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Epub 2015 Jan 31; The objective of this study was to characterize the mechanics of maximal running sprint acceleration in high-level athletes. Four elite (100-m best time 9.95-10.29 s) and five sub-elite (10.40-10.60 s) sprinters performed seven sprints in overground conditions. A single virtual 40-m sprint was reconstructed and kinetics parameters were calculated for each step using a force platform system and video analyses. Anteroposterior force (FY), power (PY), and the ratio of the horizontal force component to the resultant (total) force (RF, which reflects the orientation of the resultant ground reaction force for each support phase) were computed as a function of velocity (V). FY-V, RF-V, and PY-V relationships were well described by significant linear (mean R(2) of 0.892 ± 0.049 and 0.950 ± 0.023) and quadratic (mean R(2) = 0.732 ± 0.114) models, respectively. The current study allows a better understanding of the mechanics of the sprint acceleration notably by modeling the relationships between the forward velocity and the main mechanical key variables of the sprint. As these findings partly concern world-class sprinters tested in overground conditions, they give new insights into some aspects of the biomechanical limits of human locomotion.

Epub 2015 Jul 17; Overground sprint studies have shown the importance of net horizontal ground reaction force impulse (IMPH) for acceleration performance, but only investigated one or two steps over the acceleration phase, and not in elite sprinters. The main aim of this study was to distinguish between propulsive (IMPH+) and braking (IMPH−) components of the IMPH and seek whether, for an expected higher IMPH, faster elite sprinters produce greater IMPH+, smaller IMPH−, or both.Nine high-level sprinters (100-m best times range: 9.95–10.60 s) performed 7 sprints (2×10 m, 2×15 m, 20 m, 30 m and 40 m) during which ground reaction force was measured by a 6.60 m force platform system. By placing the starting-blocks further from the force plates at each trial, and pooling the data, we could assess the mechanics of an entire “virtual” 40-m acceleration.IMPH and IMPH+ were significantly correlated with 40-m mean speed (r=0.868 and 0.802, respectively; P

Epub 2015 Oct.; Previous studies have reported that reaction time in gait initiation was affected by emotion eliciting pictures. This study examined the effect of a change in the delay between image onset and the imperative “go” on reaction time. From a standing posture, 19 young adults had to walk (several steps) toward pleasant or unpleasant images in two conditions. In the short condition, the word “go” appeared 500 ms after image onset and participants were instructed to initiate gait as soon as possible after the word go appeared. In the long condition, the same procedure was used but the word “go” appeared 3000 ms after image onset. Results demonstrated that motor responses were faster for pleasant pictures than unpleasant ones in the short condition. In contrast, no significant difference was found between both categories of pictures in the long condition. Moreover, we found that self ratings of valence of unpleasant pictures were less unpleasant in the long condition than in the short one whereas there was no difference for pleasant pictures between both conditions. This result reflected a change in the affective significance of unpleasant pictures in the long condition. We also found in the long condition, that the body was inclined forward and to the stance limb during the standing posture and importantly with a similar extent for pleasant and unpleasant pictures. This change clearly reflected a facilitation of the gait initiation process. Overall, results suggested that this gait facilitation when confronted to unpleasant pictures resulted from emotional regulation processes enabling to reappraise these pictures and to override the initial avoidance tendency that they caused.

Epub 2012 Oct 30; Assessing implicit learning in the continuous pursuit-tracking task usually concerns a repeated segment of target displacements masked by two random segments, as referred to as Pew's paradigm. Evidence for segment learning in this paradigm is scanty and contrasts with robust sequence learning in discrete tracking tasks. The present study investigates this issue with two experiments in which participants (N = 56) performed a continuous tracking task. Contrary to Pew's paradigm, participants were presented with a training sequence that was continuously cycled during 14 blocks of practice, but Block 12 in which a transfer sequence was introduced. Results demonstrate sequence learning in several conditions except in the condition that was obviously the most similar to previous studies failing to induce segment learning. Specifically, it is shown here that a target moving too slowly combined with variable time at which target reversal occurs prevents sequence learning. In addition, data from a post-experimental recognition test indicate that sequence learning was associated with explicit perceptual knowledge about the repetitive structure. We propose that learning repetition in a continuous tracking task is conditional on its capacity to (1) allow participants to detect the repeated regularities and (2) restrict feedback-based tracking strategies.

In cohort studies, variables are measured repeatedly and can be considered as trajectories. A classic way to work with trajectories is to cluster them in order to detect the existence of homogeneous patterns of evolution. Since cohort studies usually measure a large number of variables, it might be interesting to study the joint evolution of several variables (also called joint-variable trajectories). To date, the only way to cluster joint-trajectories is to cluster each trajectory independently, then to cross the partitions obtained. This approach is unsatisfactory because it does not take into account a possible co-evolution of variable-trajectories. KmL3D is an R package that implements a version of k-means dedicated to clustering joint-trajectories. It provides facilities for the management of missing values, offers several quality criteria and its graphic interface helps the user to select the best partition. KmL3D can work with any number of joint-variable trajectories. In the restricted case of two joint trajectories, it proposes 3D tools to visualize the partitioning and then export 3D dynamic rotating-graphs to PDF format.

International audience; forthcoming

Purpose: To investigate changes in diffusion tensor imaging (DTI) measures in limbic system white matter of patients with temporal lobe epilepsy (TLE) using diffusion tensor tractography. Materials and Methods: DTI metrics including fractional anisotropy (FA), λ1, λ2, λ3, and trace (Tr) coefficients were obtained from tractography for bilateral fornix, superior and inferior cingulum fibers in 18 patients and 10 healthy controls. Hippocampal signal-to-noise ratio (SNR) quantitative analysis was performed in order to confirm the magnetic resonance imaging (MRI) hippocampal lesion presence or absence in TLE patients. Results: Nine patients presented unilateral hippocampal sclerosis (TLE+HS) and nine patients had no signal abnormalities on conventional MRI (TLE−HS). On the ipsilateral seizure side, all three investigated tracts showed significant DTI indices abnormalities in both patient groups when compared with controls, most marked on the inferior cingulum. Contralateral to the seizure side, the three tracts presented significant DTI parameters in only the TLE+HS group when compared with controls. Conclusion: The DTI abnormalities found in the TLE−HS group may suggest that in the inferior cingulum the structural integrity is more affected than in the fornix or superior cingulum white matter bundles. The eigenvalues taken separately add complementary information to the FA and Tr metrics and may be useful indices in better understanding the architectural reorganization of limbic system tracts in TLE patients without HS. J. Magn. Reson. Imaging 2012;36:561–568. © 2012 Wiley Periodicals, Inc.

