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Rowing is a complex sport where technique can significantly impact performance. A better understanding of the rowers' technique and neuromuscular activations during scull rowing, along with their impact on rowing performance, could greatly help trainers and athletes. Twelve male rowers were asked to row at their competitive stroke rate, and we collected data describing neuromuscular activations, trunk and arm kinematics, as well as technical determinants such as oar angles and angle asymmetries. We fitted linear mixed-effect models to investigate the effects of these variables on power production and boat speed. A larger effective angle had the greatest positive effect on power output, and slip angles had the largest negative effects. Increased elbow flexion at catch had the greatest negative effect on speed. Angle asymmetries affected neither power nor speed. Increased upper limb neuromuscular activity during the first and third quarters of the drive phase helped reduce slip angles, thus increasing performance. Power and speed were influenced similarly by the predictor variables. Still, they showed subtle differences, indicating that the strategies to maximize power production might not be the best ones to also achieve the maximum speed. [ABSTRACT FROM AUTHOR]

Objective: School-behavior-health difficulties (SBHDs) may alter physical/mental capabilities and consequently increase injury risk during daily activities. This study assessed the associations of potential SBHDs and their cumulative number (SBHDcn) with various injury types among younger adolescents. Methods: The study population included 1,559 middle-school adolescents in France (10–18 years, 98% under 16,778 boys and 781 girls). They completed a questionnaire at school-year end collecting socioeconomic features (nationality, family structure, parents' education/occupation/income), school/out-of-school injuries during the school-year (dependent variables), and SBHDs starting before the school-year (low academic performance, alcohol/tobacco/cannabis/other-illicit-drugs use, physical/verbal violence, sexual abuse, perpetrated violence, poor social support, poor general health status, sleep difficulty, depressive symptoms, and suicide attempt). Data were analyzed using logistic regression models and Kaplan–Meier estimates. Results: Injuries were frequent during school-physical/sports-training (10.9%), other-school-training (4.7%), school-free-time (7.4%), out-of-school-sports-activity (16.5%), and traffic (2.2%). Single injury (one injury all injury types combined) and ≥2 injury types affected 23.3 and 7.9% of subjects, respectively. The proportion of adolescents without SBHDs decreased with age more quickly among those with each injury type than among those without injury. Various SBHDs were associated with most injury types, single injury, and ≥2 injury types (sex-age-adjusted odds/relative-risk ratios reaching 11, p <.001). A dose–effect association was found between SBHDcn 1–2/3-5/≥6 and both single injury and ≥2 injury types (sex-age adjusted relative risk ratios reaching 12.66, p <.001, vs. SBHDcn = 0). Socioeconomic features had a moderate confounding role in these associations. Conclusions: SBHDs strongly predict injuries among adolescents. Our findings may inform healthcare providers about their prominent role in detecting/reducing SBHDs and injuries. [ABSTRACT FROM AUTHOR]

Objective: Lack of regular physical activity (LPA) and the number of days/week with physical activity >60 minutes/day (Ndw) may be associated with school-health-relational difficulties (SHRDs) during the life-course. This study assessed their associations and the confounding role of socioeconomic features (nationality, family structure, parents' education/occupation/income) among younger adolescents. Methods: This cross-sectional population-based study included 1,559 middle-school adolescents from north-eastern France (10–18 years, 98% under 16 years, 778 boys and 781 girls). They completed over one-hour teaching period a questionnaire collecting last-12-month LPA and last-7-day Ndw (dependent variables), and risk factors including socioeconomic features, SHRDs (previous grade repetitions, last-12-month poor general health status/physical health/psychological health/social-relationships, depressive symptoms (and age at onset and duration from onset); cumulated number noted SHRDcn). Data were analyzed using logistic/linear regression models. Results: LPA was common (32.5%) and associated with all SHRDs (sex-age-adjusted odds ratio saOR reaching 1.99, p <.001) and depressive-symptoms duration (saOR 1.63 (p <.05) and 2.11 (p <.001) for 1–2 and ≥3 years, respectively, vs. no depressive symptoms). A dose-effect association was found between SHRDcn and LPA (24.0, 33.7, 45.6, and 53.5%; saOR 1.59, 2.58, and 3.43; for SHRDcn 1–2, 3–4, and ≥5 respectively, vs. SHRDcn = 0, p <.001). Ndw was similarly associated with all SHRDs and SHRDcn (sex-age-adjusted regression coefficient reaching −1.10 day/week, p <.001). These results were robust when controlling for socioeconomic features (18%60 min/day (Ndw). • These links are robust when controlling for socioeconomic features which have a strong confounding role. • The risk of LPA and reduced Ndw increase with the duration of depressive symptoms from their onset. • Prevention to detect/reduce SHRDs may improve physical activity, especially for most at-risk adolescents. [ABSTRACT FROM AUTHOR]

