Balance control and adaptation of kinematic synergy in aging adults during forward trunk bending

The present study focuses on the organization of kinematic synergy and its adaptation to an unstable support surface during upper trunk movements in aging adults. Seven healthy aging adults (49-66 years old) were instructed to bend the trunk forward (the head and the trunk together) by about 40 degrees and to stabilize their final position, in the standard condition (both feet on the ground), and on a seesaw swinging in the sagittal plane. Kinematic synergy was quantified by performing a principal components analysis on the hip, knee and ankle angle changes during the movement. The results indicate that trunk bending was represented by a single component (PC1) in both conditions, indicating a strong coupling between the angle changes during the movement. The results also show a reorganization of the contribution of PC1 to the three angles when the balance constraints are increased in the seesaw condition. It is concluded that kinematic synergy is preserved during trunk bending in aging adults, regardless of the support conditions. It can also be adapted when the balance constraints are increased by changing the ratio between the angles, indicating a modification of interjoint coordination without modifying the movement's trajectory.     

How a plantar pressure-based,tongue-placed tactile biofeedback modifies postural control mechanisms during quiet standing

The purpose of the present study was to determine the effects of a plantar pressure-based, tongue-placed tactile biofeedback on postural control mechanisms during quiet standing. To this aim, 16 young healthy adults were asked to stand as immobile as possible with their eyes closed in two conditions of No-biofeedback and Biofeedback. Centre of foot pressure (CoP) displacements, recorded using a force platform, were used to compute the horizontal displacements of the vertical projection of the centre of gravity (CoG _v ) and those of the difference between the CoP and the vertical projection of the CoG (CoP-CoG _v ). Analysis of the CoP-CoG _v displacements showed larger root mean square (RMS) and mean power frequencies (MPF) in the Biofeedback than in the No-biofeedback condition. Stabilogram-diffusion analysis further showed a concomitant increased spatial and reduced temporal transition point co-ordinates at which the corrective processes were initiated and an increased persistent behaviour of the CoP-CoG _v displacements over the short-term region. Analysis of the CoG _v displacements showed decreased RMS and increased MPF in the Biofeedback relative to the No-biofeedback condition. Stabilogram-diffusion analysis further indicated that these effects mainly stem from reduced spatio-temporal transition point co-ordinates at which the corrective process involving CoG _v displacements is initiated and an increased anti-persistent behaviour of the CoG _v displacements over the long-term region. Altogether, the present findings suggest that the main way the plantar pressure-based, tongue-placed tactile biofeedback improves postural control during quiet standing is via both a reduction of the correction thresholds and an increased efficiency of the corrective mechanism involving the CoG _v displacements.     

膝骨性关节炎患者平衡功能障碍及其影响因素分析

目的 探讨膝骨性关节炎（KOA）患者平衡功能及其相关影响因素。方法 选取2014年12月至2017年9月合肥市第二人民医院骨科收治的单膝受累30例KOA患者为观察对象,采用平衡测试仪对患者进行平衡功能检测,比较健、患侧测试完成耗时及平均轨迹误差,收集患者体质量指数、K-L分级、疼痛指数、美国膝关节协会评分（KSS）等指标,利用多元回归分析上述指标对患者平衡功能的影响。结果 患者健、患侧平衡指标比较,患侧平均轨迹误差值（46.63±25.30）%大于健侧值（40.77±23.85）%,差异有统计学意义（t=-2.299,P<0.05）;多元回归分析示：KSS临床评分对睁眼时前-后平均运动速度（t=-2.593,P<0.05）及重心摆动轨迹长度（t=-2.178,P<0.05）的影响具有统计学意义,对两者变异的解释比例分别为19%、15%,而疼痛指数对闭眼轨迹长度/睁眼轨迹长度比（Romberg值长度比）的影响具有统计学意义（t=-2.641,P<0.05）,解释比例为20%。结论 KOA患者存在平衡功能障碍;膝关节疼痛指数及KSS临床评分对于评估KOA患者平衡功能障碍具有重要意义。     

老年脑卒中偏瘫患者的平衡训练

对１０９例老年脑卒中偏瘫患者平衡训练进行观察，发现患者经训练后，各项能力都有明显改善。与老年前期组相比无差别。训练对恢复运动及日常生活活动很有价值。观察还表明，平衡能力由高到低呈规律性变化，对指导平衡训练及判断预后有参考作用。     

Associations Between Adherence to the Physical Activity and Exercise Program Applied in the LAST Study and Functional Recovery After Stroke

ObjectiveTo investigate the associations between participants’ adherence to a physical activity and exercise program after stroke and functional recovery 18 months after inclusion.DesignSecondary analyses of the intervention arm in the multisite randomized controlled trial Life After Stroke (LAST).SettingPrimary health care services in 3 Norwegian municipalities.ParticipantsOf the participants enrolled (N=380), 186 (48.9%) were randomized to the intervention. The study sample comprised community dwelling individuals included 3 months after stroke, with mean age of 71.7 ± 11.9 years and 82 (44.1%) women. According to the National Institutes of Health Stroke Scale, 97.3% were diagnosed as having mild (National Institutes of Health Stroke Scale<8) and 2.7% with moderate (8-16 on the National Institutes of Health Stroke Scale) stroke.InterventionMonthly coaching by physiotherapists encouraging participants to adhere to 30 minutes of daily physical activity and 45-60 minutes of weekly exercise.Main Outcome MeasuresThe primary outcome was Motor Assessment Scale (MAS). Secondary outcome measures were 6-minute walk test, Timed Up and Go (TUG), Berg Balance Scale (BBS), and the physical domains of the Stroke Impact Scale (SIS). Adherence was assessed by combining participants’ training diaries and physiotherapists’ reports.ResultsThe relationship between adherence and functional recovery was analyzed with simple and multiple linear regression models. Adjusted for age, sex, dependency, and cognition, results showed statistically significant associations between adherence and functional outcomes after 18 months, as measured by MAS, TUG, BBS, and SIS (P≤.026).ConclusionsIncreased adherence to physical activity and exercise was associated with improved functional recovery after mild to moderate stroke. This emphasizes the importance of developing adherence-enhancing interventions. Dose-response studies are recommended for future research.     

