A novel tool to quantify physical activities: ambulatory accelerometry in psychopharmacology

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 1 (CRPS1). The ULAM is based on 24h ambulatory monitoring of body segment accelerations and enables valid and objective quantification of mobility and upper limb activity in transversal studies.

AIMS

To explore upper limb activity over time in acute upper limb CRPS1 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 CRPS1 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 CRPS1, but between-measurement variability needs careful consideration.

The validation of a novel activity monitor in the measurement of posture and motion during everyday activities

BACKGROUND

Accurate measurement of physical activity patterns can be used to identify sedentary behaviour and may facilitate interventions aimed at reducing inactivity.

OBJECTIVE

To evaluate the activPAL physical activity monitor as a measure of posture and motion in everyday activities using observational analysis as the criterion standard.

METHODS

Wearing three activPAL monitors, 10 healthy participants performed a range of randomly assigned everyday tasks incorporating walking, standing and sitting. Each trial was captured on a digital camera and the recordings were synchronised with the activPAL. The time spent in different postures was visually classified and this was compared with the activPAL output.

RESULTS

Intraclass correlation coefficients (ICC 2,1) for interdevice reliability ranged from 0.79 to 0.99. Using the Bland and Altman method, the mean percentage difference between the activPAL monitor and observation for total time spent sitting was 0.19% (limits of agreement -0.68% to 1.06%) and for total time spent upright was -0.27% (limits of agreement -1.38% to 0.84%). The mean difference for total time spent standing was 1.4% (limits of agreement -6.2% to 9.1%) and for total time spent walking was -2.0% (limits of agreement -16.1% to 12.1%). A second-by-second analysis between observer and monitor found an overall agreement of 95.9%.

CONCLUSION

The activPAL activity monitor is a valid and reliable measure of posture and motion during everyday physical activities.

Continuous monitoring of upper-limb activity in a free-living environment

OBJECTIVE

To develop and evaluate a system for the objective measurement of upper-limb activity during a person's activities of daily living.

DESIGN

Construct validation study.

SETTING

Home and work environment.

PARTICIPANTS

Ten able-bodied participants and 10 stroke patients.

INTERVENTIONS

A novel activity monitor was developed for monitoring upper-limb activity. The Strathclyde Upper-Limb Activity Monitor (SULAM) gave a signal proportional to the vertical displacement of the wrist with respect to the shoulder. Participants wore the SULAM on both upper limbs for 8 hours while performing their normal daily activities.

MAIN OUTCOME MEASURES

SULAM-derived variables quantified the total upper-limb activity and the range in which movement of the upper limb occurred.

RESULTS

Data showed that the dominant arm of the able-bodied participants was 19% more active than the nondominant arm, whereas the unaffected arms of the group of stroke patients was used 3 to 6 times more than their affected arm. For all the variables, in both groups, there were significant differences between their upper limbs except for movement below midtrunk. There were also significant differences between groups for bimanual movement time ( P =.000) and composite movement time ( P =.000).

CONCLUSIONS

The results suggest that the quantification of vertical position of the wrist with respect to the shoulder might reflect upper-limb activity. By using the SULAM, it is possible to monitor upper-limb activity over the course of a person's normal day, with minimal interference. This study provides preliminary evidence of the SULAM as a useful tool for objectively evaluating interventions aimed at improving upper-limb activity and function.

Haemodynamic responses to physical activity and body posture during everyday life

OBJECTIVE

To determine the relationships between body posture and physical activity and systemic haemodynamics during everyday life.

METHODS

Continuous measurements were performed in 34 subjects (16 hypertensive, 12 male), aged 49 +/- 13 (mean +/- standard deviation) years. Blood pressure (BP) was measured in the brachial artery. Physical activity and posture were measured with four accelerometers. Beat-to-beat values of systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were computed from the pressure waveforms. Multiple correlation coefficients (R) between activity and haemodynamic variables were computed and responses to physical activity were estimated with random regression models.

RESULTS

The overall percentages of variance in SBP, DBP, HR, SV, CO and SVR explained by activity (R2) were 32, 28, 56, 44, 74, and 45%, respectively. The SBP and HR increased linearly with increasing levels of activity (19 mmHg and 30 beats/min when activity increased 90 percentiles). Other variables showed parabolic relationships. The initial decrease in SV and CO (14 ml and 0.5 l/min) and increase in DBP and SVR (9 mmHg and 2 mmHg min/l) with increasing levels of activity coincided with changes in posture (lying-sitting-standing). The subsequent SV and CO increase (23 ml and 3.7 l/min) and DBP and SVR decrease (8 mmHg and 8 mmHg min/l) coincided with changes in activity (standing-moving generally-walking).