Musculoskeletal disorders (MSDs) are the main occupational diseases and are pathologies of multifactorial origin, with posture being one of them. This creates new human-robot collaboration situations that can modify operator behaviors and performance in their task. These changes raise questions about human-robot team performance and operator health. This study aims to understand the consequences of introducing a cobot on work performance, operator posture, and the quality of interactions. It also aims to evaluate the impact of two levels of difficulty in a dual task on these measures. For this purpose, thirty-four participants performed an assembly task in collaboration with a co-worker, either a human or a cobot with two articulated arms. In addition to this motor task, the participants had to perform an auditory task with two levels of difficulty (dual task). They were equipped with seventeen motion capture sensors. The collaborative work was filmed with a camera, and the actions of the participants and co-worker were coded based on the dichotomy of idle and activity. Interactions were coded based on time out, cooperation, and collaboration. The results showed that performance (number of products manufactured) was lower when the participant collaborated with a cobot rather than a human, with also less collaboration and activity time. However, RULA scores were lower—indicating a reduced risk of musculoskeletal disorders—during collaboration with a cobot compared to a human. Despite a decrease in production and a loss of fluidity, likely due to the characteristics of the cobot, working in collaboration with a cobot makes the task safer in terms of the risk of musculoskeletal disorders. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of technical and core stability parameters on rowing ergometer performance defined as mean power at the handle. Twenty-four high-level rowers were evaluated at their competitive stroke rate on an instrumented RowPerfect 3 ergometer to determine leg, trunk and arm power output, while trunk and pelvis 3D kinematics were measured. Linear mixed models revealed that mean power at the handle was predicted by the power output of legs, trunk and arms (r2 = 0.99), with trunk power being the best predictor. Time to peak power, work ratio and mean to peak power ratio were relevant technical parameters significantly predicting the different segments' power. In addition, a greater trunk range of motion significantly influenced the power produced by this segment. Accordingly, achieving an earlier peak power together with enhanced work production at the trunk and arm levels, as well as distributing the segments power over the whole drive phase, could serve as recommendations for technical training of rowers on dynamic ergometers in order to produce higher power output. Furthermore, the trunk appears to play a major role as a power producer within the kinetic chain from the legs to the arms. [ABSTRACT FROM AUTHOR]

Immersive virtual reality makes possible to perceive and interact in a standardized, reproductible and digital environment, with a wide range of simulated situations possibilities. This study aimed to measure the potential effect of virtual reality on time and number of steps when performing a locomotor task, in a young adult's population. Sixty young adults (32W, 28M, mean age 21.55 ± 1.32), who had their first immersive virtual reality experience, performed a locomotor task based on "Timed Up and Go" (TUG) task in real, in virtual reality in a stopped train and in virtual reality in a moving train. Time and number of steps variables representing primary locomotion indicators were measured and compared between each condition. Results showed significant increases in time and number of steps in the two virtual reality conditions compared to real but not between the two virtual reality conditions. There was an effect of virtual reality in young adults when performing the locomotor task. It means that technological and digital characteristics of the immersive virtual reality experience led to modify motor strategies employed. Adding a plausible visual optic flow did not appear to affect motor control further when the information is negligible and not essential for performing the task. [ABSTRACT FROM AUTHOR]

Background/Aims: Falling among the elderly is a major public health issue, especially with the advancing age of the baby boomers. The fall risk assessment tests for many lack a context that would bring them closer to everyday life. Thus, immersive virtual reality, which makes it possible to simulate everyday situations, could make it possible to strengthen the quality of the assessment of the risk of falls. However, it is necessary to understand how the use of a virtual reality device influences the motor control of elderly participants. If vestibular physiotherapists use VR to virtualize their tools, what impact would a visual simulation of movement have on motor control in a locomotor task, if this simulation were plausible? Methods: Sixty-two elders (70.8 ± 6.7 years old) completed a Timed Up and Go task under 3 conditions: real, virtual reality, and virtual reality with visual and sound movement information. The virtual reality task takes place in a train either stationary at a station or in uniform linear motion. The time and number of steps were recorded using video, and comparisons between conditions were made using Friedman's test. Results: The results show a significant increase in the time and number of steps in "virtual reality" condition compared to the "real" condition. They do not show significant differences between the 2 virtual conditions. Conclusion: The use of a running virtual train to provide plausible movement is particularly distinguished from vestibular physiotherapy applications with first a fixed visual support partially obscuring the optical flow. This visual aid coupled with the attention dedicated to the task inhibits the effect of the moving environment on locomotion. However, the visual optical flow will potentially have an effect in people with fear of falling. Virtual reality shows great potential for the simulation of realistic environments for the assessment of the risk of falls and opens up avenues for the development of tests. [ABSTRACT FROM AUTHOR]

