Search

It is common to get the impression that someone moves rather slowly or quickly in everyday life. In motor control, the natural pace of movement is captured by the concept of vigour, which is often quantified from the speed or duration of goal-directed actions. A common phenomenon, here referred to as the vigour law, is that preferred speed and duration idiosyncratically increase with the magnitude of the motion. According to the direct-matching hypothesis, this vigour law could thus underlie the judgment of someone else's movement vigour.We conducted a series of three experiments (N = 80) to test whether the vigour law also exists in perception and whether it is linked to that of action. In addition to measuring participants' vigour, we also asked them to judge the quickness of stimuli representing horizontal arm reaching movements varying through amplitudes, speeds, and durations.Results showed that speed and duration of movements perceived as neither fast nor slow (i.e., natural pace) increased with amplitude, thereby indicating that the vigour law holds when an observer judges the natural pace of others' movements. Results also revealed that this judgment was population-based (related to the average vigour of all participants) rather than individual-based (participant's own vigour).

It is common to get the impression that someone moves rather slowly or quickly in everyday life. In motor control, the natural pace of movement is captured by the concept of vigour, which is often quantified from the speed or duration of goal-directed actions. A common phenomenon, here referred to as the vigour law, is that preferred speed and duration idiosyncratically increase with the magnitude of the motion. According to the direct-matching hypothesis, this vigour law could thus underlie the judgement of someone else’s movement vigour. We conducted a series of three experiments ( N = 80) to test whether the vigour law also exists in perception and whether it is linked to that of action. In addition to measuring participants’ vigour, we also asked them to judge the quickness of stimuli representing horizontal arm reaching movements varying through amplitudes, speeds, and durations. Results showed that speed and duration of movements perceived as neither fast nor slow (i.e., natural pace) increased with amplitude, thereby indicating that the vigour law holds when an observer judges the natural pace of others’ movements. Results also revealed that this judgement was population-based (related to the average vigour of all participants) rather than individual-based (participant’s own vigour).

Objective This study aimed to investigate how load expectations modulate neuromuscular and postural strategies in the anticipation of a freestyle lifting task with varying expected loads in individuals with and without chronic low back pain (cLBP). Methods Forty-seven participants, 28 with cLBP pain and 19 without, were recruited and completed a series of freestyle lifting trials (3 sets of box lifted for a total of 36 lifts). Verbal cues were used to modulate their expectations about the boxes’ weight: no expectation, lighter or heavier load expectations. Following each set, participants rated their perceived exertion on a visual analog scale. During the lifting protocol, kinematics (time to maximal flexion, angular velocity and joint angles), electromyography muscle activity (erector spinae and quadriceps) and center of pressure displacement were simultaneously recorded. Results Results showed that time to maximal knee flexion was modulated by load expectations in both groups (mean lighter load expectations = 1.15 ± 0.32 sec.; mean heavier load expectations = 1.06 ± 0.31 sec.). Results also showed a load expectations X group interaction for that time to maximal hip and lumbar flexion. Time to maximal hip flexion decreased with heavier load expectations (mean lighter load expectations = 1.20 ± 0.36; mean heavier load expectations = 1.16 ± 0.33) for cLBP only. Time to maximal lumbar flexion increased with heavier load expectation (mean lighter load expectations = 1.41 ± 0.27 sec.; mean lighter load expectations = 1.46 ± 0.29 sec.) for participants without LBP. However, no difference in lumbar, hip nor knee angles were observed between groups or conditions. Results highlighted significant load expectation effects for erector spinae electromyography activity, as lower muscle activations was observed for both groups with heavier load expectations (mean = 0.32 ± 0.15), compared to lighter load expectations (mean = 0.52 ± 0.27). Force plates analyses did not reveal any significant load expectation effects. Conclusion Present findings showed that load expectations modulate movement strategies and muscle activation similarly but not identically in individuals with chronic low back pain and healthy adults during freestyle lifting. Results of the present study partially differ from previous studies and suggest only minor differences in lifting strategies between healthy individuals and individuals with cLBP experiencing low level of pain and disability. More studies are needed to investigate the potential role of load expectations in the development and persistence of chronic low back pain.