International audience; Purpose : Age-related fMRI changes have not been extensively studied for language, whereas important adaptive mechanisms have been seen in other cognitive fields. This study examined age-related changes in fMRI activation during language tasks and, in particular, their dynamic course.Patients and methods fMRI was performed on 22 young and 21 old healthy right-handed subjects during a silent category word-generation task. Activation and dynamics of BOLD signals were studied separately during the first and second portions of each 30-s block.Results : Activation of the left frontal lobe was initially similar in young and old participants; however, it decreased after 30s in the old participants. On the other hand, additional areas were initially involved only in old subjects and especially in the default mode network.Conclusion :This study showed age-related differences in the dynamics of fMRI activation during a silent word-generation task, suggesting a different pattern of language function with aging.

International audience; Le but de cet article est de synthétiser les travaux portant sur les effets de l’attention volontaire sur l’apprentissage d’une habileté motrice. Les premiers modèles d’apprentissage considèrent que l’apprenant franchit plusieurs étapes au cours desquelles la sollicitation des processus attentionnels diminue (Fitts & Posner, 1967). Ainsi, la réalisation d’un mouvement nécessiterait d’engager de l’attention en début d’apprentissage alors qu’elle serait automatique en fin d’apprentissage. Cet article propose de vérifier cette affirmation au regard des recherches récentes qui révèlent que l’apprenant débutant module volontairement son attention a fin d’optimiser la réalisation de ses gestes.Cette focalisation attentionnelle est dite « interne » ou « externe » si elle porte respectivement sur le mouvement lui-même ou sur des éléments extérieurs au corps. La focalisation de l’attention a des répercutions importantes à la fois sur les performances et l’apprentissage. Ainsi, une focalisation externe entraîne de meilleurs résultats qu’une focalisation interne. L’explication de ce phénomène est controversée. Deux hypothèses seront présentées : celle de « l’action contrainte » formulée par Wulf (2007) et celle des « processus conscients » de Masters (Masters & Maxwell, 2004). En fin, cet article se terminera par la présentation des conséquences de ces travaux sur l’enseignement.

International audience; à venir

International audience; à venir

International audience; à venir

International audience; PURPOSE: Diffusion tensor imaging (DTI) can provide quantitative information of brain abnormalities in patients with temporal lobe epilepsy (TLE) that are not detectable with conventional magnetic resonance imaging (MRI).METHODS: Seventeen patients with medically TLE were selected for the study. The patients and ten healthy subjects underwent 25 directions DTI acquisition. The patients were separated into two groups based on the MRI findings: eight TLE MRI-negative patients with no signal abnormalities on conventional MRI and nine TLE patients with hippocampal sclerosis (HS). Fractional anisotropy (FA), mean diffusivity (MD), and the three diffusivities (lambda(1), lambda(2) and lambda(3)) were measured in bilateral hippocampi of controls, MRI-negative, and HS patients. Comparisons between the three groups were performed for hippocampi ipsi- and contralateral to epileptogenic zone.RESULTS: The ipsilateral hippocampus of MRI-negative patients presented statistical increased anisotropy and no significant difference in diffusivities versus controls. Significant differences in anisotropy and diffusivities were detected between the ipsilateral hippocampus of HS when compared with controls.CONCLUSION: DTI depicted hippocampal abnormalities in TLE patients with a normal conventional MRI different from those found in patients with HS. Diffusivity and anisotropy indices provide significant differences inside hippocampus and should be jointly considered to improve the DTI measurements specificity in TLE patients.

International audience; à venir

National audience; Un ensemble de recherches récentes suggèrent que les troubles de la personnalité décrits par le DSM-IV peuvent être évalués à partir d’un modèle général de description de la personnalité : le modèle à cinq facteurs (five-factor model: FFM). Dans cet article, nous présentons une méthode permettant de calculer des scores pour les différents troubles de la personnalité à partir du FFM. Sur la base de profils de personnalité prototypiques fournis par des experts pour chacun des troubles décrits par le DSM-IV, il est possible d’identifier, puis d’additionner les scores obtenus pour les traits de personnalité caractéristiques de chacun des troubles et d’obtenir un score de type dimensionnel pour chacun d’eux. Les scores ainsi obtenus pour les différents troubles de la personnalité sont comparés (corrélations et efficacité diagnostique) à des évaluations plus explicites et directes de symptômes décrits par le DSM-IV, réalisées sur deux échantillons de patients. Pour la plupart des troubles de la personnalité, à l’exception des troubles de la personnalité obsessionnelle–compulsive et histrionique, la validité convergente, la spécificité, la sensibilité et le potentiel de prédictivité négative (NPP) varient de « modérés » à « satisfaisants ». La validité discriminante, qui permet l’examen de la comorbidité entre les différents troubles, est équivalente à celle obtenue par des méthodes d’évaluation explicites et directes. Nous envisageons finalement les avantages de cette méthode en pratique clinique : facilité de l’évaluation de la personnalité, facilité de la cotation, existence de données de référence normatives.

The aim of this study was to verify the impact of ethnicity on the maximal power-vertical jump relationship. Thirty-one healthy males, sixteen Caucasian (age: 26.3 ± 3.5 years; body height: 179.1 ± 5.5 cm; body mass: 78.1 ± 9.8 kg) and fifteen Afro-Caribbean (age: 24.4 ±2.6 years; body height: 178.9 ± 5.5 cm; body mass: 77.1 ± 10.3 kg) completed three sessions during which vertical jump height and maximal power of lower limbs were measured. The results showed that the values of vertical jump height and maximal power were higher for Afro-Caribbean participants (62.92 ± 6.7 cm and 14.70 ± 1.75 W∙kg-1) than for Caucasian ones (52.92 ± 4.4 cm and 12.75 ± 1.36 W∙kg-1). Moreover, very high reliability indices were obtained on vertical jump (e.g. 0.95 < ICC < 0.98) and maximal power performance (e.g. 0.75 < ICC < 0.97). However, multiple linear regression analysis showed that, for a given value of maximal power, the Afro-Caribbean participants jumped 8 cm higher than the Caucasians. Together, these results confirmed that ethnicity impacted the maximal power-vertical jump relationship over three sessions. In the current context of cultural diversity, the use of vertical jump performance as a predictor of muscular power should be considered with caution when dealing with populations of different ethnic origins.