The aims of this study were twofold: first, to compare core stability and knee joint loading between sidestepping experts and nonexperts; secondly, to determine core predictors of knee joint loading. Thirteen handball male players (experts) and 14 karatekas (nonexperts) performed six unanticipated 45° sidestepping manoeuvers, while trunk and pelvis 3D kinematics as well as ground reaction forces were measured, and peak knee abduction moment (PKAM) was determined. Student t-tests enabled a comparison of both groups and a linear mixed model approach was used to identify PKAM predictors. Sidestepping experts demonstrated significantly lower pelvis rotation towards the new movement direction at the initial contact than nonexperts (4.9° vs. 10.8°) and higher PKAM (0.539 vs. 0.321 Nm/kg-bwt). Trunk medial lean, trunk axial rotation and pelvis anterior tilt at the initial contact predicted PKAM, while trunk axial rotation, pelvis medial lean and posterior ground reaction force predicted PKAM during the weight acceptance phase. Despite higher PKAM, handball players might not be at a higher risk of anterior cruciate ligament injury as the knee joint loading remained at a relatively low level during this sidestepping task. Core stability, in its three dimensions, is a key determinant of knee joint loading. [ABSTRACT FROM AUTHOR]

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Vertigo has been described after the practice of mountain bike. This study aimed to investigate the prevalence of vertigo following competitions or training sessions of downhill mountain biking (DMB) or road cycling (RC). One hundred and two DMB riders, 79 road cyclists and 73 control participants filled in a survey intended to evaluate the prevalence of vertigo in daily living activities and following competitions or training sessions. Vertigo causal factors (crashes, head trauma, fatigue, characteristics of the path/road ridden) were recorded. DMB riders and road cyclists did not report more vertigo during daily living activities than controls. But DMB riders older than 30 had more risk to report vertigo than age-matched road cyclists (OR: 5.06, 95% CI: 1.23–20.62). Road cyclists aged between 20 and 29 were 2.59-fold (95% CI: 1.06–6.27) more likely to report vertigo than controls. After competitions and training sessions, DMB riders were 2.33-fold (95% CI: 1.22–4.41) more likely to report vertigo than road cyclists. Vertigo causal factors were crash with head trauma in DMB riders and fatigue in road cyclists. Vertigo during daily living activities may be of concern for cyclists, particularly older DMB riders. The accumulation of impacts (crashes, vibrations) during the career of a DMB rider may generate micro-traumatisms of the central nervous system and/or peripheral vestibular structures, particularly the otolith organs. In RC, the pathophysiological mechanisms generating vertigo might be effort-related disturbance of homeostasis. To avoid injuries, DMB riders should be aware that vertigo may occur at the end of training sessions or competitions. [ABSTRACT FROM PUBLISHER]

Many studies were interested in the consequence of vestibular dysfunction related to cochlear implantation on balance control. This pilot study aimed to assess the effects of unilateral cochlear implantation on the modalities of balance control and sensorimotor strategies. Posturographic and vestibular evaluations were performed in 10 patients (55 ± 20 years) with profound hearing loss who were candidates to undergo unilateral multichannel cochlear implantation. The evaluation was carried out shortly before and one year after surgery. Posturographic tests were also performed in 10 age-matched healthy participants (63 ± 16 years). Vestibular compensation was observed within one year. In addition, postural performances of the patients increased within one year after cochlear implantation, especially in the more complex situations, in which sensory information is either unavailable or conflicting. Before surgery, postural performances were higher in the control group compared to the patients' group. One year after cochlear implantation, postural control was close to normalize. The improvement of postural performance could be explained by a mechanism of vestibular compensation. In addition, the recovery of auditory information which is the consequence of cochlear implantation could lead to an extended exploration of the environment possibly favoring the development of newbalance strategies. [ABSTRACT FROM AUTHOR]