People usually move at a self-selected pace in everyday life. Yet, the principles underlying the formation of human movement vigour remain unclear, particularly in view of intriguing inter-individual variability. It has been hypothesized that how the brain values time may be the cornerstone of such differences, beyond biomechanics. Here, we focused on the vigour of self-paced reaching movement and assessed the stability of vigour via repeated measurements within participants. We used an optimal control methodology to identify a cost of time (CoT) function underlying each participant’s vigour, considering a model of the biomechanical cost of movement. We then tested the extent to which anthropometric or psychological traits, namely boredom proneness and impulsivity, could account for a significant part of inter-individual variance in vigour and CoT parameters. Our findings show that the vigour of reaching is largely idiosyncratic and tend to corroborate a relation between the relative steepness of the identified CoT and boredom proneness, a psychological trait relevant to one’s relationship with time in decision-making.

It is well recognized that chronic low back pain (cLBP) can be estimated from nonverbal pain behaviors. However, only a few studies examined how clinicians rely on those when estimating specific outcomes, such as pain intensity and pain disability. Therefore, the present study examines (1) if facial expressions and guarding behaviors (including speed of the movement and lifting strategy) contribute to the prediction of pain intensity and disability in patients with cLBP; and (2) if these pain behaviors have been given the same importance according to the outcome. Twenty-five experienced clinicians and thirty-one novice clinicians were asked to estimate low back pain intensity and disability from a realistic virtual character performing a lifting lowering task. The studied pain behaviors were manipulated across different conditions. Pain intensity and disability were judged higher when the character moved more slowly and displayed painful facial expression. Speed of the movement and facial expressions explained a greater portion of variance when related to pain intensity assessment than to pain disability assessment. Results also showed a significant interaction between the lifting strategy, the speed of the movement and facial expressions, but only when estimating the character’s pain-related intensity. Novice clinicians rated pain disability higher than experienced clinicians did. Although pain-related concepts, pain intensity and related disability are not estimated through the same pain behaviors by clinicians. Clinical experience does not contribute to clinical judgments through the use of nonverbal pain behaviors when estimating pain outcomes but contributes to pain disability rating overall.

The primary aim of this study was to determine whether the levels of obsessive passion (OP) and harmonious passion for a suspended leisure activity contribute to pain catastrophizing and pain intensity in patients undergoing the rehabilitation process. The secondary aim was to examine whether the levels of passion associated with a maintained leisure activity offset the contribution of having a leisure activity suspended to pain intensity and catastrophizing. Ninety-one outpatients from functional rehabilitation units (Mage=37, SD=13.44 years) completed measures of pain catastrophizing, pain intensity, and passion about valued leisure activities (one they were prevented from practicing and one they remained able to practice). Correlation analysis showed that the level of OP for a suspended valued leisure activity was positively associated with pain catastrophizing and pain intensity. Results showed that pain catastrophizing mediated the relationship between this level of passion and pain intensity. The levels of harmonious passion and OP for a maintained valued leisure activity did not offset the contribution of OP for a suspended leisure activity to pain-related outcomes. When prevented from practicing a valued leisure activity, only OP contributes to the prediction of pain catastrophizing and pain intensity. The contribution of pain catastrophizing provides a potential explanation for why the level of OP for a suspended leisure activity is related to pain intensity ratings. The benefits of maintaining a valued leisure activity during rehabilitation do not seem sufficient to counterbalance the maladaptive effects of being prevented from the practice of a previous/another valued leisure activity.