Athletes and coaches believe that adequate sleep is essential for peak performance. There is ample scientific evidence which support the conclusion that sleep loss seems to stress many physiological functions in humans. The aim of this study was to determine the effect of one night's sleep deprivation on intermittent exercise performance in the evening of the following day. Ten male Taekwondo players performed the Yo-Yo intermittent recovery test (YYIRT) in three sleep conditions (reference sleep night [RN], partial sleep deprivation at the beginning of night [PSDBN], partial sleep deprivation at the end of night [PSDEN]) in a counterbalanced order, allowing a recovery period ≥q36 hr in between them. Heart rate peak (HRpeak), plasma lactate concentrations (Lac) and rating of perceived exertion (RPE) were measured during the test. A significant effect of sleep restriction was observed on the total distance covered in YYIRT (P

Epub 2015 Oct 26. Erratum in: Exp Brain Res. 2016 Apr.; This study explored the directional specificity of fear of falling (FoF) effects on the stabilizing function of anticipatory postural adjustments (APA). Participants (N = 71) performed a series of lateral leg raises from an elevated surface in three conditions: in the "Control condition", participants stood at the middle of the surface; in the two test conditions, participants were positioned at the lateral edge of the surface so that the shift of the whole-body centre-of-mass during APA for leg raising was directed towards the edge ("Approach condition") or was directed away from the edge ("Avoidance condition"). Results showed that the amplitude of APA was lower in the "Approach condition" than in the "Control condition" (p < .01); this reduction was compensated for by an increase in APA duration (p < .05), so that both postural stability and motor performance (in terms of peak leg velocity, final leg posture and movement duration) remained unchanged. These changes in APA parameters were not present in the "Avoidance condition". Participants further self-reported a greater FoF (p < .001) and a lower ability to avoid a fall (p < .001) in the "Approach condition" (but not in the "Avoidance condition") than in the "Control condition". The results of this study show that the effects of FoF do not solely depend on initial environmental conditions, but also on the direction of APA relative to the location of the postural threat. These results support the so-called Motivational Direction Hypothesis, according to which approach and avoidance behaviours are primed by emotional state.

Sleep loss is among the most common yet frequently overlooked problems. This disruptive influence is associated with an adverse lipid profile (LP) and consequently results in an increased risk of cardiovascular disease. Furthermore, it has been well established that athletes are increasingly confronted with sleep problems. The aim of this study was to explore the effect of one night of partial sleep deprivation (PSD) on the cardiovascular profile and LP in young, trained athletes. Ten male Taekwondo athletes were randomized for three sleep conditions in a counterbalanced order: (i) following a baseline sleep night (BN), (ii) following PSD at the beginning of the night (PSDBN), and (iii) following PSD at the end of the night (PSDEN). Basal cardiovascular physiological measures were recorded, and blood samples were taken in the fasted state following each sleep session (i.e., in the morning at 07:00 h). The results showed that myoglobin and creatine phosphokinase increased significantly after PSDEN but not after PSDBN. By contrast, no alteration was observed in the LP and physiological parameters following the two types of PSD. In conclusion, these results show that PSDEN increases cardiac damage biomarkers significantly, even though they do not reach clinical significance. Thus, one night of PSD does not affect the physiological responses and biomarkers of LP in Taekwondo athletes.

International audience; Previous studies yielded evidence for an interaction between age and valence in numerous cognitive processes. But, to date, no research has been conducted in the field of motor skills. In this study, we examined the age-related differences in the organization of an emotionally goal-directed locomotion task. Faced with a pleasant, unpleasant, or neutral picture displayed to the side of a stop button, younger and older adults were instructed to walk toward the button (intermediate goal) and push it to turn-off the picture (final goal). Kinematic and ground reaction forces were recorded. The main findings indicated that older adults' response times (RTs) did not differ across the valence picture. The fastest RTs were found in younger adults when faced with pleasant pictures, suggesting that older people may focus either on intermediate or final goals, depending on their value of pleasantness, and prioritize positive goals. We also found that the spatial coding of locomotion (trajectory and final body position) was affected in the same way by the valence of the intermediate goal in both age groups. Taken together, these findings provide new perspectives regarding the potential role of the emotional valence of the intermediate and final goals on the cognitive processes involved in action coding, such as in mental representations of action in older adults.

Purpose The aim of this study was to investigate the effect of natural Pomegranate juice supplementation on performance and acute and delayed responses of muscle soreness and biomarkers of muscle damage after a weightlifting training session. Methods Nine elite weightlifters (21±0.5 years) performed two Olympic-Weightlifting-sessions after either placebo (PLA) or natural pomegranate juice (POMj) supplementations. Heart rate, blood pressure and blood samples (hematological parameters, muscle damage and C-reactive protein (CRP)) were collected at rest, 3min and 48h after each session. Weightlifting performance, RPE, and DOMS were also assessed after each training session. Results T-test showed higher performance (+8.30%) and lower RPE values (-4.37%) using POMj supplementation (p0.05). Additionally, during the 48h following the training session, POMj improved the recovery kinetic of SBP (p

Epub ahead of print; BACKGROUND: The effects of a six-week maximal voluntary isometric co-contraction (MIVCC) training program of the elbow flexor and extensor muscles on maximal and explosive muscle strength have been studied. METHODS: Sixteen active men underwent 6-week MIVCC. Maximal rate of force development (MRFD) of the elbow flexor (MRFDflex) and extensor (MRFDext) were measured in addition to maximal voluntary contraction (MVC) of these muscles (MVCflex and MVCext) before (T0), after 4-week (T1) and 6-week (T2) MIVCC training program. During each test session, integrated electromyographic activity (iEMG) of agonistic and antagonistic muscles during MVC, MRFD, submaximal contractions (30 and 60% MVC) and MIVCC of the elbow flexor and extensor muscles were measured. RESULTS: At T2, MVCflex (13.3±11.7%) and MVCext (22.5±6.1%) increased significantly (P

