The stroke rate influences performance, technique and core stability during rowing ergometer

The aim of this study is to determine the effect of stroke rate on performance, technique and core stability during rowing ergometer. Twenty-four high-level rowers performed maximal intensity one-minute bouts at 20, 28 and 34 spm on a RowPerfect3 ergometer. Power at the handle, legs, trunk and arms levels were determined, and core kinematics and neuromuscular activations were measured. The power at the handle was enhanced with a higher stroke rate in the first half of the drive phase due to higher segment's powers. This resulted in technical changes, as for instance greater mean to peak power ratio at each segment level. The higher trunk power preceded a delayed trunk extension but without significant increase in the erector spinae activation. This underlines the role of the core stability to transfer forces at a higher stroke rate. However, no co-activation parameters between trunk flexors and extensors helped further to understand this force transfer. Rowing at low stroke rate can be a training strategy to work on earlier trunk extension, while maintaining erectors spinae levels of activation. Training at higher stroke rate will induce a rowing technique closer to competition with greater neuromuscular activations, and maximise power production.

Characterizing the effects of an ergonomic handle on upper limbs kinematics and neuromuscular activity, comfort, and performance during ergometer rowing

Articular stress and discomfort during repetitive movements may impact the risk of injuries of the upper limbs during ergometer rowing, especially when using a regular circular handle. Therefore, the purpose of the study was to propose and evaluate the influence of an ergonomic handle on upper limbs biomechanics, comfort and performance during ergometer rowing. An ergonomic irregular hexagon handle, with a 1:1.25 width/length diameters ratio, has been developed. Left upper limb kinematics and neuromuscular activity, perceived comfort and power production were monitored for 29 expert rowers. The ergonomic handle increased the perceived comfort while maintaining the overall articular stress and performance as the same level compared to the regular handle. We recommend using irregular hexagon handles with 1:1.25 ratio for ergometer rowing. Further improvements of the ergonomic handle such as an individualization based on the user's hand length may further enhance comfort and achieve better performance.

Prediction of rowing ergometer performance by technical and core stability parameters

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.

Influence of sidestepping expertise and core stability on knee joint loading during change of direction

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.

Does the Management of Visual and Audible Motion Information during an Immersive Virtual Reality Timed Up and Go Test Impact Locomotor Performance in the Elderly?

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.

The trunk's contribution to postural control under challenging balance conditions

BACKGROUND

The double inverted pendulum model is imprecise when applied to studies of postural control. Although multijoint analyses have improved our understanding of how balance is maintained, the exact role of the trunk remains unclear.

RESEARCH QUESTIONS

What is the trunk's contribution in postural control with respect to the other joints and how do trunk muscles control trunk kinematics?

METHODS

Thirty-six healthy athletes (handball, karate, long jump) performed a highly challenging balance task while the ground support was dynamically tilted in the sagittal plane. The center of force (CoF) as well as lower limb joint angles and the trunk-pelvis angle were respectively measured with a force platform and inertial measurement units. The amplitude, sway path and standard deviation of the CoF and the joint angles were then calculated. Electromyography was used to record the activity of the rectus abdominis, external obliquus, and erector spinae muscles. Multiple linear regressions were computed to determine the joints' and muscles' contributions (β-coefficients) in predicting CoF variables and trunk kinematics, respectively.

RESULTS

The linear combination of joint kinematic variables accounted for between 33 % and 75 % of the variance in the CoF. The ankle had the highestβ and was a significant predictor of all CoF variables. The trunk yielded the second highest β-coefficient and was a significant predictor of the CoF sway path. Electromyography variables accounted for no more than 35 % of the variance in the trunk kinematics, and erector spinae activity was the only significant predictor.

SIGNIFICANCE

The trunk appears to be the second most important element during this specific postural task, in the magnitude of body sway in particular. But neuromuscular control of these trunk processes is difficult to characterize with surface electromyography only. The trunk should be taken into account when seeking to improve overall postural control (e.g. during training, rehabilitation).

