Static Postural Sway Research Articles

Increased static postural sway after energy drink consumption: A randomized trial

Background: Energy drinks consumption continues to grow since its appearance in the United States in 1997. Available evidence indicates that caffeine, their main ingredient, can alter the central nervous system (CNS). However, it is unknown how energy drinks alter the CNS postural control mechanism. The purpose of this study was to investigate how energy drinks can affect postural control after sensory perturbations during stance. Methods: 20 healthy adults, (11 males; 9 females) averaging 26.1 years of age, stood on a MatScan™ pressure mat, which measured center of pressure (CoP), anteroposterior (AP) and mediolateral (ML) postural sways during eight different balance tests (BALT’s). BALT's were designed to alter or cancel the systems involved in postural control: visual, vestibular and somatosensory. Subjects were randomly assigned to a caffeine group and an energy drink group. MANOVA analysis was performed for all variables of interest. Results: In the caffeine group, the AP sway of the Eyes Closed test on a stable surface was statistically significant. In the energy drinks group, we observed a general tendency of participants to increase CoP slightly, AP and ML sway in most of the BALT’s after the consumption of an energy drink. However, this increase was not statistically significant. These results suggest that in healthy young adults, the sensory re-weighting mechanism can overcome postural perturbation and maintain overall postural control. Conclusions: We observed an overall tendency to increase postural instability after the ingestion of energy drinks.

Impaired balance is related to the progression of diabetic complications in both young and older adults

AimsTo investigate the balance ability in younger and older adults with diabetes and evaluate the associations between balance ability and microvascular complications. MethodsThis cross-sectional observational study compared 162 participants and 177 controls with and without type 2 diabetes, respectively. Balance ability was assessed using two static (one-legged stance and postural sway area) and two dynamic (Timed Up and Go [TUG] and Functional Reach) tests. Diabetic microangiopathy was also evaluated. ResultsParticipants with diabetes, including both younger (<50years) and older (≥50years) participants, showed significantly worse balance ability in all four tests and were more likely to have a history of falls than the controls (all P<0.01). In all age groups, severe impairment of balance ability was associated with progression of diabetic microvascular complications. In all and older diabetic adults, a longer duration of diabetes (P=0.022) and higher TUG test score (P=0.004), and female sex (P=0.01) and higher TUG score (P=0.001), respectively, were related to a history of falls. On the other hand, among younger diabetic adults, only a non-significant association with longer duration of diabetes (P=0.066) was observed. ConclusionsImpaired balance ability correlates with microvascular diabetic complications. Accurate assessment of balance ability in adults with diabetes could predict the risk of falls, particularly benefitting people with diabetic complications.

Static postural sway of women with and without fibromyalgia syndrome: A cross-sectional study

BackgroundThere is a frequent complaint about balance problems among fibromyalgia syndrome patients; however, there are not enough studies that have shown static postural sway of women with fibromyalgia syndrome. This study aimed to compare static postural sway of women with and without fibromyalgia syndrome. MethodsThis is a cross-sectional study in which twenty-nine women with fibromyalgia syndrome and 20 without took part. A posturography evaluation was performed in six different situations (bipedal, right tandem and left tandem, with eyes opened and closed), and questionnaires for clinical depression symptoms, clinical anxiety symptoms, sleep quality, and Visual Analogue Scales for Pain and Fatigue were applied. Mann-Whitney U test was used to check differences among groups; Wilcoxon matched-pair test was used to check differences intragroup; Cohen d coefficient was used to measure effect sizes and Pearson Correlation Coefficient was used for correlations among variables. Level of significance adopted was 5%. FindingsWomen with fibromyalgia syndrome have presented worse postural sway than women without fibromyalgia syndrome in all situations (P<0.05), and worse scores in all questionnaires (P<0.05). In the eyes closed situations, women with fibromyalgia syndrome presented worse postural sway than women without in the same conditions. InterpretationWomen with fibromyalgia syndrome have worse performance in the static posture test, more prominent in reduced support bases with eyes closed. Pain, fatigue, depression and anxiety may have directly influenced postural sway in fibromyalgia syndrome patients.

