Publications of François Tubez
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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 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 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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See detailHow much should you jump? Reproducibility evaluation of a 3-dimensional fatigability countermovement jump test
Paulus, Julien ULiege; Schwartz, Cédric ULiege; Tubez, François ULiege et al

Conference (2017, July 02)

Introduction With the stop jump, the counter movement jump (CMJ) is probably the most used jump in sport. In the literature, a number of studies use the counter movement jump to explore (neuro-)muscular ... [more ▼]

Introduction With the stop jump, the counter movement jump (CMJ) is probably the most used jump in sport. In the literature, a number of studies use the counter movement jump to explore (neuro-)muscular fatigability [1-4]. However, due to the continuous [1-3] (or semi-continuous [4]) character of the test, the CMJ become drop jumps from the second one. Nevertheless, the drop jump isn't the most frequent jump type in sport. These evaluations, with (semi-)continuous jumps, don't reflect the sport reality and therefore a more effective (neuro-)muscular jumping fatigability evaluation must be validated. Methods Nineteen volleyball players (23,5 ± 3,3 years, 187,6 ± 6,6 cm, 77,5 ± 8,5 kg), with no history of (major) lower limb injury, submitted to two jumping fatigability tests, with seven days between each session, under the direction of a single researcher. The jumping fatigability tests consists of the repetition of 50 maximal CMJ at the rate of 33bpm. Between each CMJ, the subject were asked to make a full triple-extension and to wait the next auditory and visual signal of the metronome to start the hip-knee-ankle flexion. With these instructions, each jump remains a CMJ. Subjects were asked to leap as high as possible from the first to the last CMJ. The jumping height was recorder for each jump with three dimensional camera. The reproducibility was assessed by Standard Error of Measurement (SEM), Minimal Difference needed to be considered real (MD), Coefficient of Variation (CV), Pearson Correlation Coefficient (PCC) with 95% confidence interval, Effect Size Cohen (ES Cohen) with 90% confidence interval, paired Student's t-test, Intraclass Correlation Coefficient (ICC 2,1) with 95% confidence interval and Magnitude-Based Inferences (MBI). Results The results summary is available in the Table 1. In this table, only few parameters are presented and only for the partial sums of the first 10, 20, 25, 30, 40 and 50 jumps. Our analyses were based on the partial sums per interval of one jump and all statistical tests listed in "Methods" section have been considered. The partial sum with twenty-five CMJ have an excellent reproducibility (MBI with 0/99/1; ICC with 0.961 [0.902/0.985]; ES Cohen with -0.03 [-0.17/0.10]; PCC with 0.966 [0.911/0,987] and p-value < 0.0001). Moreover, it induce a great height decrease (-23%) and its duration (45.5 s) is similar to the recommendation for the knee fatigability isokinetic protocol [5]. MBI (+/trivial/-) Height decrease ICC (2,1) Test duration 10 0/100/0 -12,7% 0.967 18 s 20 0/99/1 -19,0% 0.964 36 s 25 0/99/1 -23,0% 0.961 46 s 30 0/98/1 -25,6% 0.955 55 s 40 0/98/1 -32,1% 0.950 73 s 50 0/98/2 -38,4% 0.943 91 s Table 1: reproducibility statistics results depending on the number of jumps considered (magnitude-based inferences (MBI) with percentage chances of better/trivial/worst retest vs test results; height jump decrease (last jump / better jump); ICC (2,1); test duration). Discussion Because of the (semi-)continuous character of a majority of fatigability jumping test [1-4], our test is the first, at our knowledge, to explore the reproducibility of a strict CMJ jumping fatigability task. Considering the statistical (relative and absolute) reproducibility results, twenty-five maximal CMJ seems to be the best compromise between reliability of the data and physiological interpretability of test's results. Indeed, its (relative and absolute) reproducibility is excellent and it induces a greater height decrease than shorter test while remaining similar in total duration than other fatigability tests which explore the anaerobic lactic system. References 1. Bosco et al, Eur J Appl Physiol Occup Physiol, 51(3):357-364, 1983. 2. Cormack et al., Int J Sports Physiol Perform, 3(2):131-44, 2008. 3. Dal Pupo et al., J Sci Med Sport, 17(6):650-5, 2014. 4. Meckel et al., J Strength Cond Res, 29(8):2122-7, 2015. 5. Bosquet et al., Int J Sports Med, 31(2):82-8, 2010. [less ▲]

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See detailRelevance of early stretching in overhead athletes
Schwartz, Cédric ULiege; Tubez, François ULiege; Croisier, Jean-Louis ULiege et al

Conference (2017, June 16)

Overhead athletes often develop, over time, a tightness of the posterior structures of the shoulder, which may be associated with injuries. Ten symptomatic (with pain) and ten asymptomatic players with a ... [more ▼]

Overhead athletes often develop, over time, a tightness of the posterior structures of the shoulder, which may be associated with injuries. Ten symptomatic (with pain) and ten asymptomatic players with a tight shoulder were compared and the effect of a self-applied stretching program was evaluated. Before and after the stretching program, pain and stiffness of the shoulder were evaluated. Our results demonstrate that risk factors for shoulder pain such as glenohumeral internal rotation deficit and total range of motion deficit may only be limited in symptomatic athletes. The mobility of the shoulder was significantly improved after the stretching program for both groups. Pain was reduced when present. Because of the limited differences between the symptomatic and asymptomatic athletes, clinicians may find it advantageous to initiate early prevention or rehabilitation programs. [less ▲]

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See detailInfluence of the laboratory context and the size of the markers set on the tennis serve evaluation
Tubez, François ULiege; Forthomme, Bénédicte ULiege; Croisier, Jean-Louis ULiege et al

Conference (2017, June 15)

