Ambulatory Activity Monitoring Research Articles

On the use of actigraphy in clinical evaluation of diurnal blood pressure profile

AbstractA disturbed diurnal blood pressure profile is one of the most important risk factors of cardiovascular diseases. This review analyzes the use of simultaneous diurnal ambulatory blood pressure monitoring (ABPM) and motion activity monitoring (actigraphy) to obtain additional information for correct interpretation of ABPM results in clinically significant decision-making. The article considers practical aspects of actigraphy in expert ABPM for clock-independent calculation of the parameters of nighttime and daytime blood pressure (BP); detection of BP changes during sleep; connection with respiratory disturbances during sleep, motion activity, and body position; and sleep deprivation in shift workers. Original illustrations of simultaneous ABPM and actigraphy are provided.

Energy Cost During the 6-Minute Walk Test and Its Relationship to Real-World Walking After Stroke: ACorrelational, Cross-Sectional PilotStudy.

After experiencing stroke, individuals expend more energy walking than people who are healthy. However, among individuals who have experienced stroke, the correlation between the energy cost of walking, as measured by validated tests (such as the 6-minute walk test), and participation in walking, as measured by more sensitive tools (such as an ambulatory activity monitor), remains unknown. The main objective of this study was to determine whether the energy cost of walking is correlated with participation in walking. This study was a correlational, cross-sectional pilot study. Data from 23 participants who had experienced chronic stroke were analyzed. On the first day, data on oxygen uptake were collected using a portable metabolic system while participants walked during the 6-minute walk test. Then, the ambulatory activity monitor was placed on the participants' nonparetic ankle and removed 9days later. The energy cost of walking was calculated by dividing the mean oxygen uptake recorded during the steady state by the walking speed. The energy cost of walking was correlated with the following: the number of steps (Spearman rank correlation coefficient [rs]=-0.59); the percentage of time spent in inactivity (rs=0.48), low cadence (rs=0.67), medium cadence (rs=-0.56), high cadence (rs=-0.65), and the percentages of steps taken at low cadence (rs=0.65) and high cadence (rs=-0.64). Individuals who were physically inactive, convenience sampling, and a small sample size were used in this study. Higher energy costs of walking were associated with fewer steps per day and lower cadence in real-world walking in individuals who had experienced stroke.

The comfort, acceptability and accuracy of energy expenditure estimation from wearable ambulatory physical activity monitoring systems in soldiers

The comfort, acceptability and accuracy of energy expenditure estimation from wearable ambulatory physical activity monitoring systems in soldiers

Reliably estimating ambulatory activity in youth with arthrogryposis

Purpose: Quantification of the physical activity levels using pedometers and accelerometers in children and adolescents with mobility limitations has recently allowed researchers and practitioners to track real-life outcomes of new interventions in this particular population. Questions remain concerning the reliability of ambulatory activity monitoring in functionally challenged youth. The purpose of the analysis, therefore, was to document the minimal number of days required to reliably estimate ambulatory activity levels in children with arthrogryposis. Methods: Thirteen boys and girls with arthrogryposis (average age 10.9 years) completed stepping activity monitoring using a two-dimensional accelerometer over a period of up to 15 consecutive days. Generalizability theory was applied to identify sources of variance in daily step counts (generalizability study, G study) and to determine the number of days necessary to obtain a reliable coefficient of ≥0.80 (decision study, D study). Results: G study results showed that intra-individual variability was larger (58.4% of total variance) than inter-individual variability (28.7% of total variance). D study indicated that 9 days of monitoring was required to reach a stable measure of ambulatory activity. Conclusions: Due to relatively greater variability in step counts across days of the week, a longer monitoring period was required for youth with arthrogryposis.Implication for RehabilitationLarge proportion of variance in daily step counts was attributable to unidentifiable sources of variance, suggesting further exploration of factors that influence on the walking activity in youth with arthrogryposis.Step activity monitoring of youth with arthrogryposis should occur over a 9-day period to reliably capture their habitual level of ambulation.Rehabilitation programs aimed to promote increased stepping in youth with arthrogryposis which can utilize the findings of the present study to appropriately track their effectiveness.

