools and context within the Laboratory of Human Movement Analysis of the University of Liège. We partially recreated a tennis court in our laboratory. The parameters of the tennis serve kinematics were evaluated using a 3D analysis system. The kinetics of leg drive were measured using force platforms. Final performance was determined by the speed of the racket at impact as well as a personal system for assessing the accuracy of the serve. This first part gives essential information to the coaches and the researchers, who are interested in the specific evaluation of this gesture to bring their player(s) towards the highest level. Thereafter, some experimental conditions have been verified. We evidenced that the test protocol described and used in our laboratory is reproducible. The number of markers and the laboratory environment do not create an obstacle for the realization of the performance. Despite the variety of tennis serve protocols in the literature, it seems that we are the only ones to have validated our test procedure. Our process could serve as a reference for the implementation of the tennis serve evaluation. In the second part of this thesis, we used the validated protocol to study the gestures of the player and the link with the performance or the pathology. We thereby studied the kinematic sequence, the "trophy position" and the specific case of a player with a pathological history.We have looked into the role of the proximal-distal sequence on the players’ performance. To achieve this goal, we compared several categories of players and observed a different sequence according to the age and the game level. Indeed, international adult players trigger the sequence of actions later than young national players. This would limit the time transmission of energy from the pelvis to the shoulders. The interest of a shorter period is certainly linked to a better organization of muscle prestretching within the kinematic chain and could explain a higher level of these international adult players. Later, the "trophy position" was specifically studied within this sequence. Mastering this "trophy position" seems essential to achieve a high performance serve. Differences for this position were observed during the development of the elite player. Adults have, amongst other things, greater knee flexion and more pronounced pelvis and trunk rotations in the "trophy position" than children. The results also showed a modified serve sequence between children and adults, confirming what the literature sets forth. Children seem to have difficulty coordinating trunk rotations with knee flexion or triggering leg thrust with the propulsion phase of the racket and the forward swinging phase of the racket. The characteristics observed in adults may explain the better performance in this group. To finish this second part, the specific case of a professional player with a history of abdominal injury was analyzed. The purpose of this study was to bring a great precision in the observation and the understanding of the stroke. To achieve this, we cross-checked the results obtained by different evaluations. We hypothesized the origin of his injury, highlighting inaccurate kinematics at the start of the "trophy position". Indeed, the back foot relay at the start of the leg drive may have generated an inaccurate anterior pelvic tilt and excessive abdominal tensions. This thesis contributes to the evaluation and comprehension of the tennis serve. It provides to the coach or the medical entourage of the player practical information related to this movement. These data are intended to improve performance and prevent the occurrence of the pathology. Our observations demonstrate the real interest of the participation of a biomechanist in the multidisciplinary support of the player. [less ▲]

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See detailLa position « armée », un instant clé dans l’apprentissage du service au tennis ? Influence de l’âge et du niveau de jeu.
Tubez, François ULiege; Forthomme, Bénédicte ULiege; Croisier, Jean-Louis ULiege et al

Poster (2018, February 24)

Introduction Lors de la réalisation du service au tennis, la position armée semble être un instant clé essentiel à la réussite du geste. Elle est le point de départ de la phase de frappe et conditionne la ... [more ▼]

Introduction Lors de la réalisation du service au tennis, la position armée semble être un instant clé essentiel à la réussite du geste. Elle est le point de départ de la phase de frappe et conditionne la bonne réalisation de celle-ci. Dans cette étude, nous étudions les caractéristiques biomécaniques de cet instant en comparant des joueurs de niveaux et d’âges différents. Matériel et Méthode Nous avons étudié les paramètres biomécaniques de la position armée de 24 joueurs, répartis en 3 groupes de niveaux et d’âges différents. Les tests ont été réalisés dans un laboratoire aménagé avec un système d’analyse optoélectronique en 3D (Codamotion). Résultats et Discussion Nous avons pu observer des différences significatives entre certains groupes, à savoir la séquence de la gestuelle, la rotation externe d’épaule, la rotation de la ceinture scapulaire dans le plan transversal ou encore la flexion des genoux. Les analyses portant sur notre groupe de joueurs professionnels nous ont permis de déterminer les paramètres d’une position armée optimale. Conclusion Notre étude a montré l’existence de différences significatives entre les groupes au niveau des amplitudes de certaines articulations à la position armée. Le niveau de jeu et l’âge des sujets influencent donc cette position, moment clef dans la réussite du service. [less ▲]

