Adaptation in motor strategies for postural control associated with sensory reweighting.

The purpose of this study was to identify and differentiate the motor strategies associated with sensory reweighting adapted during specific sensory integration tasks by healthy young adults. Thirty-six subjects (age range: 21-33 years) performed standing computerized dynamic posturography balance tasks across progressively increasing amplitudes of visual (VIS), somatosensory (SOM) and both (VIS+SOM) systems perturbation conditions. Adaptation in the motor strategy was measured as changes in electromyographic (EMG) activities and joint angles. The contribution of the perturbed sensory input in maintaining postural stability was calculated to determine the sensory reweighting. A multivariate design was used to model a linear combination of motor adaptation variables that discriminates specific sensory integration tasks. Results showed a significant progressive decrease in postural sway per unit amplitude of sensory perturbation in each condition, indicating dynamic sensory reweighting. Linear discriminant function analysis indicated that the adaptation in motor strategy during the VIS condition was associated with increased activity of EMG and joint angles in the upper body compared to the lower body. Conversely, during the SOM and VIS+SOM conditions, the adaptation in motor strategy was associated with decreased activity of EMG and joint angles in the lower body compared to the upper body. Therefore, the adaptation in motor strategies associated with sensory reweighting were different for different sensory integration tasks.

Exploration of arm weight effects on hemiparetic stroke participants' gait performance.

BACKGROUND: This study explores the potential benefits of an arm weight intervention for improving gait performance in stroke survivors. Consistent with an interlimb neural coupling mechanism, the investigators hypothesized that arm weight would improve gait performance. METHODS: Nine stroke and nine healthy participants (1 female; age: 58.0 ± 6.8 years) participated. Participants walked over-ground at their preferred speed in four conditions: no weight (C1), non-hemiparetic (healthy: dominant) side weights (C2), hemiparetic (non-dominant) side weights (C3), and bilateral weights (C4). Statistical analyses included repeated analysis of variance (ANOVA) and paired t-test planned comparisons to explore the effects of added weight on gait speed, step width, step length, cadence, and arm swing amplitude. Single-subject analyses used randomization tests to delineate further the weight's effect on gait speed. FINDINGS: The stroke group walked significantly faster with arm weight (p = 0.048), exhibiting large ANOVA (η2p = 0.28) and C1 vs. C4 planned comparison (p = 0.021; dD = 0.95) effect sizes. Four of nine stroke participants significantly increased gait speed in at least one condition, and seven of nine exhibited large effect size increases (d = 0.85-4.71). The stroke group's hemiparetic-side step length and cadence significantly (p = 0.008) increased in C4 compared to C1, exhibiting large effect size increases (rb = 0.96). Four of nine healthy participants significantly increased gait speed in at least one condition, with five of nine exhibiting large effect size increases (d = 0.80-6.63). INTERPRETATION: This study's exploratory results demonstrate arm weight's potential for improving higher-functioning stroke survivors' gait performance. Arm weight addition merits further investigation as a possible rehabilitation intervention in the stroke population.

Kinematic Validation of Postural Sway Measured by Biodex Biosway (Force Plate) and SWAY Balance (Accelerometer) Technology.

BACKGROUND: The Biodex Biosway® Balance System and SWAY Balance® Mobile smartphone application (SBMA) are portable instruments that assess balance function with force plate and accelerometer technology, respectively. The validity of these indirect clinical measures of postural sway merits investigation. PURPOSE: The purpose of this study was to investigate the concurrent validity of standing postural sway measurements by using the portable Biosway and SBMA systems with kinematic measurements of the whole body Center of Mass (COM) derived from a gold-standard reference, a motion capture system. STUDY DESIGN: Cross-sectional; repeated measures. METHODS: Forty healthy young adults (21 female, 19 male) participated in this study. Participants performed 10 standing balance tasks that included combinations of standing on one or two legs, with eyes open or closed, on a firm surface or foam surface and voluntary rhythmic sway. Postural sway was measured simultaneously from SBMA, Biosway, and the motion capture system. The linear relationships between the measurements were analyzed. RESULTS: Significant correlations were found between Biosway and COM velocity for both progressively challenging single and double leg stances (τ b = 0.3 to 0.5, p < 0.01 to <0.0001). SBMA scores and COM velocity were significantly correlated only for single leg stances (τ b = -0.5 to -0.6, p < 0.0001). SBMA scores had near-maximal values with zero to near-zero variance in double leg stances, indicating a ceiling effect. CONCLUSION: The force plate-based Biodex Biosway is valid for assessing standing postural sway for a wide range of test conditions and challenges to standing balance, whereas an accelerometer-based SWAY Balance smartphone application is valid for assessing postural sway in progressively challenging single leg stance but is not sensitive enough to detect lower-magnitude postural sway changes in progressively challenging double leg stances.

