Pattern description and reliability parameters of six force–time related indices measured with plantar pressure measurements

BackgroundFunctional interpretation of plantar pressure measurements is commonly done through the use of ratios and indices which are preceded by the strategic combination of a subsampling method and selection of physical quantities. However, errors which may arise throughout the determination of these temporal indices/ratio calculations (T-IRC) have not been quantified. The purpose of the current study was therefore to estimate the reliability of T-IRC following semi-automatic total mapping (SATM).MethodsUsing a repeated-measures design, two experienced therapists performed three subsampling sessions on three left and right pedobarographic footprints of ten healthy participants. Following the subsampling, six T-IRC were calculated: Rearfoot-Forefoot_fti, Rearfoot-Midfoot_fti, Forefoot medial/lateral_fti, First ray_fti, Metatarsal 1-Metatarsal 5_fti, Foot medial-lateral_fti.FindingsPatterns of the T-IRC were found to be consistent and in good agreement with corresponding knowledge from the literature. The inter-session errors of both therapists were similar in pattern and magnitude. The lowest peak inter-therapist error was found in the First ray_fti (6.5 a.u.) whereas the highest peak inter-therapist error was observed in the Forefoot medial/lateral_fti (27.0 a.u.) The magnitude of the inter-session and inter-therapist error varied over time, precluding the calculation of a simple numerical value for the error. The difference between both error parameters of all T-IRC was negligible which underscores the repeatability of the SATM protocol.ConclusionThe current study reports consistent patterns for six T-IRC and similar inter-session and inter-therapist error. The proposed SATM protocol and the T-IRC may therefore serve as basis for functional interpretation of footprint data.     

Relationship between postural sway on an unstable platform and ankle plantar flexor force steadiness in community-dwelling older women

BackgroundForce steadiness is evaluated as force variability during constant force exertion around a target level. Ankle plantar flexor force steadiness is reported to be related to postural sway on an unstable platform in healthy young adults; however, this relationship in older adults is unclear.Research questionThis study aimed to investigate whether ankle plantar flexor force steadiness was related to postural sway on stable and unstable platforms in older adults.MethodsTwenty-six community-dwelling older women participated in this study (72 ± 6 years). Maximal isometric strength and force steadiness at 5%, 20 %, and 50 % of the maximal strength of ankle plantar flexion were assessed. Postural sway in the anteroposterior direction during bipedal standing was measured on stable and unstable platforms.ResultsThe results showed that force steadiness at any intensity level and maximal isometric strength were not related to postural sway on the stable platform. Force steadiness at 20 % of maximal strength alone was significantly correlated with postural sway on the unstable platform (ρ = 0.441, p < 0.05).SignificanceThese results indicate that the ability to control muscle force could be important for postural stability on an unstable platform in older adults.     

Acute effects of ankle plantar flexor force-matching exercises on postural strategy during single leg standing in healthy adults

BackgroundAnkle plantar flexor force steadiness, assessed by measuring the fluctuation of the force around the submaximal target torque, has been associated with postural stability.Research questionTo investigate whether a force-matching exercise, where submaximal steady torque is maintained at the target torque, can modulate postural strategy immediately.MethodsTwenty-eight healthy young adults performed ankle plantar flexor force-matching exercises at target torques of 5%, 20%, and 50% of maximum voluntary contraction (MVC), in a randomized crossover trial. Participants with their ankle in a neutral position were instructed to maintain isometric contraction at each target torque, as measured by a dynamometer, for 20 s with 3 sets of 5 contractions. Before and after the force-matching exercises, the anterior-posterior velocities and standard deviation of the center of pressure (COP) on the stable platform and the tilt angle of the unstable platform during 20-seconds single-leg standing were measured. The velocities and standard deviations of the COP and tilt angle before and after the exercises were compared using paired t-tests.ResultsThe tilt angle velocity of an unstable platform significantly decreased after the force-matching exercise at a target torque of 5% MVC (p = 0.029), whereas it was unchanged after the exercises at target torques of 20% and 50% MVC. The standard deviations of the tilt angle of unstable platform test did not change significantly after any exercise. Furthermore, no significant differences were observed in the COP velocities or standard deviations on the stable platform test after any exercise.SignificanceOur findings suggest that repeated exertion training at low-intensity contractions can affect postural stability in an unstable condition. Particularly, force-matching exercise at very low-intensity torque, such as 5% of MVC, may be an effective method to improve postural control in the unstable condition, but not in a stable condition.     

