Assessment of free-living daily physical activity in older claudicants: validation against the doubly labeled water technique

Quality Evaluation of Free-living Validation Studies for the Assessment of 24-Hour Physical Behavior in Adults via Wearables: Systematic Review

Background

Wearable technology is a leading fitness trend in the growing commercial industry and an established method for collecting 24-hour physical behavior data in research studies. High-quality free-living validation studies are required to enable both researchers and consumers to make guided decisions on which study to rely on and which device to use. However, reviews focusing on the quality of free-living validation studies in adults are lacking.

Objective

This study aimed to raise researchers’ and consumers’ attention to the quality of published validation protocols while aiming to identify and compare specific consistencies or inconsistencies between protocols. We aimed to provide a comprehensive and historical overview of which wearable devices have been validated for which purpose and whether they show promise for use in further studies.

Methods

Peer-reviewed validation studies from electronic databases, as well as backward and forward citation searches (1970 to July 2021), with the following, required indicators were included: protocol must include real-life conditions, outcome must belong to one dimension of the 24-hour physical behavior construct (intensity, posture or activity type, and biological state), the protocol must include a criterion measure, and study results must be published in English-language journals. The risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool with 9 questions separated into 4 domains (patient selection or study design, index measure, criterion measure, and flow and time).

Results

Of the 13,285 unique search results, 222 (1.67%) articles were included. Most studies (153/237, 64.6%) validated an intensity measure outcome such as energy expenditure. However, only 19.8% (47/237) validated biological state and 15.6% (37/237) validated posture or activity-type outcomes. Across all studies, 163 different wearables were identified. Of these, 58.9% (96/163) were validated only once. ActiGraph GT3X/GT3X+ (36/163, 22.1%), Fitbit Flex (20/163, 12.3%), and ActivPAL (12/163, 7.4%) were used most often in the included studies. The percentage of participants meeting the quality criteria ranged from 38.8% (92/237) to 92.4% (219/237). On the basis of our classification tree to evaluate the overall study quality, 4.6% (11/237) of studies were classified as low risk. Furthermore, 16% (38/237) of studies were classified as having some concerns, and 72.9% (173/237) of studies were classified as high risk.

Conclusions

Overall, free-living validation studies of wearables are characterized by low methodological quality, large variability in design, and focus on intensity. Future research should strongly aim at biological state and posture or activity outcomes and strive for standardized protocols embedded in a validation framework. Standardized protocols for free-living validation embedded in a framework are urgently needed to inform and guide stakeholders (eg, manufacturers, scientists, and consumers) in selecting wearables for self-tracking purposes, applying wearables in health studies, and fostering innovation to achieve improved validity.

Association between low level of physical activity and mobility limitation in older adults: evidence from the SABE study

Several studies are limited by verifying the level of physical activity with questionnaires and not through objective measurement in older adults. This article aims to analyze the association between a low level of physical activity with accelerometry) and mobility limitation in older adults. A population-based cross-sectional study conducted with 543 older adults. Multiple regression analysis was performed using hierarchical analysis, grouping the variables into two blocks ordered according to the precedence with which they acted on the outcomes. Among the evaluated older adults, 13.7% presented mobility limitations and among these 60.39% were in the low level of physical activity group. Older adults with a low level of physical activity (OR = 3.49 [2.0 - 6.13]), aged 75 and over (OR = 1.97 [1.03 - 3.72]), living without a partner (OR = 2.01 [1.09 - 3.68]), having difficulty performing basic (OR = 2.49 [1.45 - 4.28]) and instrumental (OR = 2.28) [1.18 - 4.36]) activities of daily life, and multimorbidity (OR = 2.06 [1.04 - 4.08]) were independently associated with mobility limitation. A low level of physical activity increases the chance of mobility limitation in older adults, regardless of sociodemographic and clinical variables.