Human cognitive processing limits can lead to difficulties in performing two tasks simultaneously. This study aimed to evaluate the effect of cognitive load on both simple and complex postural tasks. Postural control was evaluated in 128 noninstitutionalized elderly people (mean age = 73.6 ± 5.6 years) using a force platform on a firm support in control condition (CC) and mental counting condition (MCC) with eyes open (EO) and eyes closed (EC). Then, the same tests were performed on a foam support. Sway path traveled and area covered by the center of foot pressure were recorded, low values indicating efficient balance. On firm support, sway path was higher in MCC than in CC both in EO and EC conditions ( p < 0.001). On foam support, sway path was higher in CC than in MCC in EC condition ( p < 0.001), area being higher in CC than in MCC both in EO ( p < 0.05) and EC (p < 0.001) conditions. The results indicate that cognitive load alters balance control in a simple postural task (i.e. on firm support), which is highlighted by an increase of energetic expenditure (i.e. increase of the sway path covered) to balance. Awareness may not be increased and the attentional demand may be shared between balance and mental task. Conversely, cognitive load does not perturb the realization of a new complex postural task. This result showed that postural control is prioritized ('postural first' principle) when seriously challenged. [ABSTRACT FROM AUTHOR]

Skull vibration induces nystagmus in unilateral vestibular lesion (UVL) patients. Vibration of skull, posterior cervical muscles or inferior limb muscles alters posture in recent UVL patients. This study aimed to investigate the postural effect of vibration in chronic compensated UVL patients. Vibration was applied successively to vertex, each mastoid, each side of posterior cervical muscles and of triceps surae in 12 UVL patients and 9 healthy subjects. Eye movements were recorded with videonystagmography. Postural control was evaluated in eyes open (EO) and eyes closed (EC) conditions. Sway area, sway path, anteroposterior and medio-lateral sways were recorded.A vibration induced nystagmus (VIN) beating toward the healthy side was obtained for each UVL patient during mastoid vibration. In EO, only sway path was higher in UVL group during vibration of mastoids and posterior cervical muscles.The EO postural impairments of UVL patients could be related to the eye movements or VIN, leading to visual perturbations, or to a proprioceptive error signal, providing an erroneous representation of head position. The vibration-induced sway was too small to be clinically useful. Vestibulo-ocular reflex observed with videonystagmography during mastoid vibration seems more relevant to reveal chronic UVL than vestibulo-spinal reflex observed with posturography. [ABSTRACT FROM AUTHOR]

Postural control impairments and dizziness, which are major health problems with high secondary morbidity and mortality, increase with aging. Elevated homocysteine (Hcy) level is an age-related metabolic disorder, known to be involved in cardiovascular, neurological, and multisensory dysfunctions. Elevated Hcy level might be involved in sensory balance control systems impairment and dizziness occurrence. Dizziness, fitness Instrumental Activity of Daily Living scale (fitness IADL), systolic arterial pressure with ankle-brachial blood pressure index and homocysteinemia were studied in 61 noninstitutionized elderly women. Clinical balance tests (timed 'Up and Go', 10-m walking and one-leg balance) and posturography (including sensory conflicting situations [SCS] and cognitive conflicting situations [CCS]) were performed. Clinical balance control was lower in dizzy women who presented particularly poor stability in SCS. Dizziness was related to low fitness IADL scores (odds ratio [OR] 0.452, 95% CI 0.216-0.946) and to elevated Hcy (OR 8.084, 95% CI 1.992-32.810). Elevated Hcy was correlated with balance disorders both in SCS and CCS. Dizziness is associated with a reduced ability in balance control management. Hcy is related both to dizziness and low postural performance. This relation between elevated Hcy levels and balance impairments, resulting in dizziness, may be explained by its angiotoxicity and neurotoxicity. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis: To evaluate the age-related effects of vestibular schwannoma (VS) on postural control and whether the postoperative postural strategies differ according to age. Study Design: Longitudinal, transversal study. Methods: Forty-seven VS patients were split into three groups according to age (group I, 14 patients aged from 30 to 44 years; group II, 21 patients aged from 45 to 59 years; and group III, 12 patients aged from 60 to 75 years). All patients underwent vestibular and posturographic testing shortly before as well as 8 days and 3 months after surgical tumor removal. Results: Vestibular and postural performance followed a classical time course with degradation just after surgery and recovery 3 months after surgery, whatever the age group. However, in the elderly the improvement of postural performances compared to preoperatively was more important, especially in conflicting situations. Conclusions: Despite of age-related decline in postural control and cognitive processes, neuroplasticity allowed not only a recovery but even an improvement of balance after surgical VS removal in the elderly. This study highlights the interest of VS surgery even at a more advanced age. Laryngoscope, 2012 [ABSTRACT FROM AUTHOR]