A drop landing screening approach to monitor an individual using functional data analysis: An ACL injury case study

ObjectivesTo explore the practicality of using functional principal components analysis (fPCA) and intra-athlete z-score changes for individual athlete monitoring post-ACL injury and surgery.DesignA single athlete case study using within-athlete repeated measures in the context of applied athlete monitoring.MethodsUsing single leg (left) drop landing (3 landings per session) onto a force plate, the athlete completed 6 sessions prior (healthy) and 3 sessions post-ACL injury/surgery. Maximum vertical ground reaction force (vGRF), time to stabilisation (TTS) and outputs from fPCA (fPC scores) for the healthy sessions were used to develop intra-athlete means and standard deviations for each variable. Post-surgery measures were given z-scores relative to the healthy mean and standard deviation for each variable. The standard normal deviate (z = 1.96) was used as a threshold to flag landings that could be indicative of changes in movement behaviour.ResultsMaximum vGRF revealed no post-surgery trials that exceeded the standard normal deviate threshold based on the healthy data. TTS identified one landing post-surgery that exceeded the threshold. Scores for fPC2, fPC3 and fPC4 revealed landings that exceeded the threshold, with fPC4 demonstrating landings greater than the threshold for every trial (except two) post-surgery.ConclusionsIncluding fPCA identified significant and stable changes to the landing strategy (particularly within fPC4). When used in conjunction with other measures such as maximum vGRF and TTS, fPCA has the potential to provide meaningful insights into athlete monitoring models regarding changes to movement characteristics after injury.     

Digital bathroom scales with open source software provide valid dynamic ground reaction force data for assessment and biofeedback

BackgroundMeasuring dynamic vertical ground reaction force allows for assessment of important clinical and physical capacity factors such as weight bearing asymmetry, force distribution, and rate of force development. However, current technologies for accurately assessing ground reaction force are typically expensive.Research QuestionThe aim of this study was to examine the validity and reliability of obtaining static and dynamic ground reaction force data from low-cost modified digital bathroom scales.MethodsFour modified bathroom scales, two units each of two different brands, were examined. Repeated mechanical loading trials were performed with known loads ranging from 0.01 to 65 kg, with acquired data compared against the known loading to calculate accuracy, hysteresis, and non-linearity. Dynamic trials consisting of 5 times sit-to-stand and weight-shifting were performed by 32 adults. Absolute and relative agreement intraclass correlation coefficient, and Pearson’s and Spearman’s correlations were performed to determine validity and reliability for the mechanical tests. Bland-Altmann plots were created for each comparison. Mean absolute error (MAE) and unbiased cross-correlation were performed on the dynamic data, comparing the calibrated data to the known values from a Bertec force platform.ResultsHysteresis and non-linearity were excellent (<0.2 % full-scale), and mechanical test results showed excellent reliability and validity. Cross-correlation results for the dynamic data were excellent, however MAE for the more rapid sit-to-stand task was higher than the slower weight-shifting test. This may have been due to the low default sampling rate for the lowest noise setting of the HX711 amplifier (10 Hz).SignificanceIn summary, our results suggest that digital bathroom scales can be easily and inexpensively modified to obtain accurate vertical ground reaction force data, with sensitivity to detect changes of as little as 0.01 kg.     

Measuring body weight distribution during sit-to-stand in patients with early knee osteoarthritis

People with severe degenerative conditions, such as osteoarthritis (OA), have been shown to have altered movement patterns during sit-to-stand. However it remains unclear whether such alterations exist in people with early OA, in the absence of pain. This study aimed to determine if a novel seat could be used to discriminate people with early OA compared with controls. The sit-to-stand task was performed by 20 people with early medial knee OA and 20 age and gender-matched control subjects, using an instrumented seat. OA subjects showed altered weight distribution in the transition phase from sit to stand, in that they placed more load through their unaffected side. Task duration was significantly longer for OA subjects, and ground reaction force integrals were significantly greater for both legs of OA subjects. OA subjects had significantly higher knee flexion and adduction moments in their unaffected compared with affected side. This study has demonstrated that a novel instrumented seat can be used to discriminate people with early medial knee OA during the sit-to-stand activity. These results may be relevant for early interventions to delay or prevent changes in muscle function of the affected limb as well as contralateral knee or hip osteoarthritis in these patients.     