Interinstrument Reliability of the ActiGraph GT3X+ Ambulatory Activity Monitor During Free-Living Conditions in Adults.

Currently, no studies have investigated interinstrument reliability of the ActiGraph (AG) GT3X+ in free-living conditions. Nineteen adults (11 males, 8 females; aged 36.8 ± 11.9 years) wore a pair of AG's (one on each hip), during all waking hours for 1 day. Raw outputs were generated for total counts, steps, wear time and mean counts per minute. Intensity outputs were derived for time (minutes) spent in <moderate, moderate, vigorous, very vigorous and moderate-to-vigorous physical activity (MVPA). Intraclass correlation (ICC), absolute percent difference (APD), coefficient of variation (CV), Bland-Altman plots, and paired t tests were used to evaluate reliability. Interinstrument reliability was high (CV < 5%) for raw count and derived intensity outputs, except vigorous and very vigorous activity. ICC, CV, and APD values for vigorous and very vigorous were .97, 12.28, 17.36% and .98, 18.15, 25.67%, respectively. Amalgamating moderate, vigorous, and very vigorous into a single MVPA category reduced the CV and APD values to 2.85 and 4.02%, and increased the ICC value to .99. No significant differences were found between contralateral units for any outputs (P > .05). Reliability decreases beyond moderate intensities. MVPA displays superior interinstrument reliability than individual intensity categories. Research question permitting, reporting time in MVPA may maximize reliability.

Do Patients With Multiple Sclerosis Show Different Daily Physical Activity Patterns From Healthy Individuals?

Background. Reduced physical activity is an important consequence of multiple sclerosis (MS). However, little is known about the real quantity and type of daily activities that people with MS perform in their own home environment. Objective. To gain insight into differences in the amount and patterns of physical activities performed over a 24-hour period in the own community environment of patients with MS and healthy individuals. Methods. A total of 43 ambulatory patients with MS and 26 age- and gender-matched healthy individuals participated. Physical activity recorded with an ambulatory activity monitor was classified into postures and motions. Multilevel analyses were conducted to investigate whether the pattern of physical activities across daily periods (morning, afternoon, and evening) was dependent on the group (MS vs healthy individuals). Results. Results showed a significant overall lower amount of dynamic activity as compared with a group of healthy controls (P < .001). Patients with MS started with lower physical activity levels already in the morning (P < .001), and this difference persisted in the afternoon (P = .002) and evening (P = .032). Conclusion. Activity monitoring gives insight into real-world daily physical behavior. Our findings suggest that patients with MS may adopt a deliberate anticipatory strategy of lower activity in the morning, which persists throughout the day. Future trials evaluating daily changes in physical activity behavior should simultaneously sample self-report measures of energy levels and fatigue to elucidate the complex interaction between symptoms and physical activity.

Promotion of physical activity and fitness in sedentary patients with Parkinson’s disease: randomised controlled trial

Objective To evaluate whether a multifaceted behavioural change programme increases physical activities in patients with Parkinson’s disease.Design Multicentre randomised controlled trial.Setting 32 community hospitals in the Netherlands, collaborating in a...

Physical activity of moderately impaired elderly stroke patients during rehabilitation

In older adults, physical activity (PA) is promoted for public health preventive effort. It is also a major target in the rehabilitation process. Existing assessment tools in the clinical routine do not include any aspects of PA or participation and are often prone to floor or ceiling effects. The aim of this study was to document the process of rehabilitation by activity monitoring without floor or ceiling effects. Ninety-two stroke patients of a geriatric rehabilitation unit (mean age 82 years, ±6.21 years, 61% women) were included in an observational study to assess physical capacity (balance, chair rise, gait speed) and PA at admission and two weeks thereafter. PA was measured through an ambulatory activity monitor based on accelerometers and gyroscopes and showed no floor or ceiling effects. Floor effects were however documented for measures of physical capacity (admission 5–11%; follow-up 2–9%) and ceiling effects were registered for the balance test (admission 17.4%; follow-up 22.8%). Improvements were documented for measures of physical capacity as well as for PA (all p < 0.001). We conclude that the assessment of PA by activity monitoring is a valuable measure to document objectively the process of rehabilitation without floor or ceiling effects.

