Adaptive treadmill walking encourages persistent propulsion

BackgroundAdaptive treadmills allow real-time changes in walking speed by responding to changes in step length, propulsion, or position on the treadmill. The stride-to-stride variability, or persistence, of stride time during overground, fixed-speed, and adaptive treadmill walking has been studied, but persistence of propulsion during adaptive treadmill walking remains unknown. Because increased propulsion is often a goal of post-stroke rehabilitation, knowledge of the stride-to-stride variability may aid rehabilitation protocol design.Research questionHow do spatiotemporal and propulsive gait variables vary from stride to stride during adaptive treadmill walking, and how do they compare to fixed-speed treadmill walking?MethodsEighteen young healthy subjects walked on an instrumented split-belt treadmill in the adaptive and fixed-speed modes for 10 minutes at their comfortable speed. Kinetic data was collected from the treadmill. Detrended fluctuation analysis was applied to the time series data. Shapiro-Wilk tests assessed normality and one-way repeated measures ANOVAs compared between adaptive, fixed-speed, and randomly shuffled conditions at a Bonferroni-corrected significance level of 0.0055.ResultsStride time, stride length, step length, and braking impulse were persistent (α > 0.5) in the adaptive and fixed-speed conditions. Adaptive and fixed-speed were different from each other. Stride speed was persistent in the adaptive condition and anti-persistent (α < 0.5) in the fixed-speed condition. Peak propulsive force, peak braking force, and propulsive impulse were persistent in the adaptive condition but not the fixed-speed condition (α ≈ 0.5). Net impulse was non-persistent in the adaptive and fixed-speed conditions. All variables were non-persistent in the shuffled condition.SignificanceDuring adaptive treadmill walking, increases in propulsive force and impulse persist for multiple strides. Persistence was stronger on the adaptive treadmill, where increased propulsion translates into increased walking speed. For post-stroke gait rehabilitation where increasing propulsion and speed are goals, the stronger persistence of adaptive treadmill walking may be beneficial.     

Reliability of the fluctuations within the stride time series measured in runners during treadmill running to exhaustion

BackgroundThe fluctuations within stride time series (i.e., stride time variability and complexity) during running exhibit long-range correlation. Detecting the breakdown of the long-range correlation was proposed for monitoring the occurrence of running-related injuries during running. However, the stride time fluctuations were only measured from the unilateral side. In addition, the reliability of the stride time fluctuations of within-subject repeated measures remains largely unknown, particularly during exhaustive running.PurposesThis study investigated between-side and between-day reliabilities of the stride time variability and complexity of right and left sides during an exhaustive running.MethodsThe stride time variability and complexity of bilateral sides were obtained while 24 healthy participants performed a 31-minute treadmill running at their individual anaerobic threshold speed. Seven of the 24 participants performed the treadmill running test twice at two different days 5–7 days apart. Limits of agreement (LoA) and intraclass correlation coefficient (ICC) were respectively used to assess the absolute and relative between-side and between-day reliabilities.ResultsThe stride time variability and complexity of right and left sides were highly symmetrical (LoA: (-0.500%, 0.459%) and (-0.052, 0.051), respectively; ICC: 0.94 (0.87, 0.97) and 0.98 (0.95, 0.99), respectively). The overall stride time variability and complexity revealed good between-day reliability (LoA: (-1.044%, 0.724%) and (-0.067, 0.115), respectively; ICC: 0.78 (0.45, 0.92) and 0.81 (0.48, 0.93), respectively). However, the segmented stride time complexity showed poor between-day reliability (ICCs<0.40).ConclusionThe findings demonstrated that the stride time series showed equivalent fluctuations between right and left sides and good between-day reliability in fluctuations during exhaustive running. Given the poor between-day reliability in the segmented stride time series, stride time series during exhaustive running could be collected from either right or left side and should be processed as an overall in the future.     

Evaluation of tools for annual capture of adherence to immunosuppressive medications after renal transplantation – a single‐centre open prospective trial

Annual assessment of adherence would strengthen long‐term outcome assessments from registry data. The objective of this study was to evaluate tools suitable for annual routine capture of adherence data in renal transplant recipients. A single‐centre open prospective trial included 295 renal transplant recipients on tacrolimus. Two‐thirds of the patients were included 4 weeks post‐transplant, randomized 1:1 to intensive or single‐point adherence assessment in the early phase and 1‐year post‐transplant. One‐third were included 1‐year post‐transplant during a cross‐sectional investigation. Adherence was assessed using multiple methods: The “Basel Assessment of Adherence to Immunosuppressive Medication Scale” (BAASIS^©) questionnaire was used to assess self‐reported adherence. The treating clinician scored patient′s adherence and tacrolimus trough‐concentration variability was calculated. In the analyses, the data from the different tools were dichotomized (adherent/nonadherent). The BAASIS^© overall response rate was over 80%. Intensive BAASIS^© assessment early after transplantation increased the chance of capturing a nonadherence event, but did not influence the 1‐year adherence prevalence. The adherence tools generally captured different populations. Combining the tools, the nonadherence prevalence at 1 year was 38%. The different tools identified to a large degree different patients as nonadherent. Combining these tools is feasible for annual capture of adherence status.     

