Biomedical subjects

J B Bussmann

Publications and source records attributed to J B Bussmann.

14 recordsLinked to original sources

PubMed2001

Comparing predictive validity of four ballistic swing phase models of human walking.

It is unclear to what extent ballistic walking models can be used to qualitatively predict the swing phase at comfortable walking speed. Different study findings regarding the accuracy of the predictions of the swing phase kinematics may have been caused by differences in (1) kinematic input, (2) model characteristics (e.g. the number of segments), and (3) evaluation criteria. In the present study, the predictive validity of four ballistic swing phase models was evaluated and compared, that is, (1) the ballistic walking model as originally introduced by Mochon and McMahon, (2) an extended version of this model in which heel-off of the stance leg is added, (3) a double pendulum model, consisting of a two-segment swing leg with a prescribed hip trajectory, and (4) a shank pendulum model consisting of a shank and rigidly attached foot with a prescribed knee trajectory. The predictive validity was evaluated by comparing the outcome of the model simulations with experimentally derived swing phase kinematics of six healthy subjects. In all models, statistically significant differences were found between model output and experimental data. All models underestimated swing time and step length. In addition, statistically significant differences were found between the output of the different models. The present study shows that although qualitative similarities exist between the ballistic models and normal gait at comfortable walking speed, these models cannot adequately predict swing phase kinematics.

Adult↗

PubMed2001

Everyday physical activity in adolescents and young adults with meningomyelocele as measured with a novel activity monitor.

We measured the extent of hypoactivity in adolescents and young adults with meningomyelocele with an activity monitor. The activity monitor is based on long-term ambulatory monitoring of signals from body-fixed accelerometers during everyday life and is aimed at the assessment of mobility-related activities. Measurements were performed during 2 consecutive weekdays in 14 patients with meningomyelocele (aged 14 to 26 years) and in 14 matched, healthy subjects. Mean duration of dynamic activities (composite measure) was less in the patients (6.5 +/- 2.3%) than in comparison subjects (12.7 +/- 4.3%, P =.001). Number of walking or wheelchair-driving periods was 122 +/- 48 in the patients and 185 +/- 65 in the comparison subjects (P =.01). Resting heart rate was higher in the patients (70 +/- 7 beats/min vs 64 +/- 5 beats/min, P =.01). Time spent with dynamic activities was correlated with ambulatory status (r(s) = 0.55, P <.05). Adolescents and young adults with meningomyelocele, particularly the nonambulators, are considerably hypoactive.

Activities of Daily Living↗

PubMed2001

Measuring daily behavior using ambulatory accelerometry: the Activity Monitor.

Advanced ambulatory systems that measure aspects of overt human behavior during normal daily life have become feasible, owing to developments in data recording and sensor technology. One such instrument is the Activity Monitor (AM). This paper provides a technical description of the AM and information about its validity and current applications. The AM is based on ambulatory accelerometry, the aim of which is to assess postures and motions for long-term (> 24-h) measurement periods during normal daily life. Accelerometers are attached to the thighs, trunk, and lower arms, and signals are continuously stored in a digital portable recorder. In the postmeasurement analysis, postures and motions are detected by means of custom-made software programs. Validity studies performed on different populations showed high agreement scores between the computerized and automatic AM output and the visually analyzed video recordings. The AM has so far been applied in rehabilitation, psychophysiology, and cardiology but has many possibilities in behavioral research.

Activities of Daily Living↗

PubMed2000

Outcome measures for complex regional pain syndrome type I: an overview in the context of the international classification of impairments, disabilities and handicaps.

PURPOSE: To determine the availability of relevant and objective outcome measures concerning complex regional pain syndrome type I (CRPS I) for rehabilitation medicine. METHOD: Outcome measures were classified according to the International Classification of Impairments, Disabilities and Handicaps. For each outcome measure a description of concept, operationalization into variables and instrument was given. We performed a PUBMED MEDLINE search (1980-1998) using the following keywords: complex regional pain syndrome, reflex sympathetic dystrophy, impairment, disability, handicap, (long-term) outcome and effect/efficacy. RESULTS: Most outcome measures were concentrated on impairments, whereas measures at the level of disabilities and handicaps, the most relevant levels for rehabilitation medicine, were mentioned in very few studies. Objective outcome measures were merely found at the level of impairment. CONCLUSION: The results indicate a need for the development of relevant outcome measures at the level of disabilities and handicaps that can objectively measure treatment efficacy for CRPS I.