Use of Functional Linear Models to Detect Associations between Characteristics of Walking and Continuous Responses Using Accelerometry Data

Various methods exist to measure physical activity. Subjective methods, such as diaries and surveys, are relatively inexpensive ways of measuring one’s physical activity; however, they are prone to measurement error and bias due to self-reporting. Wearable accelerometers offer a non-invasive and objective measure of one’s physical activity and are now widely used in observational studies. Accelerometers record high frequency data and each produce an unlabeled time series at the sub-second level. An important activity to identify from the data collected is walking, since it is often the only form of activity for certain populations. Currently, most methods use an activity summary which ignores the nuances of walking data. We propose methodology to model specific continuous responses with a functional linear model utilizing spectra obtained from the local fast Fourier transform (FFT) of walking as a predictor. Utilizing prior knowledge of the mechanics of walking, we incorporate this as additional information for the structure of our transformed walking spectra. The methods were applied to the in-the-laboratory data obtained from the Developmental Epidemiologic Cohort Study (DECOS).

Association between Physical Activity Levels and Body Composition among Healthy Older Japanese Adults during a Snowy Winter: A Cross-Sectional Study

BACKGROUND

Despite a long average lifespan, increased life expectancy does not guarantee higher quality of life.

METHODS

To contribute in understanding some determinants of healthy life expectancies in older Japanese individuals in a snowy winter region, we investigated the indicators of health. Local residents (n = 124) in the city of Iwamizawa volunteered for health examinations from January 2016 to March 2016. We recorded activity via daily steps for 2-week periods. In addition, we measured body composition, grip strength, and assessed nutritional status.

RESULTS

Analysis of body composition and daily activity indicated that women who walked more than 4000 steps had lower fat mass and increased muscle mass. Men with >3.0 metabolic equivalents (METs) when walking had lower body fat.

CONCLUSION

For healthy older Japanese individuals in this snowy winter region, walking >4000 steps daily for women and exercise of >3.0 METs for men may indicate health-promoting activities.

Custom-Made Daily Routine Increases the Number of Steps Taken by Frail Older Adults

This study examined whether the number of steps taken by frail older adults increased after two types of interventions (custom-made daily routine [CDR] vs. exercise) were conducted over 12 weeks. The participants were 36 frail older adults aged 84.5 ± 6.0 years who attended a day-care center. They were assigned to one of three groups: CDR (n = 13), home-based exercise (HE, n = 10), or control (CON, n = 13). A wrist-worn accelerometer was used to measure their step count in 24 hr for 6 days. The CDR group demonstrated a daily step count change of approximately 25%, which was significantly higher than that of the CON group (effect size [r] = .51, p = .040). There were no significant changes in the HE group. Thus, a CDR might be useful for increasing the number of steps in frail older adults.

Instrumental activities of daily living and number of daily steps in frail older females

[Purpose] Reportedly, males take fewer steps than females among frail older adults. The step count of frail older adults may be influenced by domestic roles in the instrumental activities of daily living. In this study, we aimed to investigate the association between instrumental activities of daily living and the number of steps in frail older females. [Participants and Methods] In this cross-sectional study, we included 27 frail older females aged 84.4 ± 6.5 years who attended a day-care center. We used the Fillenbaum’s instrumental activities of daily living screener and measured the number of steps using an accelerometer, functional independence measure, grip strength, and short physical performance battery. We investigated the association between instrumental activities of daily living and daily steps. Furthermore, we compared the outcomes of the differences in the independence using a subscale of instrumental activities of daily living. [Results] Instrumental activities of daily living and step counts showed a significant correlation. Participants dependent on meal preparation and housework took significantly fewer steps per day. The dependence of their activities also caused low functional independence measure and weak grip strength. [Conclusion] In frail older females, decreased ability for instrumental activities of daily living were associated with fewer steps. Domestic roles may increase the daily steps in frail older adults.

Wearable Sensor Technology Efficacy in Peripheral Vascular Disease (wSTEP): A Randomized Controlled Trial

OBJECTIVE

To evaluate the effect of using wearable activity monitors (WAMs) in patients with intermittent claudication (IC) within a single-center randomized controlled trial.

BACKGROUND

WAMs allow users to set daily activity targets and monitor their progress. They may offer an alternative treatment to supervised exercise programs (SEPs) for patients with IC.

METHODS

Thirty-seven patients with IC were recruited and randomized into intervention or control group. The intervention consisted of a feedback-enabled, wrist-worn activity monitor (WAM) in addition to access to SEP. The control group was given access to SEP only. The outcome measures were maximum walking distance (MWD), claudication distance (CD), and quality of life as measured by the VascuQol questionnaire. Participants were assessed upon recruitment, and at 3, 6, and 12 months.