CONCLUSIONS

Our findings show that normal daily posture and activity are only moderate determinants of BP, but main determinants of HR and CO variation.

Impairments and activity limitations in subjects with chronic upper-limb complex regional pain syndrome type I

OBJECTIVE

To determine the degree of impairments and activity limitations and their interrelationship in complex regional pain syndrome type I (CRPS type I).

DESIGN

Cross-sectional study interrelating impairments and objectively measured activity limitations.

SETTING

Ambulatory and home environment.

PARTICIPANTS

Thirty nonacute upper-limb CRPS type I subjects.

INTERVENTIONS

Not applicable. Main outcome measures Sensory, motor, and autonomic impairments, as well as activity-limitation outcome measures. The latter were objectively measured with a novel upper-limb activity monitor (based on ambulatory accelerometry).

RESULTS

All subjects were impaired to some degree but with a large variability with respect to magnitude. Regarding activity limitations, the involved upper limb was clearly less active (lower intensity and percentage of activity) than the noninvolved side. Impaired active range of motion (adjusted R(2) range, 18%-39%) and grip strength (adjusted R(2) range, 12%-45%) were the most important factors explaining variance in activity limitations.

CONCLUSIONS

All subjects were still impaired nearly 3 years after the causative event. The involved upper limb was also clearly less active than the noninvolved side, especially when the subjects were sitting and when the dominant side was involved. The more impairments a subject had, especially motor impairments, the more activity limitations were present.

Obesity in patients with craniopharyngioma: assessment of food intake and movement counts indicating physical activity

Patients with childhood-onset craniopharyngioma (CP) often suffer from obesity. We evaluated two important etiological factors of obesity development, energy intake and physical activity. Energy intake was supposed to be high due to a disturbed hypothalamic regulation of appetite. We used a validated nutritional diary to determine the 1-wk food intake in 27 CP patients (12 with intrasellar tumors and 15 with hypothalamic tumors) and 1027 controls who were a representative sample of the 7- to 16-yr-old German population. In 2 accelerometry settings, we determined movement counts indicating physical activity. Nineteen CP patients were comparable to 26 controls for age and body mass index. One setting was a clinical one during weight reduction; the other was an out-patient setting. Daily energy intake was 1916 +/- 677 kcal (mean +/- SD) in intrasellar CP patients, 2075 +/- 877 kcal in hypothalamic CP patients, and 2476 +/- 815 kcal in non-CP controls. Patients suffering from CP showed fewer movement registrations [clinical setting, 228 vs. 298 cpm for obese controls (P = 0.01); out-patient setting, 228 vs. 282 cpm for controls (P = 0.08)]. Differences were most pronounced during leisure time (382 cpm in CP patients vs. 546 cpm in obese controls; P = 0.002; clinical setting). Our findings suggest that reduced physical activity, rather than increased energy intake, in CP patients is responsible for the obesity development noted in these subjects.

Impact of upper limb complex regional pain syndrome type 1 on everyday life measured with a novel upper limb-activity monitor

Complex regional pain syndrome type 1 (CRPS1) often leads to serious activity limitations in everyday life. To date, however, limitations in patients with CRPS1 of an upper limb have not been objectively measured.Therefore, the aim of this study was to determine the long-term impact of upper limb CRPS1 on general mobility and upper limb usage during everyday life, as measured with a novel upper limb-activity monitor (ULAM). In ten female chronic CRPS1 patients and ten healthy control subjects, 24-h activity patterns were measured with the ULAM. This ULAM consists of body-fixed acceleration sensors, connected to a recorder worn around the waist. The ULAM automatically detects upper limb activity during mobility-related activities. Several outcome measures related to general mobility and upper limb usage were compared between patients and controls. The results showed that CRPSI in the dominant upper limb had modest impact on general mobility; i.e. on the percentages spent in body positions and body motions and on mean intensity of body activity. For upper limb usage outcome measures during sitting, there was a marked difference between CRPS1 patients and controls. Especially patients with dominant side involvement clearly showed less activity of their involved limb during sitting, indicated by significant differences for the mean intensity (P=0.014), percentage (P=0.004), and proportion (P=0.032) of upper limb activity. It is concluded that these ten chronic CRPS1 patients still had limitations in upper limb usage during everyday life, 3.7 years (average) after the causative event.