Activities of Daily Living↗

PubMed2000

Analysis and decomposition of signals obtained by thigh-fixed uni-axial accelerometry during normal walking.

The use of piezo-resistive uni-axial accelerometer signals in gait analysis is complicated by the fact that the measured signal is composed of different types of acceleration. The aim of the study is to obtain insight into the signal from a tangential accelerometer attached to the thigh during walking. Six subjects walk with three different speeds. Simultaneous measurements are performed with accelerometers, footswitches and an opto-electronic system. The components of the accelerometer signal are calculated from the opto-electronic system. A clear relationship is found between the measured and calculated accelerometer signals (range RMS: 0.76-3.69 m x s(-2), range rms: 0.22-0.61). The most pronounced feature is a high positive acceleration peak (> 10 m x s(-2)) at the end of the cycle. The gravitational acceleration during one cycle is characterised by a sinusoidal shape, whereas the inertial acceleration contains higher-frequency components (up to 20 Hz). During the major part of the gait cycle, the gravitational and inertial acceleration make opposing contributions to the signal As a result, the gravitational acceleration influences the amplitudes of the measured acceleration signal, the shape and peaks of which are mainly determined by the inertial acceleration. Because the gravitational and inertial accelerations differ in frequency components, the application for gait analysis remains feasible.

Acceleration↗

PubMed2000

Towards an objective quantitative assessment of daily functioning in migraine: a feasibility study.

Migraine is a chronic disabling disorder, with migraine episodes significantly reducing quality of life and leading to impaired functioning (physically, socially, emotionally) both at home and at work. We explored whether ambulatory accelerometry can be used as an objective method to quantify the behavioral aspects of migraine-related disability. Four body mounted uni-axial piezo-resistive accelerometers were used to quantify the time spent in different body postures (lying, sitting, standing), physical activities (walking, cycling) and a general index of body motility during eight migraine attacks and subsequent recovery periods of six patients in their habitual environment. The migraine attacks and recovery periods could be monitored after about 1 h, which was the time required for the investigator to travel to the patient and for the sensors to be attached. In order to quantify the influence of a migraine episode on daily activities, we also performed measurements during a headache-free baseline period of the same patients. Overall, the procedures functioned well, indicating that ambulatory accelerometry measurements before, during and after a migraine attack are feasible to perform. Furthermore, our quantitative data revealed that migraine always influenced behavior by reducing overall body motility and that, dependent upon the severity of the attack, the effectiveness of acute treatment and the time of day, the time spent in various body positions, dynamic activities, and the number of postural transitions were affected. This feasibility study showed that ambulatory accelerometry can provide the objective behavioral effect parameters for the evaluation of migraine and its treatment on daily functioning in the habitual environment of migraine patients.

Activities of Daily Living↗

PubMed2000

Validity of ambulatory accelerometry to quantify physical activity in heart failure.

The purpose was to assess the validity of a novel Activity Monitor to quantify physical activity in congestive heart failure. The Activity Monitor is based on long-term ambulatory monitoring of signals from body-fixed accelerometers. Information can be obtained on which mobility-related activity is performed, when, how intense, and for how long. Ten patients performed several functional activities. Continuous registrations of accelerometer signals were made and the output was compared with visual analysis of simultaneously made video recordings (reference method). Overall results showed an agreement between both methods of 90%. Percentages of sensitivity and predictive value were higher than 80% for most activities. Overall number of transitions was determined well (Activity Monitor, 153; video, 149; p = 0.33). It was concluded that the Activity Monitor is a valid instrument to quantify several aspects of everyday physical activity in congestive heart failure.

Exercise↗

PubMed2000

Measuring physical strain during ambulation with accelerometry.