Movement vigor is an important feature of motor control that is thought to originate from cortico-basal ganglia circuits and processes shared with decision-making, such as temporal reward discounting. Accordingly, vigor may be related to one’s relationship with time, which may, in turn, reflect a general trait-like feature of individuality. While significant interindividual differences of vigor have been typically reported for isolated motor tasks, little is known about the consistency of such differences across tasks and movement effectors. Here, we assessed interindividual consistency of vigor across reaching (both dominant and nondominant arm), walking, and gazing movements of various distances within the same group of 20 participants. Given distinct neural pathways and biomechanical specificities of each movement modality, a significant consistency would corroborate the trait-like aspect of vigor. Vigor scores for dominant and nondominant arm movements were found to be highly correlated across individuals. Vigor scores of reaching and walking were also significantly correlated across individuals, indicating that people who reach faster than others also tend to walk faster. At last, vigor scores of saccades were uncorrelated with those of reaching and walking, reaffirming that the vigor of stimulus-elicited eye saccades is distinct. These findings highlight the trait-like aspect of vigor for reaching movements with either arms and, to a lesser extent, walking. NEW & NOTEWORTHY Robust interindividual differences of movement vigor have been reported for arm reaching and saccades. Beyond biomechanics, personality trait-like characteristics have been proposed to account for those differences. Here, we examined for the first time the consistency of interindividual differences of vigor during dominant/nondominant arm reaching, walking, and gazing to assess the trait-like aspect of vigor. We found a significant consistency of vigor within our group of individuals for all tested tasks/effectors except saccades.

Fear of pain is an emotional state linked to a host of negative events, including exaggerated pain perception, distress, and chronic pain. Although many studies have shown that women experience fear of pain more than men do, little is known about the factors that might explain these sex differences. According to an individual-difference approach, it seems valuable to examine the contribution of personality factors, which are considered as major antecedents of cognitions and emotions, including fear. The present study focuses on the potential mediating role of neuroticism – and its six specific facets –in the sex-fear of pain relationship for fear of severe pain, fear of minor pain, and fear of medical pain. Given that neuroticism is greater in women and that this personality trait contributes to the fear of pain, we hypothesized that neuroticism would mediate the sex-fear of pain relationship. Due to the previously established link between experience of pain and the fear of pain, we controlled for the previous experience of pain in the mediation model. Participants ( n = 133 women; 96 men) completed measures of previous experiences of pain, neuroticism, and fear of pain. Using Preacher and Hayes’ SPSS script, we used a bootstrapping method with n = 5000 bootstrap resamples to test the model. Bootstrapped mediation analyses revealed that neuroticism significantly (within a 95% confidence interval) mediated the sex-fear of severe pain relationship. Working within a 90% confidence interval, neuroticism also significantly mediated the sex-fear of pain relationship for fear of minor pain and fear of medical pain. Although the global trait of neuroticism contributed to sex differences in fear of minor pain, it was specifically the neuroticism facet of anxiety that mediated the relationship between sex and fear of severe pain and sex and fear of medical pain. The results suggest that women experience more fear of pain partly because they are more neurotic than men and provide the first evidence that neuroticism in an integral part of the process that differentiates the sexes in fear of pain. Given that the proportion of variance accounted for in each of the mediation models (8% at most), there is a clear need for further research to elucidate more fully the mechanisms that underlie sex differences in the fear of pain.

Background.Through real-time behavioral observation systems, pain behaviors are commonly used by clinicians to estimate pain intensity in patients with low back pain. However, little is known about how clinicians rely on pain-related behaviors to make their judgment. According to the Information Integration Theory (IIT) framework, this study aimed at investigating how clinicians value and integrate information from lumbopelvic kinematics (LK), a protective pain behavior, and facial expression intensity (FEI), a communicative pain behavior, to estimate pain in patients with chronic low back pain (cLBP).Methods.Twenty-one experienced clinicians and twenty-one novice clinicians were asked to estimate back pain intensity from a virtual character performing a trunk flexion-extension task.Results.Results revealed that both populations relied on facial expression and that only half of the participants in each group integrated FEI and LK to estimate cLBP intensity. Among participants who integrated the two pain behaviors, averaging rule predominated among others. Results showed that experienced clinicians relied equally on FEI and LK to estimate pain, whereas novice clinicians mostly relied on FEI.Discussion.The use of additive rule of integration does not appear to be systematic when assessing others’ pain. When assessing pain intensity, communicative and protective pain behaviors may have different relevance.

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.