The rapid recovery of vertical force propulsion production and postural sway after a specific fatigue protocol in female handball athletes

BackgroundMuscle fatigue is characterized by a decrease in muscle performance, accompanied by an increase in perceived exertion to produce a desired amount of force. The duration of the fatigue effects is not completely clear regarding postural sway and force production in athletes.Research questionWhat is the effect of a specific fatigue protocol in postural sway and force production in female handball athletes and the recovery time necessary for these variables?MethodsTwenty female handball athletes participated in this study. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. They stood upright in one-leg posture on a force plate. For the maximum propulsion force (F_MAX), they performed a countermovement jump on the force plate. The center of pressure (COP) and the F_MAX were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase.ResultsThe F_MAX decreased ∼9.5% after the fatigue protocol, whereas de COP area increased 224%. During the recovery phase, the F_MAX and the COP area returned to baseline values after five minutes.SignificanceThe first five minutes immediately after the fatigue protocol represent the time interval where the fatigue effects are still present. Future studies willing to investigate the effects of fatigue in athletes should perform the analysis within this short time-window.     

招飞体检可疑肾积水情况分析

目的 分析招飞体检中超声对可疑肾积水的诊断情况,探讨可疑肾积水产生的原因,诊断依据及判定标准。方法 选取参加某地区2017—2018年度空军招飞体检的学生为研究对象,对其临床资料进行回顾性分析。结果 参加某地区空军招收飞行学员全面体检的高中毕业生1197人,检出36例可疑肾积水,其中17人确诊肾结石合并肾积水,招飞结论不合格,占可疑受检人数的47.2%。另19人经多体位检查排除明显结石或其他继发性病变,嘱咐学生排尿后复查,4人排尿后积水未见明显改变,招飞结论不合格,占可疑受检人数的11.1%。12人排尿后肾积水减轻,肾盂分离小于10 mm,招飞结论为待结,占可疑受检人数的33.3%。3人排尿后肾积水消失,招飞结论合格,占可疑受检人数的8.3%。结论 建议招飞体检中,对肾积水范围在10～15 mm的可疑肾积水需谨慎淘汰,应嘱学生排尿后反复检查,减少招飞误诊淘汰。     

Assessment of sub-division of plantar pressure measurement in children

Methods for the measurement of plantar pressure are poorly defined particularly when describing sub-sections of the plantar surface of the foot in the presence of deformity. The aim of this study was to assess foot pressure measurement in healthy children, using an automatic technique of sub-area definition that has the potential for objective evaluation of treatment of foot deformity. Twelve healthy children were examined on three occasions. Plantar pressure data were collected and time synchronised with force plate and stereophotogrammetric data. The footprint was divided into five sub-sections by using the position of the markers on the foot at mid-stance projected onto the pressure footprint. Repeatability for peak pressure and peak force was assessed. Automatic sub-area definition based on marker placement was found to be reliable in healthy children. A comparison of results revealed that peak vertical force was a more consistent measure than peak pressure for each of the five sub-areas. This suggests that force may be a more appropriate measurement for outcome studies.     

ACR–ABS–ACNM–ASTRO–SIR–SNMMI practice parameter for selective internal radiation therapy or radioembolization for treatment of liver malignancies

PurposeThe American College of Radiology (ACR), American Brachytherapy Society (ABS), American College of Nuclear Medicine (ACNM), American Society for Radiation Oncology (ASTRO), Society of Interventional Radiology (SIR), and Society of Nuclear Medicine and Molecular Imaging (SNMMI) have jointly developed a practice parameter on selective internal radiation therapy (SIRT) or radioembolization for treatment of liver malignancies. Radioembolization is the embolization of the hepatic arterial supply of hepatic primary tumors or metastases with a microsphere yttrium-90 brachytherapy device.Materials and MethodsThe ACR -ABS -ACNM -ASTRO -SIR -SNMMI practice parameter for SIRT or radioembolization for treatment of liver malignancies was revised in accordance with the process described on the ACR website (https://www.acr.org/ClinicalResources/Practice-Parameters-and-Technical-Standards) by the Committee on Practice Parameters—Interventional and Cardiovascular Radiology of the ACR Commission on Interventional and Cardiovascular, Committee on Practice Parameters and Technical Standards—Nuclear Medicine and Molecular Imaging of the ACR Commission on Nuclear Medicine and Molecular Imaging and the Committee on Practice Parameters—Radiation Oncology of the ACR Commission on Radiation Oncology in collaboration with ABS, ACNM, ASTRO, SIR, and SNMMI.ResultsThis practice parameter is developed to serve as a tool in the appropriate application of radioembolization in the care of patients with conditions where indicated. It addresses clinical implementation of radioembolization including personnel qualifications, quality assurance standards, indications, and suggested documentation.ConclusionsThis practice parameter is a tool to guide clinical use of radioembolization. It focuses on the best practices and principles to consider when using radioemboliozation effectively. The clinical benefit and medical necessity of the treatment should be tailored to each individual patient.     