Impact of using immersive virtual reality over time and steps in the Timed Up and Go test in elderly people

Today, falls constitute a substantial health problem, especially in the elderly, and the diagnostic tests used by clinicians present often a low sensitivity and specificity. This is the case for the Timed Up and Go test which lacks contextualization with regard to everyday life limiting the relevance of its diagnosis. Virtual reality enables the creation of immersive, reproducible and secure environments, close to situations encountered in daily life, and as such could improve falling risk assessment. This study aims to evaluate the effect of immersive virtual reality by wearing a virtual reality headset with a non-disturbing virtual environment compared to real world on the Timed Up and Go test completion. Thirty-one elders (73.7 ± 9 years old) volunteered to participate in the study and the mean times and number of steps to complete a Timed Up and Go were compared in two conditions: actual-world clinical and virtual reality conditions. The results showed that the mean completion times and most of the mean number of steps of the Timed Up and Go in virtual reality condition were significantly different to those in clinical condition. These results suggest that there is a virtual reality effect and this effect is significantly correlated to the time taken to complete the Timed Up and Go. This information will be of interest to quantify the potential part of virtual reality effect on the motor control, measured in a virtual task using virtual controlled disturbances.

Prediction of Balance Compensation After Vestibular Schwannoma Surgery

Background Balance compensation after vestibular schwannoma (VS) surgery is under the influence of specific preoperative patient and tumor characteristics. Objective To prospectively identify potential prognostic factors for balance recovery, we compared the respective influence of these preoperative characteristics on balance compensation after VS surgery. Methods In 50 patients scheduled for VS surgical ablation, we measured postural control before surgery (BS), 8 (AS8) days after, and 90 (AS90) days after surgery. Based on factors found previously in the literature, we evaluated age, body mass index and preoperative physical activity (PA), tumor grade, vestibular status, and preference for visual cues to control balance as potential prognostic factors using stepwise multiple regression models. Results An asymmetric vestibular function was the sole significant explanatory factor for impaired balance performance BS, whereas the preoperative PA alone significantly contributed to higher performance at AS8. An evaluation of patients' balance recovery over time showed that PA and vestibular status were the 2 significant predictive factors for short-term postural compensation (BS to AS8), whereas none of these preoperative factors was significantly predictive for medium-term postoperative postural recovery (AS8 to AS90). Conclusions We identified specific preoperative patient and vestibular function characteristics that may predict postoperative balance recovery after VS surgery. Better preoperative characterization of these factors in each patient could inform more personalized presurgical and postsurgical management, leading to a better, more rapid balance recovery, earlier return to normal daily activities and work, improved quality of life, and reduced medical and societal costs.

Vertigo in downhill mountain biking and road cycling

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.

"Postural first" principle when balance is challenged in elderly people

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.

Clinical interest of postural and vestibulo-ocular reflex changes induced by cervical muscles and skull vibration in compensated unilateral vestibular lesion patients

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.

Specific injuries induced by the practice of trampoline, tumbling and acrobatic gymnastics

PURPOSE

The recreational and competitive practice of acrobatic sports, that is, trampoline, tumbling and acrobatic gymnastics (ACRO), is growing rapidly around the world. Many studies described the injuries affecting young artistic gymnasts, but only few concerned acrobatic sports.

METHODS

During a 5-year period, 357 traumatic events were collected in young acrobats practicing trampoline, tumbling or ACRO. Accident characteristics, level of expertise and training, injury location (upper limb, spine and lower limb), type of tissue injured (bone, cartilage, muscle, ligament and tendon) and provoking factors (intrinsic/behavioural and extrinsic) were investigated.

RESULTS

Acrobats of national and international levels were mostly injured. Injuries occurring in acrobatic sports concerned predominantly the lower limbs and concerned in this body part mainly damages to ligaments. Forearm and knee injuries were preferentially related to trampoline. Ankle injuries were preferentially related to tumbling. Wrist injuries were preferentially related to ACRO. Upper limb bone damage and upper limb tendon damage were preferentially related to trampoline and ACRO, respectively. Intrinsic/behavioural factors were the main injury determinant in the three acrobatic sports.

CONCLUSIONS

The main injuries in acrobatic sports (i.e. lower limbs) are similar to those observed in artistic gymnastics. Specific injuries may result from falls and incomplete and/or erroneous figure's landing and may also depend to the type of the landing surface.

LEVEL OF EVIDENCE

II.

Visuo-oculomotor deficiency at early-stage idiopathic scoliosis in adolescent girls

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To determine whether adolescent idiopathic scoliosis (AIS) at onset is associated with oculomotor dysfunction and whether these oculomotor anomalies are correlated to the amplitude of the spine deformation.

SUMMARY OF BACKGROUND DATA

AIS is related to abnormalities of postural control. To date, few studies have focused on visuo-oculomotor and vestibulo-ocular functions at early-stage AIS.