Balance control interferes with the tracing performance of a pattern with mirror-reversed vision in older persons

GeroScience - When tracing a template with mirror-reversed vision (or distorted vision), the sensory information arising from the movement does not match the expected sensory consequences. In such...     

Test-retest reliability of stability outcome measures during treadmill walking in patients with balance problems and healthy controls

BackgroundImprovement of balance control is an important rehabilitation goal for patients with motor and sensory impairments. To quantify balance control during walking, various stability outcome measures have described differences between healthy controls and patient groups with balance problems. To be useful for the evaluation of interventions or monitoring of individual patients, stability outcome measures need to be reliable.Research questionWhat is the test-retest reliability of six stability outcome measures during gait?MethodsPatients with balance problems (n = 45) and healthy controls (n = 20) performed two times a two-minute walk test (2MWT). The intraclass correlation coefficient (ICC) and Bland-Altman analysis (coefficient of repeatability; CR) were used to evaluate the test-retest reliability of six stability outcome measures: dynamic stability margin (DSM), margin of stability (MoS), distance between the extrapolated centre of mass (XCoM) and centre of pressure (CoP) in anterior-posterior (XCoM-CoP_AP) and medial-lateral (XCoM-CoP_ML) direction, and inclination angle between centre of mass (CoM) and CoP in anterior-posterior (CoM-CoP_AP-angle) and medial-lateral (CoM-CoP_ML-angle) direction. A two way mixed ANOVA was performed to reveal measurement- and group-effects.ResultsThe ICCs of all stability outcome measures ranged between 0.51 and 0.97. Significant differences between the measurements were found for the DSM (p = 0.017), XCoM-CoP_AP (p = 0.008) and CoM-CoP_AP-angle (p = 0.001). Significant differences between controls and patients were found for all stability outcome measures (p < 0.01) except for the MoS (p = 0.32). For the XCoM-CoP distances and CoM-CoP angles, the CRs were smaller than the difference between patients and controls.SignificanceBased on the ICCs, the reliability of all stability outcome measures was moderate to excellent. Since the XCoM-CoP_ML and CoM-CoP_ML-angle showed no differences between the measurements and smaller CRs than the differences between patients and controls, the XCoM-CoP_ML and CoM-CoP_ML-angle seem the most promising stability outcome measures to evaluate interventions and monitor individual patients.     

Relationship between Nintendo’s Wii balance board derived variables and clinical balance scores in individuals with stroke

BackgroundThe Wii Balance Board (WBB) is widely studied as a balance testing platform and is reliable in detecting changes in the body’s center of pressure (COP). However, the relationship between WBB derived measures and clinical tests of balance is currently unknown.Research questionTo investigate the association between static and dynamic COP measures from the WBB with balance tests commonly used in chronic stroke.MethodsThis retrospective study included sixty-nine individuals with stroke who performed the Berg Balance Score (BBS), the Mini-BESTest and WBB assessments as a part of their baseline measurements. The WBB assessments included body weight symmetry and a dynamic target matching task that measured Reaction Time (RT) and Completion Time (CT).ResultsBody weight symmetry performed with eyes open was significantly different between participants who were classified as high and moderate balance using the Mini-BESTest (p = 0.03). A significant negative linear correlation was observed between the BBS and CT (rho = -0.29, p = 0.021) and between the Mini-BESTest and RT (rho=-0.246, p = 0.05).SignificanceWe provide preliminary but weak evidence supporting the relationship between WBB derived variables in relevance to the BBS and Mini-BESTest. Further research is needed to fully understand the clinical utility of the WBB especially in a larger sample and to generalize these results to stroke survivors at all levels of ability.     

Instrumented platforms for balance and proprioceptive assessment in patients with total knee replacement: A systematic review and meta-analysis

BackgroundThe functional outcome of total knee replacement (TKR) is usually satisfying. However, patients may show functional limitations for years after surgery, which have been ascribed to impairments in balance and proprioception, mainly during standing tasks. A number of instrumentations and parameters have been used, rising confusion for clinical decisions on the assessment of patients.Research questionWhich are the most widespread and consistent procedures to assess balance and proprioception following TKR?MethodsA literature review was conducted in Pubmed, PEDro, and Cochrane database. From a total sample of 112 articles, 23 original studies published between 2008 and 2019 met inclusion criteria. The primary outcomes selected were variables related to balance and proprioception assessment in static and dynamic tasks performed with instrumented platforms. Data from papers using the same instrumentation, on patients with unilateral TKA and at least 12 months postoperatively were synthesized quantitatively in a random effect meta-analysis.ResultsFourteen articles were appropriate for the review. A large variability was found both in the instrumentation and the parameters used. The Neurocom Balance Master System™ was the most used instrument (four articles). On a total population of 186 patients with unilateral TKR 12 months postoperatively, a low degree of heterogeneity was found adopting the random effect in the four tasks explored (Firm and Foam Surface both with Eyes Open and Eyes Closed).SignificanceThis review found a large variability in the instrumentation used to assess balance and proprioception in patients operated on TKR. The meta-analysis demonstrated that the Neurocom Balance Master System™ for static assessment of balance showed an acceptable consistency and can be considered as a reference for further studies. However, balance and proprioception impairments following TKR have not been widely quantified by means of instrumented platforms. Further research is needed to address this issue, and improve clinical practice.