Immediate effects of perturbation treadmill training on gait and postural control in patients with Parkinson’s disease

The study investigates immediate adaptations of gait and balance to a single session of perturbed treadmill walking in patients with Parkinson’s disease. 39 Parkinson’s patients in stage 1–3.5 of the Hoehn and Yahr Scale were randomized into one of two groups, stratified by disease severity: The experimental group (n=19) walked on a treadmill prototype which constantly applied perturbation by small three-dimensional tilting movements of the walking surface. The control group (n=20) trained on the identical treadmill without perturbations. Patients walked on the treadmill for 20min. Primary outcome measure was overground walking speed. Secondary outcomes were postural sway during quiet standing and spatiotemporal gait parameters during treadmill walking. Outcomes were measured repeatedly throughout the training session and after 10min retention. The experimental group significantly increased overground walking speed after intervention compared to the control group (p=0.014; ES=+0.41). Gait variability during treadmill walking significantly decreased after walking with perturbation. Sway area increased with treadmill walking only in the control group (p=0.009; ES=+0.49). No other postural sway measures changed over time. Subgroup analyses revealed that in the experimental group patients with more pronounced motor impairment demonstrated larger increases in overground walking speed (p=0.016; ES=+0.40) and stance phase symmetry (p=0.011; ES=−0.42). In conclusion, a single session of perturbation treadmill training led to gait improvements, which were more pronounced compared to unperturbed treadmill walking. Effects on static postural sway were less pronounced.

Athlete And Non-athlete Quiet Stance Postural Performance

Measures of postural performance have been studied extensively in athletes, focusing primarily on static standing; however, little is known regarding postural performance in athletes versus non-athletes during static stance and functional postural assessments. PURPOSE: The purpose of this study was to investigate differences in static and dynamic postural sway assessments of center of pressure (CoP) in athlete and non-athlete populations. METHODS: 28 collegiate athletes (ATH) (21 female, mean age 18.4 ± 0.67 years, 7 male, mean age 19.42 ± 2.14 years) and 30 college-age non-athlete controls (NON) (21 female, mean age 22.2 ± 1.05 years, 9 male, mean age 22.85 ± 1.34 years) completed two trials of eyes open and eyes closed quiet standing for 30 seconds, and the WiiFit Soccer Heading Game. During quiet stance, participants were instructed to stand with their feet together and stand as still as possible on the Wii Fit board, which was placed over a force plate. For the WiiFit Soccer Heading Game, participants were instructed to keep their eyes in the center of the screen as much as possible while shifting their weight from side to side to play the game. Raw CoP data was collected using a force platform (1000Hz) and analyzed further using a custom code. Peak Excursion Velocity (PEV) and Root Mean Square (RMS) excursion in the anteroposterior (AP) and mediolateral (ML) directions was calculated from the data along with 95% Confidence Ellipse (CE). RESULTS: One-way ANOVAs revealed that ATH had significantly lower (p=0.048) CoP RMS in the ML direction (4.1 ± 1.3 mm) and significantly (p=0.012) lower eyes open CE (0.3 ± 0.1 mm) during the quiet stance eyes open trials when compared to NON (4.9 ± 1.9 mm) and (0.4 ± 0.2mm), respectively. There were no significant differences between groups regarding PEV in the ML and AP directions with eyes open, eyes closed, or dynamic (WiiFit) situations. CONCLUSIONS: These results suggest that athletes are more stable with eyes open during quiet upright stance. However, during a dynamic postural task, which may more closely resemble athletic performance, no differences were observed. These findings suggest that ATH use different postural mechanisms than NON during quiet upright stance with eyes open. This could be due to an enhanced utilization of visual cues as a result of a visually rich training paradigm.

The relationship between hippocampal volume and static postural sway: results from the GAIT study.