This report identifies fundamental problems to be addressed in order to build relevant clinical tests of human balance while standing. The stated purpose of these tests is identification of lesion site and/or definition of functional balance deficits in a specific patient. During a recent consensus meeting (ESCEBD), 60 researchers and experienced clinical users of posturography (14 European countries, 9 different disciplines) inventoried and critically analyzed the various methodologies of posturography currently used for clinical evaluation. To complement posturography, alternative methods of assessment of balance control were considered. The indications for the clinical use of posturography were defined as well as recommendations regarding measurement parameters, type of perturbations and signal analysis techniques to improve assessment of balance control. Consensus was reached that a force platform cannot be considered as a technique which is sufficient on its own to perform a clinically relevant test for the assessment of neuro-otological and musculo-skeletal conditions, evaluation of compensation or treatment (rehabilitation) or prediction of falls. It should be supported by complementary methods, such as segment motion analysis, body-fixed 2D or 3D accelerometer-gyroscope or electromyography. At present, no generally applicable posturography test is available with reasonable sensitivity and specificity for the diagnosis of balance disorders. Perturbation techniques are most likely needed to enhance the diagnostic yield of posturography. [ABSTRACT FROM AUTHOR]

Abstract: Motor skills during sport activity are influenced by practice-related constraints and leads to the development of appropriate postural sensorimotor strategies. Fencing is highly requiring visual monitoring and high-speed motor skills while retaining efficient balance control. Conversely, pistol shooting is a static activity requiring a high control of body sway. This study aimed to evaluate balance control and the related neurosensory organisation through reproducible postural tasks with and without sensory conflict. Twelve expert fencers, 10 expert shooters and 10 sedentary controls have performed a static posturographic test and a sensory organisation test (in 6 different sensory situations based upon sway-referenced vision and support surface, C1 to C6). Shooters yielded a better balance control during C1 (eyes open) and C2 (eyes closed) than fencers and controls. Fencers showed a better balance control in C5 (eyes closed with sway-referenced support surface) than shooters and controls. While this study confirms the beneficial effects of physical activities on balance control, a differential effect on balance characteristics due to the acquired specific motor skills was also noted. In addition to high proprioceptive sensitivity in sportsmen, dynamic constraints in fencing force fencers to permanently select the most relevant information to manage better sensory conflicting situations. [Copyright &y& Elsevier]

Abstract: This study aimed to determine the sensorimotor strategies privileged by mountain bikers (MTB) and road cyclists (RC) for balance control. Twenty-four MTB and 24 RC (off-road Olympics, world, continental and national champions, Tour-de-France participants, on-road world cup race winner) volunteered to answer a questionnaire about the characteristics of cycling practice and perform a sensory organization test, aiming to evaluate balance control in 6 different sensory situations based upon visual and support surface perturbations (C1ES to C6ES). RC balance performances were better than those of MTB both during quiet stance eyes opened (C1ES, p =0.011) and when only somatosensory information is disrupted (C4ES, p =0.039), highlighting a higher use of vision to control balance in RC. Moreover, a positive correlation was shown in the whole population (MTB+RC) between the visual ratio (R VIS =C4ES/C1ES) and the proportion of riding distance of on-road cycling (ρ =0.28, p =0.054). In MTB, the use of proprioception (somatosensory ratio: R SOM =C2ES(eyes closed)/C1ES) was increased by a higher intensity of off-road cycling (ρ =0.49, p =0.018) and that of vision (R VIS) by a higher intensity of on-road cycling (ρ =0.41, p =0.048). The difference in sensory organization between MTB and RC could be explained by adaptive processes elaborated from environmental stimulations and technical specificities of these disciplines. [Copyright &y& Elsevier]

