Differences In Balance Control Research Articles

Symmetric unipedal balance in quiet stance and dynamic tasks in older individuals

Previous evidence of increased difference of muscular strength between the dominant and non-dominant legs in older adults suggests the possibility of dissimilar balance control between the legs (between-leg asymmetry) associated with aging. In the current investigation, we evaluated between-leg asymmetries in older adults when performing quiet and dynamic balance tasks. Fifty-two physically active and healthy older adults within the age range of 60 to 80 years were recruited. Participants performed balance tasks in unipedal stance, including quiet standing and cyclic sway (rhythmic oscillation) of the non-supporting leg in the anteroposterior or mediolateral directions, producing foot displacements with amplitudes of 20 cm paced in 1 Hz through a metronome. Body balance was evaluated through trunk accelerometry, by using the sensors embedded into a smartphone fixed at the height of the 10th-12th thoracic spines. Analysis revealed lack of significant differences in balance control between the legs either when comparing the right versus left or the preferred versus non-preferred legs, regardless of whether they were performing quiet stance or dynamic tasks. Further examination of the data showed high between-leg correlation coefficients (rs range: 0.71–0.84) across all tasks. Then, our results indicated symmetric and associated between-leg balance control in the examined older adults.

A comparison of the effects of mediolateral surface and foot placement perturbations on balance control and response strategies during walking

BackgroundBalance perturbation studies during walking have improved our understanding of balance control in various destabilizing conditions. However, it is unknown to what extent balance recovery strategies can be generalized across different types of mediolateral balance perturbations. Research questionDo similar mediolateral perturbations (foot placement versus surface translation) have similar effects on balance control and corresponding balance response strategies? MethodsKinetic and kinematic data were previously collected during two separate studies, each with 15 young, healthy participants walking on an instrumented treadmill. In both studies, medial and lateral balance perturbations were applied at 80% of the gait cycle either by a treadmill surface translation or a pneumatic force applied to the swing foot. Differences in balance control (frontal plane whole body angular momentum) and balance response strategies (hip abduction moment, ankle inversion moment, center of pressure excursion and frontal plane trunk moment) between perturbed and unperturbed gait cycles were evaluated using statistical parametric mapping. ResultsBalance disruptions after foot placement perturbations were larger and sustained longer compared to surface translations. Changes in joint moment responses were also larger for the foot placement perturbations compared to the surface translation perturbations. Lateral hip, ankle, and trunk strategies were used to maintain balance after medial foot placement perturbations, while a trunk strategy was primarily used after surface translations. SignificanceSurface and foot placement perturbations influence balance control and corresponding response strategies differently. These results can help inform the development of perturbation-based balance training interventions aimed at reducing fall risk in clinical populations.

Brain oscillatory activity in adolescent idiopathic scoliosis

Pathophysiology of Adolescent Idiopathic Scoliosis (AIS) is not yet completely understood. This exploratory study aims to investigate two aspects neglected in clinical practice: a defective postural central nervous system control in AIS, and alterations of body schema due to scoliosis spinal deformities. We recorded EEG data and balance data in four different standing positions in 14 adolescents with AIS and in 14 controls. A re-adaptation of the Image Marking Procedure (IMP) assessed body schema alterations on the horizontal (Body Perception Indices (BPIs)) and vertical direction (interacromial and bisiliac axes inclinations). Our results revealed no differences in balance control between groups; higher EEG alpha relative power over sensorimotor areas ipsilateral to the side of the curve and a significant increase of theta relative power localized over the central areas in adolescents with AIS. The difference in BPI shoulder and BPI waist significantly differed between the two groups. The inclinations of the perceived interacromial axes in adolescents with AIS was opposite to the real inclination. Increased theta activity and alpha lateralization observed may be a compensatory strategy to overcome sensorimotor dysfunction mirrored by altered body schema. Scoliosis onset might be preceded by sensorimotor control impairments that last during curve progression.