The role of the hippocampus in postural control, in particular in maintaining upright stance, has not been fully examined in normal aging. This study aims to examine the association of postural sway with hippocampal volume while maintaining upright stance in healthy older individuals. Seventy healthy individuals (mean age 69.7±3.4years; 41.4% women) were recruited in this study based on cross-sectional design. Hippocampal volume (quantified from a three-dimensional T1-weighted MRI using semi-automated software), three center of pressure (COP) motion parameters (sway area, path length of anterior-posterior (AP) and medial-lateral (ML) displacement) while maintaining upright stance (eyes open and closed), and the relative difference between open and closed eye conditions were used as outcome measures. Age, sex, body mass index, lower limb proprioception, distance vision, 15-item geriatric depression scale score, total cranial volume, and white matter abnormalities were used as covariates. The sway area decreased from open to closed eye condition but this variation was non-significant (P=0.244), whereas path length of AP and ML displacement increased significantly (P<0.003). Increase in sway area from open to closed eyes was associated with greater hippocampal volume (β -18.21; P=0.044), and a trend for an association of increase in path length of AP displacement (P=0.075 for open eyes and P=0.071 for closed eyes) with greater hippocampal volume was reported. The hippocampus is involved in upright postural control in normal aging, such that an increase in sway area of COP motion from open to closed eyes is associated with greater hippocampal volume in healthy older adults.

Girls with generalized joint hypermobility display changed muscle activity and postural sway during static balance tasks

Objectives: To study knee muscle activity and static postural sway in girls with generalized joint hypermobility (GJH).Method: Sixteen girls with GJH and 11 girls with non-GJH (NGJH) aged 14 years, randomly recruited among schoolchildren, participated in this study. GJH inclusion criteria were: Beighton score minimum 6/9 and one hypermobile knee; for NGJH: Beighton score maximum 5/9 and no knees with hypermobility. The participants performed a static two-legged balance test with eyes open (2EO) and eyes closed (2EC) and a one-legged stance test with eyes open (1EO). Postural sway (centre of pressure path length, COPL) was calculated, along with rambling and trembling components. Surface electromyography (sEMG) from the quadriceps (Q), hamstrings (H), and gastrocnemius (G) muscles was recorded, expressed as a percentage of the maximum voluntary EMG (%MVE), and the co-contraction index (CCI) of Q, H, and G muscle activity was calculated. Knee function was self-reported using the Knee Injury and Osteoarthritis Outcome Score for children (KOOS-Child).Results: GJH had a significantly lower lateral HQ CCI and a higher medial/lateral HQ CCI ratio in all balance tasks. Group mean EMG varied from 1.3%MVE in Q (during 2EO) to 15.7%MVE in G (during 1EO). GJH had larger postural sway length than NGJH during 2EC (COPL 1.64 vs. 1.37 m/min, p < 0.001). Rambling and trembling components did not differ between groups.Conclusions: Girls with GJH and at least one hypermobile knee performed, compared with NGJH, static balance tasks with higher medial knee muscle activity relative to the lateral activity, and larger postural sway when vision was eliminated. The short- and long-term consequences should be studied further.

Comparison of Shod vs Nonshod Training on Balance and Postural Sway in Older Adults