Objective During rehabilitation of hemiparetic patients, physiotherapists face a discrepancy between motor skills during analytical exercises and functional abilities observed during gait. A muscle recruitment difference in the two situations could explain this gap. Among pathologic motricity manifestations observed in hemiparetic patients (Gracies 2005), exist the spastic co contraction phenomenon that presently concerned our work. Indeed, the main objective of this study was to compare co-contractions in hemiparetic subjects between an analytical exercise modality and a functional exercise modality, i.e. gait. Our hypothesis was that the co contraction is increased during gait as compared to an analytical exercise and could consequently lead to a decrease of gait ability in patients. Material/Patients and methods Muscular activity of knee flexors and extensors was recorded by surface EMG in analytic exercises and during the swing phase of gait, in a group of hemiparetic subjects (SH) and a group of healthy subjects (SS). Co-contraction index in duration and in magnitude was calculated from EMG data and allowed us the comparison between the 2 exercise modalities. Results Twelve SH and 11 SS were included. ICC differed between analytical and functional modalities in SH ( P Discussion - Conclusion Discussion: the observed results show a significant difference between co-contractions observed analytically and during gait in SH. These results validate the initial hypothesis since in most cases, co-contractions are increased during gait. If the conditions of muscle recruitment differ in analytic conditions and during gait, it seems unsuited to propose analytical exercises with the aim to improve gait parameters. This finding therefore suggests a more functional rehabilitation, according to the concept of task-oriented training: rehabilitate gait by gait.

La danse est une activite physique et artistique, pourtant les danseurs sont rarement consideres comme des athletes de haut niveau et la question du suivi de leur sante est peu integree a leur formation et a leur parcours professionnel. On constate aussi une carence dans les curriculum de formation des professionnels de sante concernant le theme de la sante du danseur. Ces dernieres annees, les recherches en sciences et medecine de la danse et les applications dans le domaine de la preparation physique, de la prise en charge medicale ou paramedicale ont ete nombreuses en Europe et a l'International. En France, ce champ est tres recent mais sollicite de plus en plus l'interet des chercheurs en sciences du sport et du mouvement mais aussi des institutions du secteur choregraphique. Cet article envisage d'interroger les liens entre danse et sante, en proposant dans un premier temps des temoignages et dans un second temps, en proposant un etat des lieux de la recherche en sciences de la danse et en presentant des possibilites d'application de ces recherches. / Dance is a physical and an artistic activity, yet the dancers are rarely considered as athletes. Therefore, the question of monitoring their health is poorly integrated within their training programs and their dance careers. There is also a lack of consideration in the training curriculum of health professionals on the topic of the dancer's health. In recent years, the field of dance medicine and science research and its applications has been growing in Europe and abroad. In France, this research in this field is very recent but increasingly seeks the interest of sport and movement science researchers and of the dance institutions. This article questions the issue of health in dance by presenting, on one hand, testimonies and on the other hand, a state of the art of the dance science research field, as well as some applications.

Background Longitudinal data are data in which each variable is measured repeatedly over time. One possibility for the analysis of such data is to cluster them. The majority of clustering methods group together individual that have close trajectories at given time points. These methods group trajectories that are locally close but not necessarily those that have similar shapes. However, in several circumstances, the progress of a phenomenon may be more important than the moment at which it occurs. One would thus like to achieve a partitioning where each group gathers individuals whose trajectories have similar shapes whatever the time lag between them. Method In this article, we present a longitudinal data partitioning algorithm based on the shapes of the trajectories rather than on classical distances. Because this algorithm is time consuming, we propose as well two data simplification procedures that make it applicable to high dimensional datasets. Results In an application to Alzheimer disease, this algorithm revealed a “rapid decline” patient group that was not found by the classical methods. In another application to the feminine menstrual cycle, the algorithm showed, contrarily to the current literature, that the luteinizing hormone presents two peaks in an important proportion of women (22%).

Epub ahead of print; The aim of this study was to compare the kinetic and kinematic parameters of standing and crouch sprint starts. Parallel starts (PS), false starts (FS), jump starts (JS) and crouch starts (3PS) were compared. Eighteen participants performed each start on a force plate and six infrared cameras captured the three-dimensional coordinates of 36 retro-reflective markers. Performance during a five-metre sprint (T5m) was analysed. Duration of the start phase (Tstart), mean values of horizontal and total ground reaction forces (GRFs) (Fx_mean and Ftot_mean), ratio of force (RF), maximal power (Pmax) and kinetic energy (KE) of each limb were calculated. Significant differences were found for T5m, Tstart, KE, Pmax, Fx_mean, Ftot_mean and RF for the crouch start compared to the other starts (P ≤q 0.05). Significant correlations were found between T5m and Tstart (r = 0.59; P ≤q 0.001), and T5m and Pmax, Fx_mean and RF (-0.73 ≤q r ≤q -0.61; P ≤q 0.001). To conclude, the crouch start resulted in the best performance because Tstart was shorter, producing greater Pmax, Fx_mean with a more forward orientation of the resultant force. Greater KE of the trunk in each start condition demonstrated the role of the trunk in generating forward translation of the centre of mass (CM).

Aim Very few studies have investigated the temporal specificity of melatonin (MEL) ingestion upon short-term maximal athletic performances. The aim of the present study was to explore the effect of morning MEL ingestion on cognitive and physical performances measured in the afternoon. Methods Twelve soccer players from a Tunisian squad (17.9 ± 1.3 years, 1.74 ± 0.06 m and 62.0 ± 8.8 kg) participated in the present study. They performed two testing sessions at 08:00 h, 12:00 h and 16:00 h after either MEL (5mg) or placebo (PLA) ingestion, in a randomized order. During each period, the participants performed the following cognitive and physical tests: reaction time and vigilance tests, medicine-ball throw (MBT), five jumps, handgrip strength (HG), and agility tests. Results cognitive and physical performances were significantly higher at 16:00 h compared to 08:00 h during the two conditions (p < 0.05). Moreover, performances of MBT and HG were lower in the morning with MEL in comparison to PLA (p < 0.05). However, MEL ingestion did not affect physical and cognitive performances measured at 12:00 h and 16:00 h. Conclusion morning MEL ingestion has no unfavourable effect on afternoon physical and cognitive performances in soccer players.