Differences in balance control despite self-reported resolution of pregnancy-related pelvic girdle pain. A cross-sectional study

BackgroundMotor control patterns are altered when women with pregnancy-related pelvic girdle pain (PGP) experience pain. In low back pain, these adaptations can persist after recovery. ObjectivesThis study aimed to assess balance control in postpartum women with and without a history of PGP during pregnancy. DesignCross-sectional study. MethodEighteen postpartum women who reported to be recovered from PGP, and twelve postpartum women without a history of PGP during pregnancy performed two clinical tests: the single leg stance and active straight leg raise test. Primary outcomes were ground reaction forces measured with a force platform. ResultsMultiple linear regression analyses showed smaller lateral displacement (β = −11cm; 95%CI: 19 to −3; p = 0.008) and lower displacement velocity of the Centre of Pressure (COP) (Ratio of Geometric Means (RGM) 0.76; 95%CI: 0.59 to 0.99; p = 0.043) during single leg stance in the participants with a history of PGP compared to participants without a history of PGP. Push-off force (β = −4.8 N; 95%CI: 22.0 to 12.5; p = 0.57) and asymmetry of push-off force (RGM 1.77; 95%CI: 0.62 to 5.04; p = 0.27) did not differ between groups. During the active straight leg raise test, no differences in lateral displacement (β = 3 cm; 95%CI: 3 to 8; p = 0.30) and COP displacement velocity (RGM 1.03; 95%CI: 0.70 to 1.52; p = 0.87) were observed. ConclusionsAlthough the women with a history of PGP considered themselves recovered, their balance control during single leg stance was poorer compared to those without a history of PGP. No differences were found during the active straight leg raise test.

Warm-Up Improves Balance Control Differently in the Dominant and Non-Dominant Leg in Young Sportsmen According to Their Experience in Asymmetric or Symmetric Sports.

The aim of this study was to investigate the acute effects of a warm-up on balance control and inter-limb balance asymmetries by analyzing the influence of the nature of the sport practiced by participants. Twelve sportspeople were recruited. They had to stand on a force plate for 30 s in a one-leg stance on their dominant (used to perform skilled movements) and non-dominant leg (used to support the body) before and 2, 5, 10, 15 and 20 min after a 10 min warm-up exercise performed at moderate intensity on a cycle ergometer. The center of foot pressure displacements was recorded. Statistical analysis was performed by considering one group of all participants and with two subgroups according to the symmetrical or asymmetrical nature of the sport they practiced. The warm-up exercise improved acute balance control only on the dominant leg after a 20 min rest without significantly reducing inter-limb balance asymmetries. This effect was more characteristic of participants with experience in asymmetric sports. These results confirm previous findings of the greater sensitivity of the dominant leg to the physiological state and reveal that between-leg differences in balance control appear mainly in subjects with experience in asymmetric sports in a specific physiological condition (post-warm-up state).

Center of pressure plausibility for the double-link human stance model under the intermittent control paradigm

Despite human balance maintenance in quiet conditions could seem a trivial motor task, it is not. Recently, the human stance was described through a double link inverted pendulum (DIP) actively controlled at the ankle with an intermittent proportional (P) and derivative (D) control actions based on the sway of a virtual inverted pendulum (VIP) that links the ankle joint with the DIP center of mass. Such description, encompassing both the mechanical model and the intermittent control policy, was referred as the DIP/VIP human stance model, and it showed physiologically plausible kinematic patterns. In this study a mathematical formalization of the Center of pressure (COP) for a DIP structure was developed. Then, it was used in conjunction with an intermittently controlled DIP/VIP model to assess its kinetic plausibility. Three descriptors commonly employed in posturography were selected among six based on their capability to discriminate between young (Y) and elderly (O) adults groups. Then, they were applied to assess whether variations of the P–D parameters affect the synthetic COP. The results showed that DIP/VIP model can reproduce COP trajectories, showing characteristics similar to the Y and O groups. Moreover, it was observed that both P and D parameters increased passing from Y to O, indicating that the COP obtained from the DIP/VIP model is able to highlight differences in balance control between groups. The study hence promote the use of DIP/VIP in posturography, where inferential techniques can be applied to characterize neural control.