RESULTS

Patients in the WAM group showed significant improvement in MWD at 3 and 6 months (80-112 m, to 178 m; P < 0.001), which was sustained at 12 months. The WAM group also increased CD (40 vs 110 m; P < 0.001) and VascuQol score (4.7 vs 5.8; P = 0.004). The control group saw a temporary increase in VascuQol score at 6 months (4.5 vs 4.7; P = 0.028), but no other improvements in MWD or CD were observed. Significantly higher improvements in MWD were seen in the WAM group compared with that in the control group at 6 months (82 vs -5 m; P = 0.009, r = 0.47) and 12 months (69 vs 7.5 m; P = 0.011, r = 0.52).

CONCLUSIONS

The study demonstrates the significant, sustained benefit of WAM-led technologies for patients with IC. This potentially resource-sparing intervention is likely to provide a valuable adjunct or alternative to SEP.

Validation of Gait Characteristics Extracted From Raw Accelerometry During Walking Against Measures of Physical Function, Mobility, Fatigability, and Fitness

Background

Data collected by wearable accelerometry devices can be used to identify periods of sustained harmonic walking. This report aims to establish whether the features of walking identified in the laboratory and free-living environments are associated with each other as well as measures of physical function, mobility, fatigability, and fitness.

Methods

Fifty-one older adults (mean age 78.31) enrolled in the Developmental Epidemiologic Cohort Study were included in the analyses. The study included an "in-the-lab" component as well as 7 days of monitoring "in-the-wild" (free living). Participants were equipped with hip-worn Actigraph GT3X+ activity monitors, which collect raw accelerometry data. We applied a walking identification algorithm and defined features of walking, including participant-specific walking acceleration and cadence. The association between these walking features and physical function, mobility, fatigability, and fitness was quantified using linear regression analysis.

Results

Acceleration and cadence estimated from "in-the-lab" and "in-the-wild" data were significantly associated with each other (p < .05). However, walking acceleration "in-the-lab" was on average 96% higher than "in-the-wild," whereas cadence "in-the-lab" was on average 20% higher than "in-the-wild." Acceleration and cadence were associated with measures of physical function, mobility, fatigability, and fitness (p < .05) in both "in-the-lab" and "in-the-wild" settings. In addition, "in-the-wild" daily walking time was associated with fitness (p < .05).

Conclusions

The quantitative difference in proposed walking features indicates that participants may overperform when observed "in-the-lab." Also, proposed features of walking were significantly associated with measures of physical function, mobility, fatigability, and fitness, which provides evidence of convergent validity.

Lack of functional benefits following infrainguinal bypass in peripheral arterial occlusive disease patients

This study aimed to determine whether peripheral arterial occlusive disease (PAOD) patients with critical limb-threatening ischemia experienced functional benefits following lower extremity revascularization. Twenty ambulatory patients (aged 68 - 7 years) underwent infrainguinal revascularization to alleviate their symptoms. Peripheral hemodynamic and functional measures were obtained on each patient 1 week prior to and 3-4 months following revascularization. Critical limb-threatening ischemia was alleviated by surgery in all patients because the ankle/brachial index (ABI) increased 133% (p, 0.001) from 0.33 6 0.06 to 0.77 6 0.09. Despite the marked peripheral hemodynamic improvement following revascularization, little gains were noted in functional measures. The 6-min walking distance was unchanged (p = 0.739) from 85 6 9 m to 101 6 11 m. Additionally, the free-living daily physical activity, measured by an accelerometer worn over a 2-day period, was unchanged (p = 0.996) from 214 6 46 kcal/day to 215 6 83 kcal/day. In contrast, self-perceived ambulatory function improved by 142% to 271% (p, 0.001), and self-perceived physical activity increased 134% to 156% (p, 0.001). In conclusion, limb salvage following infrainguinal bypass does not translate into improvements in measured ambulation or in measured physical activity in PAOD patients, even though the patients perceive these measures to be better.