Objective Although audio and visual information constitute relevant channels to communicate pain, it remains unclear to what extent observers combine and weight these sources of information when estimating others' pain. The present study aimed to examine this issue through the theoretical framework of the Information Integration Theory. The combination and weighting processes were addressed in view of familiarity with others' pain. Method Twenty-six participants familiar with pain (novice podiatry clinicians) and thirty non-specialists were asked to estimate the level of pain associated with different displayed locomotor behaviors. Audio and visual information (i.e., sound and gait kinematics) were combined across different intensities and implemented in animated human stick figures performing a walking task (from normal to pathological gaits). Results The novice clinicians and non-specialists relied significantly on gaits and sounds to estimate others' pain intensity. The combination of the two types of information obeyed an averaging rule for the majority of the novice clinicians and an additive rule for the non-specialists. The novice clinicians leaned more on gaits in the absence of limping, whereas they depended more on sounds in the presence of limping. The non-specialists relied more on gaits than on sounds. Overall, the novice clinicians attributed greater pain levels than the non-specialists did. Conclusion Depending on a person's clinical experience, the combination of audio and visual pain-related behavior can qualitatively change the processes related to the assessment of others' pain. Non-verbal pain-related behaviors as well as the clinical implications are discussed in view of the assessment of others' pain.

Objectives The main goal of this study was to determine to what extent load expectations modulate neuromechanical adaptations in individuals with and without chronic low back pain (cLBP) when lifting and lowering various loads. The second goal was to assess the feasibility of a simple lifting protocol during which expectations about loads were manipulated. Methods Seventeen participants with cLBP and 18 participants without low back pain were asked to lift and lower boxes of mild to moderate loads. Two kinds of expectations (lighter and heavier) were respectively associated to each experimental block. Self-reported exertion was assessed to control for expectations modulation. Erector spinae and vastus lateralis electromyography (EMG) activity were recorded and kinematics angle calculated. Results The results showed a main effect of expectations, with loads introduced as heavier being associated to a higher exertion compared with loads introduced as lighter. EMG activity analyses revealed significant interaction involving expectations, movement phase, and loads, as well as significant differences between groups. Kinematic angles did not reveal any significant effect of expectations nor group during the lifting phase. Conclusions Psychological factors may contribute to neuromechanical adaptations to low back pain. Our preliminary findings show that expectations about loads may result in neuromechanical differences between individuals with cLBP and those without cLBP. This pilot study showed that testing the manipulation of expectations and EMG records was feasible but highlighted the need to go beyond single infrared markers to assess kinematics.

International audience; This research investigated whether and how self-determined motivation predicts perceived susceptibility to injury during competition (marathon). Two correlational studies including 378 (Study 1) and 339 (Study 2) marathon runners were conducted. Participants filled out a questionnaire the day before the race measuring self-determined motivation, perceived susceptibilities to marathon-related injury and to keep running through pain, and control variables. Study 1 showed that self-determined motivation was negatively related to perceived susceptibility to marathon-related injury. Study 2 replicated this finding and showed that this relationship was partially mediated by perceived susceptibility to keep running through pain during the race. Moreover, results indicated that the predictive role of self-determination was mostly driven by controlled forms of motivation, and more particularly external regulation. These results suggest that self-determined motivation for sport is a protective factor of injury.

Background/Study Context: The automatic propensity to orient to the location where other people are looking is the main way of establishing joint attention with others. Whereas joint attention has been mostly investigated with young adults, the present study examines age-related differences in the magnitude and time course of joint attention.Methods: Forty-three community-dwelling seniors and 43 younger adults performed a visuospatial task. The procedures closely follow those of gaze-cueing tasks commonly used to investigate joint attention.Results: The findings revealed that a gaze-cueing effect occurs for both younger and older adults, with an equivalent average magnitude but with different time courses. The effect peaks later in older adults.Conclusion: Age-related differences in joint attention could be linked to a more general cognitive slowing rather than to poorer basic social skills. The present study adds to the growing interest in gerontological research regarding social attention.

Drawing upon both heuristic- and threat-based approaches, we sought to examine whether perceived similarity with injury-prone people and perceived control over injury occurrence would directly contribute to perceived risk and whether these variables would mediate the previous injury-perceived risk relationship. Judokas (n = 207) reported the number of injuries experienced in the past year and then completed measures of perceived similarity, perceived control, and injury risk perception. Analyses revealed that perceived similarity and perceived control directly contributed to perceived risk of injury; only perceived similarity acted as a partial mediator of the injury-perceived risk relationship. These findings are discussed in relation to the potential influence of the sport context, which universally involves the acceptance of a high risk of injury.