The purpose of this study was to identify the influence on the tennis serve evaluation of 1/ the test environment and 2/ the number of the markers placed of the player. Two different studies were ... [more ▼]

The purpose of this study was to identify the influence on the tennis serve evaluation of 1/ the test environment and 2/ the number of the markers placed of the player. Two different studies were performed. The first compared a 4 vs. 28 marker set in a laboratory the same day. The second compared a 4 markers test in a laboratory with a 4 markers test on an official tennis court one week apart. We observed similar results between the different tests of both studies. [less ▲]

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See detailReproducibility of a tennis serve protocol
Tubez, François ULiege; FORTHOMME, Bénédicte ULiege; Croisier, Jean-Louis ULiege et al

Conference (2016, July 08)

INTRODUCTION Serve in modern tennis game is a real offensive weapon for players. In kinematic analysis, it is the most studied stroke of this game because it is the only stroke played in a closed skill ... [more ▼]

INTRODUCTION Serve in modern tennis game is a real offensive weapon for players. In kinematic analysis, it is the most studied stroke of this game because it is the only stroke played in a closed skill. Players have a maximum of control on this stroke. It is unclear whether 3D kinematic tests are reproducible for the same player under identical conditions and if a familiarization session is necessary. In practice, with professional players, who have little time available to perform tests, familiarization sessions are difficult. The aim of our study is to measure the reproducibility of a 3D serve protocol test. METHODS Nine tennis players (righties, regional level, 20 ± 2 years) were asked to hit first flat serves in a 1 m² area placed on the "T" zone of deuce diagonal of the tennis court. Two identical tests are performed one week apart. For each test, we selected the three best serves of the 25 trials (with the highest speed and the highest accuracy). Kinetics measurements were performed using a 3D analysis system (Codamotion), a force platform (Kistler) and a radar gun. 28 markers were placed on the players’ bodies to measure kinematics of the movements: ankles, knees, hips, trunk, shoulder, elbow and wrist dominant side. We measured ball speed, leg drive, linear velocity of the racket and joints, joints range of motion and maximum angular velocities at different positions (armed, maximum external rotation and impact) (1). RESULTS All analyzed parameters (linear speeds of racket and joints, leg drive force, joint angles and angular velocities) are reproducible with exception of a small part of them. Our study shows that 5,7% (7 of 122 measurements) joint position parameters and 8,3% (4 of 48 measures) angular velocity parameters are not reproducible from a session to another. DISCUSSION Various errors sources encountered in 3D analysis can justify the presence of non-reproducible parameters (2-3). However, after this work, we can state that the established protocol provides reproducible results when analyzing the tennis serve. [less ▲]

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See detailBiomechanical Analysis of Abdominal Injury in Tennis Serves. A Case Report
Tubez, François ULiege; Forthomme, Bénédicte ULiege; Croisier, Jean-Louis ULiege et al

in Journal of Sports Science and Medicine (2015), 14

The serve is an important stroke in any high level tennis game. A well-mastered serve is a substantial advantage for players. However, because of its repeatability and its intensity, this stroke is ... [more ▼]

The serve is an important stroke in any high level tennis game. A well-mastered serve is a substantial advantage for players. However, because of its repeatability and its intensity, this stroke is potentially deleterious for upper limbs, lower limbs and trunk. The trunk is a vital link in the production and transfer of energy from the lower limbs to the upper limbs; therefore, kin-ematic disorder could be a potential source of risk for trunk injury in tennis. This research studies the case of a professional tennis player who has suffered from a medical tear on the left rectus abdominis muscle after tennis serve. The goal of the study is to understand whether the injury could be explained by an inappropriate technique. For this purpose, we analyzed in three dimensions the kinematic and kinetic aspects of the serve. We also performed isokinetic tests of the player’s knees. We then compared the player to five other professional players as refer-ence. We observed a possible deficit of energy transfer because of an important anterior pelvis tilt. Some compensation made by the player during the serve could be a possible higher abdominal contraction and a larger shoulder external rotation. These partic-ularities could induce an abdominal overwork that could explain the first injury and may provoke further injuries. [less ▲]

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See detailUSING INERTIA MEASUREMENT UNIT (IMU) FOR EXERCISE ANALYSIS
Jidovtseff, Boris ULiege; Bruls, Olivier ULiege; Tubez, François ULiege et al

in 7th International conference on strength training - abstract book (2010)

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See detailAnalyse comparative de différentes modalités d’électrostimulation du quadriceps fémoral
Tubez, François ULiege

Master's dissertation (2009)

Objectif : Cette étude a pour but d’apprécier la pertinence d’une innovation technologique (fonction Mi-Scan, société Compex) proposée dans la gamme des stimulateurs à vocation rééducative et/ou sportive ... [more ▼]

Objectif : Cette étude a pour but d’apprécier la pertinence d’une innovation technologique (fonction Mi-Scan, société Compex) proposée dans la gamme des stimulateurs à vocation rééducative et/ou sportive. Cette analyse porte sur l’efficacité excitomotrice et sur les qualités métrologiques de cette fonction. Méthode : Une comparaison des moments de forces évoqués électriquement au niveau du quadriceps avec et sans l’aide de cette fonction a été réalisée, et ce à intensité sous-maximale et maximale de stimulation. Par ailleurs, cette fonction a été explorée dans des conditions identiques à diverses reprises (étude de reproductibilité). Résultats : Il n’existait pas d’efficacité supérieure d’un montage utilisant la fonction "Mi" par rapport à un montage ne possédant pas cette fonctionnalité. De manière additionnelle, nos résultats ont permis de mettre en évidence que la reproductibilité des mesures effectuées par le senseur "Mi" était médiocre. Discussion : De grandes réserves doivent donc être émises concernant la validité et la fiabilité de cet outil. [less ▲]

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