Abstract: Human cognitive processing limits can lead to difficulties in performing two tasks simultaneously. In this respect, the mobilization of attentional resources seems to be more important in voluntary than in reflexive visuo-oculomotor movements. With this in mind, this study aimed to determine the differentiated effects of carrying out cognitive tasks on reflexive and voluntary movements generated by the visuo-oculomotor system. Eye movements were recorded with a videonystagmography system in 20 healthy adults. Prosaccade and antisaccade latency and accuracy were determined, as was the gain of regular smooth pursuit. The cognitive tasks comprised a backward counting task in steps of seven or thirteen and were carried out during the three oculomotor tasks. Whatever the backward counting, the cognitive tasks caused an increase in latency and a decrease in accuracy in the prosaccades and antisaccades as well as a drop in smooth pursuit gain. Despite a high degree of prosaccade, antisaccade and pursuit predictability, the oculomotor parameters were altered during dual-task fulfilment, and voluntary movements were more vulnerable than reflexive movements. Cognitive task achievement during oculomotor tasks requires greater attentional resource mobilization, and the reduction in visuo-oculomotor performance is even greater since the oculomotor task places more demand on the cognitive resources. Attention is thus a crucial cognitive process for the maintenance of adequate reflexive and voluntary oculomotor performance. Concurrently performing tasks have broader implications in motor coordination degradation understanding in situations like handheld phone when driving or in management of organisational and environmental constraints in occupational activities. [Copyright &y& Elsevier]

Abstract: In children, vasovagal syncope (VVS) is the most common cause of syncope and motion sickness (MS) is also very frequent, with many symptoms of an autonomic nature. To study a possible relationship between VVS susceptibility and MS susceptibility in young patients, 21 children (10 boys, 11.3±2.6 years) with recurrent syncope or presyncope were explored with a questionnaire concerning their vasovagal symptoms, susceptibility to MS and familial history. A tilt-table test and a dynamic posturography with Equitest (Sensory Organisation Test (SOT), in six conditions) were performed. Children were divided into two groups: A with a positive tilt-table test and particular susceptibility to VVS (n =13/21, six boys) and B with negative tilt-table test. A control group of 30 healthy children (15 boys, 11.4±2.4 years) was studied for MS susceptibility and familial history. VVS susceptibility was related to MS susceptibility (MS susceptibility was 69.3% in Group A versus 12.5% in Group B (p =0.0237) and 16.7% in control group (p =0.0028)) and also to SOT scores which are related both to the role of vestibule in equilibrium and to MS susceptibility, with lower values in Group A than Group B (condition 5: 47.9±12.3% versus 66.0±13.8%, p =0.0189 and vestibular (ratio of conditions 5/1): 51.8±12.7% versus 71.3±13.5%, p =0.0147). Our study demonstrates, for the first time, a relationship between VVS susceptibility and MS susceptibility in a population of children with a particular susceptibility to VVS. This paradigm may prove useful in better understanding the mechanisms underlying the susceptibility to VVS and MS. [Copyright &y& Elsevier]

Abstract: Unilateral vestibular lesion, as acoustic neuroma and its surgical removal, leads to impaired balance control. After initial vertigo and postural instability corresponding to unilateral vestibular deafferentation, improvement in symptoms and global balance functions occurs by a process called vestibular compensation. In this respect, this prospective study aimed to assess the differential contribution of sensory inputs to the regulation of posture during the recovery process after acoustic neuroma removal. Twenty-seven patients with acoustic neuroma underwent vestibular and posturographic testings, shortly before and 8 days, 1 month and 3 months after surgical removal of the tumour. Immediately after vestibular deafferentation, vestibular function was asymmetrical, postural performances were altered, especially in eyes closed conditions and in sensory challenged situations. One month, and more particularly 3 months after surgery, restoration and even improvement of vestibular and balance performances occurred, associated with a lower number of falls, development of more appropriate sensorimotor strategies and better resolution of sensorial conflicts. Postural perturbations are related to erroneous vestibular afferences, leading to incoherence in information about head position and interference with somatosensory and visual pathways. The time-course implementation of central adaptive mechanisms, characterized by substitution by other sensory afferences and new behavioural strategies, leads to an improvement of balance performance. [Copyright &y& Elsevier]