Effects of arm weight on gait performance in healthy subjects.

Previous studies have investigated how additional arm weights affect gait. Although light weights (0.45 kg) seemed to elicit performance improvements in Parkinsonian patients, it was not studied how light weights affect gait parameters in healthy individuals. It is important to understand normal responses in a healthy population so that clinical effects might be better understood. Therefore, the purpose of this study was to investigate the effects of arm weights on arm swing amplitude, gait performance, and muscle activity in healthy people. Twenty-two subjects walked overground at their preferred speed under different weight carriage conditions (C1: no weight; C2: unilateral arm weight; C3: bilateral arm weights; C4: waist weights). Gait speed increased in C2 (p = 0.018) and C4 (p = 0.013) when compared with C1(C1: 1.21 ±â€¯0.08; C2: 1.25 ±â€¯0.11; C3: 1.24 ±â€¯0.11; C4: 1.25 ±â€¯0.11 m/s) with an increase in cadence during C2 (p < 0.001), C3 (p = 0.008), and C4 (p < 0.001) (C1: 105.5 ±â€¯5.2; C2: 108.5 ±â€¯5.6; C3: 107.9 ±â€¯5.6; C4: 108.5 ±â€¯5.3 steps/min) and in tibialis anterior electromyographic activity on the unweighted side in C2 (p = 0.048) (C1: 21.05 ±â€¯4.59; C2: 25.10 ±â€¯6.10; C3: 23.93 ±â€¯4.75; C4: 24.33 ±â€¯6.32 µV). The results indicate that an additional sensory input with the application of the weights may result in an overcompensation with the whole body and facilitate faster walking speed when applied on one arm or around the waist. The locations of the weights and amount of the weights may elicit different responses. Various strategies of adding weights should be further investigated as a potential intervention to improve performance in individuals with various gait impairments. Although there is evidence for benefits of this intervention in Parkinsonian patients, further study is warranted in other patient populations, such as stroke patients, who might benefit from this intervention to improve gait performance.

Functional gait assessment: concurrent, discriminative, and predictive validity in community-dwelling older adults.

BACKGROUND: The Functional Gait Assessment (FGA) is a reliable and valid measure of gait-related activities. OBJECTIVE: The purpose of this study was to determine the concurrent, discriminative, and predictive validity of the FGA in community-dwelling older adults. DESIGN: This was a prospective cohort study. METHODS: Thirty-five older adults aged 60 to 90 years completed the Activities-specific Balance Confidence Scale (ABC), Berg Balance Scale (BBS), Dynamic Gait Index (DGI), Timed "Up & Go" Test (TUG), and Functional Gait Assessment (FGA) during one session. Falls were tracked by having participants complete a monthly fall calendar for 6 months. Spearman correlation coefficients were used to determine concurrent validity among the ABC, BBS, TUG, DGI, and FGA. To determine the optimum scores to classify fall risk, sensitivity (Sn), specificity (Sp), and positive and negative likelihood ratios (LR+ and LR-) were calculated for the FGA in classifying fall risk based on the published criterion scores of the DGI and TUG and for the FGA, TUG, and DGI in identifying prospective falls. Receiver operator curves with area under the curve were used to determine the effectiveness of the FGA in classifying fall risk and of the DGI, TUG, and FGA in identifying prospective falls. RESULTS: The FGA correlated with the ABC (r=.053, P<.001), BBS (r=.84, P<.001), and TUG (r=-.84, P<.001). An FGA score of

Effects of multidisciplinary Internet-based program on management of heart failure.

OBJECTIVES: To develop and test the effectiveness of an Internet-based self management program by multidisciplinary health care professionals for patients with heart failure (HF). METHODS: The comprehensive educational material for HF was created and posted on a website. A computer with Internet connection and computer training were provided first. A secure and simple web-based recording system of vital signs and health behaviors and a mechanism for feedback regarding each participant's record were developed. A randomized controlled trial with a one-year intervention was conducted using a total of 40 patients who were assessed three times in their homes. An intention-to-treat analysis used multivariate statistics. RESULTS: The treatment group had a high (85%) adherence to the intervention. Only the treatment group showed a significant improvement in the knowledge level (p < 0.001), amount of exercise (p = 0.001), and quality of life (p = 0.001), and reduction in HF related symptoms (dyspnea, p = 0.001; fatigue, p = 0.003; functional emotion, p < 0.001), blood pressure (systolic, p = 0.002; diastolic, p < 0.001), frequency of emergency room visit, and length of hospital stay (both p = 0.001). CONCLUSIONS: An effective program to change one's behaviors in managing HF takes a multidisciplinary approach to create and provide feedback regarding a patient's daily record, which can be accomplished through Internet use.