Among older adults, falls are the leading cause of death due to injury and hospitalization. With age, cutaneous sensation in the foot sole diminishes, contributing to balance impairment. Discovering an effective method for retraining the mechanoreceptors of the feet will possibly increase balance control. Training the different physiological systems involved in balance maintenance is important for decreasing fall risks. PURPOSE: To investigate whether a balance training intervention involving barefoot training (BT) yields better static and dynamic balance, and postural sway values than a group wearing shoes (WS). METHODS: Twelve older adults (65-92 years) were randomly assigned into a BT or WS group. Both groups participated in 50 minute exercise sessions three days a week for six weeks. The sessions included strength, balance, and stretching exercises based on the Stay Active and Independent for Life program. All participants completed a functional reach test (FRT), single-leg stance (SLS), timed up and go (TUG), 30 second chair stand (CS), and postural sway analysis with eyes open (SEO) and eyes closed (SEC). RESULTS: A 2x6 ANOVA found no significant difference between the two groups for the FRT, SLS, TUG, CS, SEO, or SEC tests. Pearson correlations were run to identify relationships between variables. As would be expected there was a positive significant correlation between the static balance measures of SLS and FRT (r = .634, p = 0.027), as well as SEO and SEC in the postural sway test (r = .780, p = .003). There were negative significant correlations between the chair stand and TUG (r = -.848, p = .000), and SEC (r = -.577, p = .050). CONCLUSION: There was no difference in static and dynamic balance and postural sway between the two groups, but leg strength had an impact on dynamic balance and postural sway with visual input. Future research should consider a larger sample size and a longer intervention.

Relationships between presynaptic inhibition and static postural sway in subjects with and without diabetic neuropathy.

[Purpose] Diabetic peripheral neuropathy can often lead to balance impairment. The spinal reflex is a mechanism that is reportedly important for balance, but it has not been investigated in diabetic peripheral neuropathy patients. Moreover, inhibitory or facilitatory behavior of the spinal reflex—known as presynaptic inhibition—is essential for controlling postural sway. The purpose of this study was to compare the differences in as presynaptic inhibition and balance in subjects with and without diabetic peripheral neuropathy to determine the influence of presynaptic inhibition on balance in diabetic peripheral neuropathy patients. [Subjects and Methods] Presynaptic inhibition and postural sway were tested in eight patients (mean age, 58±6 years) and eight normal subjects (mean age, 59±7 years). The mean percent difference in conditioned reflex amplitude relative to the unconditioned reflex amplitude was assessed to calculate as presynaptic inhibition. The single-leg balance index was measured using a computerized balance-measuring device. [Results] The diabetic peripheral neuropathy group showed lower presynaptic inhibition (47±30% vs. 75±22%) and decreased balance (0.65±0.24 vs. 0.38±0.06) as compared with the normal group. No significant correlation was found between as presynaptic inhibition and balance score (R=0.37). [Conclusion] Although the decreased as presynaptic inhibition observed in diabetic peripheral neuropathy patients may suggest central nervous system involvement, further research is necessary to explore the role of presynaptic inhibition in decreased balance in diabetic peripheral neuropathy patients.

Postural Stability of Older Female Scottish Country Dancers in Comparison with Physically Active Controls

Physical activity assists older individuals’ functional ability and postural stability. Recently, Scottish country dance (SCD) was reported as being a beneficial form of physical activity for functional ability in older females. This study aims to examine the effect of SCD on postural stability. Scottish country dancers (n = 20) were compared with physically active controls (n = 33) for static postural sway measured on a force platform. The Romberg and Tandem stances were used under ‘eyes open’ and ‘eyes closed’ conditions. Ninety-five percent ellipse area and sway velocity were calculated from the center of pressure displacement. Ninety-five percent ellipse area was the same for both groups in all tests. The control group had greater sway velocity for all tests (P < .01) except Tandem eyes closed. SCD participation resulted in similar postural sway as participation in other physical activities, however nondancers may need a greater amount of regulatory activity to maintain balance.

Postural Stability of Older Female Scottish Country Dancers in Comparison With Physically Active Controls

Physical activity assists older individuals' functional ability and postural stability. Recently, Scottish country dance (SCD) was reported as being a beneficial form of physical activity for functional ability in older females. This study aims to examine the effect of SCD on postural stability. Scottish country dancers (n = 20) were compared with physically active controls (n = 33) for static postural sway measured on a force platform. The Romberg and Tandem stances were used under 'eyes open' and 'eyes closed' conditions. Ninety-five percent ellipse area and sway velocity were calculated from the center of pressure displacement. Ninety-five percent ellipse area was the same for both groups in all tests. The control group had greater sway velocity for all tests (P < .01) except Tandem eyes closed. SCD participation resulted in similar postural sway as participation in other physical activities, however nondancers may need a greater amount of regulatory activity to maintain balance.