The study investigated the effect of the time-of-day at which maximal isometric voluntary co-contraction (MIVCC) training is conducted on the adaptation and diurnal variation of maximal and explosive force production. Twenty active men underwent a 6-week (3 times per week) MIVCC training of the right elbow joint. The participants were randomly assigned to a morning training group (MTG, 07:00-08:00 hours) and evening training group (ETG, 17:00-18:00 hours). The maximal voluntary force (MVF) and maximal rate of force development (MRFD) during isometric elbow flexion (MVFF and MRFD(F)) and extension (MVF(E) and MRFD(E)) were recorded before (T0) and after (T1) training in the morning and evening. At T0, MVF and MRFD were higher in the evening compared with those in the morning for the MTG and ETG (p ≤q 0.05). At T1, MVFF and MVFE increased in the morning and evening for both groups (p < 0.001). The MRFD(F) and MRFD(E) increased only if training and test session were scheduled at the same time. The relative increase of MVF was greater at the specific time of training for the MTG (12 and 17.6% in MVF(F) and MVF(E), respectively) and ETG (9.8 and 13.4% in MVF(F) and MVF(E), respectively). The diurnal variations in MVF and MRF(D) during flexion and extension disappeared in the MTG and persisted in the ETG. Maximal isometric voluntary co-contraction training enhanced muscle strength whatever the time-of-day at which the training was scheduled without alteration of explosive force. In contrast, to optimize the muscle strength, our results suggested that morning training may be accompanied by the greatest muscle strength gain and blunted muscle strength variation observed between the morning and evening.

Single and continuous vertical jumping tests, as well as the Wingate anaerobic test (WAnT), are commonly used to assess the short-term muscle power of female volleyball players; however, the relationship among these tests has not been studied adequately. Thus, the aim of the present study was to examine the relationship of single and continuous vertical jumps with the WAnT in female volleyball players. Seventy adolescent (age 16.0 ˘ 1.0 years, body mass 62.5 ˘ 7.1 kg, height 170.4 ˘ 6.1 cm, body fat 24.2% ˘ 4.3%) and 108 adult female volleyball players (age 24.8 ˘ 5.2 years, body mass 66.5 ˘ 8.7 kg, height 173.2 ˘ 7.4 cm, body fat 22.0% ˘ 5.1%) performed the squat jump (SJ), countermovement jump (CMJ), Abalakov jump (AJ), 30 s Bosco test and WAnT (peak power, Ppeak; mean power, Pmean). Mean power in the Bosco test was correlated (low to large magnitude) with Pmean of the WAnT (r = 0.27, p = 0.030 in adolescents versus r = 0.56, p < 0.001 in adults). SJ, CMJ and AJ also correlated with Ppeak (0.28 ď r ď 0.46 in adolescents versus 0.58 ď r ď 0.61 in adults) and with Pmean (0.43 ď r ď 0.51 versus 0.67 ď r ď 0.71, respectively) of the WAnT (p < 0.05). In summary, the impact of the Bosco test and WAnT on muscle power varied, especially in the younger age group. Single jumping tests had larger correlations with WAnT in adults than in adolescent volleyball players. These findings should be taken into account by volleyball coaches and fitness trainers during the assessment of short-term muscle power of their athletes. Sin financiación No data JCR 2016 No data SJR 2016 No data IDR 2016 UEM

EPUB ahead of print; BACKGROUND: To evaluate the effect of two types of partial sleep deprivation (PSD) on biomarkers of muscle and cardiac injuries in response to acute intermittent exercise in professional athletes.METHODS: In a counterbalanced order, Ten healthy male Taekwondo athletes were asked to perform the Yo-Yo Intermittent Recovery Test (YYIRT) in three conditions, allowing a 36 h recovery period in between: i) following a full night of habitual sleep known as a reference sleep night (RN); ii) following PSD in the beginning of the night (PSDBN), and iii) following PSD in the end of the night (PSDEN). Heart rate (HR) and arterial oxygen saturation (SaO2) were measured during exercise. Blood samples were taken just before and 3 min after the YYIRT to measure biomarkers related to muscle and cardiac injuries.RESULTS: No significant effect of PSD was observed for physiological parameters (i.e., HR and SaO2). However, a significant alteration of resting ultra-sensitive C-reactive protein (P < 0.05) and myoglobin (MYO) (P < 0.01) levels was detected after PSDEN. Furthermore, all biomarkers related to muscle and cardiac injuries were altered by exercise. Likewise, compared to RN, PSD affected creatine phosphokinase and MYO levels in response to exercise (P < 0.05).CONCLUSION: The present study indicates that PSDEN increase the resting us-CRP and MYO levels, and that the two types of PSD increase the CPK and MYO levels in response to acute intermittent exercise, among Taekwondo athletes, in the evening of the following day. However, no rise of the physiological responses has been observed after the two types of PSD, at rest and in response to the exercise.

Purpose:To verify the hypothesis that the peak power (PP) of a Wingate test (WT) is an underestimation of maximal power (Pmax) computed from the force–velocity test (FVT), to examine possible fatigue effect on Pmax, and to investigate the effect of load on mean power (MP) and fatigue index (FI) during a WT in trained and recreational men.Methods:Ten recreational (22.9 ± 1.7 y, 1.81 ± 0.06 m, 73.3 ± 10.4 kg) and 10 highly trained subjects (22.7 ± 1.4 y, 1.85 ± 0.05 m, 78.9 ± 6.6 kg) performed 2 WTs with 2 loads (8.7% and 11% of body mass [BM]) and an FVT on the same cycle ergometer, in randomized order.Results:Optimal load was equal to 10% BM in recreational participants. Given the quadratic relationship between load and power, the underestimation of Pmax was lower than 10% for the average values of trained and recreational participants with both loads. However, PP with a load equal to 8.7% BM was a large underestimation (~30%) of Pmax in the most powerful individuals. In addition, PP was not greater than Pmax of FVT for the same load. FI was independent of the load only if it was expressed relative to PP. The optimal load for MP during WT was close to the optimal load for PP.Conclusions:The optimal load for WT performance should be approximately equal to 10% BM in recreational subjects. In powerful subjects, the FVT appears to be more appropriate in assessing maximal power, and loads higher than 11% BM should be verified for the WT.