METHODS

Fifty-three adolescent girls were diagnosed with AIS (mean age: 11.6 ± 2.1 yr) on clinical and radiological criteria (mean Cobb angle: 14.8° ± 5.0°). Visuo-oculomotor and vestibulo-ocular functions were studied with video-oculography, including saccades, smooth pursuit, caloric test, and pendular rotation, with visual vestibular ocular reflex and vestibulo-ocular reflex sequences. Two patient groups were defined according to the mean Cobb angle: group 1 included 29 patients with a Cobb angle from 5° to 14° and group 2 included 24 patients with a Cobb angle from 15° to 25°.

RESULTS

The group 2 showed different saccade characteristics than group 1: higher latencies for saccade sequences characterized by temporal uncertainty and predictive direction; lower velocity regardless of the type of the saccades. No difference was observed for saccadic accuracy and smooth-pursuit gain. For the visual vestibular ocular reflex, group 2 showed lower total maximal slow-phase velocity than group 1, whereas the vestibulo-ocular reflex (tested in dark) did not differ between groups. No difference was observed concerning the caloric vestibular test.

CONCLUSION

Patients with a Cobb angle of 15° or more presented normal vestibulo-ocular responses but altered visuo-oculomotor functions, especially for the saccadic latency and velocity. This could be the result of a dysfunction of oculomotor pathways at cerebellar and/or brainstem level. These central disorders may be incriminated in the development of AIS.

Impact of pre-operative regular physical activity on balance control compensation after vestibular schwannoma surgery

Vestibular compensation after unilateral vestibular deafferentation is modulated by certain individual characteristics, such as pre-operative visual neurosensory preference or vestibular pattern. Physical activity (PA) allows the implementation of new sensorimotor and behavioral strategies leading to an improvement of balance control. This study aimed to evaluate the effect of the level of PA before surgery on balance compensatory mechanisms in patients after vestibular schwannoma (VS) surgery. Thirty patients with VS, 15 considered as regularly physically active and 15 as sedentary participated in this study, including an evaluation of gaze control by videonystagmography and postural control by a sensory organization test. Patients considered as physically active before surgery presented the best pattern of postural compensation, with the classical decrease in postural performances at short term (i.e. eight days) and the increase in postural performances at middle and long terms (i.e. 90 and 180 days, respectively) after surgery. For the sedentary patients, the consequences of surgery were more difficult to manage at short term, even though this did not prevent the ability to compensate well later on. Pre-operative practice of PA promotes the neuroplasticity of neural networks involved in motor learning, which allows to benefit of physical therapy more rapidly and efficiently.

Biological determinants of postural disorders in elderly women

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.

Drug-resistant temporal lobe epilepsy is associated with postural control abnormalities

Epilepsy is responsible for falls that are not systematically associated with seizures and that therefore suggest postural impairment. There are very few studies of postural control in patients with epilepsy and none of them focus on temporal lobe epilepsy (TLE), although part of the vestibular cortex is located in the temporal cortex. The aim of this study was to evaluate the characteristics of postural control in a homogeneous population of patients with complex partial TLE. Twenty-six patients with epilepsy and 26 age-matched healthy controls underwent a sensory organization test combining six conditions, with and without sensory conflicting situations. Patients with epilepsy displayed poorer postural control, especially in situations where vestibular information is necessary to control balance. In addition to potential antiepileptic drug side effects, vestibular dysfunction could be related to the temporal pathology. Our study allows for a better understanding of the mechanism underlying falls in this population of patients.

Pre-operative vestibular pattern and balance compensation after vestibular schwannoma surgery

This longitudinal study aimed to assess the sensorimotor balance strategies before and after vestibular schwannoma (VS) surgery according to the degree of pre-operative vestibular lesion. Thirty-eight VS patients were split in three groups according to caloric vestibular test results before surgery; nine had a symmetrical vestibular response (vestibular normoreflexy), 19 with a decreased response of more than 20% of the affected side (vestibular hyporeflexy) and 10 with an absent caloric response on the side of the affected labyrinth (vestibular areflexy). They underwent pendular rotary vestibular testing (RVT), allowing to evaluate gain and directional preponderance of the vestibulo-ocular reflex, and a sensory organisation test (SOT), evaluating balance control in six conditions (C1 to C6). These tests were performed shortly before, and 8 and 90 days after surgery. Directional preponderance performances of patients with vestibular normoreflexy or hyporeflexy followed a classical time-course with a huge asymmetry just after surgery and a recovery to pre-operative performances at 90 days; patients with vestibular areflexy were relatively stable in time. Variation in SOT performances of patients with vestibular normoreflexy, especially in the more complex C4 to C6, followed a classical time-course with an important postural degradation just after surgery and a recovery to pre-operative performances at 90 days. Patients with vestibular areflexy showed no balance degradation just after surgery and a marked increase in performances at 90 days after surgery, especially in C5 and C6. Performances of patients with vestibular hyporeflexy were intermediate, close to performances of patients with vestibular normoreflexy before surgery and close to performances of patients with vestibular areflexy at 8 and 90 days after surgery. Pre-operative vestibular function alteration triggers an adaptive process, characterized by a restoration of the symmetry of the vestibular nuclei activity and by sensory substitution and new behavioural strategies, allowing the anticipation of unilateral vestibular deafferentation effects.