The effect of whole body vibration training on postural sway in patients with spinal cord injury: a pilot study

Objective: The aim of this study was to determine the impact of the application of whole body vibration training (WBV) on the balance ability of patients with an American Spinal Injury Association (ASIA) type C or D spinal cord injury. Design: Randomized controlled trial. Methods: Twelve patients with spinal cord injury were enrolled in this study. The participants were randomized to an experimental group (n=6) or control group (n=6). The subjects in the experimental group received WBV exercise and the control group received the sham exercise without vibration. The vibrations were adjusted vertically to the patient at a 30 Hz frequency and 3 mm amplitude. The whole body vibration lasted for 16 minutes in total including 5-minutes warm-up and cool-down at the beginning and end of the program, respectively. The static sitting balance ability was assessed by measuring the postural sway while sitting on the force plate with the eyes opened or closed. Postural sway length was measured for 30 seconds with a self-selected comfortable position. Results: In the static balance test, the anterio-posterior, medio-lateral, and total postural sway length with the eyes open and closed was improved significantly before and after the intervention in the experimental group (p<0.05). The experimental group showed significantly more improvement than the control group (p<0.05). Conclusions: Our results demonstrated that WBV training has a positive effect on improving static sitting balance and enhanced control of postural sway in patients with an ASIA-C or D type spinal cord injury.

The development of an accelerometer-based measure of human upright static anterior-posterior postural sway under various sensory conditions: Test–retest reliability, scoring and preliminary validity of the Balance Accelerometry Measure (BAM)

Accelerometers are being used to assess postural control in adults, but there is little to support their reliability and validity. To estimate the test-retest reliability of the balance accelerometry measure (BAM) and to describe the known-groups validity of the BAM composite score. Two measures of standing postural sway were taken across six sensory (vision/stance surface) and motor stance (feet together or tandem) positions from eighteen patients with vestibular disorders and 84 healthy subjects. Test-retest reliability for postural sway was estimated across all conditions using intraclass correlation coefficient (ICC). A composite measure of sway standardized to young healthy subjects on eyes open firm surface stance was compared between groups. Test-retest reliability of postural sway was good (ICC ⩾ 0.74) under all sensory conditions except eyes closed/tandem stance, which was slight to poor. Analysis of the receiver operating characteristic curve for composite scores indicated significant accuracy at identification of subjects in the vestibular/balance disorder groups. Composite standard scores equal or greater than 21.1 identified subjects with vestibular disorders with an accuracy of 72% sensitivity and 68% specificity. The BAM displays good-excellent reliability for five of six sensory-motor conditions. The composite score appears to differentiate healthy from subjects with vestibular disorders.

Typical balance exercises or exergames for balance improvement?

Balance training is an effective intervention to improve static postural sway and balance. The purpose of the present study was to investigate the effectiveness of the Nintendo Wii Fit Plus exercises for improving balance ability in healthy collegiate students in comparison with a typical balance training program. Forty students were randomly divided into two groups, a traditional (T group) and a Nintendo Wii group (W group) performed an 8 week balance program. The "W group" used the interactive games as a training method, while the "T group" used an exercise program with mini trampoline and inflatable discs (BOSU). Pre and Post-training participants completed balance assessments. Two-way repeated measures analyses of variance (ANOVAs) were conducted to determine the effect of training program. Analysis of the data illustrated that both training program groups demonstrated an improvement in Total, Anterior-posterior and Medial Lateral Stability Index scores for both limbs. Only at the test performed in the balance board with anterior-posterior motion, the improvement in balance ability was greater in the "T group" than the "W group", when the assessment was performed post-training (p=0.023). Findings support the effectiveness of using the Nintendo Wii gaming console as a balance training intervention tool.