Determinants of ambulatory blood pressure response to physical activity

OBJECTIVES

Previous studies reported that the association between physical activity, measured with a wrist-worn accelerometer, and ambulatory blood pressure is rather weak and that the inter-individual variation in the degree of association is high. The aim of the present study was to quantify the responses of ambulatory blood pressure (BP) and heart rate (HR) to physical activity, and to determine the effect of age, gender, body mass index, mean BP and HR level and the use of antihypertensive medication on these responses.

PATIENTS AND METHODS

Twenty-seven subjects (24 hypertensive) underwent 24-h ambulatory monitoring of BP, HR and physical activity. Physical activity was measured with four accelerometers mounted on the trunk and legs. The daytime BP and HR responses to physical activity and the possible modulating effects of the various subject characteristics on these responses were estimated with Random Regression Models.

RESULTS

Increasing physical activity from a very low level (e.g. watching television) to a moderate level (e.g. shopping) caused an average response of systolic blood pressure (SBP) of 11.6 mmHg, of diastolic blood pressure (DBP) of 7.0 mmHg and of HR of 16.1 beats/min. The SBP response to activity was about 2 mmHg larger for the overweight subjects than for subjects with normal weight, and the SBP, DBP and HR responses increased about 0.8 mmHg, 0.6 mmHg and 0.7 beats/min, respectively, with every 10 years increase in age. The between-subjects variances in estimated responses were low and were almost completely explained by differences in overweight and age between subjects. The average within-subject variances, however, were high.

CONCLUSIONS

Normal daily physical activity explains only a small part of the BP and HR variability. The BP and HR responses to activity are modestly affected by age. Overweight has a small effect on the SBP response to activity.

Ambulatory measurement of upper limb usage and mobility-related activities during normal daily life with an upper limb-activity monitor: a feasibility study

The aim of this research was to assess the ability of an upper limb-activity monitor (ULAM) to discriminate between upper limb usage and non-usage in healthy and disabled subjects during normal daily life. The ULAM was based on ambulatory accelerometry and consisted of several acceleration sensors connected to a small recorder worn around the waist. While wearing this ULAM, four healthy and four disabled subjects performed an activity protocol representing normal daily life upper limb usage or non-usage. The motility feature (derived from the raw acceleration signals) was used as a measure of the extent of upper limb usage. Agreement scores between ULAM output and videotape recordings (reference method) were calculated. ULAM data that were of special interest for rehabilitation were detected satisfactorily (overall agreement 83.9%). There were no systematic differences in the agreement percentages between healthy and disabled subjects for mobility-related activities (p = 0.345) and the different forms of upper limb usage or non-usage (p= 0.715). The ULAM can be used in future studies in subjects with upper limb disorders to discriminate between upper limb usage and non-usage during performance of mobility-related activities to determine activity limitations.

Ambulatory accelerometry to quantify involuntary movements and tics in the syndrome of Gilles de la Tourette

Gilles de la Tourette syndrome is a chronic neuropsychiatric disorder characterized by recurrent and involuntary tics, in addition to complex behavioral symptoms. Objective quantification of the nonspecific movements in Tourette patients can contribute much to understanding the pathophysiology of this disease. We used three accelerometers to characterize head movement patterns and to objectively quantify head motility in the lateral, sagittal, and transversal planes in 9 Tourette patients and 14 controls during periods of rest, conversation, and watching a videotape with an entertaining program. Characteristic head movement patterns can be documented by means of accelerometry. Head motility levels in the lateral, sagittal, and transversal planes were significantly higher in the patients than in the controls during all the procedures. The patients and the controls showed a similar significant increase in head motility during conversation, but not during video watching. This first study shows that for both standardized and ambulatory research, accelerometry may provide an objective tool by which to quantify the severity and temporal dynamics of tics or nonspecific movements.

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.

Assessment of body position to quantify its effect on nocturnal blood pressure under ambulatory conditions

BACKGROUND

Nocturnal blood pressure readings may be influenced by body position because of variation in the vertical distance between heart and cuff level.