Long-term effects of vestibular compensation on balance control and sensory organisation after unilateral deafferentation due to vestibular schwannoma surgery

The time-course of central adaptive mechanisms after vestibular schwannoma surgical removal allows, 3 months after surgery (middle term), a satisfactory recovery of balance control. However, the long-term evolution of postural control beyond the end of usual medical follow-up remains unknown. This longitudinal prospective study aimed to assess the long-term effects of vestibular compensation on balance control and sensory organisation in patients operated on for vestibular schwannoma. Thirty-six patients with vestibular schwannoma underwent vestibular and sensory organisation tests, shortly before and 3 months, 6 months and 1 year after surgery. Postural control performances improved 3 months after surgery compared with before surgery; they continued to improve at 6 and 12 months after surgery, especially in conditions highly soliciting vestibular information. In the long term, strategies based on sensorimotor and/or behavioural substitution seem to be reinforced and fine-tuned, particularly in complex postural situations, for which only vestibular information is reliable to control balance.

On the role of knee joint in balance control and postural strategies: effects of total knee replacement in elderly subjects with knee osteoarthritis

This study aimed to evaluate the role of the knee joint in the neurosensory organization of balance control and the generation of postural sensorimotor strategies. Ten patients, aged over 60 years and having undergone unilateral total knee replacement (TKR) for osteoarthritis, and 20 controls were submitted to static and dynamic posturographic tests and to a sensory organization test (SOT) aiming at evaluating postural control in quiet stance and during movement. The patients were submitted to these evaluations after the disappearance of pain (TKR(1)) and at the end of a 6-week rehabilitation program (TKR(2)). Balance control being greatly improved at TKR2 compared to TKR1, the patients attain a quality of postural regulation similar to that of the controls; some postural abnormalities did however persist for the static test. Moreover, SOT values at TKR(2) close to those of the controls highlighted an improvement in motor response, better management in altered proprioceptive information situations, and greater use of the ankle to control balance. This model of intervention on the knee joint, namely knee replacement due to osteoarthritis, has shown that gradual functional sensorimotor restoration after TKR, due to intrasensory proprioceptive compensation either at knee, or at other joint levels (hip/ankle), improves dynamic balance control. This reacquisition allows the knee joint to recover its corrective compensatory role in postural regulation allowing, through neuroplasticity, the modification of muscular activation sequences and, thus, the implementation of anticipatory sensorimotor strategies.

Visual sensorial preference delays balance control compensation after vestibular schwannoma surgery

BACKGROUND

Balance control performance after vestibular schwannoma surgical removal follows a course that is characterised by a deterioration in postural performance immediately after unilateral vestibular deafferentation (uVD) and a recovery process (vestibular compensation). However, sensory strategies for balance vary during tumoral growth, which could lead to differences in the preferential use of sensory afferences. This longitudinal study aimed to assess the post-operative sensorimotor strategies of postural regulation according to sensory preference of balance control before surgery.

METHODS

Twenty-two patients with vestibular schwannoma (11 relying less on vision (G1), 11 relying more on vision (G2), to control balance before surgery), underwent vestibular, subjective visual vertical (SVV), static posturography and sensory organisation (SOT) tests, before and 8 days, 1 and 3 months after surgery.

RESULTS

In G1 patients, little static posturographic and SOT performance deterioration after uVD was observed, despite vestibular test and SVV modifications. In G2 patients, uVD-related modifications followed a time-course characterised by a degradation in posturographic and SOT, vestibular and SVV performances immediately after uVD and a progressive restoration and even improvement 1 month and particularly 3 months after surgery.