The Relationship of the BODE Index to Oxygen Saturation During Daily Activities in Patients with Chronic Obstructive Pulmonary Disease

The frequency of oxygen desaturation during daily activities in chronic obstructive pulmonary disease (COPD) is poorly defined. The BODE index predicts survival in COPD. The purpose of this study was to determine the relationship between BODE scores and oxygen saturation during daily activities. Seventy-eight patients with COPD (FEV(1) = 37%) underwent ambulatory oximetry and activity monitoring. We defined four activity categories: Walking, Slow-Intermittent-Walking (SIW), Active-Not-Walking (ANW), and Rest. We quantified oxygen desaturation during activity using a desaturation index (DSI = % time oxygen saturation <90%). BODE scores were categorized into three groups: group I (0-3), II (4-6), and III (7-10). The percentage of patients demonstrating oxygen desaturation (DSI ≥ 10%) during each activity was 55% for Walking, 35% for SIW, 15% for ANW, and 28% for Rest. There was a strong association between BODE score and desaturation for Walking and SIW. During Walking, 21, 44, and 86% of patients in BODE groups I, II, and III, respectively, demonstrated desaturation. The DSI for Walking and SIW was increased in patients in BODE groups II and III compared to group I (P < 0.006, P < 0.007, respectively). BODE score was also linked to long-term oxygen therapy (LTOT) usage; the majority of patients not on LTOT (89%) had a BODE score <7. The majority of patients on LTOT (84%) demonstrated desaturation during Walking, but 42% of patients not on LTOT also demonstrated desaturation. In this subgroup of patients not on LTOT, all patients with a BODE score ≥ 7 demonstrated desaturation during Walking. The link between the BODE index and oxygen desaturation during daily activities suggests that desaturation is linked to disease severity. Our data suggest that patients with a BODE score ≥ 7 should be evaluated for desaturation during daily activities. Use of the BODE index to screen for exertional desaturation may have value as a tool that can lead to the earlier identification of patients who may be candidates for LTOT.

The Effects of Thoracic and Cervical Spinal Cord Lesions on the Circadian Rhythm of Core Body Temperature

Individuals with a spinal cord injury (SCI) have compromised afferent and efferent information below the lesion. Intact afferent information regarding skin temperature and the ability to regulate skin blood flow lead to an altered heat balance, which may impact the circadian variation in core body temperature (Tcore) and sleep-wake cycle. The authors assessed the circadian variation of Tcore in SCI individuals and able-bodied controls matched for the timing of the sleep-wake cycle. The authors examined subjects who had a high (cervical) or a low (thoracic) lesion. Intestinal Tcore (telemetry system) and physical activity (ambulatory activity monitor) levels were measured continuously and simultaneously in 8 tetraplegics, 7 paraplegics, and 8 able-bodied controls during one 24-h period of “normal” living. The regression slope between activity and Tcore was also calculated for each 2-h bin. Circadian rhythm parameters were estimated with partial Fourier time-series analysis, and groups were compared with general linear models, adjusted for the influence of individual wake-time. The (mean ± SD) dominant period length for controls, paraplegics, and tetraplegics were 24.4 ± 5.4 h, 22.5 ± 5.0 h, and 16.5 ± 5.1 h, respectively (p = .02). A significantly more pronounced 8-h harmonic was found for the variation in Tcore of SCI individuals (p = .05). Tetraplegics showed the highest nocturnal mean Tcore (p = .005), a 5-h phase-advanced circadian trough time (p = .04), and more variable relationships between physical activity and Tcore (p = .03). Taken together, tetraplegics demonstrate a pronounced disturbance of the circadian variation of Tcore, whereas the variation of Tcore in paraplegics was comparable to able-bodied controls. (Author correspondence: D.Thijssen@fysiol.umcn.nl)

Promoting walking amongst older patients in rehabilitation: are accelerometers the answer?