Validation of a smartphone embedded inertial measurement unit for measuring postural stability in older adults

BackgroundIdentifying older adults with increased fall risk due to poor postural control on a large scale is only possible through omnipresent and low cost measuring devices such as the inertial measurement units (IMU) embedded in smartphones. However, the correlation between smartphone measures of postural stability and state-of-the-art force plate measures has never been assessed in a large sample allowing us to take into account age as a covariate.Research questionHow reliably can postural stability be measured with a smartphone embedded IMU in comparison to a force plate?MethodsWe assessed balance in 97 adults aged 50–90 years in four different conditions (eyes open, eyes closed, semi-tandem and dual-task) in the anterio-posterior and medio-lateral directions. We used six different parameters (root mean square and average absolute value of COP displacement, velocity and acceleration) for the force plate and two different parameters (root mean square and average absolute value of COM acceleration) for the smartphone.ResultsTest-retest reliability was smaller for the smartphone than for the force plate (intra class correlation) but both devices could equally well detect differences between conditions (similar Cohen’s d). Parameters from the smartphone and the force plate, with age regressed out, were moderately correlated (robust correlation coefficients of around 0.5).SignificanceThis study comprehensively documents test-retest reliability and effect sizes for stability measures obtained with a force plate and smartphone as well as correlations between force plate and smartphone measures based on a large sample of older adults. Our large sample size allowed us to reliably determine the strength of the correlations between force plate and smartphone measures. The most important practical implication of our results is that more repetitions or longer trials are required when using a smartphone instead of a force plate to assess balance.     

武警新兵团体心理咨询体会

 目的 探讨在武警新兵中开展团体心理咨询的方法和经验.方法 对自愿参加团体心理咨询的108名新兵进行培训,对团体辅导前后新兵的主观感受和部队干部的观察及整个活动进行回顾性总结.结果 90.7%～97%新兵认为自我评价团体咨询有效.新兵班长的效果评价认为80.3%～84.2%的心理咨询有效.结论 团体心理咨询对解决新兵的适应问题、人际关系问题、学习问题、自我意识问题效果显著,是提高新兵心理健康的一种经济而有效的方法.     

Direct measurement of ankle stiffness during quiet standing: implications for control modelling and clinical application

In this study, we describe a device for the direct measurement of intrinsic ankle stiffness in quiet standing. It consists of a motorised footplate mounted on a force platform. By generating random sequences of step-like disturbances (1° amplitude, 150 ms duration) and measuring the corresponding displacements of the center of pressure in the antero-posterior direction, we obtained torque-rotation patterns after aligning, averaging, and scaling the postural responses. Such patterns were used for estimating the value of the ankle stiffness, which was normalized as a fraction of the critical value. In order to be confident that the measurements addressed the intrinsic ankle stiffness and were not affected in a significant way by the reflex activation of the muscles in response to the test disturbances, we performed the estimates in different ways: least squares estimates with time windows of different widths and an instantaneous estimate at the time in which the angular acceleration vanishes. The statistical analysis showed that there is no significant difference among the different methods of estimate and the inspection of the electromyographic activity in response to the perturbations showed that at least two of the estimates were certainly outside the possible influence of reflex patterns. The intrinsic ankle stiffness was evaluated to be 64 ± 8% of the critical stiffness for test disturbances of the order of 1°. We argue that this figure identifies the lower bound of the range of values which characterise normal sway in quiet standing, whereas the upper bound is given by the estimates performed with much smaller test disturbances [1] which yield a higher value: 91 ± 23%. The two estimation paradigms (with very small and very large test disturbances, respectively) are complementary also because they behave in a different way as regards the sensitivity to a bias torque: it is close to zero in the Loram & Lakie’s paradigm, whereas it is significant in our paradigm. Thus, as the bias grows, it appears that the range of stiffness values is narrowed and is pushed towards the upper bound. There is a clear potential for the clinical application of these methods, in the sense that the identification of the range of stiffness values used by a patient is a measurable index of motor organisation/reorganisation.     

How gender and boat-side affect shape characteristics of force–angle profiles in single sculling: Insights from functional data analysis

Objectives

To examine whether gender or side of the boat influenced shape characteristics of the force–angle profile in on-water single sculling.