NÍVEL DE ATIVIDADE FÍSICA, POR ACELEROMETRIA, EM IDOSOS DO MUNICÍPIO DE SÃO PAULO: ESTUDO SABE

Introdução: Estudos populacionais utilizam, geralmente, métodos indiretos de estimativa do nível de atividade física (NAF) da população. Entretanto, o erro de medida, principalmente quando se trata da população idosa, é grande. Estudos nacionais que usam medidas objetivas são escassos. Objetivo: Este estudo buscou descrever o perfil de prática de atividade física (AF) da população idosa do município de São Paulo utilizando-se acelerometria. Métodos: Este trabalho faz parte do estudo SABE, desenvolvido na capital do Estado de São Paulo e analisou os dados de 568 idosos (≥ 65 anos). O acelerômetro da marca Actigraph foi utilizado durante 3 dias consecutivos. Os idosos foram classificados segundo o NAF de acordo com as recomendações atuais de AF. O NAF foi descrito (média e IC 95%) segundo sexo e grupos etários (< 70 anos, 70 a 79 anos e ≥ 80 anos). As proporções de idosos em cada grupo de NAF foram descritas em termos relativos (%). As diferenças entre os grupos foram estimadas utilizando-se o teste generalizado de igualdade entre médias de Wald. Resultados: Os idosos considerados sedentários representaram 63,1% (48,3% dos homens e 71,7% das mulheres) e apresentaram média de idade maior; houve prevalência de 25,7% dos homens e 8,13% das mulheres classificados como fisicamente ativos, o que corresponde a apenas 14,6% do total de idosos. Os idosos gastam, em média, 12,6 (IC 95% 10,6 - 13,7) minutos por dia em atividades físicas consideradas de intensidade moderada e/ou vigorosa. A proporção de idosos fisicamente ativos é menor quanto maior for a idade. Conclusão: O NAF da população idosa do Município de São Paulo é baixo e considerado insuficiente, principalmente para o sexo feminino. Assim, houve maior proporção de idosos considerados sedentários e insuficientemente ativos quando comparados aos ativos.

Using Smartphone Sensors for Improving Energy Expenditure Estimation

Energy expenditure (EE) estimation is an important factor in tracking personal activity and preventing chronic diseases, such as obesity and diabetes. Accurate and real-time EE estimation utilizing small wearable sensors is a difficult task, primarily because the most existing schemes work offline or use heuristics. In this paper, we focus on accurate EE estimation for tracking ambulatory activities (walking, standing, climbing upstairs, or downstairs) of a typical smartphone user. We used built-in smartphone sensors (accelerometer and barometer sensor), sampled at low frequency, to accurately estimate EE. Using a barometer sensor, in addition to an accelerometer sensor, greatly increases the accuracy of EE estimation. Using bagged regression trees, a machine learning technique, we developed a generic regression model for EE estimation that yields upto 96% correlation with actual EE. We compare our results against the state-of-the-art calorimetry equations and consumer electronics devices (Fitbit and Nike+ FuelBand). The newly developed EE estimation algorithm demonstrated superior accuracy compared with currently available methods. The results were calibrated against COSMED K4b2 calorimeter readings.

Pathogenesis of the limb manifestations and exercise limitations in peripheral artery disease

Patients with peripheral artery disease have a marked reduction in exercise performance and daily ambulatory activity irrespective of their limb symptoms of classic or atypical claudication. This review will evaluate the multiple pathophysiologic mechanisms underlying the exercise impairment in peripheral artery disease based on an evaluation of the current literature and research performed by the authors. Peripheral artery disease results in atherosclerotic obstructions in the major conduit arteries supplying the lower extremities. This arterial disease process impairs the supply of oxygen and metabolic substrates needed to match the metabolic demand generated by active skeletal muscle during walking exercise. However, the hemodynamic impairment associated with the occlusive disease process does not fully account for the reduced exercise impairment, indicating that additional pathophysiologic mechanisms contribute to the limb manifestations. These mechanisms include a cascade of pathophysiological responses during exercise-induced ischemia and reperfusion at rest that are associated with endothelial dysfunction, oxidant stress, inflammation, and muscle metabolic abnormalities that provide opportunities for targeted therapeutic interventions to address the complex pathophysiology of the exercise impairment in peripheral artery disease.