The role of physical activity amongst older people in inpatient rehabilitation settings has been little studied. Walking has a number of potential benefits for older people in rehabilitation but it is not known whether increased walking improves outcomes in this population. Until now mobility monitoring has not been possible in routine practice. Recently tri-axial accelerometers have been validated for ambulatory activity monitoring in older adults. Accelerometry has the potential to explore the role of walking in older patients in rehabilitation. Providing data regarding activity levels may improve patient motivation and assist clinicians with activity prescription. Future research could determine the relationship between activity levels and patient outcomes.

Daily ambulatory activity monitoring in patients with peripheral artery disease

Background: Peripheral artery disease (PAD) is characterized by arterial lesions of the lower extremities. Patients with PAD present ambulatory dysfunction due to intermittent claudication, limiting daily physical activity and increasing morbidity. Therefore, objectively measured daily ambulation is a clinically relevant outcome in these patients.Objective: To quantify daily ambulation with a step activity monitor (Step Watch 3™; Cyma Inc., Mountlake Terrace, WA, USA) in patients with PAD.Major findings: Patients with claudication ambulate less each day than controls, as they take 1081 fewer strides (1 stride=2 steps) and spend 48 fewer minutes ambulating each day. The cadence obtained during endurance ambulation (maximum cadences for 60, 30, and 20 continuous minutes of ambulation) and short bouts of ambulation (maximum cadence for continuous minutes of ambulation and for the minute having the single highest cadence value each day) is also lower in patients. Demographic factors and comorbid conditions, particularly sex, dyslipidemia, abdominal obesity, and the number of components of metabolic syndrome, affect the ambulatory activity patterns of patients with claudication.Conclusions: Patients with claudication perform a lower amount of daily ambulatory activities and lower intense physical activities than controls, which is impaired further by comorbid conditions. The clinical implication is that patients with claudication should not only be advised to walk more during each day, but to do so at a cadence that is higher than their self-selected slower cadence. This approach will increase total daily exercise volume by increasing both the duration as well as the intensity of ambulation.

The relationship between ambulatory step activity, self-reported physical functioning and standardised timed walking in patients with haematological malignancies

Purpose. This cross-sectional study investigated the degree of association between the results of ambulatory step activity monitoring (SAM), self-reported physical functioning (SRPF) and the 6-minute standardised walking test (6-MWT) in cancer patients with haematological malignancies.Method. Assessments of ambulatory SAM, SRPF and 6-MWT were assessed in 102 patients up to 122 days (mean 78 ± 35) after haematopoietic stem cell transplantation (HSCT). To determine the association between measures of walking, the Pearson product moment correlation coefficient (r) including the 95%CI and the r2 were calculated. Simple linear regression analyses were performed to estimate the ambulatory step activity from SRPF and the 6-MWT.Results. The average age was 47 years (±12) and body mass index 23.4 (±4). The correlations were low between ambulatory SAM outputs and SRPF (ranging from −0.32 to 0.34, p < 0.01), and very low between SAM outputs and 6-MWT, (ranging from 0.21 to 0.24). The correlation between SRPF and the 6-MWT was low (0.33, p < 0.01). The correlation between SRPF and the 6-MWT was low (0.33, p < 0.01). The 95%CIs were quite narrow around r. The shared variance (r2) between the SAM and SPPF ranged between 4% and 11% and the shared variance between the SAM and 6-MWT ranged between 0.5% and 18%. Linear regression yielded weak relationships and large standard errors of estimate between the SAM, SRPF and 6-MWT.Conclusions. SRPF and the 6-MWT do not reflect daily walking activity. In clinical use (e.g. to evaluate the effects of a rehabilitation program), ambulatory step activity outputs can be considered an additional outcome to assess day-to-day walking activity in patients with haematological cancer after HSCT.