OBJECTIVES

To quantify the effect of body position on nocturnal blood pressure and to assess whether this effect influences the reproducibility of nocturnal blood pressure.

PATIENTS AND METHODS

In 16 individuals (three normotensive and 13 hypertensive) 24 h ambulatory measurement of blood pressure and body position was performed twice, separated by an interval of 2-6 weeks. Body position was measured with five acceleration sensors, which were mounted on the trunk and legs.

RESULTS

During the first night, 43 +/- 31% of blood pressure values were measured while participants were in the supine position, 29 +/- 28% when they were lying on their side with the cuffed arm down and 28 +/- 29% when they were lying on their side with the cuffed arm up. During the second night these percentages were 40 +/- 29%, 32 +/- 29% and 28 +/- 25% respectively. Blood pressure readings obtained while individuals were lying with the cuffed arm up were about 10 mmHg lower than those obtained with the individual in either the supine position or lying with the cuffed arm down. After correction for the underestimation attributable to 'cuff-up' readings, nocturnal blood pressure increased by 3 mmHg and the number of non-dippers increased from two to four. Correction did not affect the reproducibility of nocturnal blood pressure measurements (standard deviation of the differences 8.3 mmHg for systolic and 6.0 mmHg for diastolic blood pressure after correction). Dipping status was reproduced in 88% of individuals before correction, and in 87% after correction.

CONCLUSIONS

Under ambulatory conditions, a highly variable but sometimes substantial number of blood pressure readings are taken with the cuffed arm above heart level. These readings result in underestimation of nocturnal blood pressure and hence influence dipper-non-dipper classification. However, body position does not seem to have an important influence on the reproducibility of nocturnal blood pressure or dipping status.

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.

Measuring neuroleptic-induced akathisia by three-channel actometry

Three-channel actometry was used to study neuroleptic-induced akathisia (NIA), a common and often serious disorder in association of traditional neuroleptic therapy. The aim was to explore the diagnostic possibilities of actometry in NIA and to examine in detail the motor phenomenology of the disorder in detail. The actometers were attached to the ankles and waists of ten patients, suffering from NIA, and to ten matched healthy controls. Five of the patients were changed to olanzapine treatment, and these patients were re-examined during the no-NIA condition. NIA was associated with manyfold movement activity during controlled rest (sitting) but not with increased daily overall motor activity. Movement frequencies in NIA seemed to be pathognomonic. Actometry is promising for investigation and clinical assessment of NIA. Olanzapine proved to be an adequate treatment choice for NIA patients.

Current techniques for assessing physical exposure to work-related musculoskeletal risks, with emphasis on posture-based methods

Physical exposure to risks for potential work-related musculoskeletal injuries has been assessed using a variety of methods, including pen and paper based observation methods, videotaping and computer-aided analysis, direct or instrumental techniques, and various approaches to self-report assessment. These methods are critically reviewed in this paper. The applications of these techniques in ergonomic and epidemiologic studies are considered, and their advantages and shortcomings are highlighted. Finally, a strategy that considers both the ergonomics experts' view and the practitioners' needs for developing a practical exposure assessment tool is then discussed.

Influence of patient's dressing on spontaneous physical activity and length of hospital stay in surgical patients

Wearing hospital gown (HG) as opposed to plain-clothes (PC) may contribute to the general state of inactivity of hospitalised patients. We designed a randomized study to determine the influence of clothing on the level of spontaneous physical activity (SPA) and to assess the length of hospital stay. Using triaxial accelerometry we measured the SPA in two groups of surgical patients, before and after an elective operation. Twenty eight patients received instructions to wear plain-clothes (group PC) during their stay in the hospital as soon as possible from a surgical point of view. Twenty-nine patients, serving as a control group, did not receive any specific instructions and as a result, were mostly wearing hospital gowns (group HG). Following the admission to the hospital, both groups showed a 50% decrease in SPA when compared to the recordings obtained during the last 24 hours spent at home. During the postoperative period, the SPA increased progressively in both groups. Although patients in group PC tended to be more active than those in the control group, the SPA was not significantly different (P = 0.4). Similarly, patients in group PC left the hospital 10 hours earlier than patients in group HG (P = 0.4). The power of our study was nevertheless low and a sample size of 700 patients might show statistically significant results. We conclude that wearing plain-clothes when hospitalized for elective surgery is not associated with complications and could be included in postoperative rehabilitation program.

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.