CONCLUSIONS

High preference for vision before surgery intervenes in postural degradation immediately after surgery, thus delaying the short-term effects of vestibular compensation on postural control. Long-term performance being similar whatever the visual status before surgery, the time-dependent implementation of the central adaptive mechanisms due to neuroplasticity leads to a modification of neurosensory information hierarchy, allowing reliance on appropriate information, the gain varying according to the postural task to be performed.

Cognitive task fulfilment may decrease gaze control performances

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.

Extensor retinaculum syndrome after distal tibial fractures: anatomical basis

Fractures of the distal extremity of the tibia include physeal injuries among teenagers and more complex fractures among adults. Displacement causes the compression of the muscles located between the distal tibia and the superior extensor retinaculum (SER). Among the muscles of anterior compartment of the leg, the extensor hallucis longus (EHL) is particularly vulnerable due to the amount of muscle fibers extending under the SER. Consequently, a partial anterior compartment syndrome could result, affecting only the distal portion located under the SER. In clinical practice, Mubarak measured the intramuscular pressure isolated under the SER and suggested the physio-pathological hypothesis of a compression of distal muscle fibers. The aim of this study is to compare the ratios of anterior compartment muscle fibers extending under the SER. Twenty legs were dissected in order to study how much of these muscles extend under the SER, their passages possibly dividing into two of the SER, as well as their vascularization and their innervation. On the last seven legs, the engagement of the muscles were measured in the spontaneous position and with a dorsal flexion of 0 degrees . The posterior muscle fibers of this compartment always descend lower than the anterior fibers. EHL muscle fibers and those of the inconsistent fibularis tertius always extend under the retinaculum, unlike those of the tibialis anterior and of the extensor digitorum longus. The EHL muscle extends under the SER more than the other muscles. Its posterior fibers are longer when this muscle goes through a dividing into two of the retinaculum. Its vascularization seems lesser, which could explain why this muscle tends to suffer more. The deep fibular nerve innervates the anterior compartment of the leg, yet no nerve branches can be found under the upper edge of the retinaculum. In all cases, the muscle fibers do not extend as much under the SER in a 0 degrees of dorsal flexion. This anatomical study allows us to explain why the EHL is more likely to suffer from this partial compartment syndrome and confirms that when the latter occurs it is necessary, in all cases, to do emergency surgery opening the distal crural fascia and necessarily including the SER.

Experimental evaluation of a common susceptibility to motion sickness and vasovagal syncope in children

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.

Age-related part taken by attentional cognitive processes in standing postural control in a dual-task context

The aim of this work was to determine the effects of ageing on the possible mobilisation of cognitive processes in orthostatic postural balance. Seventy-nine individuals of three different age groups were placed in dual-task situations that combined standing postural control with three different cognitive tasks. Two of these three tasks, auditory-verbal and visual-verbal ones, required external information acquisition whereas the third, a mental counting task, did not require such information. The results showed contrasting variations in postural control performances that are an improvement in young subjects during cognitive tasks which required external information acquisition and a deterioration in elderly subjects during cognitive tasks which did not involve external information acquisition. The middle-aged subjects tended to develop these two types of variations simultaneously. These results confirm that cognitive processes could have a role that increases with age in ensuring postural control. The contrasting results observed between the young and old populations highlight that the allocation of cognitive resources to postural control could, on the one hand, contribute to improving postural performance in subjects with mainly automated control and, on the other, perturb this performance in subjects with mainly cognitive control.

Posturography and Risk of Recurrent Falls in Healthy Non-Institutionalized Persons Aged Over 65

BACKGROUND

A poor postural stability in older people is associated with an increased risk of falling. The posturographic tool has widely been used to assess balance control; however, its value in predicting falls remains unclear.

OBJECTIVE

The purpose of this prospective study was to determine the predictive value of posturography in the estimation of the risk of recurrent falls, including a comparison with standard clinical balance tests, in healthy non-institutionalized persons aged over 65.

METHODS

Two hundred and six healthy non-institutionalized volunteers aged over 65 were tested. Postural control was evaluated by posturographic tests, performed on static, dynamic and dynamized platforms (static test, slow dynamic test and Sensory Organization Test [SOT]) and clinical balance tests (Timed 'Up & Go' test, One-Leg Balance, Sit-to-Stand-test). Subsequent falls were monitored prospectively with self-questionnaire sent every 4 months for a period of 16 months after the balance testing. Subjects were classified prospectively in three groups of Non-Fallers (0 fall), Single-Fallers (1 fall) and Multi-Fallers (more than 2 falls).

