References of "Schwartz, Cédric"
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See detailRelevance of early stretching in overhead athletes
Schwartz, Cédric ULg; Tubez, François ULg; Croisier, Jean-Louis ULg 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 ULg; Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg 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 detailMotion analysis: a prevention tool
Schwartz, Cédric ULg; CROISIER, Jean-Louis ULg; Forthomme, Bénédicte ULg et al

Conference (2017, April 28)

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See detailFactors to be considered to perform a kinematic evaluation of the tennis serve
Tubez, François ULg; Forthomme, Bénédicte ULg; Croisier, Jean-Louis ULg et al

in Journal of Medecine and Science in Tennis (2017), 22

With the 2D video cameras and later the appearance of 3D measurement methods, the tennis serve has been increasingly studied. In order to improve the biomechanical evaluation of the tennis serve. Our goal ... [more ▼]

With the 2D video cameras and later the appearance of 3D measurement methods, the tennis serve has been increasingly studied. In order to improve the biomechanical evaluation of the tennis serve. Our goal is to provide a comprehensive view of the major factors of an evaluation protocol. [less ▲]

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See detailAlgorithm for Temporal Gait Analysis Using Wireless Foot-Mounted Accelerometers
Boutaayamou, Mohamed ULg; Denoël, Vincent ULg; Bruls, Olivier ULg et al

Book published by Springer (2017)

We present a new signal processing algorithm that extracts five gait events: heel strike, toe strike, heel-off, toe-off, and heel clearance from only two accelerometers attached on the heels of the ... [more ▼]

We present a new signal processing algorithm that extracts five gait events: heel strike, toe strike, heel-off, toe-off, and heel clearance from only two accelerometers attached on the heels of the subjects usual shoes. This algorithm first uses a continuous wavelet-based segmentation that parses the signal of consecutive strides into motionless periods defining relevant local acceleration signals. Then, the algorithm uses versatile techniques to accurately extract the five gait events from these local acceleration signals. We validated, on a stride-by-stride basis, the extraction of these gait events by comparing the results with reference data provided by a kinematic 3D analysis system and a video camera. The accuracy and precision achieved by the extraction algorithm for healthy subjects, the reduced number of accelerometer units required, and the validation results obtained, encourage us to further study this system in pathological conditions. [less ▲]

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See detailCaractéristiques et évolution de la force après rééducation de la rupture de coiffe des rotateurs
Forthomme, Bénédicte ULg; Schwartz, Cédric ULg; MAHIEU, Xavier ULg et al

in Abstract Book des XVIIIèmes RENCONTRES ISOCINETIQUES MEDIMEX / ROTSCHILD (2016, November)

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See detailGait pattern of healthy old people for fast walking condition
GILLAIN, Sophie ULg; Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg et al

in Gerontechnology (2016, September)

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See detailGait pattern of healthy old people for dual task walking condition
GILLAIN, Sophie ULg; Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg et al

in Gerontechnology (2016, September)

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See detailReproducibility of a tennis serve protocol
Tubez, François ULg; FORTHOMME, Bénédicte ULg; Croisier, Jean-Louis ULg 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 detailA Comparison of 3D Methods for Identifying the Stance Phase in Treadmill Running for Both Rearfoot and Forefoot Runners
Deflandre, Dorian ULg; Schwartz, Cédric ULg; Weertz et al

in Journal of sports Science (2016), 4

We compared six 3D methods, OptoGait, and Myotest Run for the determination of contact time for runners with different foot strike patterns. Twenty male participants were divided into two groups: the heel ... [more ▼]

We compared six 3D methods, OptoGait, and Myotest Run for the determination of contact time for runners with different foot strike patterns. Twenty male participants were divided into two groups: the heel group, who attack the ground with the heel (n = 12), and the toe group, who attack the ground with the middle/front of the foot (n = 8). They performed trials at speeds of 8 km/h then 16 km/h. To detect foot strike, the use of peak velocity of 3D markers located on the heel, the fifth metatarsal, and the great toe provided the best results for both groups. To detect the toe off, the minimum vertical position of a 3D marker placed in line with the great toe gave the most satisfactory results for both groups. In this way, the values of contact time measured with the 3D methods are consistent. Values measured with OptoGait appear consistent too, while those of the Myotest Run underestimate the contact time for both speeds. 3D analysis provides interesting opportunities for calculation of contact time for both rearfoot and forefoot runners, using specific peak velocities to determine foot strike and marker displacement to determine toe off. [less ▲]

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See detailMuscular and functional tridimensional analysis after hamstring strain
Paulus, Julien ULg; DELVAUX, François ULg; Schwartz, Cédric ULg et al

in European Journal of Physical and Rehabilitation Medicine (2016, April), 52(2), 263

Introduction The muscle injury, and more especially the hamstring strain, account for a large proportion of explosive top athletes injuries [1-3]. The subsequent down-time period has some sports and ... [more ▼]