Clinical Interest of Ambulatory Assessment of Physical Activity and Walking Capacity in Peripheral Artery Disease

The purpose of the present review was to provide, for the first time, a comprehensive analysis and synthesis of the available studies that highlighted the clinical interest of the ambulatory assessment of either physical activity (PA) or walking capacity in patients with lower extremity peripheral artery disease (PAD). We identified 96 related articles published up to March 2015 through a computer-assisted search of the MEDLINE, EMBASE, and Web of Science databases. Ambulatory-measured PA or related energy expenditure (EE) in PAD patients was performed in 87 of the 96 included studies. The main clinical interests of these measurements were (a) the assessment of PA/EE pattern; (b) the characterization of walking pattern; and (c) the control of training load during home-based walking programs. Ambulatory-measured walking capacity was performed in the remaining studies, using either Global Positioning System receivers or the Peripheral Arterial Disease Holter Control device. Highlighted clinical interests were (a) the assessment of community-based walking capacity; (b) the use of new outcomes to characterize walking capacity, besides the conventional absolute claudication distance; and (c) the association with the patient's self-perception of walking capacity. This review also provides for the clinicians step-by-step recommendations to specifically assess PA or walking capacity in PAD patients.

Sustained and shorter bouts of physical activity are related to cardiovascular health

PURPOSE

Whereas greater physical activity (PA) is known to prevent cardiovascular disease (CVD), the relative importance of performing PA in sustained bouts of activity versus shorter bouts of activity on CVD risk is not known. The objective of this study was to investigate the relationship between moderate-to-vigorous PA (MVPA), measured in bouts ≥10 and <10 min, and CVD risk factors in a well-characterized community-based sample of white adults.

METHODS

We conducted a cross-sectional analysis of 2109 participants in the Third Generation Cohort of the Framingham Heart Study (mean age = 47 yr, 55% women) who underwent objective assessment of PA by accelerometry over 5-7 d. Total MVPA, MVPA done in bouts ≥10 min (MVPA(10+)), and MVPA done in bouts <10 min (MVPA(<10)) were calculated. MVPA exposures were related to individual CVD risk factors, including measures of adiposity and blood lipid and glucose levels, using linear and logistic regression.

RESULTS

Total MVPA was significantly associated with higher HDL levels and with lower triglycerides, BMI, waist circumference, and Framingham risk score (P < 0.0001). MVPA(<10) showed similar statistically significant associations with these CVD risk factors (P < 0.001). Compliance with national guidelines (≥150 min of total MVPA) was significantly related to lower BMI, triglycerides, Framingham risk score, waist circumference, higher HDL, and a lower prevalence of obesity and impaired fasting glucose (P < 0.001 for all).

CONCLUSIONS

Our cross-sectional observations on a large middle-age community-based sample confirm a positive association of MVPA with a healthier CVD risk factor profile and indicate that accruing PA in bouts <10 min may favorably influence cardiometabolic risk. Additional investigations are warranted to confirm our findings.

Predicting doubly labeled water energy expenditure from ambulatory activity

The purpose of this study was to evaluate the potential for using accelerometer-determined ambulatory activity indicators (steps per day and cadence) to predict total energy expenditure (TEE) and physical activity energy expenditure (PAEE) derived from doubly labeled water (DLW). Twenty men and 34 women (20-36 years of age) provided complete anthropometric, accelerometer, resting metabolic rate (RMR), and DLW data. TEE and PAEE were determined for the same week that accelerometers were worn during waking hours. Accelerometer data included mean steps per day, peak 30-min cadence (average steps per minute for the highest 30 min of the day), and time spent in each incremental cadence band: 0 (nonmovement), 1-19 (incidental movement), 20-39 (sporadic movement), 40-59 (purposeful steps), 60-79 (slow walking), 80-99 (medium walking), 100-119 (brisk walking), and 120+ steps·min(-1) (indicative of all faster ambulatory activities). Regression analyses were employed to develop sex-specific equations for predicting TEE and PAEE. The final model predicting TEE included body weight, steps per day, and time in incremental cadence bands and explained 79% (men) and 65% (women) of the variability. The final model predicting PAEE included peak 30-min cadence, steps per day, and time in cadence bands and explained 76% (men) and 46% (women) of the variability. Time in cadence bands alone explained 39%-73% of the variability in TEE and 30%-63% of the variability in PAEE. Prediction models were stronger for men than for women.