Effect of underwater treadmill exercise on postural sway in horses with experimentally induced carpal joint osteoarthritis

To evaluate the effect of underwater treadmill exercise on static postural sway in horses with experimentally induced carpal joint osteoarthritis under various stance conditions. 16 horses. On day 0, osteoarthritis was induced arthroscopically in 1 randomly selected middle carpal joint of each horse. Beginning on day 15, horses were assigned to either underwater or overground (without water) treadmill exercise at the same speed, frequency, and duration. Two serial force platforms were used to collect postural sway data from each horse on study days -7, 14, 42, and 70. Horses were made to stand stationary on the force platforms under 3 stance conditions: normal square stance, base-narrow placement of the thoracic limbs, and removal of visual cues (blindfolded) during a normal square stance. The mean of 3 consecutive, 10-second trials in each condition was calculated and used for analysis. Displacement of the center of pressure differed significantly depending on the stance condition. Among horses exercised on the underwater treadmill, postural stability in both the base-narrow and blindfolded stance conditions improved, compared with findings for horses exercised on the overground treadmill. Horses exercised on the overground treadmill were only successful at maintaining a stable center of pressure during the normal square stance position. Variations in stance position had profound effects on the mechanics of standing balance in horses with experimentally induced carpal joint osteoarthritis. Underwater treadmill exercise significantly improved the horses' postural stability, which is fundamental in providing evidence-based support for equine aquatic exercise.

Effect of a Forefoot Off-loading Postoperative Shoe on Muscle Activity, Posture, and Static Balance

We investigated whether a forefoot off-loading postoperative shoe (FOPS) alters standing posture, ankle muscle activity, and static postural sway and whether any effects are altered by wearing a shoe raise on the contralateral side. Posture, ankle muscle activity, and postural sway were compared in 14 healthy participants wearing either a FOPS or a control shoe with or without a contralateral shoe raise. Participants were tested under different sensory and support surface conditions. Additionally, reductions in peak pressure under the forefoot while walking were assessed with and without a contralateral shoe raise to determine whether the FOPS continued to achieve its primary off-loading function. Compared with the control condition, wearing a FOPS moved the center of pressure posteriorly, increased tibialis anterior muscle activity, and reduced ankle plantarflexor activity. These changes decreased when a contralateral shoe raise was added. No difference in postural sway was found between footwear conditions. Forefoot peak pressure was always reduced when wearing the FOPS. The posterior shift in center of pressure toward and behind the ankle joint axis is believed to result in the increase in tibialis anterior muscle activity that now acts as the primary stabilizer around the ankle. Instability may, therefore, increase in patients with weak tibialis anterior muscles (eg, diabetic neuropathy) who need to wear offloading devices for ulcer management. We suggest that the addition of a contralateral shoe raise fitted with a FOPS may potentially be beneficial in maintaining stability while off-loading the forefoot in this patient group.

Effects of Acute Joint Effusion on Balance in Patients with Knee Osteoarthritis

The purpose of this study was to assess the effects of acute joint effusion on balance in patients with knee osteoarthritis. Forty-four female subjects with painful knee osteoarthritis participated in this single-blind, randomized, controlled clinical trial. All subjects were randomly assigned to either the injection or the control group. A volume of 20 ml of normal saline was injected into the knee joint cavity of the test subjects, who performed static and dynamic balance tests twice before and after joint infusion. The subjects in the control group performed the same tests without joint infusion. The outcome variables for static measurement were the mean speeds (millimeter per second) of the movement of the center of pressure in the mediolateral and anteroposterior directions and the mean velocity moment (square millimeter per second) with both eyes opened and eyes closed conditions. For dynamic measurement, time (second) and distance (millimeter) of the center of pressure were used. Significant interaction of the balance-test variables (mean speeds, velocity moment, time, and distance) between the groups and time (P > 0.05) was not found. There were no significant differences between the groups in any of the balance-test variables (P > 0.05). This study showed that acute joint effusion has no effect on static or dynamic postural sway in patients with knee osteoarthritis.

