Development and validation of a physical activity monitor for use on a wheelchair

Study design: Keeping physically active is important for people who mobilize using a wheelchair. However, current tools to measure physical activity in the wheelchair are either not validated or limited in their application. The purpose of this study was to develop and validate a monitoring system to measure wheelchair movement.<p></p> Methods: The system developed consisted of a tri-axial accelerometer placed on the wheel of a wheelchair and an analysis algorithm to interpret the acceleration signals. The two accelerometer outputs in the plane of the wheel were used to calculate the angle of the wheel. From this, outcome measures of wheel revolutions, absolute angle and duration of movement were derived and the direction of movement (forwards or backwards) could be distinguished. Concurrent validity was assessed in comparison with video analysis in 14 people with spinal cord injury using their wheelchair on an indoor track and outdoor wheelchair skills course. Validity was assessed using intraclass correlation coefficients (ICC(2,1)) and Bland–Altman plots.<p></p> Results: The monitoring system demonstrated excellent validity for wheel revolutions, absolute angle and duration of movement (ICC(2,1)>0.999, 0.999, 0.981, respectively) in both manual and powered wheelchairs, when the wheelchair was propelled forwards and backwards, and for movements of various durations.<p></p> Conclusion: This study has found this monitoring system to be an accurate and objective tool for measuring detailed information on wheelchair movement and manoeuvring regardless of the propulsion technique, direction and speed

Upper limb activity over time in complex regional pain syndrome type 1 as objectively measured with an upper limb-activity monitor: An explorative multiple case study

Background: An upper limb-activity monitor (ULAM) has been developed to determine activity limitations in complex regional pain syndrome type I (CRPS I). The ULAM is based on 24 h ambulatory monitoring of body segment accelerations and enables valid and objective quantification of mobility and upper limb activity in transversal studies.Aims: To explore tipper limb activity over time in acute upper limb CRPSI as measured with the ULAM in a longitudinal study, and to compare this to time courses of other outcome measures for activity limitations and impairments.Methods: Four subjects were measured four times during a treatment protocol. Several ULAM outcome measures related to upper limb usage and mobility, three questionnaires (RASQ, DASH, RAND36), and six impairment outcome indicators (VAS-momentary pain, VAS-pain resulting from effort, volume, temperature, active range of motion, strength) were used.Results: Objectively measured upper limb activity frequently improved; improvements of >5% were found for 63% of the ULAM outcome measures at final assessment. The ULAM outcome measures had a time course more similar to the body-part and CRPS I specific questionnaire RASQ than the other questionnaires. The time course of impaired temperature was most often in accordance with the ULAM, and both VAS scores showed least accordance.Conclusions: Clear changes in upper limb activity over time were frequently found as objectively measured with the ULAM, and relationships among the time courses of the ULAM and other outcome measures were largely explainable. The ULAM can validly assess upper limb activity over time in CRPSI, but between-measurement variability needs careful consideration. (C) 2005 Published by Elsevier Ltd on behalf of European Federation of Chapters of the International Association for the study of Pain

Analysis and decomposition of accelerometric signals of trunk and thigh obtained during the sit-to-stand movement

Piezoresistive accelerometer signals are frequently used in movement analysis. However, their use and interpretation are complicated by the fact that the signal is composed of different acceleration components. The aim of the study was to obtain insight into the components of accelerometer signals from the trunk and thigh segments during four different sit-to-stand (STS) movements (self-selected, slow, fast and fullflexion). Nine subjects performed at least six trials of each type of STS movement. Accelerometer signals from the trunk and thigh in the sagittal direction were decomposed using kinematic data obtained from an opto-electronic device. Each acceleration signal was decomposed into gravitational and inertial components, and the inertial component of the trunk was subsequently decomposed into rotational and translational components. The accelerometer signals could be reliably reconstructed: mean normalised root mean square (RMS) trunk: 6.5% (range 3-12%), mean RMS thigh: 3% (range 2-5%). The accelerometric signals were highly characteristic and repeatable. The influence of the inertial component was significant, especially on the timing of the specific event of maximum trunk flexion in the accelerometer signal. The effect of inertia was larger in the trunk signal than in the thigh signal and increased with higher speeds. The study provides insight into the acceleration signal, its components and the influence of the type of STS movement and supports its use in STS movement analysis

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) bath 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. Ln 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. (C) 2000 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved

Accelerometry in cardiovascular psychophysiology:New perspectives for ambulatory research

Interpretation of real-life stress-related cardiovascular responses requires knowledge of both the type and the amount of daily activities, since changes in body posture and locomotor activity have a profound effect on ambulatory recorded cardiovascular signals. Simultaneous recording of cardiovascular and locomotor activity may therefore facilitate the interpretation of prolonged cardiovascular measurements in clinical and experimental research. We evaluated accelerometry as a method to quantify both static (lying, sitting, standing) and dynamic activities in a study that was designed to assess the sedative effects of benzodiazepines on cardiovascular functioning in relation to normal daily activities. Our validation study showed that accelerometry by means of body-mounted sensors forms a valid method to quantify aspects of normal daily activities. Furthermore, our quantification of body postures and physical activity, in relation to heart rate, proved to be sufficiently sensitive to differentiate the placebo from the pharmacological conditions. Ambulatory monitoring of combined cardiovascular and accelerometer signals therefore proved to be a promising method for psychophysiological research

Accelerometry in cardiovascular psychophysiology: New perspectives for ambulatory research

Interpretation of real-life stress-related cardiovascular responses requires knowledge of both the type and the amount of daily activities, since changes in body posture and locomotor activity have a profound effect on ambulatory recorded cardiovascular signals. Simultaneous recording of cardiovascular and locomotor activity may therefore facilitate the interpretation of prolonged cardiovascular measurements in clinical and experimental research. We evaluated accelerometry as a method to quantify both static (lying, sitting, standing) and dynamic activities in a study that was designed to assess the sedative effects of benzodiazepines on cardiovascular functioning in relation to normal daily activities. Our validation study showed that accelerometry by means of body-mounted sensors forms a valid method to quantify aspects of normal daily activities. Furthermore, our quantification of body postures and physical activity, in relation to heart rate, proved to be sufficiently sensitive to differentiate the placebo from the pharmacological conditions. Ambulatory monitoring of combined cardiovascular and accelerometer signals therefore proved to be a promising method for psychophysiological research