Assessment of response fluctuations in Parkinson's disease by ambulatory wrist activity monitoring.

The aim of this study was to examine the influence of response fluctuations with dyskinesia on the 24-h motor activity pattern and measures of diurnal and nocturnal activity and immobility. Motor activity was recorded during 5 successive days in 5 patients with advanced Parkinson's disease (PD) suffering from severe response fluctuations with dyskinesia, as well as in 10 PD patients with a stable levodopa response and 10 healthy subjects. The 24-h motor activity pattern of the patients with response fluctuations provides insight into the relationship between the therapeutic regimen and 1) the frequency and duration of "on" and "off" periods, 2) the severity of the dyskinesias, and 3) the degree of sleep disruption. In accordance with the severity of their motor fluctuations, patients with response fluctuations showed a large intra- and interindividual variability of diurnal motor activity measures. Overall, the nocturnal motor activity measures in the patients with response fluctuations indicated a severely disturbed sleep when compared with the two control groups. Factors as simplicity and the potential to record unrestrained motor activity for several days continuously in all settings, make activity monitoring a welcomed acquisition in the assessment of response fluctuations in PD.

Ambulatory Activity Monitoring

Behavior is central to psychology in almost any definition. Although observable activity is a core aspect of behavior, assessment strategies have tended to focus on emotional, cognitive, or physiological responses. When physical activity is assessed, it is done so mostly with questionnaires. Converging evidence of only a moderate association between self-reports of physical activity and objectively measured physical activity does raise questions about the validity of these self-reports. Ambulatory activity monitoring, defined as the measurement strategy to assess physical activity, posture, and movement patterns continuously in everyday life, has made major advances over the last decade and has considerable potential for further application in the assessment of observable activity, a core aspect of behavior. With new piezoresistive sensors and advanced computer algorithms, the objective measurement of physical activity, posture, and movement is much more easily achieved and measurement precision has improved tremendously. With this overview, we introduce to the reader some recent developments in ambulatory activity monitoring. We will elucidate the discrepancies between objective and subjective reports of activity, outline recent methodological developments, and offer the reader a framework for developing insight into the state of the art in ambulatory activity-monitoring technology, discuss methodological aspects of time-based design and psychometric properties, and demonstrate recent applications. Although not yet main stream, ambulatory activity monitoring – especially in combination with the simultaneous assessment of emotions, mood, or physiological variables – provides a comprehensive methodology for psychology because of its suitability for explaining behavior in context.

Ambulatory Assessment

Ambulatory Assessment

Reduction of Pain-Related Fear and Disability in Post-Traumatic Neck Pain: A Replicated Single-Case Experimental Study of Exposure In Vivo

For patients with acute post-traumatic neck pain (PTNP), pain-related fear has been identified as a potential predictor of chronic disability. If such is the case, fear reduction should enhance the prevention of further pain disability and distress after traumatic neck pain disability. However, exposure-based treatments have not been tested in patients with PTNP. Using a replicated single-case crossover phase design with multiple measurements, this study examined whether the validity of a graded exposure in vivo, as compared with usual graded activity, extends to PTNP. Eight patients who reported substantial pain-related fear were included in the study. Daily changes in pain intensity, pain-related fear, pain catastrophizing, and activity goal achievement were assessed. Before and after each intervention, and at 6-month follow-up, standardized questionnaires of pain-related fear and pain disability were administered, and, to quantify daily physical activity level, patients carried an ambulatory activity monitor. The results showed decreasing levels of self-reported pain-related fear, pain intensity, disability, and improvements in physical activity level only when graded exposure in vivo was introduced, and not in the graded activity condition. The results are discussed in the context of the search for customized treatments for PTNP. This is the first study showing that the effects of graded exposure in vivo generalize to patients with chronic PTNP reporting elevated levels of pain-related fear. This could help clinicians to customize treatments for PTNP.