Epub 2012 Apr 24; International audience; This study aimed at determining the upper limb muscles coordination during a power backward giant swing (PBGS) and the recruitment pattern of motor units (MU) of co-activated muscles. The wavelet transformation (WT) was applied to the surface electromyographic (EMG) signal of eight shoulder muscles. Total gymnast's body energy and wavelet synergies extracted from the WT-EMG by using a non-negative matrix factorization were analyzed as a function of the body position angle of the gymnast. A cross-correlation analysis of the EMG patterns allowed determining two main groups of co-activated muscles. Two wavelet synergies representing the main spectral features (82% of the variance accounted for) discriminated the recruitment of MU. Although no task-group of MU was found among the muscles, it appeared that a higher proportion of fast MU was recruited within the muscles of the first group during the upper part of the PBGS. The last increase of total body energy before bar release was induced by the recruitment of the muscles of the second group but did not necessitate the recruitment of a higher proportion of fast MU. Such muscle coordination agreed with previous simulations of elements on high bar as well as the findings related to the recruitment of MU.

AIM: To explore the isokinetic concentric strength of the knee muscle groups, and the relationship between the isokinetic knee extensors strength and the vertical jump performance in young elite female basketball players.METHODS: Eighteen elite female basketball players performed a countermovement jump, and an isokinetic knee test using a Biodex dynamometer. The maximal isokinetic peak torque of the knee extensor and flexor muscles was recorded at four angular velocities (90°/s, 180°/s, 240°/s and 300°/s) for the dominant and non-dominant legs. The conventional hamstring/quadriceps ratio (H/Q) was assessed at each angular velocity for both legs.RESULTS: There was no significant difference between dominant and non-dominant leg whatever the angular velocity (all P>0.05). However, the H/Q ratio enhanced as the velocity increased from 180°/s to 300°/s (P

International audience; Gait initiation (GI) is the transient period between posture and movement. Its central programming takes into account the environmental constraints as well as the constraints induced by the body itself. Patients with peripheral sensory neuropathies display a severe proprioceptive deficit leading to balance and gait impairments and rely on a variety of compensatory mechanisms and are known to be dependent on vision. GI was studied on eight healthy subjects and five patients in order to assess the effect of somatosensory loss on the different phases of GI, combined with a manipulation of the visual inputs. Our main hypothesis is that the proprioceptive deficit would induce an adaptation of the GI process, especially when modifying the lower part of peripheral vision. The results show that the pathology induces some adaptations of the GI process, characterized by a decrease of the motor performance (assessed by the maximal anteroposterior velocity of the center of gravity at the end of the first step), a decrease in the spatial parameters (assessed by the peak amplitude of the backward shift of the center of foot pressure during the anticipation phase and the length of the first step), and a non-modification of the temporal parameters (assessed by the duration of the anticipation phase and of the first step). The suppression of the lower part of peripheral vision has no effect on the GI process. The role of the lower part of peripheral vision seems therefore to be less critical for GI, than for balance and locomotion.

International audience; The description of specific circuits in networks should allow a more realistic definition of dynamic functioning of the central nervous system which underlies various brain functions. After introducing the programmed and acquired networks and recalling the concepts of functional and effective connectivity, we presented biophysical and physiological aspects of the BOLD signal. Then, we briefly presented a few data-driven and hypothesis-driven methods; in particular we described structural equation modeling (SEM), a hypothesis-driven approach used to explore circuits within networks and model spatially and anatomically interconnected regions. We compared the SEM method with an alternative hypothesis-driven method, dynamic causal modeling (DCM). Finally, we presented independent components analysis (ICA), an exploratory data-driven approach which could be used to complete the directed brain interactivity studies. ICA combined with SEM/DCM may allow extension of the statistical and explanatory power of fMRI data.

International audience; OBJECTIVE: To establish a normative database for isometric strength measured by quantitative muscle testing (QMT) for a French adult population.DESIGN: Measurement of maximal voluntary isometric contraction.SETTING: Four clinical centers involved in neuromuscular disorders.PARTICIPANTS: A total of 315 healthy adults (147 men, 168 women) ages 20 to 80 years.INTERVENTIONS: Not applicable.MAIN OUTCOME MEASURE: Isometric torque values of 14 muscle functions (13 bilaterally and neck).RESULTS: This study led to the development of a French isometric strength normative database for adults measured by QMT. For each muscle function, predictive regression models using age, sex, and weight are proposed. Some methodologic issues concerning strength measurement are discussed.CONCLUSIONS: This database can be used to compute relative deficits in muscle strength for 27 muscle functions and also to estimate composite scores for follow-up of patients either during the natural history of their disease or during a therapeutic trial.

Epub ahead of print; This study aimed to compare the force (F)-velocity (v)-power (P)-time (t) relationships of female and male world-class sprinters. A total of 100 distance-time curves (50 women and 50 men) were computed from international 100-m finals, to determine the acceleration and deceleration phases of each race: (a) mechanical variables describing the velocity, force, and power output; and (b) F-P-v relationships and associated maximal power output, theoretical force and velocity produced by each athlete (Pmax , F0 , and V0). The results showed that the maximal sprint velocity (Vmax ) and mean power output (W/kg) developed over the entire 100~m strongly influenced 100-m performance (r>-0.80; P≤q0.001). With the exception of mean force (N/kg) developed during the acceleration phase or during the entire 100~m, all of the mechanicals variables observed over the race were greater in men. Shorter acceleration and longer deceleration in women may explain both their lower Vmax and their greater decrease in velocity, and in turn their lower performance level, which can be explained by their higher V0 and its correlation with performance. This highlights the importance of the capability to keep applying horizontal force to the ground at high velocities.

Epub 2015 Jul 1; Walking as a means to interact with the environment has a twofold goal: body displacement (intermediate goal) and the future action on the environment (final representational goal). This involves different processes that plan, program, and control goal-directed locomotion linked to motivation as an "emotional state," which leads to achieving this twofold goal. The aim of the present study was to determine whether emotional valence associated with the final representational goal influences these processes or whether they depend more on the emotional valence associated with the intermediate goal in young adults. Twenty subjects, aged 18-35 years, were instructed to erase an emotional picture that appeared on a wall as soon as they saw it. They had to press a stop button located 5 m in front of them with their right hand. Their gait was analyzed using a force platform and the Vicon system. The main results suggest that the emotional valence of the intermediate goal has the greatest effect on the processes that organize and modulate goal-directed locomotion. A positive valence facilitates cognitive processes involved in the temporal organization of locomotion. A negative valence disturbs the cognitive processes involved in the spatial organization of the locomotion and online motor control, leading to a deviating trajectory and a final body position that is more distant from the stop button. These results are discussed in line with the motivational direction hypothesis and with the affective meaning of the intended response goal.