Fractal analysis of gait in people with Parkinson’s disease: three minutes is not enough

BackgroundThe fractal dynamics of gait variability in people with Parkinson’s disease has been studied by applying the detrended fluctuation analysis (DFA) to short time series (<200 strides). However, DFA is sensitive to time series length, and it is unclear if DFA results from short time series are reliable and if they reflect the fractal dynamics of longer time series.Research questionIs DFA reliable when applied to short time series?MethodsWe applied DFA to stride time series from five 3-min trials and one 15-min trial in 12 people with Parkinson’s disease, 14 healthy older adults and 14 healthy young adults walking overground. Within each group, intraclass correlations (ICC 3,1) were performed to assess the reliability of i) the five 3-min trials together, ii) each 3-min trials to the 15-min trial, and iii) the first 150 strides from the 15-min trial to the full 15-min trial.ResultsOur three main findings are that 1) stride time α-DFA values are not consistent from trial-to-trial for short stride time series, 2) stride time α-DFA values from each 3-min trials are not consistent when compared to stride time α-DFA values from a 15-min trial, and 3) stride time α-DFA values from the first 150 strides of the 15-min trial are not consistent when compared to α-DFA values from the full 15-min trial.SignificanceOur results confirm that α-DFA values from 3-min walking trials are not reliable, and that they do not reflect the scale invariant properties of longer time series. This suggests that previous studies assessing the fractal dynamics of gait variability from about 3-min walking must be interpreted with caution. A major clinical implication is that DFA cannot be used to study gait in people unable to perform 500 strides continuously.     

Assessment of diurnal variation of stride time variability during continuous,overground walking in healthy young adults

Background: There is emerging evidence that gait variability outcomes provide unique insights regarding the status of an individual’s locomotor control system; however, there is currently limited evidence on the within-day reliability of stride time variability (STV) outcomes, or whether they demonstrate diurnal variation, when measured during continuous, overground walking in healthy young adults.Research Questions: 1) Are STV outcomes measured in the morning and afternoon during continuous, overground walking significantly different in healthy young adults? 2) What is the within-day reliability of STV outcomes measured during continuous, overground walking in healthy young adults?.Methods: Thirty-one healthy young adults (20.8 ± 3.7 years) completed two 10-minute continuous, overground walking trials on the same day (9:00-11:00am and 3:00-5:00pm) at their preferred walking speed. Data from a waist-mounted tri-axial accelerometer were used to determine the series of consecutive stride times for each trial.Results: There were no significant differences between sessions for average walking speed, average stride time, or STV. The within-day reliability was excellent for average walking speed and stride time, and generally poor to fair for STV.Significance: Healthy young adults do not appear to demonstrate diurnal variation in STV outcomes during continuous, overground walking; however, the development of a protocol to improve their reliability, as well as the establishment of normative ranges for such outcomes, would be beneficial to improve their application and interpretation in research and clinical settings.     

耳穴贴压联合涌泉穴按摩对老年原发性高血压患者血压变异性的影响

目的:探讨耳穴贴压联合涌泉穴按摩治疗老年原发性高血压的效果及对患者血压变异性(BPV)的影响。方法:将94例老年原发性高血压患者随机分为对照组(n=47)和观察组(n=47)。常规西医治疗基础上,观察组给予王不留行籽耳穴贴压联合涌泉穴按摩治疗。比较两组治疗前后收缩压(SBP)、舒张压(DBP)水平、SBP/DBP下降幅度并评估降压疗效,BPV根据24 h动态血压监测结果评估,计算两组治疗前后24h SBP标准差(24h SBP)、24h DBP标准差(24h DBP)、白天SBP标准差(dSSD)、白天DBP标准差(dDSD)、夜间SBP标准差(nSSD)和夜间DBP标准差(nDSD),记录两组治疗期间不良反应情况。结果:观察组治疗后SBP、DBP水平和下降幅度均优于对照组(P<0.05); 观察组降压总有效率97.87%明显高于对照组82.98%,差异有统计学意义(P<0.05); 对照组治疗后24h SBP、24h DSD、dSSD、dDSD较治疗前有明显下降(P<0.05),观察组治疗后24h SBP、24h DSD、dSSD、dDSD、nSSD显著低于治疗前(P<0.05),观察组治疗后24h SBP、24h DSD、dSSD均显著低于对照组,差异有统计学意义(P<0.05); 两组不良反应以头晕、头痛、恶心和眩晕为主,症状程度均较轻,患者耐受性好,组间不良反应率比较差异均无统计学意义(P<0.05)。结论:常规西医治疗基础上给予中医耳穴贴压联合涌泉穴按摩,不仅能有效降低老年原发性高血压患者血压水平和增益降压疗效,而且能显著降低BPV。