Resume Cette revue de litterature a pour objectif de presenter les travaux realises sur les determinants psychologiques de la blessure physique dans le contexte sportif. Ceux-ci mettent majoritairement en evidence le role du stress dans la survenue de blessures. D'autres recherches menees en psychologie de la sante peuvent toutefois initier des reflexions complementaires en caracterisant d'autres processus susceptibles de conduire le sportif a se blesser. Au-dela des dysfonctionnements resultant du vecu d'un episode de stress, certaines approches mettent notamment l'accent sur l'influence pathogene de l'adoption volontaire de comportements a risque ou l'influence salutogene de l'engagement dans des comportements de protection, et sur les determinants lies a l'adoption de ces comportements. Peu d'etudes cependant ont cherche a demontrer la pertinence de ces determinants dans l'identification des sportifs susceptibles de se blesser. Un modele est suggere afin d'engager les recherches selon cette perspective.

Objectives Two studies examined whether observers’ personality traits contribute to prosocial responses to others’ facial expression of pain. Experiment 1 examined the personality traits that could account for observers’ variability in estimating others’ pain intensity. Experiment 2 questioned to what extent the contribution of personality traits on inclination to help people in pain depend on observers’ beliefs about pain’ characteristics. Method 59 (experiment 1) and 76 (experiment 2) participants observed to 3-D realistic synthetic face movements mobilizing action units of pain, in order to estimate others’ pain. In experiment 2, painful localizations (e.g., chest, hand) were also manipulated. In each experiment, Big Five personality traits were assessed. Results Experiment 1 revealed that agreeableness and conscientiousness contributed to observers’ pain estimates across the increase of facial expression intensity. Experiment 2 showed that conscientiousness contributed to observers’ judgments whatever pain’ characteristics. Neuroticism was only salient for pain referring to life-threatening pain. Conclusion Prosocial response to others’ pain depends on agreeableness, conscientiousness and neuroticism. However, these links are modulated by the pain behavior elicited and observers’ belief about the characteristic of pain.

This study examined how pleasant and unpleasant emotional states influence the biomechanical organization of both forward and backward step initiation (SI). Participants (N = 31) purposely took a single step toward or away from a screen following the presentation of a pleasant (erotic), unpleasant (mutilation) or neutral (objects and landscapes) image. The main results showed that the reaction time for forward SI was shortened when individuals were exposed to pleasant pictures as compared with unpleasant pictures. The anticipatory whole-body center-ofmass velocity associated with backward SI, as well as the peak of center-of-mass velocity associated with forward SI both reached lower values when individuals were exposed to pleasant pictures as compared with neutral pictures. In contrast, unpleasant pictures did not significantly induce any change in the forward or backward SI parameters. Overall, these results obtained for whole-body approach/avoidance-like behaviors provided mitigated support for the so-called “motivational direction hypothesis.”

International audience; Understanding the motivation behind unsafe driving practices is of paramount importance with a view to preventing road violations and crashes. Although the vast majority of previous studies have reported the predictive utility of the theory of planned behaviour (TPB), these studies have been conducted within an additive framework. The present study aimed to better understand the role of the TPB constructs in predicting drivers' road violation intentions and behaviours by investigating the interaction between differentiated Perceived Behavioural Control (PBC) components (i.e. perceived capacity and autonomy) and the other TPB factors on intention and road violations. We hypothesised that attitudes or subjective norms would affect intention, and that intention would affect behaviour, only to the degree that they are accompanied by high perceived capacity or high perceived autonomy. Participants (n = 280) completed two surveys 6 months apart: the first survey (Time 1) assessed the TPB components (i.e., attitude, subjective norm, perceived behavioural control and intention); the second survey (Time 2) reported road violation behaviours. The moderator effect of differentiated PBC components was inconsistent across road violation behaviours. Drink-driving was the road violation that was best predicted by the interactive TPB components, such as both perceived capacity and autonomy moderate the contribution of subjective norms on intention formation and perceived capacity moderate the prediction of behaviour by intention. Globally, TPB was a predictor of road violation intentions and behaviours, with both additive and interactive effects. From a practical standpoint, contemporary theories of attitudes and beliefs should consider the possibility of the interactive framework for a more precise prediction of road safety behaviour.