Differences in balance control between healthy younger and older adults during steady-state walking

Each year approximately one third of older adults fall and experience extensive musculoskeletal injuries and functional disabilities. An important element in maintaining dynamic balance is the regulation of whole-body angular momentum, which is achieved by proper foot placement with respect to the body center-of-mass as well as generation of appropriate ground reaction forces. Analyzing these quantities in younger and older adults may provide insight into differences in their underlying mechanics for maintaining dynamic balance. This study examined three-dimensional whole-body angular momentum in 13 healthy older (71.8 ± 8.3 years) and 9 younger (23.2 ± 2.8 years) adults walking at their self-selected and fastest-comfortable speeds. The older adults had a significantly higher range of frontal-plane angular momentum compared to the younger adults at both speeds, suggesting poorer mediolateral balance control. This difference was related to the older adults having a wider foot placement with respect to the body center-of-mass, which when combined with the vertical ground reaction force, created a higher destabilizing external moment during single-limb stance that acts to rotate the body towards the contralateral swing leg. To counteract this destabilizing moment, the older adults generated a higher hip abduction moment. There were no differences in the range of sagittal- and transverse-plane angular momentum between age groups at either speed. These results suggest that control of dynamic balance in the frontal-plane is more challenging than in the sagittal-plane for older adults and highlight the importance of proper weight transfer mechanisms and hip abductor force production for maintaining mediolateral balance during walking.

Effects of Functional Strength Training on Functional Movement and Balance in Middle-Aged Adults

Functional movement deficiencies cause falls and injuries in adults. Functional strength training (FST) is emerging as a new training method for athletes, middle-aged and older adults, to improve functional movement: The present study was conducted in order to investigate the effects of FST on balance and functional movement in healthy and independent middle-aged adults. The sample for this study consisted of 46 physically active individuals (24 female and 22 male). A total of 46 subjects were divided based on randomly into the functional strength training (FST) group (n = 26) aged: 51.55 ± 3.73 years; height: 168.69 ± 8.8 cm; body mass: 75.88 ± 12.18; and traditional strength training (TST) group (n = 20) age: 52.85 ± 4.01; height: 166.9 ± 9.98; body mass: 76.15 ± 10.45. Each group performed 24 sessions of a training protocol three-time a week. The functional movement was assessed using the functional movement screen (FMS) protocol. Balance performance was determined by using the balance error scoring system (BESS). Bodyweight and body fat ratio were measured using bioelectric impedance. There was a significant statistical difference between FMS total scores after an eight-week FST in the FST group. After the intervention, the functional strength group tended to have significantly better balance control than the traditional strength group (p = 0.01). Statistically, significant differences were observed between pre-test and post-test in the intervention group on BMI, body fat, and body mass (p = 0.01). There were not found significant differences in balance control and FMS score in TST group. As a result of this study, FST positively affected the FMS total score and balance performance in middle-aged adults. Early detections of the deficiencies in functional movement and balance in the middle ages may reduce the risk of insufficiency and fall in adults through targeted functional strength training intervention.

Age-related differences in stair descent balance control: Are women more prone to falls than men?

Stair descent is one of the most common forms of daily locomotion and concurrently one of the most challenging and hazardous daily activities performed by older adults. Thus, sufficient attention should be devoted to this locomotion and to the factors that affect it. This study investigates gender and age-related differences in balance control during and after stair descent on a foam mat. Forty-seven older adults (70% women) and 38 young adults (58% women) performed a descent from one step onto a foam mat. Anteroposterior (AP) and mediolateral (ML) centre of pressure velocity (CoP) and standard deviation of the CoP sway were investigated during stair descent and restabilization. A two-way analysis of variance (ANOVA) revealed the main effects of age for the first 5 s of restabilization. Older women exhibited significantly higher values of CoP sway and velocity in both directions compared to the younger individuals (CoP SDAP5, 55%; CoP SDML5, 30%; CoP VAP5, 106%; CoP VML5, 75%). Men achieved significantly higher values of CoP sway and velocity only in the AP direction compared to their younger counterparts (CoP SDAP5, 50% and CoP VAP5, 79%). These findings suggest that with advancing age, men are at higher risk of forward falls, whereas women are at higher risk of forward and sideways falls.