Introduction The muscle injury, and more especially the hamstring strain, account for a large proportion of explosive top athletes injuries [1-3]. The subsequent down-time period has some sports and financial negatives consequences for the athlete, his team and/or his club [4, 5]. Despite the rehabilitation before return to play and prevention program, hamstring reinjury rates are still high (26% of all injuries) [6] and it's commonly accepted that a second injury is more severe than a first episode [2]. A more functional test could help the clinician in the return to play process decision to reduce the muscle injuries hamstring relapse. Purpose The aim of our methodology is to analyze, after medical clearance to resume sports activities, for athletes who suffered from grade II/III hamstring muscle strain, the biomechanics of the lower limbs during an explosive jump task. Method After (7,3±0,7 weeks) a grade II or III hamstring muscle tear, eight men (25±5,9 years), without past lower limb major injury, performed: - an isokinetic test (knee maximal flexion-extension in concentric at 60°.s-1 and 240°.s-1 and knee maximal flexion in eccentric at 30°.s-1); - a tridimensional biomechanics analysis of (bipodal and unipodal) squat jump and counter movement jump with Codamotion® system and Kistler® multicomponent force plates. Results A muscular lateral strength imbalance (±10% with p-value < 0,02) has been identified on the hamstring in concentric and eccentric by means of isokinetic testing, with the healthy side stronger than the pathologic. The main statistical significant outcome in the biomechanics analysis is the lower knee angle (±12% with p-value < 0,02) at the low point before the concentric pushing phase of the unipodal CMJ for the healthy leg than to the other one whereas there's no difference between both legs in an equivalent healthy population. Discussion & conclusion The tridimensional analysis appears to be complementary, not redundant, with the isokinetic strength testing due to the different nature of their informations obtained. It could be integrated in the return to play process decision expected the potentially interesting information about the player's biomechanics that it provides. References 1. 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. 2. Ekstrand, J., M. Hagglund, and M. Walden, Injury incidence and injury patterns in professional football: the UEFA injury study. Br J Sports Med, 2011. 45(7): p. 553-8. 3. Lopez, V., Jr., et al., Profile of an American amateur rugby union sevens series. Am J Sports Med, 2012. 40(1): p. 179-84. 4. Price, R.J., et al., The Football Association medical research programme: an audit of injuries in academy youth football. Br J Sports Med, 2004. 38(4): p. 466-71. 5. Verrall, G.M., et al., Assessment of player performance following return to sport after hamstring muscle strain injury. J Sci Med Sport, 2006. 9(1-2): p. 87-90. 6. Brooks, J.H., et al., Incidence, risk, and prevention of hamstring muscle injuries in professional rugby union. Am J Sports Med, 2006. 34(8): p. 1297-306. [less ▲]

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See detailExtraction of temporal gait parameters using a reduced number of wearable accelerometers
Boutaayamou, Mohamed ULg; Denoël, Vincent ULg; Bruls, Olivier ULg et al

in Proceedings of the 9th International Conference on Bio-inspired Systems and Signal Processing (2016)

Wearable inertial systems often require many sensing units in order to reach an accurate extraction of temporal gait parameters. Reconciling easy and fast handling in daily clinical use and accurate ... [more ▼]

Wearable inertial systems often require many sensing units in order to reach an accurate extraction of temporal gait parameters. Reconciling easy and fast handling in daily clinical use and accurate extraction of a substantial number of relevant gait parameters is a challenge. This paper describes the implementation of a new accelerometer-based method that accurately and precisely detects gait events/parameters from acceleration signals measured from only two accelerometers attached on the heels of the subject’s usual shoes. The first step of the proposed method uses a gait segmentation based on the continuous wavelet transform (CWT) that provides only a rough estimation of motionless periods defining relevant local acceleration signals. The second step uses the CWT and a novel piecewise-linear fitting technique to accurately extract, from these local acceleration signals, gait events, each labelled as heel strike (HS), toe strike (TS), heel-off (HO), toe-off (TO), or heel clearance (HC). A stride-by-stride validation of these extracted gait events was carried out by comparing the results with reference data provided by a kinematic 3D analysis system (used as gold standard) and a video camera. The temporal accuracy ± precision of the gait events were for HS: 7.2 ms ± 22.1 ms, TS: 0.7 ms ± 19.0 ms, HO: ‒3.4 ms ± 27.4 ms, TO: 2.2 ms ± 15.7 ms, and HC: 3.2 ms ± 17.9 ms. In addition, the occurrence times of right/left stance, swing, and stride phases were estimated with a mean error of ‒6 ms ± 15 ms, ‒5 ms ± 17 ms, and ‒6 ms ± 17 ms, respectively. The accuracy and precision achieved by the extraction algorithm for healthy subjects, the simplification of the hardware (through the reduction of the number of accelerometer units required), and the validation results obtained, convince us that the proposed accelerometer-based system could be extended for assessing pathological gait (e.g., for patients with Parkinson’s disease). [less ▲]

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See detailGender effect on the scapular 3D posture and kinematic in healthy subjects
Schwartz, Cédric ULg; Croisier, Jean-Louis ULg; Rigaux, Elise et al

in Clinical Physiology and Functional Imaging (2016)

Populations considered for shoulder analysis are often composed of various ratios of men and women. It is consequently hypothesized that gender has no significant effect on the joint kinematic. However ... [more ▼]

Populations considered for shoulder analysis are often composed of various ratios of men and women. It is consequently hypothesized that gender has no significant effect on the joint kinematic. However the literature reports, for the shoulder, differences in the range of motion between genders. The specific influence of gender on the scapula-thoracic kinematics has not been studied yet. The dominant shoulder of two populations of men and women composed of 11 subjects each were evaluated in three dimensions for three distinct motions: flexion in the sagittal plane, abduction in the frontal plane and gleno-humeral internal/external rotation with the arm abducted at 90°. Posture, kinematics and range of motion were studied separately. For flexion and abduction and with regard to the scapular kinematic, external rotation were significantly larger for women than men. The differences were of at least 5° at 120° of humeral elevation. Upward rotations were identical. Women also showed larger average active humero-thoracic range of motion. The mean differences were of 13°, 7°, 12° and 5° for abduction, flexion, internal rotation and external rotation, respectively. No difference was observed between the scapular resting positions of both populations. The observed differences concerning both the scapular and humeral patterns would indicate that the shoulder behavior of men and women should not be expected to be similar. [less ▲]

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