Optimal exercise program length for patients with claudication

BACKGROUND

This prospective, randomized controlled clinical trial determined whether an optimal exercise program length exists to efficaciously change claudication onset time (COT) and peak walking time (PWT) in patients with peripheral artery disease and claudication.

METHODS

The study randomized 142 patients to supervised exercise (n = 106) or a usual care control group (n = 36), with 80 completing the exercise program and 27 completing the control intervention. The exercise program consisted of intermittent walking to nearly maximal claudication pain 3 days per week. COT and PWT were the primary outcomes obtained from a treadmill exercise test at baseline and bimonthly during the study.

RESULTS

After exercise, changes in COT (P < .001) and PWT (P < .001) were consistently greater than changes after the control intervention. In the exercise program, COT and PWT increased from baseline to month 2 (P < .05) and from months 2 to 4 (P < .05) but did not significantly change from months 4 to 6 (P > .05). When changes were expressed per mile walked during the first 2 months, middle 2 months, and final 2 months of exercise, COT and PWT only increased during the first 2 months (P < .05).

CONCLUSIONS

Exercise-mediated gains in COT and PWT occur rapidly within the first 2 months of exercise rehabilitation and are maintained with further training. The clinical significance is that a relatively short 2-month exercise program may be preferred to a longer program to treat claudication because adherence is higher, costs associated with personnel and use of facilities are lower per patient, and more patients can be trained for a given amount of personnel time and resource utilization.

Accelerometer use with children, older adults, and adults with functional limitations

Accurately assessing physical activity behavior in children, older adults, and adults with functional limitations is essential to further our understanding of determinants of physical activity behavior in these populations and to design, implement, and evaluate interventions designed to increase physical activity participation. Objective methods to assess physical activity behavior, owing to improvements in accuracy and precision over self-report measures, have become common in research and practice settings. This article reviews the current use of objective methods to assess physical activity in observational, determinant, and intervention studies for children, older adults, and adults with functional limitations. Important considerations are presented when adopting prediction algorithms developed on one population, and using in another population that is markedly different in age, health, and functional status. Best practices are presented, along with future recommendations for research to advance this area of scientific inquiry.

Comparative validity of physical activity measures in older adults

PURPOSE

To compare the validity of various physical activity measures with doubly labeled water (DLW)-measured physical activity energy expenditure (PAEE) in free-living older adults.

METHODS

Fifty-six adults aged ≥65 yr wore three activity monitors (New Lifestyles pedometer, ActiGraph accelerometer, and a SenseWear (SW) armband) during a 10-d free-living period and completed three different surveys (Yale Physical Activity Survey (YPAS), Community Health Activities Model Program for Seniors (CHAMPS), and a modified Physical Activity Scale for the Elderly (modPASE)). Total energy expenditure was measured using DLW, resting metabolic rate was measured with indirect calorimetry, the thermic effect of food was estimated, and from these, estimates of PAEE were calculated. The degree of linear association between the various measures and PAEE was assessed, as were differences in group PAEE, when estimable by a given measure.

RESULTS

All three monitors were significantly correlated with PAEE (r=0.48-0.60, P<0.001). Of the questionnaires, only CHAMPS was significantly correlated with PAEE (r=0.28, P=0.04). Statistical comparison of the correlations suggested that the monitors were superior to YPAS and modPASE. Mean squared errors for all correlations were high, and the median PAEE from the different tools was significantly different from DLW for all but the YPAS and regression-estimated PAEE from the ActiGraph.

CONCLUSIONS

Objective devices more appropriately rank PAEE than self-reported instruments in older adults, but absolute estimates of PAEE are not accurate. Given the cost differential and ease of use, pedometers seem most useful in this population when ranking by physical activity level is adequate.