Balance Control in Patients with Subacute Non-Specific Low Back Pain, with and without Lumbar Instability: A Cross-Sectional Study.

BackgroundPatients with low back pain (LBP) have poorly coordinated neuromuscular control, which may alter the normal postural stability of the spine. Altered movement control may occur at any stage of LBP.Purpose(1) To identify differences in balance control and proprioceptive sense between subacute non-specific LBP (NSLBP) patients with and without lumbar instability (LI) and healthy subjects and (2) to investigate the correlation between factors of motor control deficits and balance.Patients and MethodsThirty-six participants matched by gender, age, and body mass index (BMI) were allocated into three groups of 12: subacute NSLBP patients with LI, subacute NSLBP patients without LI, and healthy subjects. Balance, proprioceptive sense, pain, functional disability, and fear of movement were evaluated.ResultsSubacute NSLBP patients with LI exhibited greater impairments in balance control, proprioceptive sense, and functional ability than patients without LI (p<0.05). Subacute NSLBP patients showed more impairments in balance control, proprioceptive sense, and fear of movement than healthy subjects (p<0.001), with the following effect sizes (partial η2) for static balance on stable and unstable surface: 0.597 and 0.560, anticipatory balance: 0.417, and dynamic balance: 0.536; proprioceptive sense: 0.676; and fear of movement: 0.379. Significant fair correlations were found between (1) static balance and proprioceptive sense, functional disability, and fear of movement; (2) functional reach test (FRT) and pain; and (3) the five times sit to stand test (FTSTS) and functional disability.ConclusionSubacute NSLBP patients with LI showed greater impairment in balance control than patients without LI. Reduced proprioceptive sense, increased pain, functional disability, and fear of movement were fairly related to impaired balance.

Effect of Training Level on a Visuomotor Balance Task in Youth with Previous Sport-Related Concussion.

INTRODUCTION: The demands of sport require the integration of cognition and sensory inputs to produce more complex, goal-directed movement. Howell and colleagues (1) revealed that the differences in balance control between athletes with or without previous concussion were greater in youth compared young adults during dual-task gait. PURPOSE: 1) To determine if a novel visuomotor dynamic balance task can objectively identify differences between youth hockey players with/without sport-related concussion (SRC); and 2) If there are balance control differences between players who participate in minor hockey and private hockey academy training. METHODS: Youth hockey players (N=47; age=12-17 years), who reported previous SRC (n=17) and CONTROL (n=30). Group 1 was from a minor hockey team (SRC1=4; CONTROL1=12) and group 2 a private hockey academy (SRC2=13, CONTROL2=18). Participants stood in single support on a Nintendo Wii Balance board sampled at 100Hz and performed a lower limb reaching task with their non-stance foot. Five FitLights were arranged on the floor anteriorly at +60°, +30°, and 0° and were used as Go(GREEN)/No-Go(RED) stimuli. Balance control was assessed using RMS velocity of COP (vCOP) in anterior-posterior (A/P) and medial-lateral (M/L) planes. RESULTS: There were significant differences for both A/P vCOP (SRC= 8.04cm/s; CONTROL= 11.04cm/s, p <.05) and M/L vCOP (SRC= 6.27cm/s; CONTROL= 7.72cm/s, p <.05), as the SRC group performed the task slower than CONTROL There were no significant differences between SRC1 and SRC2 in vCOP A/P (p=0.50) or M/L (p=0.26) likewise for CONTROL1 and CONTROL2 vCOP A/P (p=0.88) and M/L (p=0.97). CONCLUSION: The assessment of a visuomotor dynamic balance task can objectively identify youth athletes with previous history of SRC regardless of training levels. Incorporating cognitive-motor tasks may help to improve balance control deficits in youth post-SRC and ensure true readiness for return-to-sport. 1. Howell DR, Osternig LR, Chou LS. Adolescents demonstrate greater gait balance control deficits after concussion than young adults. The American journal of sports medicine. 2015 Mar;43(3):625-32.