Drawing upon both heuristic- and threat-based approaches, we sought to examine whether perceived similarity with injury-prone people and perceived control over injury occurrence would directly contribute to perceived risk and whether these variables would mediate the previous injury-perceived risk relationship. Judokas (n = 207) reported the number of injuries experienced in the past year and then completed measures of perceived similarity, perceived control, and injury risk perception. Analyses revealed that perceived similarity and perceived control directly contributed to perceived risk of injury; only perceived similarity acted as a partial mediator of the injury-perceived risk relationship. These findings are discussed in relation to the potential influence of the sport context, which universally involves the acceptance of a high risk of injury.

International audience; During leg flexion from erect posture, postural stability is organized in advance during "anticipatory postural adjustments" (APA). During these APA, inertial forces are generated that propel the centre of gravity (CoG) laterally towards stance leg side. This study examined how fear of falling (FoF) may influence this anticipatory postural control of medio-lateral (ML) stability. Ten young healthy participants performed a series of leg flexions at maximal velocity from low and high surface heights (6 and 66 cm above ground, respectively). In this latter condition with increased FoF, stance foot was placed at the lateral edge of the support surface to induce maximal postural threat. Results showed that the amplitude of ML inertial forces generated during APA decreased with FoF; this decrease was compensated by an increase in APA duration so that the CoG position at time of swing foot-off was located further towards stance leg side. With these changes in ML APA, the CoG was propelled in the same final (unipodal) position above stance foot as in condition with low FoF. These results contrast with those obtained in the literature during quiet standing which showed that FoF did not have any influence on the ML component of postural control. It is proposed that ML APA are modified with increased FoF, in such a way that the risk of a sideway fall induced by the large CoG motion is attenuated.

International audience; Previous studies have shown how social networks lead athletes to accept pain as a "part of the game," which generates pressure on athletes to continue competing despite being in pain. Little is known, however, about the potential coping strategies that are related to pain behavior in sport. This study of 205 combat athletes examined whether pain coping strategies, including distraction from pain, praying, reinterpreting pain sensations, ignoring pain, and pain catastrophizing, are related to athletes' inclination to play through pain. Results revealed that pain catastrophizing led athletes to reduce their physical involvement in their sport activity. Of particular interest was the moderating effect of ignoring pain such that ignoring pain significantly attenuated the negative effect of pain intensity on athletes' inclination to play through pain. Few studies have tested and supported the contribution of pain coping to the prediction of behavior in real sport situations. By identifying which coping strategies athletes could use to maintain their physical involvement despite being in (sometimes intense) pain, the current study makes an important contribution for tailoring pain management programs for this at-risk population.

In-line skating is increasing in popularity with a concomitant raise in the number of injuries associated with this activity. Studies have emphasized the value of protective gears in reducing the incidence of injuries and the subsequent need to identify the factors and processes involved in decision making about safety gear-wearing. The present study examined the contribution of the theory of planned behaviour (TPB) variables, and perceived susceptibility to and perceived severity of skating injury on the safety gear-wearing intention of adult skaters.Skaters (n=181) completed a questionnaire assessing the constructs of the TPB, perceived susceptibility to and perceived severity of skating injuries, and intention to wear safety gear.Hierarchical regression analyses revealed significant contributions of instrumental attitude and subjective norm to the prediction of safety gear-wearing intention. In addition, perceived susceptibility to and perceived severity of injuries enhanced the prediction of intentions to wear safety gear over and above the contribution of TPB components.As the TPB focuses only on behavioural evaluation, it seems promising to include threat perceptions in this theory as another aspect of health-related cognitions motivating intention formation about safety gear use. Practical implications for future campaigns and countermeasures are discussed.