This study assessed the prevalence of sensory and cognitive disabilities and falls for various age groups, sexes, and socio-occupational categories, and their associations in the Lorraine population.The sample included6,159 subjects, aged 15 years or more, randomly selected from the Lorraine population. They filled in a mailed questionnaire including socio-demographic characteristics, job, falls with physical injuries at the time of the survey, and sensory and cognitive disabilities. Data analysis was made via the adjusted odds ratios.The prevalences of sensory and cognitive disabilities were 3.0 and 4.7%, respectively, that of falls with physical injuries 2.4%: 1.2% for falls on the same level and 1.2% for falls to a lower level. Subjects aged over 70 were markedly affected, but the other age groups had relatively high prevalences as well; the workmen had the highest prevalence, followed by the foremen, farmers, craftsmen and tradesmen, and employees. A twofold risk independently of age, sex and job was found for the subjects with sensory or cognitive disabilities for all falls combined.These findings show the high prevalences of sensory and cognitive disabilities and falls with physical injuries, and their strong associations in the general population. Preventive measures are needed to detect and follow up the persons with these disabilities, limit their risk of falls and reduce occupational hazards. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: This study examined the effect of rotary auditory stimulation on postural control in the elderly. Thirty-two subjects aged over sixty were submitted to two rotary auditory stimulations, with a meaningful and a non-meaningful message, during a postural task. Although the non-meaningful task did not lead to postural control modification, the meaningful task allowed a reduction in the postural parameter values and therefore, a better stabilisation of posture. The attention, paid to the geography of the sound in understanding the story being told, forced the subject into taking into consideration the regularity and rotation of the stimulation, which meant relying on an auditory anchorage and so facilitated posture regulation. [Copyright &y& Elsevier]

Vestibular information decreases in sensitivity with ageing, and its role becomes less important in the regulation of postural control. In addition, the practice of physical activity (PA) helps to improve vestibular sensitivity. This study aimed to evaluate PA-related benefit on vestibular function in 36 subjects split into four groups according to the period of practice. Caloric and rotatory vestibular testings showed that the performance of subjects who had begun practising PA recently were close to those of subjects active for a long time, whereas those of subjects who had stopped practising at an early age were close to those of inactive subjects. Although starting to practise PA has immediate beneficial effects on the vestibule, in terms of vestibular stimulation mechanisms these effects soon disappear if this activity is stopped. [Copyright &y& Elsevier]

The contribution of intrinsic balance control factors to fall mechanisms has received little investigation in studies on occupational accidents. The aim of this study was to assess whether postural regulation in falling workers might have specificities in terms of sensorimotor strategies and neuromuscular responses to balance perturbations. Nine multi-fall-victims (MF), 43 single-fall-victims (SF) and 52 controls (C) were compared on performance measurements of static and dynamic postural control. MF and SF had the worst postural performance both in the static and slow dynamic tests, particularly in eyes closed conditions, suggesting a high dependency on visual cues and a lower use of proprioception. Moreover, the sensorial analysis showed that MF and SF relied less on vestibular input in the development of balance strategy and had more difficulties in maintaining a correct upright stance when proprioceptive input was altered. Finally, MF showed longer latency responses to unexpected external disturbance. Overall, postural control quality increased in the order MF, SF and C. MF and SF adopted particular sensorimotor organisation, placing them at an increased risk of falling in specific sensory environments. Strategies incorporating visual information involve using the cognitive processes causing delayed and less accurate fall avoidance responses, in contrast to adaptative strategies based on proprioceptive and vestibular information. [Copyright &y& Elsevier]

Neonatal screening programmes allow early treatment to limit the consequences of congenital hypothyroidism on maturation of the central nervous system, and on psychomotor and educational outcome. Consequences of age at thyroid stimulating hormone (TSH) normalization on postural control were evaluated in 17 children with congenital hypothyroidism (14 females, three males; median age 12 years 1 month, range 7 to 14 years) and in 11 control individuals (eight females, three males: median age 10 years 6 months, range 8 to 14 years). Children with congenital hypothyroidism were split into two groups according to time of TSH normalization: before (group 1) or after (group 2) 3 months of age. Posturography (static and dynamic tests), educational (school performance), and psychomotor (WISC and revised Bruininks Oseretsky tests) evaluations were carried out. Group 2 results showed significant abnormalities in postural, educational, and psychomotor aptitudes in comparison with group 1 and control children (stability, Bruininks-Oseretsky, school performance: p < or = 0.05 or p < or = 0.01). Early TSH normalization is necessary to allow for normal development of the neurosensorial afferent pathways (vestibular, proprioceptive) and of central integration (cerebellum, vestibular nuclei). [ABSTRACT FROM AUTHOR]