RESULTS

Loss of balance during the last trial of the SOT sensory conflicting condition, when visual and somatosensory inputs were distorted, was the best factor to predict the risk of recurrent falls (OR = 3.6, 95% CI = 1.3-10.11). Multi-Fallers showed no postural adaptation during the repetitive trials of this sensory condition, contrary to Non-Fallers and Single-Fallers. The Multi-Fallers showed significantly more sway when visual inputs were occluded. The clinical balance tests, the static test and the slow dynamic test revealed no significant differences between the groups.

CONCLUSION

In a sample of non-institutionalized older persons aged over 65, posturographic evaluation by the SOT, especially with repetition of the same task in sensory conflicting condition, compared to the clinical tests and the static and dynamic posturographic test, appears to be a more sensitive tool to identify those at high-risk of recurrent falls.

Why do idiopathic scoliosis patients participate more in gymnastics?

The influence of physical and sporting activities (PSA) on idiopathic scoliosis (IS) is still obscure. The aim of this study was to investigate whether such an influence exists and if so, to determine its characteristics. Two hundred and one teenagers with IS and a control group of 192 adolescents completed an epidemiological questionnaire. Those practising gymnastics were more numerous in the IS group than in the control group. Moreover, the practice of gymnastics was chosen before IS was diagnosed. As gymnastic activities are considered neither as a therapy nor as a precursor of IS, the distribution observed could be linked to a common factor that both increases the likelihood of IS and favors the practice of gymnastics. Joint laxity (JL) may be such a common factor, and was therefore tested (wrist and middle finger) on 42 girls with IS and 21 girls of a control group. IS patients, practising gymnastics or not, showed a higher JL than the control group practising gymnastics or not. Furthermore, the groups practising gymnastic activities did not show higher JL levels than the other groups. Children with a high JL could be drawn toward gymnastics because of their ability to adapt to the constraints of this sport. Girls with a high JL may therefore be prone to developing IS. The fact that most teenagers with IS practise gymnastics could be related to a higher JL.

Current physical activity improves balance control during sensory conflicting conditions in older adults

Aging process is characterized by difficulties in ensuring balance control, especially in conditions of reduced or conflicting sensory information, leading to an increased risk of falling. Conversely, the practise of physical activities (PA) has been recognized as a good approach to improve the quality of balance control. This study aimed to investigate the influence of current and/or past PA on balance-related neurosensorial organization in older adults on the maintenance of the upright stance, especially during sensory conflicting situations. Postural control was evaluated by means of the Sensory Organization Test on 130 healthy noninstitutionalized volunteers aged over 65, split into four groups according to the presence or absence of PA before or after retirement. Subjects who practised PA for a long time (Gr1) and subjects who started PA after retirement (Gr2) displayed the best postural performances and better managed sensory conflicting situations compared to subjects who had stopped PA for many years (Gr3) and subjects who had never practised PA (Gr4). Multiple regression analyses revealed that current PA was the major determinant for postural parameters during sensorial conflict compared to age, gender, body mass index and past PA. Regular PA, even when started late in life, allows appropriate reorganization of the different components of postural control during sensory conflicting situations. Indeed, active subjects were more able to compensate for suppressed or perturbed sensory information by an increased usage of another referential and so to correct their posture by adopting a more appropriate balance strategy. Thus, PA counteracts the age-related decline of postural control and could consequently reduce the risk of falling.

Sensorimotor postural rearrangement after unilateral vestibular deafferentation in patients with acoustic neuroma

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.

Effect of sporting activity practice on susceptibility to motion sickness

The theory of visuo-vestibular conflict is the most commonly accepted to explain motion sickness. Visual, vestibular and proprioceptive afferences are involved in balance control and this function can be improved by physical and sporting activities (PSA). The purpose of the present survey was to investigate the relationships between motion sickness susceptibility (MSS) in adulthood and PSA, and especially proprioceptive PSA. A questionnaire concerning MSS and PSA was filled in by 1829 students (22.3+/-3.4 years of age, 799 males). Subjects having practised a sport before the age of 18 have less MSS than the other subjects (P<0.001). It should be noted that subjects who practised proprioceptive PSA before the age of 18 have less MSS than subjects who practised bioenergetic PSA before this age. By practising PSA, subjects are less dependent on visual input and use vestibular afferences better. A process of habituation can be involved in better managing conflicting sensory afferences reducing susceptibility to motion sickness. The practice of proprioceptive PSA develops the proprioceptive afferences and improves their treatment by the central nervous system. This additional appropriate input associated with an increase in vestibular weight compared to vision helps overcome visuo-vestibular conflict.