The present study examined the reliability of the force-velocity relationship during cycling and arm cranking exercises in active males and females. Twenty male and seventeen female physical education students performed three-session tests with legs and three-session tests with arms on a friction-loaded ergometer on six different sessions in a randomized order. The reliability of maximal power(Pmax), maximal pedal rate(V0), and maximal force(F0)were studied using the coefficient of variation (CV), the intraclass correlation coefficient (ICC) and the test-retest correlation coefficient(r). Reliability indices were better for men (1.74 ≤ CV ≤ 4.36, 0.82 ≤ ICC ≤ 0.97, and 0.81 ≤r≤ 0.97) compared with women (2.34 ≤ CV ≤ 7.04, 0.44 ≤ ICC ≤ 0.98, and 0.44 ≤r≤ 0.98) and in cycling exercise (1.74 ≤ CV ≤ 3.85, 0.88 ≤ ICC ≤ 0.98, and 0.90 ≤r≤ 0.98) compared with arm exercise (2.37 ≤ CV ≤ 7.04, 0.44 ≤ ICC ≤ 0.95, and 0.44 ≤r≤ 0.95). Furthermore, the reliability indices were high forPmaxandF0whatever the expression of the results (raw data or data related to body dimensions).PmaxandF0could be used in longitudinal physical fitness investigations. However, further studies are needed to judgeV0reliability.

Epub 2014 Jul 21; The hypothesis that ethnicity and sport practice influence the relationship between maximal power in cycling (P(max)) and countermovement jump (CMJ) has been studied by relating CMJ and P(max) in two groups (volleyball players, VB, and physical education students, PES) including subjects with Caucasian (67 C) or West African (39 WA) origins. Maximal power of the arms (P(max) Arms) was also measured. A two-way analysis of variance (groups × ethnicity) showed significant effects of both factors upon CMJ, which was higher in WA and VB, P = 0.002 and P

Epub ahead of print; In order to behave adaptively, attention can be directed in space either voluntarily (i.e. endogenously) according to strategic goals, or involuntarily (i.e. exogenously) through reflexive capture by salient or novel events. The emotional or motivational values of stimuli can also influence attentional orienting. However, little is known about how reward-related effects compete or interact with endogenous and exogenous attention mechanisms. Here we designed a visual search paradigm in which goal-driven and stimulus-driven shifts of attention were manipulated by classic spatial cueing procedures, while an irrelevant, but previously rewarded stimulus also appeared as a distractor and hence competed with both types of spatial attention during search. Our results demonstrated that stimuli previously associated with a high monetary reward received higher attentional priority in the subsequent visual search task, even though these stimuli and reward were no longer task-relevant, mitigating the attentional orienting induced by both endogenous and exogenous cues.

La présente revue a pour but de faire état des travaux traitant de la relation entre la musique et la performance sportive à des efforts de courte et de longue durées.L’analyse de la littérature souligne clairement les bénéfices de la musique sur les performances motrices et/ou sportives. La plupart des études révèle que la musique écoutée avant, pendant ou après l’effort influence les processus psychophysiologiques de la performance et/ou la performance elle-même à des efforts de courte ou de longue durées. La littérature révèle toute la complexité de la relation musique–performance dans la mesure où cette relation implique un grand nombre de facteurs, de type interne, situationnel et contextuel, entrant en interaction complexe, affectant ainsi les sphères affective, cognitive, motivationnelle, physiologique et comportementale des individus.Si la littérature relate un nombre considérable de travaux confortant l’hypothèse selon laquelle la musique améliore la performance, la compréhension des mécanismes psychophysiologiques sous-tendant la relation musique–performance reste encore limitée. L’adoption de la perspective complexe et dynamique proposée dans ce présent travail pourrait permettre de faire la lumière sur les mécanismes sous-tendant cette relation.Bien que l’examen de la relation musique–performance réponde à un objectif essentiellement théorique, la compréhension de ses mécanismes devrait permettre de développer des stratégies pouvant améliorer la performance sportive.

The aim of this study was to examine the impact of emotional eliciting pictures on neuromuscular performance during repetitive supramaximal cycling exercises (RSE). In a randomized order, twelve male participants were asked to perform five 6-s cycle sprints (interspaced by 24 s of recovery) on a cycle ergometer in front of neutral, pleasant or unpleasant pictures. During each RSE, mean power output (MPO) and electromyographic activity [root mean square (RMS) and median frequency (MF)] of the vastus lateralis and vastus medialis muscles were analyzed. Neuromuscular efficiency (NME) was calculated as the ratio of MPO to RMS. Higher RMS (232.17 ± 1.17 vs . 201.90 ± 0.47 μV) and MF (68.56 ± 1.78 vs . 64.18 ± 2.17 Hz) were obtained in pleasant compared to unpleasant conditions (p < 0.05). This emotional effect persisted from the first to the last sprint. Higher MPO was obtained in pleasant than in unpleasant conditions (690.65 ± 38.23 vs . 656.73 ± 35.95 W, p < 0.05). However, this emotional effect on MPO was observed only for the two first sprints. NME decreased from the third sprint (p < 0.05), which indicated the occurrence of peripheral fatigue after the two first sprints. These results suggested that, compared with unpleasant pictures, pleasant ones increased the neuromuscular performance during RSE. Moreover, the disappearance of the beneficial effect of pleasant emotion on mechanical output from the third sprint appears to be due to peripheral fatigue.

The relationships between ankle plantar flexor musculotendinous stiffness (MTS) and performance in a countermovement vertical jump (CMJ) and maximal rate of torque development (MRTD) were studied in 27 active men. MTS was studied by means of quick releases at 20 (S0.2), 40 (S0.4), 60 (S0.6), and 80% (S0.8) of maximal voluntary torque (TMVC). CMJ was not correlated with strength indices but was positively correlated with MRTD/BM,S0.4/BM. The slopeα2and interceptβ2of the torque-stiffness relationships from 40 to 80%TMVCwere correlated negatively (α2) and positively (β2) with CMJ. The different stiffness indices were not correlated with MRTD. The prediction of CMJ was improved by the introduction of MRTD in multiple regressions between CMJ and stiffness. CMJ was also negatively correlated with indices of curvature of the torque-stiffness relationship. The subjects were subdivided in 3 groups in function of CMJ (groups H, M, and L for high, medium, and low performers, resp.). There was a downward curvature of the torque-stiffness relationship at high torques in group H or M and the torque-stiffness regression was linear in group L only. These results suggested that torque-stiffness relationships with a plateau at high torques are more frequent in the best jumpers.

