The influence of locomotor training on dynamic balance during steady-state walking post-stroke

The effect of amplitude normalization technique, walking speed, and reporting metric on whole-body angular momentum and its interpretation during normal gait

Whole-body angular momentum (WBAM) represents the cancellations of angular momenta that are produced during a reciprocal gait pattern. WBAM is sensitive to small changes and is used to compare dynamic gait patterns under different walking conditions. Study designs and the normalization techniques used to define WBAM vary and make comparisons between studies difficult. To address this problem, WBAM about each anatomical axis of rotation from a healthy control population during normal gait were investigated within four metrics: 1) range of WBAM, 2) integrated WBAM, 3) statistical parametric mapping (SPM), and 4) principal component analysis (PCA). These data were studied as a function of walking speed and normalization. Normalization techniques included: 1) no normalization, 2) normalization by height, body mass and walking speed, and 3) normalization by height, body mass and a scalar number, gravity×height, that is independent of walking velocity. Significant results were obtained as a function of walking speed regardless of normalization technique. However, the interpretation of significance within each metric was dependent on the normalization technique. Method 3 was the most robust technique as the differences were not altered from the expected relationships within the raw data. Method 2 actually inverted the expected relationship in WBAM amplitude as a function of walking speed, which skewed the results and their interpretation. Overall, SPM and PCA statistical methods provided better insights into differences that may be important. However, depending on the normalization technique used, caution is advised when interpreting significant findings when comparing participants with disparate walking speeds.

The influence of backward versus forward locomotor training on gait speed and balance control post-stroke: Recovery or compensation?

Backward walking training has been reported to improve gait speed and balance post-stroke. However, it is not known if gains are achieved through recovery of the paretic limb or compensations from the nonparetic limb. The purpose of this study was to compare the influence of backward locomotor training (BLT) versus forward locomotor training (FLT) on gait speed and dynamic balance control, and to quantify the underlying mechanisms used to achieve any gains. Eighteen participants post chronic stroke were randomly assigned to receive 18 sessions of either FLT (n = 8) or BLT (n = 10). Pre- and post-intervention outcomes included gait speed (10-meter Walk Test) and forward propulsion (time integral of anterior-posterior ground-reaction-forces during late stance for each limb). Dynamic balance control was assessed using clinical (Functional Gait Assessment) and biomechanical (peak-to-peak range of whole-body angular-momentum in the frontal plane) measures. Balance confidence was assessed using the Activities-Specific Balance Confidence scale. While gait speed and balance confidence improved significantly within the BLT group, these improvements were associated with an increased nonparetic limb propulsion generation, suggesting use of compensatory mechanisms. Although there were no improvements in gait speed within the FLT group, paretic limb propulsion generation significantly improved post-FLT, suggesting recovery of the paretic limb. Neither training group improved in dynamic balance control, implying the need of balance specific training along with locomotor training to improve balance control post-stroke. Despite the within-group differences, there were no significant differences between the FLT and BLT groups in the achieved gains in any of the outcomes.

Efficacy and Cost over 12 Hospitalization Weeks of Postacute Care for Stroke

Few studies have investigated changes in functional outcomes and economic burden in patients in the postacute care cerebrovascular disease (PAC-CVD) program. We, for the first time, retrospectively investigated changes in functional performance and the national health insurance (NHI) cost over 12 PAC-CVD hospitalization weeks and evaluated the therapeutic effects of the PAC-CVD program on the NHI cost. Specifically, the functional outcomes and NHI cost of 263 stroke patients in the PAC-CVD program were analyzed. The repeated measures t test was used to compare functional performance over 0-3 weeks, and a one-way repeated measures multivariate analysis of variance was used to compare functional performance and NHI costs during weeks 0-6 and 0-9. The Wilcoxon signed-rank test was used to compare functional performance over weeks 9-12. Hierarchical multiple regression was used to estimate the effects of functional performance on NHI costs during weeks 3, 6, and 9. Over weeks 0-12, all functional performance measures demonstrated significant improvements. Changes in NHI costs varied depending on whether hospitalization was extended. At any time point, functional performance did not have a significant impact on NHI cost. Therefore, the PAC-CVD program may aid patients with stroke in sustainably regaining functional performance and effectively controlling economic burden.

Design and evaluation of a multimodal balance training system

OBJECTIVE

Current balance training systems are designed exclusively for one particular type of training and assessment. Additionally, they comprise monotonous training programs. Therefore, patients in different stages of rehabilitation must use different balance training models from different manufacturers, resulting in high treatment cost. Furthermore, large spaces are required to accommodate the balance training machines, and doctors and physiotherapists have to learn to operate multiple machines. We aimed to design a multimodal balance training and assessment system that can accommodate the assessment and training of static, dynamic, reactive and proactive balance to satisfy individual needs.

METHODS

The difficulty associated with combining static, dynamic, reactive and proactive balance training in a single system was to use radial and circumferential driving mechanisms together with a clutch mechanism, whereby circumferential and radial drivers were installed in the base of the system to drive a compound foot plate system with interchangeable springs, in order to adjust stiffness using the clutch. Based on the kinematic equation, the influence of system parameters on the change of the body's center of gravity were evaluated. The parameters included the radial offset of the driving mechanism (r), circumferential angle of rotation (θ), height of the base of the balance training system (h), horizontal distance between the body's standing center of gravity and the center of the foot plate (R), thickness of the padding mat (ΔH) and inclination angle (α).

RESULTS

The difficulties associated with combining static, dynamic, reactive and proactive balance training models in a single system were solved using radial and circumferential driving mechanisms together with a clutch mechanism. The foot plate can swing back and forth within ±20° around the X-axis, swing left and right within ±20° around the Y-axis, swing diagonally within ±20°, swing 360° around the Z-axis, and adjust the height along the Z-axis. Furthermore, the inclination angle α, circumferential angle of rotation θ, and speed (dα/dt and dθ/dt) of the system can be controlled in real time.

CONCLUSION

The developed balance training system is suitable for patients in different stages of rehabilitation. By providing multiple functionalities, this system can ensure high use rates, reduce costs and save space.

Dynamic Balance during Human Movement: Measurement and Control Mechanisms

Walking can be exceedingly complex to analyze due to highly nonlinear multi-body dynamics, nonlinear relationships between muscle excitations and resulting muscle forces, dynamic coupling that allows muscles to accelerate joints and segments they do not span, and redundant muscle control. Walking requires the successful execution of a number of biomechanical functions such as providing body support, forward propulsion and balance control, with specific muscle groups contributing to their execution. Thus, muscle injury or neurological impairment that affects muscle output can alter the successful execution of these functions and impair walking performance. The loss of balance control in particular can result in falls and subsequent injuries that lead to the loss of mobility and functional independence. Thus, it is important to assess the mechanisms used to control balance in clinical populations using reliable methods with the ultimate goal of improving rehabilitation outcomes. In this review, we highlight common clinical and laboratory-based measures used to assess balance control and their potential limitations, show how these measures have been used to analyze balance in several clinical populations, and consider the translation of specific laboratory-based measures from the research laboratory to the clinic.