VOLUME OF CONVEX HULL: A TECHNIQUE FOR QUANTIFYING HUMAN POSTURAL STABILITY

Many disorders, such as nervous system disorders, can affect orientation of the body segments in 3D space negatively. Patients with these disorders often show body segments instability during stance tasks. Nowadays, 3-axis gyroscopes are about to be used to measure postural stability. The main objective of the paper is to describe a method which would be suitable for quantifying postural stability and 3D movement as a whole using a cheap 3-axis gyroscope. New method based on the volume of a 3D convex hull (CH) obtained by plotting pitch, roll and yaw angles versus each other was proposed for quantitative evaluation of 3D trunk sway. The sway was measured while patients with degenerative cerebellar disorder (Pts) and eleven healthy subjects (HSs) performed quiet stance on a firm surface (FiS) and foam surface (FoS) with open eyes (OE) and closed eyes (CE). The CH was used to identify differences in balance control, and there were significant differences found between the two groups. The median (Mdn) of the volume of Pts with OE on FiS is four times larger than the Mdn of the volume of HS with OE on FiS. The Mdn of the volume of Pts with CE on FoS is 80 times larger than the Mdn of the volume of HS with CE on FoS. It was therefore found that the volume of CH is suitable for quantifying postural sway and identifying differences in balance control.

Trajectory length of pitch vs. roll: Technique for assessment of postural stability

Background: Patients with disorders of nervous or musculoskeletal system often show instability of the body segments during the stance tasks. Traditionally, stabilometric platforms are used to measure body sway. However, these devices are expensive and do not allow the evaluation of the individual movements of body segments. At present, accelerometers or gyroscopes are used to measure the movements of the body segments. For these new motion capture (MoCap) systems, methods for quantitative evaluation of a body segment movement are being developed. Objective: The main objective of this paper is to describe a new method which would be suitable for quantifying postural stability and identifying differences in balance control using data recorded by an inexpensive 2-DoF gyroscope. Methods: Method based on total length of trajectory (TL) in a 2-D plot of angles was proposed for quantitative evaluation of the trunk and feet sway. The sway was measured during quiet stance of ten middle-aged patients (Pts) with degenerative cerebellar disorder and eleven young healthy subjects (HS) standing with eyes open (EO) on a firm surface (FiS) and eyes closed (EC) on a foam surface (FoS). Data were obtained using three gyroscopes (Xsens) to measure roll and pitch angular movements of the trunk, and left and right foot. The pitch versus roll plots of the trunk and feet were created and the trajectory lengths of the pitch vs. roll angle were calculated. Results: Although the results vary while measuring different segments of the body, the method showed significant differences between the two different groups. Significant differences between the HS and Pts were found in EO standing on a FiS for TLs of the trunk (p = .02) and TLs of the feet (p < .01). Similarly in EC standing on a FoS significant differences (p < .01) between groups were found for TLs of both the trunk and the feet (p < .01). Conclusions: It was found that the TL of pitch vs. roll is suitable for quantifying postural sway and identifying differences in balance control. The technique, based on the length of the pitch angle vs. roll angle trajectory can be used even where MoCap systems can only measure two sway angles which could extend the clinical information of the body sway.

Effects of different types of exercise on muscle activity and balance control.

[Purpose] This study analyzed the effects of isotonic, isokinetic, and isometric exercises of ankle joint muscles on lower extremity muscle activity and balance control. [Subjects and Methods] The subjects were 30 healthy adults (15 males) in their 20s who were randomly assigned to three different exercise method groups of 10 people each. The isokinetic exercise group performed three sets at an angular velocity of 60°/sec, including a single rest period after every set of 10 repetitions. The isometric exercise group performed three sets consisting of three 15 repetitions of a 15-second exercise followed by a 5-second rest. [Results] Multivariate analysis of variance revealed that depending on the exercise method, the non-dominant tibialis anterior, gastrocnemius muscle, and peroneus longus showed significant differences in muscle activity for weight-bearing non-dominant sides; when the dominant side was weight-bearing, the dominant gastrocnemius and peroneus longus showed significant differences in muscle activity; and the non-dominant and dominant sides showed significant differences in balance control depending on the duration of support in the area. [Conclusion] Muscle fatigue from the three exercise methods produced a decline in muscle activity and balance control; due to the fatigue before exercise, the side that did not perform the exercises was affected.