Determinants of accident proneness: a case-control study in railway workers

BACKGROUND

Accident proneness or workers who have more frequent occupational injuries is common but the role of occupational and individual factors has rarely been studied.

AIM

To assess the relationships of certain occupational and individual characteristics with frequency of occupational injuries.

METHOD

This case-control study included 1305 male workers with occupational injuries during 1999-2000 and 1305 controls from a railway company. A standardized questionnaire was completed by the occupational physician in the presence of the subject. The data were analysed using logistic regression.

RESULTS

Having more than one injury was associated with short service in the present job, younger age, sleep disorders, smoking, requesting a job change, physical disability and lack of physical activity. Safety training was negatively related to injury frequency. Short service in the present job was the only significant factor for single injuries.

CONCLUSION

This study identified a number of work and individual factors that predicted occupational injury frequency and may be useful in designing preventative measures. Occupational physicians could assist workers to be more aware of the risks and to find remedial measures.

Prevalence of sensory and cognitive disabilities and falls, and their relationships: a community-based study

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 included 6,159 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.

Bilateral subthalamic nucleus stimulation improves balance control in Parkinson's disease

BACKGROUND

Parkinson's disease (PD), the most common basal ganglia degenerative disease, affects balance control, especially when patients change balance strategy during postural tasks. Bilateral chronic stimulation of the subthalamic nucleus (STN) is therapeutically useful in advanced PD, and reduces the motor signs of patients. Nevertheless, the effects of STN stimulation on postural control are still debatable.

AIMS

To assess the impact of bilateral STN stimulation on balance control in PD and to determine how basal ganglia related sensorimotor modifications act on neurosensorial organisation of balance and motor postural programming.

METHODS

Twelve subjects aged 45-70 years underwent unified Parkinson's disease rating scale motor (part III) clinical tests, static and dynamic posturography, including sensory organisation and adaptation tests, shortly before and six months after bilateral implantation of electrodes into the STN.

RESULTS

The postoperative static test showed an improvement in postural control precision both in eyes open and eyes closed conditions. The dynamic test highlighted the decreased number of falls and the ability of the patients to develop more appropriate sensorimotor strategies when stimulated. The sensory organisation test showed an improvement of equilibrium score and, thus, a better resolution of sensorial conflicts.

CONCLUSIONS

STN stimulation allowed a reduction in rigidity and therefore an improvement in the ability to use muscular proprioception as reliable information, resulting in vestibulo-proprioceptive conflict suppression. STN stimulation has a synergistic effect with levodopa for postural control. Accordingly, non-dopaminergic pathways could be involved in postural regulation and STN stimulation may influence the functioning of these pathways.

Long-term exposure to solvents impairs vigilance and postural control in serigraphy workers

OBJECTIVES

To investigate the effects of solvent exposure (mainly aromatic hydrocarbons) on central regulation of vigilance and postural control, particularly in occasional difficult situations that provide sensorial conflicts.

METHODS

Twenty-two workers occupationally exposed to solvents for an average of approximately 6 years and 21 controls were compared by the use of a questionnaire on their state of vigilance and quality of sleep and on performance measurements of postural control under six different sensorimotor conditions. Their current median exposure levels to aromatic hydrocarbons was 80.1 mg/m(3).

RESULTS

Exposed workers reported reduced alertness but not disturbance of sleep quality compared with controls. Moreover, they had the worst postural performance in all sensory conditions and demonstrated a reduced ability to resolve sensory conflict situations. The precision of stance was clearly affected by solvent exposure in contrast with energy consumption required to regulate proper balance control.

CONCLUSIONS

The depressive effect of aromatic hydrocarbon exposure on cortical and subcortical structures controlling vigilance and postural stability could lead to increased risk of occupational accident, especially due to falls. The detection of central neurotoxic effects by posturographic and vigilance tests could be useful in preventive strategies.

Chronic exposure to anesthetic gases affects balance control in operating room personnel

Exposure to anesthetic gases is known to alter certain structures and functions of the central nervous system. As the effects of long-term exposure on balance control mechanisms have been the subject of few investigations, these were evaluated in 53 operating room personnel exposed to anesthetic gases and in 53 non-exposed individuals. Balance control was assessed by static and dynamic posturography. Exposed workers had the worst static and dynamic postural performances, particularly in the eyes closed condition, suggesting increased dependency on vision and decreased use of proprioception. This poorer ability to modify the weight and to switch the different cues controlling balance suggests central information processing disorders. By impairing information and its central integration, exposure to anesthetics gases leads to inappropriate organization of sensorimotor stabilization strategies.