PURPOSE: To study the feasibility of ambulatory accelerometry in the evaluation of physical strain in walking at different speeds and different levels of economy. METHODS: Twelve able-bodied subjects performed a walking test on a treadmill with increasing walking speed. After a 6-wk period, these measurements were repeated, with an additional test of perturbed walking. Motility (the intensity of body segment movements, measured with accelerometry), heart rate, and oxygen uptake were simultaneously recorded. Feasibility was determined by comparing motility with percentage heart rate reserve (%HRR), using oxygen uptake (VO2) as reference. The relation with oxygen uptake, the sensitivity to change when walking speed increased and gait was perturbed, and intrasubject and intersubject variability were studied. RESULTS: Walking with increasing walking speed resulted in a higher pooled r2 value (0.91) and a lower residual standard deviation (1.44 mL x kg(-1) x min(-1)) for the motility-VO2 relation than for the %HRR-VO2 relation (0.84 and 1.92 mL x kg(-1) x min(-1), respectively). Furthermore, the motility-VO2 relation for this part of the protocol showed lowest interindividual differences. The sensitivity to changes due to an increase in walking speed, and the test-retest reliability were the highest for motility. Walking with a brace resulted in a lower pooled r2 value for the motility-VO2 relation than for the %HRR-VO2 relation (0.31 and 0.67, respectively); the sensitivity to changes due to walking with a brace was lower for motility than for %HRR. CONCLUSION: Compared with heart rate, accelerometry allows accurate measurement with little error in any able-bodied individual, without the need for individual calibration. The response of motility to changes and differences in economy in patients requires further study.

Acceleration↗

PubMed1999

Effects of prosthetic mass and mass distribution on kinematics and energetics of prosthetic gait: a systematic review.

OBJECTIVE: To introduce the theoretical models used in literature that describe the relation between prosthetic inertial loading and amputee gait and to derive specific predictions from these models: to systematically review experimental studies on the relation between prosthetic inertial loading and energetics and kinematics of lower-limb prosthetic gait; and to compare the review outcomes with predictions derived from theoretical models. DATA SOURCES: Studies selected from Medline and from examining references in the selected Medline publications. STUDY SELECTION: Theoretical models were selected that are used in the present literature to predict the effects of prosthetic mass and mass distribution on kinematics and energetics of prosthetic gait. Experimental studies were selected that investigated the effects of prosthetic mass or center of mass location on the economy, self-selected walking speed, stride length, or stride frequency of lower limb amputee patients. DATA EXTRACTION: The design and methodologic quality was assessed using a checklist of nine criteria. Data on economy, self-selected walking speed, stride frequency, and stride length were extracted from the studies selected. DATA SYNTHESIS: The predictions of the theoretical models suggest that inertial loading of the present lightweight prostheses need not be decreased and sometimes may need to be increased to improve the gait of amputee patients. The methodologic quality of most of the experimental studies was limited. Review of the experimental studies suggests that the inertial loading of the present lightweight prostheses need not be further reduced. The discrepancy between theoretical models and experimental findings may be related to both the poor methodologic quality of the experiments as well as to the limited predictive value of the existing models.

Amputation, Surgical↗

PubMed1998

Ambulatory accelerometry to quantify motor behaviour in patients after failed back surgery: a validation study.

In the treatment of patients with pain, measures related to (pain) behaviour are of major importance. Ambulatory activity monitoring can be used to obtain insight into actual behaviour. This study was designed to validate the Activity Monitor (AM), an instrument based on long-term ambulatory monitoring of accelerometer signals, to assess several physical activities during normal daily life. Ten failed back surgery (FBS) patients performed a number of functional activities in and around their own houses. During the measurements, continuous ambulatory registrations of accelerometer signals were made, based on four body-mounted accelerometers (one on each upper leg, two on the trunk). Video recordings made simultaneously with the measurements were used as a reference. The continuous output of the AM (postures, transitions, dynamic activities) was compared with visual analysis of the videotapes. The overall results showed an agreement between AM output and video analysis of 87% (inter subject range: 83-88%). The maximal error in the determination of the duration of activities was 0.3%. The overall number of dynamic periods was determined well (AM: 359; video: 368), while the number of transitions was slightly overestimated (AM: 228; video: 205). The results when using the three-sensor version of the AM were somewhat less accurate (overall agreement from 87% to 82%). The AM appeared to be a valid instrument to quantify aspects of behaviour of FPS patients, such as duration of activities and number of transitions. This new technique of ambulatory measurement of mobility activities seems to be a relevant and promising extension of the techniques currently used in the evaluation of pain treatment.