Age-related neuromuscular function and dynamic balance control during slow and fast balance perturbations

This study investigated age-related differences in dynamic balance control and its connection to reflexes and explosive isometric plantar flexor torque in 19 males (9 Young aged 20-33 yr, 10 Elderly aged 61-72 yr). Dynamic balance was measured during Slow (15 cm/s) and Fast (25 cm/s) anterior and posterior perturbations. H/M-ratio was measured at 20% of maximal M-wave (H/M20%) 10, 30, and 90 ms after perturbations. Stretch reflexes were measured from tibialis anterior and soleus during anterior and posterior perturbations, respectively. In Slow, Elderly exhibited larger peak center-of-pressure (COP) displacement (15%; P < 0.05) during anterior perturbations. In Fast, Young showed a trend for faster recovery (37%; P = 0.086) after anterior perturbations. M-wave latency was similar between groups (6.2 ± 0.7 vs. 6.9 ± 1.2 ms), whereas Elderly showed a longer H-reflex latency (33.7 ± 2.3 vs. 36.4 ± 1.7 ms; P < 0.01). H/M20% was higher in Young 30 ms after Fast anterior (50%; P < 0.05) and posterior (51%; P < 0.05) perturbations. Plantar flexor rapid torque was also higher in Young (26%; P < 0.05). After combining both groups' data, H/M20% correlated negatively with Slow peak COP displacement (r = -0.510, P < 0.05) and positively with Fast recovery time (r = 0.580, P < 0.05) for anterior perturbations. Age-related differences in balance control seem to be more evident in anterior than posterior perturbations, and rapid sensory feedback is generally important for balance perturbation recovery.

Vestibulo-ocular response and balance control in children and young adults with mild-to-moderate intellectual and developmental disability: A pilot study

The vestibulo-ocular response (VOR) may not be fully developed in children with an intellectual and developmental disability (IDD). This study aimed to identify the presence of VOR deficit in children and young adults with unspecified mild-to-moderate intellectual and developmental disability and its effect on balance control. Twenty-one children and young adults with IDD ranging in age from 8 to 22 years (mean 17.5 ± 3.9 years) were included in the study. The VOR was evaluated with the Head Impulse Test and the Static and Dynamic Visual Acuity Test (S&D-VAT). Postural stability was measured in an upright standing position by the Clinical Test for Sensory Interaction in Balance (CTSIB), single leg stance (SLS) during eyes open and eyes closed, and Romberg stance under eyes open and eyes closed conditions using a force platform. Reduced vestibulo-ocular responses were found in 13 of 21 (62%) participants who were able to complete testing. In the fifth condition of the CTSIB (standing on foam with eyes closed), those without VOR deficit were able to maintain balance longer than those with VOR deficit (29 s [median 30] vs. 12s [median 7.3], respectively; p=0.03). The study demonstrates potential effects of VOR deficit in children and young adults with IDD and some significant differences in balance control between those with and without a VOR deficit. VOR function in children and young adults with IDD should be routinely tested to enable early detection of deficits.

The Role of Clinical and Instrumented Outcome Measures in Balance Control of Individuals with Multiple Sclerosis

Purpose. The aim of the study was to investigate differences in balance control between individuals with multiple sclerosis (MS) and healthy control subjects using clinical scales and instrumented measures of balance and determine relationships between balance measures, fatigue, and disability levels in individuals with MS with and without a history of falls. Method. Twelve individuals with MS and twelve healthy controls were evaluated using the Berg Balance and Activities-specific Balance Confidence Scales, Modified Clinical Test of Sensory Interaction on Balance, and Limits of Stability Tests as well as Fatigue Severity Scale and Barthel Index. Results. Mildly affected individuals with MS had significant balance performance deficits and poor balance confidence levels (P < 0.05). MS group had higher sway velocities and diminished stability limits (P < 0.05), significant sensory impairments, high fatigue and disability levels (P < 0.05). Sway velocity was a significant predictor of balance performance and the ability to move towards stability limits for the MS group. For the MS-fallers group, those with lower disability levels had faster movement velocities and better balance performance. Conclusion. Implementation of both clinical and instrumented tests of balance is important for the planning and evaluation of treatment outcomes in balance rehabilitation of people with MS.