Added cognitive load through rotary auditory stimulation can improve the quality of postural control in the elderly

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.

Physical activity after retirement enhances vestibulo-ocular reflex in elderly humans

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.

Higher visual dependency increases balance control perturbation during cognitive task fulfilment in elderly people

Ageing results in a decrease in balance control and correlatively raises the risk of falling. Furthermore, dual task situations can increase this age-related imbalance. Within this context, this study aimed to determine the differentiated effects of carrying out cognitive tasks on balance control in 40 healthy older adults. The visuo-verbal Stroop task did not affect postural regulation precision whereas a mental counting task provoked higher instability. Moreover, the results showed a correlation between the degree of visual dependency and postural perturbation. Executing a mental counting task can cause reorientation of visual attention from external landmarks to internal visual images of the calculation. As elderly subjects are more dependent on visual information to ensure balance control, this loss of external visual anchorage when executing a mental task therefore explains the balance perturbation observed.

Sensorial organisation favouring higher visual contribution is a risk factor of falls in an occupational setting

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.

Effect of age at thyroid stimulating hormone normalization on postural control in children with congenital hypothyroidism

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).

Relationships of job, age, and life conditions with the causes and severity of occupational injuries in construction workers

OBJECTIVES

To assess the relationships of job, age, and life conditions with the causes and severity of occupational injuries in male construction labourers.

METHODS

The sample included 880 male construction workers having had at least one occupational injury with subsequent sick leave. The survey used a standardised questionnaire, filled in by the occupational physician in the presence of the subject: socio-demographic data, job, safety training, smoking habit, alcohol consumption, sporting activities, physical disabilities, hearing, vision, and sleep disorders. Statistical analysis was via the logistic regression method.

RESULTS

Logistic models showed that falls and injuries from the handling of objects or hand tools was similar for all jobs, while masons, plumbers and electricians had a higher risk of injury from moving objects, and carpenters, roofers and civil-engineering workers were more exposed to injury from construction machinery and devices. Age <30 was related to injury from hand tools [adjusted OR (95%CI) 2.20 (1.28-3.79)]; sleep disorders and hearing disorders to those from moving objects [ORs 2.29 (1.27-4.12) and 1.85 (1.01-3.41) respectively]; no sporting activity to those from the handling of objects [OR 1.54 (1.09-2.17)]; and being overweight to falls on the same level [OR 2.04 (1.30-3.21)] and falls to a lower level [OR 1.55 (1.13-2.13)]. Injuries from the handling of objects were less frequent in overweight workers [OR 0.62 (0.46-0.84)]. Injuries with hospitalisation or sick leave > or =60 days were associated with age > or =30 and hearing disorders.

CONCLUSIONS

The causes of injuries were related to jobs. Prevention through working conditions could be made against the revealed risks. The risks for each worker depended on age, body mass index, hearing disorders, sleep disorders, and sporting activities. The occupational physician could inform the workers of these risks and encourage them to practise sporting activities and reduce their hearing disorders and sleep disorders.

Influence of Regular Proprioceptive and Bioenergetic Physical Activities on Balance Control in Elderly Women

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.

Individual characteristics in occupational accidents due to imbalance: a case-control study of the employees of a railway company

BACKGROUND

Falls are frequent occupational accidents, and are responsible for a significant amount of lost working time and, more importantly, for a high mortality. The factors involved in falling mechanisms can be of external or individual origin, the latter being less well identified.

AIMS

To assess the relations between certain individual characteristics and occupational accidents due to imbalance.

METHODS

A total of 427 male employees, who had been victims of at least one occupational accident with sick leave due to imbalance (cases) and 427 controls were recruited among the employees of a large French railway company. A standardised questionnaire on life conditions and professional factors, and a description of the accidents was filled in by an occupational physician for each subject.

RESULTS

Some job categories were more affected by a specific release mechanism of work related falls. Certain individual characteristics such as smoking, alcohol consumption, inactivity, sleep disorders, and request for a job change were correlated with the occurrence of occupational accidents. Sick leaves of eight days or over were more frequent in older and overweight injured workers. Some lesions were linked with the specific fall released mechanisms.

CONCLUSIONS

Individual characteristics can increase the risk of occupational accidents, especially falling. This study identified subjects most at risk on whom prevention related to working conditions and falls could be focused.