B. Nienhuis - Academia.edu (original) (raw)

Papers by B. Nienhuis

British Journal of Clinical Pharmacology, 2013

In many European countries as well as in the USA, the leaflet, or even the packaging of indometha... more In many European countries as well as in the USA, the leaflet, or even the packaging of indomethacin, contains a specific warning to refrain from activities requiring mental alertness and motor coordination, such as driving a car. In this placebo-controlled randomized study with a crossover design we attempted to find evidence for that warning. METHODS Indomethacin 75 mg slow release or a visually identical placebo with similar flavour was taken orally twice daily for 2.5 days. It was suggested that indomethacin affects the motor coordination required to avoid obstacles successfully during walking and that this effect will be even stronger when simultaneously performing a cognitive task that puts mental alertness to the test. Nineteen healthy middle-aged individuals (60 Ϯ 4.7 years, eight female) performed an obstacle avoidance task on a treadmill), combined with a cognitive secondary task. Biceps femoris (BF) muscle response times, obstacle avoidance failure rates and composite scores ((100 ¥ accuracy)/verbal response time) were used to evaluate the data. RESULTS No differences between indomethacin and placebo were found on the outcome measures regarding motor coordination, avoidance failure rates (P = 0.81) and BF response times (P = 0.47), nor on the performance on the secondary cognitive task (P = 0.12).

Archives of physical medicine and rehabilitation, 1991

Postural control in persons with lower limb amputation was studied using a cognitive approach to ... more Postural control in persons with lower limb amputation was studied using a cognitive approach to motor learning. The aim of this study was to show that an important characteristic of the central reorganization process after a lower limb amputation is the gradually decreasing need of attentional resources to perform a motor task. A dual-task procedure was developed to estimate the level of automaticity of a quiet, upright standing task. The effect of a concurrent attention-demanding task (Stroop task) on the efficiency of balance control was determined using force-platform measurements at the start and the end of the rehabilitation process. In contrast with a control group, the amputation group showed interference effects on body sway caused by the concurrent task both at the start (p less than .05) and, less severe, at the end of rehabilitation (p less than .05). Improvement of balance control was significant only for the dual-task condition (p less than .05). The results corroborat...

Clinical Rehabilitation, 1998

To determine the focus of clinical gait analysis in order to explain the observed mismatch betwee... more To determine the focus of clinical gait analysis in order to explain the observed mismatch between the available technology for movement analysis and the aims of clinical rehabilitation medicine. Literature search using two different interactive computerized search systems. The selected studies on clinical gait analysis were screened on the type of tasks they employed in the assessment of gait. The tasks were divided into impairment-orientated and disability-orientated. The results indicated a dominance of simple motor tasks focusing at the level of impairments. In only 15 out of the 96 reviewed articles were tasks used that were aimed at the level of disabilities. A gap exists between the conceptual frameworks used in clinical rehabilitation medicine and those used in clinical movement analysis.

Archives of physical medicine and rehabilitation, 1992

The postural organization in patients with hereditary motor and sensory neuropathy (HMSN) type I ... more The postural organization in patients with hereditary motor and sensory neuropathy (HMSN) type I or II was studied clinically by means of a force platform. Balance was registered in 14 barefooted HMSN patients and healthy matched control subjects during quiet stance. The effect of visual deprivation was tested to determine the degree of visual dependency. The effect of the simultaneous performance of a concurrent attention-demanding task (Stroop task) was tested to estimate the level of balance automaticity. In comparison with control subjects, the HMSN patients showed a basically decreased efficiency of postural control (p less than .01) as well as an increased visual control of posture (p less than .05) in both directions of sway. No loss of balance automaticity was found, which suggested an on-line central adaptation to the slowly developing peripheral impairments. The results provide a starting point for understanding the balance problems and gross motor disabilities in HMSN pat...