Different gait tasks distinguish immediate vs. long-term effects of concussion on balance control.

The purpose of this study was to longitudinally compare the sensitivity of previously documented paradigms for measuring balance control during gait following a concussion. We hypothesized that gait with a concurrent cognitive task would be most sensitive to the effects of concussion on dynamic balance control. Individuals with concussion (n = 30) and matched controls (n = 30) performed a single task of level walking, attention divided walking, and an obstacle-crossing task at two heights. Testing occurred four times post-injury. Balance control during gait was assessed with whole-body center of mass and center of pressure motion. The single-task level walking task did not result in any significant differences in balance control between individuals with concussion and control subjects. Within 48 hours post-injury, individuals with concussion walked slower and allowed less motion of their center of mass in the sagittal plane when attention was divided during walking, but there were no group differences by day 6 for this task. Group differences in balance control during obstacle crossing was unremarkable during the first two testing sessions, but by day 14 individuals with concussion displayed less mediolateral motion of their center of mass. Attention divided gait is able to better distinguish gait adaptations immediately following a concussion, but obstacle crossing can be used further along in the recovery process to detect new gait adaptations.

Sensitivity of Accelerometry to Assess Balance Control During Sit-to-Stand Movement

Accelerometry has the potential to measure balance, defined as high-frequency body sway, ambulatorily in a simple and inexpensive way. The aim of this study was to determine and compare the sensitivity of accelerometric balance parameters during the sit-to-stand (STS) movement. Eleven healthy subjects (four males, 28.2 +/-7.9 years) and 31 patients with stroke (21 males; 63.3+/-12.8 years) were included. The healthy subjects performed STS movements in four conditions with different levels of difficulty. Data of the patients were compared 1) with healthy subjects, 2) between patient subgroups, and 3) between different phases of recovery to assess the sensitivity of accelerometry for differences in balance control. Accelerometers were attached to the trunk, and force plate measurements were simultaneously done in the healthy subjects. Main outcome measures were root mean square (rms) and area under the curve (AUC) derived from the high-frequency component of the transversal acceleration signal of the trunk. In all comparisons there was a significant difference in AUC data ( p < 0.05), and AUC appeared to be more sensitive than rms. Variability in AUC was not completely or mainly the result of changes and differences in the duration of the STS movement. As a conclusion, accelerometry is a potentially valuable technique to measure balance during the STS movement.

Postural balance and health-related factors in middle-aged and older women with injurious falls and non-fallers.

Older fallers aged over 70 years have shown impaired balance abilities, but it is unclear if impairment in balance control can be detected among fallers who are in their 50's and 60's. The aim of this study was to analyze possible differences in balance control and other health-related factors between female fallers and non-fallers aged 50-68 years. Women 50-68 years of age (N=40) who had fallen outside and needed medical attention were recruited through a larger fall accident study. Non-fallers (N=97) were women representing the same age group who had not fallen during the preceding 12 months. A battery of standing force platform balance tests were administered together with an interview on health status, use of medication, dizziness, vision, hearing, and physical activity. Significant differences were not found between women with injurious falls and non-fallers in the various balance tests. In the younger age group (50-58 years), chronic illnesses, use of medication, dizziness, and self-reported problems with vision and hearing were more common in fallers than in non-fallers. Our results suggest that, in active and independent women aged 50-68 years, it is not possible to use standing force platform balance tests to detect differences between fallers and non-fallers. However, younger women (50-58 years) with injurious falls reported more health-related problems than other groups, a fact which should be taken into consideration to prevent further development of fall-related problems.