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See detailMise en place d’un protocole de mesure de force musculaire des membres inférieurs à l’aide d’un pèse-personne
Liégeois, Kenny; Tubez, François ULiege

in Kinesitherapie, La Revue (2018, February 08), 18(194), 42-43

Objectif L’objectif de cette étude est de proposer le pèse-personne (Fig. 1) comme une alternative d’évaluation de la force musculaire des membres inférieurs. Pour ce faire, nous tentons de démontrer la ... [more ▼]

Objectif L’objectif de cette étude est de proposer le pèse-personne (Fig. 1) comme une alternative d’évaluation de la force musculaire des membres inférieurs. Pour ce faire, nous tentons de démontrer la répétabilité du protocole. Méthodologie L’étude porte sur vingt-neuf sujets âgés de 18 à 26 ans et étudiants en kinésithérapie. Les mesures ont été réalisées grâce à un pèse-personne digital placé sur un support attaché sur un espalier. Les positions d’évaluation sont au nombre de quatre, deux pour chaque groupe musculaire ; une en course interne et l’autre en course externe. La répétabilité de l’outil est évaluée et analysée grâce à un test Anova pour la comparaison des essais à un même temps, et pour la comparaison des valeurs à J0 et J7, nous avons utilisé le test de Pearson. Résultats Les 29 sujets ont terminé l’étude. La répétabilité de l’outil et du protocole mis en place a montré une forte corrélation ; avec un coefficient de corrélation intraclasse entre 0,90-0,98 (P-value < 0,05). Ensuite, les données ont été triées par groupe musculaire et course articulaire en regroupant tous les essais, ce qui a permis de réaliser un test Anova prouvant alors la répétabilité du procédé par une différence non significative. Conclusion Cette étude permet d’élargir les perspectives d’évaluation de la force musculaire. En comparaison aux autres méthodes quantitatives, le pèse-personne est peu co-teux et de surcroît, déjà intégré dans l’environnement du kinésithérapeute. [less ▲]

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See detailWhich tool for a tennis serve evaluation? A review
Tubez, François ULiege; Schwartz, Cédric ULiege; Paulus, Julien ULiege et al

in International Journal of Performance Analysis in Sport (2018)

For coaches, the most common and easiest way to analyse the tennis serve is to refer to their own vision. However, human vision is insufficient to observe high-speed motion with great precision. With the ... [more ▼]

For coaches, the most common and easiest way to analyse the tennis serve is to refer to their own vision. However, human vision is insufficient to observe high-speed motion with great precision. With the improvement of technology, it is now possible to study the gesture from a quantitative point of view. The quantitative evaluation of the tennis serve focuses on the kinematics and kinetics of the player but also on the stroke result, which includes the ball speed and the ball trajectory. This review aims to highlight the current tools available for players, coaches, medical staffs and biomechanical researchers, to evaluate the tennis serve. This overview will provide information to the player’s entourage in order to choose the right tools depending on their specific purposes. All of these tools can be applied in performance improvement and injury prevention. [less ▲]

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See detailNormalizing shoulder EMG: an optimal set of maximum isometric voluntary contraction tests considering reproducibility
Schwartz, Cédric ULiege; Tubez, François ULiege; WANG, François-Charles ULiege et al

in Journal of Electromyography and Kinesiology (2017), 37

Normalization of the electromyography (EMG) signal is often performed relatively to maximal voluntary activations (MVA) obtained during maximum isometric voluntary contraction (MVIC). The first aim was to ... [more ▼]

Normalization of the electromyography (EMG) signal is often performed relatively to maximal voluntary activations (MVA) obtained during maximum isometric voluntary contraction (MVIC). The first aim was to provide an inter-session reproducible protocol to normalize the signal of eight shoulder muscles. The protocol should also lead to a level of activation >90% of MVA for >90% of the volunteers. The second aim was to evaluate the influence of the method used to extract the MVA from the EMG envelope on the normalized EMG signal. Thirteen volunteers performed 12 MVICs twice (one-week interval). Several time constants (100 ms to 2 s) were compared when extracting the MVA from the EMG envelope. The EMG activity was also acquired during an arm elevation. Our results show that a combination of nine MVIC tests was required to meet our requirements including reproducibility. Both the number of MVIC tests and the size of the time constant influence the normalized EMG signal during the dynamic activity (variations up to 15%). A time constant of 1 s was a good compromise to extract the MVA. These findings are valuable to improve the reproducibility of EMG signal normalization. [less ▲]

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