OBJECTIVE: The purpose of this study was to analyze the effects of clearing and skirting obstacles during the gait on the energetic cost of walking (ECW) of patients with chronic hemiplegia. The hypothesis was that hemiplegia would have a greatest increase in the ECW than in the healthy group. DESIGN: Fifteen healthy subjects and 17 patients with chronic hemiplegia completed two 6-min walking sessions: one with obstacles and the other without obstacles. During both sessions, the patients were equipped with a portable gas analyzer to measure oxygen uptake (V˙o2). Gait velocity and ECW were calculated. RESULTS: In both groups, gait velocity was lower in the with-obstacles condition and the ECW was significantly higher. V˙o2 was greater in the with-obstacles condition for the healthy group, whereas it remained unchanged for the group with hemiplegia. CONCLUSIONS: Results demonstrated that the addition of obstacles during gait increased the ECW and decreased mean walking speed in both the healthy subjects and the patients with hemiplegia. More interestingly, the authors found differences in adaptation strategies between the healthy subjects and the patients with hemiplegia. During the with-obstacles condition, the oxygen uptakes of the healthy subjects increased and mean walking speed decreased, whereas, in the subjects with hemiplegia, only mean walking speed decreased. CONCLUSIONS: Results demonstrated that the addition of obstacles during gait increased the ECW and decreased mean walking speed in both the healthy subjects and the patients with hemiplegia. More interestingly, the authors found differences in adaptation strategies between the healthy subjects and the patients with hemiplegia. During the with-obstacles condition, the oxygen uptakes of the healthy subjects increased and mean walking speed decreased, whereas, in the subjects with hemiplegia, only mean walking speed decreased.

Epub 2013 Aug 28; BACKGROUND: The role of arm motion during the long jump has been well studied. The aim of this study was to quantify the effect of forearm mass on impulse and the kinematics of the flight phase in an upper limb amputee.CASE DESCRIPTION AND METHODS: A world-record paralympic long jumper carried out jumps in three conditions: wearing his usual forearm prosthesis and with 0.3 and 0.4 kg added mass. A motion capture system including force plates was used to record the jump.FINDINGS AND OUTCOME: At take-off, the addition of 0.4 kg to the prosthesis decreased the vertical velocity of the centre of mass but increased horizontal velocity. These modifications were associated with an increase in landing distance and an improvement of the synchronization between arms.CONCLUSION: Increasing forearm mass appears to improve long jump performance. Further studies need to evaluate the optimal prosthetic mass for both training and competition.CLINICAL RELEVANCE: This biomechanical analysis of the long jump highlighted the effects of changing prosthesis mass on performance. This methodological approach may be useful in the context of sport and performance research.

Research into the biomechanical manifestation of fatigue during exhaustive runs is increasingly popular but additional understanding of the adaptation of the spring-mass behaviour during the course of strenuous, self-paced exercises continues to be a challenge in order to develop optimized training and injury prevention programs. This study investigated continuous changes in running mechanics and spring-mass behaviour during a 5-km run. 12 competitive triathletes performed a 5-km running time trial (mean performance: ̴17 min 30 s) on a 200 m indoor track. Vertical and anterior-posterior ground reaction forces were measured every 200 m by a 5-m long force platform system, and used to determine spring-mass model characteristics. After a fast start, running velocity progressively decreased (- 11.6%; P0.001) in the middle part of the race before an end spurt in the final 400-600 m. Stride length (- 7.4%; P0.001) and frequency (- 4.1%; P=0.001) decreased over the 25 laps, while contact time (+ 8.9%; P0.001) and total stride duration (+ 4.1%; P0.001) progressively lengthened. Peak vertical forces (- 2.0%; P0.01) and leg compression (- 4.3%; P0.05), but not centre of mass vertical displacement (+ 3.2%; P0.05), decreased with time. As a result, vertical stiffness decreased (- 6.0%; P0.001) during the run, whereas leg stiffness changes were not significant (+ 1.3%; P0.05). Spring-mass behaviour progressively changes during a 5-km time trial towards deteriorated vertical stiffness, which alters impact and force production characteristics.

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This research focuses on the impact of emotions--defined as "motivational states"--on the organization of goal directed locomotion in children with autism. Walking toward a goal involves both cognitive processes responsible for movement planning and automatic processes linked to movement programming. To these processes, motivation leading to achieving the goal is added. For some authors, a deficit of planning and/or programming processes is highlighted in autism. Others stand for some impairment of the emotional system. The aim of this research is to link these two viewpoints and to determine if, in children with autism, the organization of locomotion is affected by a positive/aversive emotion conferred to an object to fetch. Twenty-nine children participated in the study (11 children with autism--mean age 122 months; 9 mental age-matched controls--mean age 36 months; and 9 chronological age-matched controls--mean age 122 months). They were instructed to go and get a positive or aversive emotional valence object located straight ahead, at 30° to the right or straight ahead then moved at mid-distance to the right. Gait analysis was performed using the Vicon system. The main results suggest that a positive emotional context promotes the cognitive processes involved in movement planning while an aversive emotional context blocks it or disturbs it in children with autism. No emotions effect is observed on movement programming. It is suggested that emotions triggered off and modulated movement planning and that the deficit observed was related to a developmental impairment rather than to a developmental delay.

The present investigation verified that strength is improved by a training programme consisting of repetitions of maximal isometric voluntary co-contractions without increasing co-activations during contractions against external resistances. Ten participants performed 12 training sessions (four sets of 6 × 4 second maximal isometric co-contraction of the elbow flexor and extensors, 3 days a week for 4 weeks). Surface electromyograms of triceps and biceps brachii were collected during maximal voluntary isometric elbow flexion and extension against a force transducer. Maximal voluntary isometric force increased significantly after training, by 13.8 ± 6.0% (extension) and 9.6 ± 9.5% (flexion), but the observed increases in EMG of agonist muscles during maximal voluntary contraction were not significant. No significant changes in the levels of co-activation of the elbow flexors and extensors were observed. No significant change was observed for all the parameters in a control group of ten participants. These results indicated that the strength improvements after co-contraction training occur without increases in co-activation level.