Background: Balance disorders increase considerably with age due to a decrease in posture regulation quality, and are accompanied by a higher risk of falling. Conversely, physical activities have been shown to improve the quality of postural control in elderly individuals and decrease the number of falls. The aim of this study was to evaluate the impact of two types of exercise on the visual afferent and on the different parameters of static balance regulation.Methods: Static postural control was evaluated in 44 healthy women aged over 60 years. Among them, 15 regularly practiced proprioceptive physical activities (Group I), 12 regularly practiced bioenergetic physical activities (Group II), and 18 controls walked on a regular basis (Group III).Results: Group I participants displayed lower sway path and area values, whereas Group III participants displayed the highest, both in eyes-open and eyes-closed conditions. Group II participants displayed intermediate values, close to those of Group I in the eyes-open condition and those of Group III in the eyes-closed condition. Visual afferent contribution was more pronounced for Group II and III participants than for Group I participants.Conclusions: Proprioceptive exercise appears to have the best impact on balance regulation and precision. Besides, even if bioenergetic activity improves postural control in simple postural tasks, more difficult postural tasks show that this type of activity does not develop a neurosensorial proprioceptive input threshold as well, probably on account of the higher contribution of visual afferent. [ABSTRACT FROM AUTHOR]

Ageing is associated with a decrease in the quality of balance regulation, in particular through dysfunctions of gaze control and postural stabilization, which results in an increased risk of falling. Conversely, the practice of physical and sporting activities has been shown to improve every level of postural regulation. This study is to assess the effects of the practice of physical activities on vestibulospinal reflex and ocular movements of visual and vestibular origins in elderly people. Gaze control and posture stabilization were evaluated in 13 healthy aged women who regularly practised physical activities and in 13 healthy aged sedentary women of a similar age, by dynamic posturographic test with electromyography, as well as electronystagmography with caloric and rotational vestibular tests, ocular saccades, smooth pursuit and optokinetic tests. The gaze and posture control performance of the active group was better; the proprioceptive and vestibular sensitivities were higher, visual detection quality was good, and reaction time was low. Regular physical activity develops or maintains the efficiency of the reflexes involved in postural control, especially through adequate neurosensorial information, which allows the central integrative structures to generate a more appropriate motor response. [Copyright &y& Elsevier]

Postural instability can be the result of various factors, including fatigue. Although it is well known that exercise-induced fatigue may be responsible for a decrease in performance, its effects on postural control, as well as those of hydration, have been relatively little explored. This study evaluated the effects of fatigue, with and without rehydration, on postural control in 10 healthy subjects who regularly practice sports activities. All subjects were submitted to three types of ergocycle exercises: maximal oxygen uptake (V0 2[sub max]) and submaximal exercises in no-hydrated and hydrated conditions at a power corresponding to approximately 60% of the V0 2[sub max] of each subject. Static posturographic tests were performed immediately before (control) and after exercises. The postural control performance decreased from the best to the worst: control, hydration, dehydration, and V0 2[sub max]. Fast Fourier transformation of the center of foot pressure showed three patterns of amplitude spectral density, with an increase of spectral amplitude for dehydration, more important for Vo[sub 2max] conditions. Spectral amplitudes for control and hydration conditions were relatively similar. This hierarchy suggests that fatigue mainly alters muscular effectors and sensory inputs, such as proprioception, resulting in poor postural regulation. Moreover, fluid ingestion could be responsible for the preservation of muscular functions and of sensory afferences accurately regulating postural control. [ABSTRACT FROM AUTHOR]

Background: Ageing is associated with a reduction in balance, in particular through dysfunction of each level of postural control, which results in an increased risk of falling. Conversely, the practice of physical activities has been shown to modulate postural control in elderly people.Objective: This study examined the potential positive effects of two types of regular physical and sporting activities on vestibular information and their relation to posture.Methods: Gaze and postural stabilisation was evaluated by caloric and rotational vestibular tests on 18 healthy subjects over the age of 60 who regularly practised low-energy or bioenergetic physical activities and on 18 controls of a similar age who only walked on a regular basis. These subjects were also submitted to static and dynamic posturographic tests.Results: The control group displayed less balance control, with a lower vestibular sensitivity and a relatively high dependency on vision compared to the group practising low-energy physical activities, which had better postural control with good vestibular sensitivity and less dependency on vision. The postural control and vestibular sensitivity of subjects practising bioenergetic activities was average, and required higher visual afferent contribution.Conclusion: Low-energy exercises, already shown to have the most positive impact on balance control by relying more on proprioception, also appear to develop or maintain a high level of vestibular sensitivity allowing elderly people practising such exercises to reduce the weight of vision. [ABSTRACT FROM AUTHOR]