International audience; Whether individuals take steps to protect themselves against sport-related injury may depend on their perceived susceptibility to injury (Williams-Avery & MacKinnon, 1996). However, little is known about the determinants of perceived susceptibility to sport-related injury. The purpose of the present study is to identify the relations of previous experiences with injury, neuroticism, and passion with perceived susceptibility to sport-related injury among competitive runners. One hundred and seventy competitive runners reported the number of injuries sustained during the last year and completed the neuroticism scale of the NEO-PIR and the Passion Scale. Separate regression analysis revealed that previous experiences with injury, neuroticism, and obsessive passion were significant positive predictors of perceived susceptibility, whereas harmonious passion was significantly and negatively related to perceived susceptibility. When considered simultaneously, previous experiences, neuroticism, and obsessive passion explained unique variance in perceived susceptibility to sport-related injury. This study revealed that perceived susceptibility to sport-related injury is dependent on several distinct variables. Thus, to be effective, injury preventive actions aimed at runners' behaviour modification need to take into account that runners' perceived susceptibility to sport has multiple predictors.

International audience; Little is known about factors associated with perceptions of susceptibility to sport-related injuries. The purpose of the present study was to examine previous experiences with injury and personality factors as predictors of rugby players' perceived susceptibility to injury. In line with an individual-based approach, it was hypothesized that neuroticism and global self-esteem would be related to perceived susceptibility to sport injuries over and above previous experiences with injuries. Rugby players (N = 235) were asked to report about previous experiences with injury and were administered measures of neuroticism and global selfesteem. Multiple regression analysis revealed that previous experiences with injury were positively related to perceived susceptibility to sport-related injuries. Analyses also supported that neuroticism and global self-esteem are of crucial importance in colouring perceptions of susceptibility to sport-related injury, while statistically controlling for previous injuries. Of particular interest, neuroticism predicted perceived susceptibility, over and above global self-esteem and previous experiences with injury. This study is the first to focus on determinants of perceived susceptibility to sport-related injury and supports the potential role of personality factors and individual dispositions in shaping perceived susceptibility to health problems.

International audience; Cette revue de littérature a pour objectif de présenter les travaux réalisés sur les déterminants psychologiques de la blessure physique dans le contexte sportif. Ceux-ci mettent majoritairement en évidence le rôle du stress dans la survenue de blessures. D'autres recherches menées en psychologie de la santé peuvent toutefois initier des réflexions complémentaires en caractérisant d'autres processus susceptibles de conduire le sportif à se blesser. Au-delà des dysfonctionnements résultant du vécu d'un épisode de stress, certaines approches mettent notamment l'accent sur l'influence pathogène de l'adoption volontaire de comportements à risque ou l'influence salutogène de l'engagement dans des comportements de protection, et sur les déterminants liés à l'adoption de ces comportements. Peu d'études cependant ont cherché à démontrer la pertinence de ces déterminants dans l'identification des sportifs susceptibles de se blesser. Un modèle est suggéré afin d'engager les recherches selon cette perspective.