Experimental Brain Research, 2002

Experimental Brain Research, 2005

In the present study the obstacle avoidance strategy during treadmill walking was investigated in... more In the present study the obstacle avoidance strategy during treadmill walking was investigated in ten young (aged 19-32) and ten older females (aged 65-78). Minimisation of displacement of the foot from its original landing position has been proposed to be the main criterion for the selection of alternate foot placement. Each participant performed 60 obstacle avoidance trials. Foot-obstacle configurations were varied in order to obtain both lengthening and shortening avoidance reactions. For each trial it was calculated how much lengthening and how much shortening of the stride was required minimally for successful avoidance. The difference between required lengthening and required shortening was expressed as a percentage of the control stride length and was used as a measure of minimal displacement. The behavior of young females was in agreement with the minimal displacement criterion. The older females, however, exhibited a strong preference for stride lengthening, even in situations in which stride shortening would be highly favorable. The explanation for the long step strategy preference of the older females is discussed in terms of age-related changes in decision-making, differences between young and older persons in the unobstructed gait pattern, and safety considerations.

$Research paper thumbnail of Incorporating in vivo fall assessments in the simulation of femoral fractures with finite element models$

Medical engineering & physics, Jan 16, 2015

Femoral fractures are a major health issue. Most experimental and finite element (FE) fracture st... more Femoral fractures are a major health issue. Most experimental and finite element (FE) fracture studies use polymethylmethacrylate cups on the greater trochanter (GT) to simulate fall impact loads. However, in vivo fall studies showed that the femur is loaded distally from the GT. Our objective was to incorporate in vivo fall data in FE models to determine the effects of loading position and direction, and size of simulated impact site on the fracture load and fracture type for a healthy and an osteoporotic femur. Twelve sets of loading position and angles were applied through 'near point loads' on the models. Additional simulations were performed with 'cup loads' on the GT, similar to the literature. The results showed no significant difference between fracture loads from simulations with near point loads distally from the GT and those with cup loads on the GT. However, simulated fracture types differed, as near point loads distally from the GT generally resulted in ...

Scandinavian journal of rehabilitation medicine, 1992

Postural control was assessed in persons with a unilateral lower limb amputation before and after... more Postural control was assessed in persons with a unilateral lower limb amputation before and after their rehabilitation. The centre-of-pressure fluctuations during quiet upright standing on a dual-plate force platform were registered with and without visual information in order to identify relevant determinants of balance restoration. In addition, static (weight distribution) as well as dynamic (control activity) asymmetry characteristics were examined. Besides a small improvement in balance control with full visual information (fore-aft sway, p less than 0.06; lateral sway, p less than 0.05), there was a major decrease in visual dependency (fore-aft and lateral sway, p less than 0.05) indicating a somatosensory re-integration process. Postural asymmetry in comparison with matched control subjects was most apparent and only significant in dynamic terms and remained constant across rehabilitation. It is concluded that after a lower limb amputation a central reorganization of postural ...

Archives of physical medicine and rehabilitation, 1993

Platform stabilometry is increasingly applied to monitor or re-educate standing balance in clinic... more Platform stabilometry is increasingly applied to monitor or re-educate standing balance in clinical rehabilitation. Consequently, insight is needed into the validity, reliability, and sensitivity of different force-platform parameters. This study focuses on the intrasubject variability as the major source of variance (unreliability) in the study of human motor skills. The intrasubject variability of several, commonly applied force-platform parameters was determined across ten repeated tests of quiet two-legged standing in healthy subjects to identify the most consistent and stable parameters in the quantification of postural control. The variability of the root mean square (RMS) amplitude, peak-to-peak amplitude, mean frequency, and RMS velocity of the fore-aft and lateral components of the center-of-pressure fluctuations was investigated under varying (visual and cognitive) task conditions. The results indicate that all selected parameters show considerable intrasubject variability...

2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012

Brain Computer Interfaces could be useful in rehabilitation of movement, perhaps also for gait. U... more Brain Computer Interfaces could be useful in rehabilitation of movement, perhaps also for gait. Until recently, research on movement related brain signals has not included measuring electroencephalography (EEG) during walking, because of the potential artifacts. We investigated if it is possible to measure the event Related Desynchronization (ERD) and event related spectral perturbations (ERSP) during walking. Six subjects walked on a treadmill with a slow speed, while EEG, electromyography (EMG) of the neck muscles and step cycle were measured. A Canonical Correlation Analysis (CCA) was used to remove EMG artifacts from the EEG signals. It was shown that this method correctly deleted EMG components. A strong ERD in the mu band and a somewhat less strong ERD in the beta band were found during walking compared to a baseline period. Furthermore, lateralized ERSPs were found, depending on the phase in the step cycle. It is concluded that this is a promising method to use in BCI research on walking. These results therefore pave the way for using brain signals related to walking in a BCI context.

IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2014

Recently, brain-computer interface (BCI) research has extended to investigate its possible use in... more Recently, brain-computer interface (BCI) research has extended to investigate its possible use in motor rehabilitation. Most of these investigations have focused on the upper body. Only few studies consider gait because of the difficulty of recording EEG during gross movements. However, for stroke patients the rehabilitation of gait is of crucial importance. Therefore, this study investigates if a BCI can be based on walking related desynchronization features. Furthermore, the influence of complexity of the walking movements on the classification performance is investigated. Two BCI experiments were conducted in which healthy subjects performed a cued walking task, a more complex walking task (backward or adaptive walking), and imagination of the same tasks. EEG data during these tasks was classified into walking and no-walking. The results from both experiments show that despite the automaticity of walking and recording difficulties, brain signals related to walking could be classified rapidly and reliably. Classification performance was higher for actual walking movements than for imagined walking movements. There was no significant increase in classification performance for both the backward and adaptive walking tasks compared with the cued walking tasks. These results are promising for developing a BCI for the rehabilitation of gait.

Parkinsonism & Related Disorders, 2008

Poster Session II Italy). The evaluation of gait patients was performed in the OFF state and in t... more Poster Session II Italy). The evaluation of gait patients was performed in the OFF state and in the ON state (50 minutes after taking Levodopa).

Journal of Electromyography and Kinesiology, 1996

After nervous system damage, functional recovery usually occurs. It is of great clinical importan... more After nervous system damage, functional recovery usually occurs. It is of great clinical importance to follow the course of recovery and, when possible, predict the extent. This measurement and prediction of recovery is one of the main challenges facing clinicians today. The majority of assessment procedures currently employed, however, are impairment-oriented; that is, these procedures are oriented primarily at the disease or organ level. Until now, few procedures have been available that focus at the disability or behavioural level. This lack of disability-oriented assessment procedures hinders the development and evaluation of rehabilitation programmes, as impairment-oriented assessment scores have little relevance for the prediction of daily functioning. In this paper, a preliminary task-set is presented that may function as an impetus for the development of novel disability-oriented assessment procedures in neurological rehabilitation. Motor behaviour is not assessed in vacua, rather as the end result of a continuous interaction between motor, sensory and cognitive processes. With this task set, it is possible to evaluate the changing influence of sensory and cognitive factors on the quality of motor performance over time. These changes, it is argued, are a crucial component of functional recovery. Copyright 0 1996 Elsevier Science Ltd

Journal of Biomechanics, 2012

Sideways falls onto the hip are a major cause of femoral fractures in the elderly. Martial arts (... more Sideways falls onto the hip are a major cause of femoral fractures in the elderly. Martial arts (MA) fall techniques decrease hip impact forces in sideways falls. The femoral fracture risk, however, also depends on the femoral loading configuration (direction and point of application of the force). The purpose of this study was to determine the effect of fall techniques, landing surface and fall height on the impact force and the loading configuration in sideways falls. Twelve experienced judokas performed sideways MA and Block ('natural') falls on a force plate, both with and without a judo mat on top. Kinematic and force data were analysed to determine the hip impact force and the loading configuration. In falls from a kneeling position, the MA technique reduced the impact force by 27%, but did not change the loading configuration. The use of the mat did not change the loading configuration. Falling from a standing changed the force direction. In all conditions, the point of application was distal and posterior to the greater trochanter, but it was less distal and more posterior in falls from standing than from kneeling position. The present decrease in hip impact force with an unchanged loading configuration indicates the potential protective effect of the MA technique on the femoral fracture risk. The change in loading configuration with an increased fall height warrant further studies to examine the effect of MA techniques on fall severity under more natural fall circumstances.

Journal of Biomechanics, 2009

Plantar pressure measurement provides important information about the structure and function of t... more Plantar pressure measurement provides important information about the structure and function of the foot and is a helpful tool to evaluate patients with foot complaints. In general, average and maximum plantar pressure of 6-11 areas under the foot are used to compare groups of subjects. However, masking the foot means a loss of important information about the plantar pressure distribution pattern. Therefore, the purpose of this study was to develop and test a simple method that normalizes the plantar pressure pattern for foot size, foot progression angle, and total plantar pressure. Moreover, scaling the plantar pressure to a standard foot opens the door for more sophisticated analysis techniques such as pattern recognition and machine learning.