Acceleration↗

PubMed1998

Quantification of physical activities by means of ambulatory accelerometry: a validation study.

The objective of the study was to assess the validity of an activity monitor (AM) within a psychophysiological study. The AM was based on four body-fixed accelerometers and discriminated postures, transitions, and dynamic activities. Three subjects participated in each of two 4-hr sessions. During each session, consisting of two protocols, ambulatory accelerometer and heart rate measurements were made. The output of the AM was compared with simultaneously recorded video tapes. An overall agreement between AM and video of 88 and 96% was found. The number of transitions and dynamic periods, and the duration of activities were well determined. Posture-related heart rate changes were demonstrated. A three-sensor configuration hardly influenced the validity scores. The AM appeared to be a valid instrument to quantify aspects of physical activity, and offers new possibilities for ambulatory psychophysiological research.

Adult↗

PubMed1998

Techniques for measurement and assessment of mobility in rehabilitation: a theoretical approach.

OBJECTIVE: Mobility is an important construct in rehabilitation; many instruments have emerged which measure or assess (aspects of) mobility. In the selection or development of an appropriate technique, knowledge about the fundamentals of rehabilitation medicine is needed, as well as about essential characteristics of techniques and fundamental differences between them. The aim of this paper is to classify, assess and discuss current techniques which are or can be used to measure aspects of mobility. DESIGN: Eight techniques (physical science techniques, clinimetry, observation, diaries, questionnaires, actigraphy, physiological techniques and activity monitors) are classified, assessed and discussed, based on the level of outcome measures, the aspect of mobility they measure, and methodological and practical criteria. RESULTS AND CONCLUSIONS: Rehabilitation medicine has a particular need for instruments that enable measurement of outcome measures on the level of activity and role fulfillment. Techniques differ in the type and number of mobility aspects they measure. Furthermore, important differences exist based on methodological and practical criteria. One optimal technique does not exist: the choice of a technique always depends on a complexity of factors, such as clinical problem, research questions, the mobility aspect of interest, required methodological strength, costs and availability.

Activities of Daily Living↗

PubMed1995

A device for long-term ambulatory monitoring in trans-tibial amputees.

Long-term monitoring of walking in trans-tibial amputees (TTA) is considered important for prosthetic prescription and therapy evaluation. The purpose of this study was to develop a device with the following design criteria: lightweight, easy attachment to the prosthesis, energy and memory capacity for five days and practical in clinical use. The prototype (CAMP: Continuous Ambulatory Monitoring of Prosthetic walking) consists of a cylindrical unit containing an accelerometer, a miniature computer and six batteries. Specifications, data acquisition and processing, instructions for users and first results are presented and discussed. The CAMP prototype proved to be a useful device for measuring relevant aspects of prosthetic use for up to five days.

Amputees↗

PubMed1992

Different methods to estimate total power and its components during lifting.

A more fundamental understanding about the act of manual lifting can be provided by the assessment of the total production of power and the power generated in joints. The present study is concerned with the validity of the estimations of these parameters. Four subjects lifted an 18.8 kg load while they were filmed and ground reaction forces were measured. The total generated power was calculated in three ways: (1) by summation of joint powers, (2) on the basis of the rate of change of the summed energy contents of human body segments, and (3) on the basis of the rate of change of the body energy estimated from ground reaction forces. The results were compared. Furthermore, at a segmental level the power supplied to or absorbed from a segment was compared to the rate of change of its energy content. The resulting instantaneous power curves from the three different methods showed a high level of agreement, which supports their validity. However, some minor discrepancies were observed. The major cause of the observed difference between the rate of change of the summed segmental energy contents and the summed joint powers was found at a segmental level. It was observed that segmental link lengths (i.e. distances between proximal and distal markers) changed during movement, which yielded discrepancies between the power flow to or from a segment and the rate of change of its energy content.

Adult↗