The aim of this thesis is to investigate the influence of emotions on the planning and execution of whole body voluntary movement. The effect of emotions was test thanks to the motivational direction hypothesis which supposed that 1) pleasant stimuli should facilitate approach and perturb avoidance behaviors. 2) Unpleasant stimuli should facilitate avoidance and perturb approach behaviors. Two experimental protocols have been chosen to pursue the investigation: Forward and backward gait initiation (study 1) and lateral elevation of the leg (studies 2-4). The emotions were manipulated by exposing the subjects to pictures of the International Affective Pictures System (inducing pleasant and unpleasant emotions, study 1) and by placing the subjects at the edge of an elevated platform (inducing fear of falling). Movements were performed on force platform (studies 1-3). Kinematic parameters of leg movement were recorded by the system of motion capture VICON (studies 2 and 3). Psychological parameters (valence and arousal dimensions of emotions fear of falling) were assessed by questionnaires. Results of the first study showed that pleasant pictures facilitated approach behaviors (as observed in the reactivity) and perturbed avoidance behaviors (as observed in the velocity of centre of mass during anticipatory postural adjustment (APA) prior to the execution of a backward step), compared to unpleasant or neutral pictures. However, these pleasant pictures also perturbed approach behaviors (as observed in the peak of centre of mass velocity during the execution of a forward step). Results of the second study showed that approach behaviors toward the postural threat (i.e, the void) were perturbed (as observed in the amplitude and duration of APA), compared to avoidance behaviors. The third study focused on the inter-individual differences in the relation between postural threat and organization of movement. Results revealed that balance confidence of the participants dealing with increased postural threat. In other terms, participants reported a high confidence in their own balance control were least perturbed than those reported a low balance confidence and vice versa. Finally, in the fourth study we tried to explain these inter-individual differences. The self-esteem seems to explain these differences. In conclusion, the results of this thesis seem to partially confirm the hypothesis of motivational direction. Put together, the results help improve our general understanding of the influence of emotions on the planning and execution of voluntary movements.Keywords: Anticipatory Postural Adjustments, Approach-Avoidance, Emotions, Motivational Direction Hypothesis, Motor Control; Résumé : L’objectif de cette thèse était d’investiguer l’influence des émotions sur l’organisation biomécanique de mouvements volontaires complexes, c’est-à-dire mobilisant l’ensemble du corps. L’effet des émotions a été testé par le biais de l’hypothèse de la direction motivationnelle selon laquelle 1) les stimuli plaisants faciliteraient les comportements d’approche et perturberaient les comportements d’évitement et 2) les stimuli déplaisants faciliteraient les comportements d’évitement et perturberaient les comportements d’approche. Deux modèles expérimentaux du mouvement complexe ont été choisis : l’initiation du pas vers l’avant et vers l’arrière (étude 1) et l’élévation latérale de la jambe (études 2 à 4). Les émotions étaient manipulées en exposant les participants à des images de l’International Affective Pictures System (induisant des émotions plaisantes et déplaisantes, étude 1) et en plaçant les participants au bord d’une plateforme surélevée (induisant une peur de chuter, études 2 à 4). Les mouvements étaient réalisés sur une plateforme de force (études 1 à 3). La cinématique du mouvement de la jambe oscillante était enregistrée grâce au système de capture de mouvements VICON (études 2 et 3). Les paramètres psychologiques (dimension de valence et d’activation des émotions, peur de chuter) étaient évalués grâce à des questionnaires. Les résultats de la première étude ont montré que les émotions plaisantes facilitaient les comportements d’approche (en termes de réactivité) et perturbaient les comportements d’évitement (en termes de vitesse du centre des masses lors des ajustements posturaux anticipateurs (APA) associés à un pas vers l’arrière), comparativement aux images déplaisantes et neutres. Cependant ces images semblaient aussi pouvoir perturber les comportements d’approche (en termes de pic de vitesse du centre des masses lors de l’exécution du pas vers l’avant). Les résultats de la deuxième étude ont démontré que les comportements d’approche envers la menace posturale (c’est-à-dire le vide) étaient perturbés (en termes d’amplitude et de durée des APA), comparativement aux comportements d’évitement. La troisième étude s’est ensuite intéressée à l’existence de différences interindividuelles dans la relation entre la menace posturale (et donc la peur de chuter) et l’organisation du mouvement volontaire. Les résultats ont révélé que la confiance en l’équilibre était un facteur de protection à la menace posturale. Ainsi, les participants reportant une forte confiance en leur équilibre étaient moins perturbés par la menace posturale que les participants reportant une faible confiance en leur équilibre. Enfin, la quatrième étude a cherché à expliquer l’existence de ces différences interindividuelles. Les résultats ont montré que l’estime globale de soi pouvait expliquer une partie de ces différences. En conclusion, les résultats de cette Thèse ne semblent confirmer que partiellement l’hypothèse de la direction motivationnelle. Pris ensemble, ces résultats ont permis d’améliorer la compréhension des processus sous-jacents à l’influence des émotions sur l’organisation du mouvement volontaire.Mots clés : Ajustements Posturaux Anticipateurs, Approche-Évitement, Contrôle Moteur, Émotions, Hypothèse de la Direction Motivationnelle