Evaluation of ActiTrac® (ambulatory activity monitor) in Parkinson's Disease

At present, the evaluation of Parkinson's Disease (PD) relies mainly on Unified Parkinson's Disease Rating Scale (UPDRS). Other objective measures have been proposed, including functional studies, timed tests and ambulatory activity monitors (AAM). We carried out a prospective study to analyze the utility and correlation of the AAM: ActiTrac with UPDRS scores and timed tests in patients with PD. We studied 28 patients with idiopathic PD (age: 62 +/- 11 years; duration of illness: 7.7 +/- 4.4 years; clinical stage 2.3 +/- 0.39). Motor evaluation included UPDRS and five timed tests: Purdue Pegboard test and those proposed in CAPIT protocol, pronation-supination (PS), finger dexterity (FD), movement between two points (MTP) and walking test (WT). Clinical evaluation was performed in off condition, at 9 a.m., (12h off their medication). Finally, ActiTrac was placed on the wrist (more affected side) continuously for at least 72h. ActiTrac activity was correlated (Spearman) with total UPDRS (r: - 0.53, p < 0.005) and motor UPDRS (r:- 0.46, p: 0.01); UPDRS rigidity subscore (r:- 0.52, p < 0.01); UPDRS bradykinesia subscore (r:- 0.48; p:0.01); FD (r: - 0.47 p: 0.01), WT (r: - 0.49, p < 0.01) and Purdue test (r:0.54; p < 0.01). ActiTrac seems to be a reasonably accurate method to evaluate motor activity in PD.

Validation of a patient activity monitor to quantify ambulatory activity in an amputee population

The ability to objectively measure an amputee's walking activity over prolonged periods can provide clinicians with a useful means of evaluating their patients' outcomes. The present study aimed to validate the temporospatial data output from a commercially available ambulatory activity monitor (PAM, Ossur) fitted to trans-tibial and trans-femoral amputees, against data that was simultaneously captured from a three dimensional motion analysis system (Qualisys Medical AB, Gothenburg, Sweden). Results indicate that the PAM monitor provides accurate measures of temporospatial aspects of amputee gait for walking speeds above 0.75 m/s.

Quantification of everyday motor function in a geriatric population

This pilot study evaluated variability in physical activities and the correlations between walking, two types of postural transitions, and falls efficacy with an ambulatory activity monitor. An 11-subject convenience sample wore the monitor for 2 consecutive days; in addition, 7 subjects carried the monitor on 1 day of the following week. Demographic characteristics of the sample were age: mean +/- standard deviation [SD] = 87.8 +/- 2.5 yr, body mass index: mean +/- SD = 25.3 +/- 2.1 kg/m(2), and Mini-Mental State Examination score: mean +/- SD = 27.5 +/- 2.0. Analyzed movements were sit-to-stand (SiSt) and stand-to-sit postural transitions, dynamic activity (walking), and static behavior (sitting, standing, lying). Significant correlations were found for the SiSt transition duration (TD) between days (intraclass correlation coefficient = 0.78). No differences were found between the durations of sitting (p = 0.8), lying (p = 0.72), standing (p = 0.06), and walking (p = 0.6). These parameters showed highly variable correlation coefficients. A significant correlation was observed between falls efficacy and SiSt measures (r = 0.84, p < 0.01, df = 9). We reliably determined the SiSt TD after subjects wore the monitor for 1 day in the home environment. Poor correlations between 2 consecutive measurement days for dynamic and static activity underline the necessity of recording further days to assess physical activity levels in the geriatric population.