MRI‐related static magnetic stray fields and postural body sway: A double‐blind randomized crossover study

We assessed postural body sway performance after exposure to movement induced time-varying magnetic fields in the static magnetic stray field in front of a 7 Tesla (T) magnetic resonance imaging scanner. Using a double blind randomized crossover design, 30 healthy volunteers performed two balance tasks (i.e., standing with eyes closed and feet in parallel and then in tandem position) after standardized head movements in a sham, low exposure (on average 0.24 T static magnetic stray field and 0.49 T·s(-1) time-varying magnetic field) and high exposure condition (0.37 T and 0.70 T·s(-1)). Personal exposure to static magnetic stray fields and time-varying magnetic fields was measured with a personal dosimeter. Postural body sway was expressed in sway path, area, and velocity. Mixed-effects model regression analysis showed that postural body sway in the parallel task was negatively affected (P < 0.05) by exposure on all three measures. The tandem task revealed the same trend, but did not reach statistical significance. Further studies are needed to investigate the possibility of independent or synergetic effects of static magnetic stray field and time-varying magnetic field exposure. In addition, practical safety implications of these findings, e.g., for surgeons and others working near magnetic resonance imaging scanners need to be investigated.

Effects of Localized and General Fatigue on Static and Dynamic Postural Control in Male Team Handball Athletes

In team sports, sensorimotor impairments resulting from previous injuries or muscular fatigue have been suggested to be factors contributing to an increased injury risk. Although it has been widely shown that physical fatigue affects static postural sway, it is still questionable as to what extent these adaptations are relevant for dynamic, sports-related situations. The objective of this study was to determine the effects of whole-body and localized fatigue on postural control in stable and unstable conditions. Nineteen male team handball players were assessed in 2 sessions separated by 1 week. Treadmill running and single-leg step-up exercises were used to induce physical fatigue. The main outcome measures were center of pressure (COP) sway velocity during a single-leg stance on a force plate and maximum reach distances of the star excursion balance test (SEBT). The COP sway velocity increased significantly (p < 0.05) after general (+47%) and localized fatigue (+10%). No fatigue effects were found for the SEBT. There were no significant correlations between COP sway velocity and SEBT mean reach in any condition. The results showed that although fatigue affects static postural control, sensorimotor mechanisms responsible for regaining dynamic balance in healthy athletes seem to remain predominantly intact. Thus, our data indicate that the exclusive use of static postural sway measures might not be sufficient to allow conclusive statements regarding sensorimotor control in the noninjured athlete population.

Neuromotor effects of short‐term and long‐term exposures to trichloroethylene in workers

Health effects of long-term exposure to organic solvents at low levels are a major concern in industrialized countries. To assess the neuromotor impact of trichloroethylene objectively, static postural sway and hand tremor parameters, along with urinary trichloroethanol (TCOH) and trichloroacetic acid (TCAA) levels, were investigated in 57 workers without obvious neurological disorders and 60 control subjects. The workers had been occupationally exposed to trichloroethylene for 0.1-37 years. The cumulative exposure index (CEI) was calculated from their occupational history and total trichloro-compounds (TCOH + TCAA). Median levels in the workers were 1.7 mg/L for TCOH and 2.5 mg/L for TCAA, and the maximum ambient trichloroethylene concentration was estimated to be <22 ppm from the previously reported equation using TCOH + TCAA. Sway parameters with eyes open and tremor intensity in dominant hand were significantly larger in the exposed workers than in the control subjects when adjusting for possible confounders. A significant dose-effect association was seen between two sway parameters and urinary TCOH level in the workers. Tremor intensities in non-dominant hand differed significantly among three groups of the workers divided according to the CEI. These findings suggest that trichloroethylene exposure, even at low levels of less than the short-term exposure limit by the ACGIH, can affect the neuromotor function of workers. The postural instability appears to result from recent exposure, and the increased tremor may occur due to short-term and long-term exposures. Hereafter, such objective measures, along with subjective symptoms, should be carefully used for the occupational exposure limit setting.