Reliability of the Baltimore Activity Scale Questionnaire for Intermittent Claudication

We assessed the reliability of the Baltimore Activity Scale for Intermittent Claudication (BASIC) for the evaluation of physical activity levels in individuals with intermittent claudication. We also identify the characteristics of the patients that influence the reliability of this questionnaire. A total of 38 men and women with peripheral artery disease and symptoms of intermittent claudication participated in the study. BASIC was administered to patients by the same evaluator at 2 different visits, separated by 7 days. The concordance coefficient ranged from .43 (How often do you walk at a fast pace?) to .85 (What happens when you feel pain while you walk?). The concordance coefficient of BASIC total score was .60. Higher concordance coefficients were observed in women (.66 vs .55), in younger patients (.63 vs .56), and in patients with lower ankle-brachial index (.64 vs .55). The reliability of BASIC questionnaire ranged from moderate to good in patients with claudication.

Patient-focused endpoints in advanced cancer: criterion-based validation of accelerometer-based activity monitoring

BACKGROUND & AIMS

Objective assessment of daily physical activity (PA) by body-worn accelerometers offers potential as a novel endpoint in the clinical management of advanced cancer patients. This study aimed to assess criterion-based validity of an accelerometer-based activity monitoring system (AM-system), ActivPAL™, using two different methods.

METHODS

Advanced cancer in patients and outpatients (Karnofsky Performance Status (KPS) 40-100). ActivPAL™ measurements were validated against (i) observations and (ii) energy expenditure (EE) measured by 2-week doubly-labelled water (DLW) protocol.

RESULTS

Absolute errors for mean time spent in different body positions (<0.1%) and number of transfers (0%) were low. Step count error was significantly higher in patients with KPS 40-60 (non-self caring) compared to KPS 70-100 (self-caring) (33 vs. 24%, p = 0.006). Post-hoc mathematical analysis demonstrated that absolute errors for the mean energy expenditure of activity (EEA) (1.4%) and mean total EE (0.4%) were low, but agreement was also low.

CONCLUSIONS

AM-systems provide valid estimates of body positions and transfers, but not step count, especially in non-self caring patients. ActivPAL™ can derive estimates of EE but there is considerable variability in results, which is consistent, in part, with the inaccuracy in step count. Further studies are required to assess the validity of different endpoints derived from AM-systems in advanced cancer patients.

Resting energy expenditure in patients with intermittent claudication and critical limb ischemia

OBJECTIVE

The primary aim of this study was to compare the resting energy expenditure of patients with intermittent claudication and critical limb ischemia. A secondary aim was to identify predictors of resting energy expenditure.

METHODS

One hundred patients limited by intermittent claudication and 40 patients with critical limb ischemia participated in this study. Patients were assessed on resting energy expenditure, body composition, ankle brachial index (ABI), and calf blood flow.

RESULTS

Patients with critical limb ischemia had a lower resting energy expenditure than patients with intermittent claudication (1429 +/- 190 kcal/day vs 1563 +/- 229 kcal/day; P = .004), and higher body fat percentage (34.8 +/- 7.8% vs 31.5 +/- 7.8%; P = .037), higher fat mass (30.0 +/- 9.3 kg vs 26.2 +/- 8.9 kg;P = .016), and lower ABI (0.31 +/- 0.11 vs 0.79 +/- 0.23; P < .001). Resting energy expenditure was predicted by fat free mass (P < .0001), age (P < .0001), ABI (P < .0001), ethnicity (P < .0001), calf blood flow (P = .005), and diabetes (P = .008). Resting energy expenditure remained lower in the patients with critical limb ischemia after adjusting for clinical characteristics plus fat free mass (1473 +/- 27.8 kcal/day [mean +/- SEM] vs 1527 +/- 19.3 kcal/day; P = .031), but it was no longer different between groups after further adjustment for ABI and calf blood flow (1494 +/- 25.2 kcal/day vs 1505 +/- 17.7 kcal/day; P = .269).

CONCLUSION

Resting energy expenditure is decreased with a progression in peripheral arterial disease (PAD) symptoms from intermittent claudication to critical limb ischemia. Furthermore, patients with critical limb ischemia who are most susceptible for decline in resting energy expenditure are older, African American patients with diabetes. The lower resting energy expenditure of patients with critical limb ischemia, combined with their sedentary lifestyle, suggests that they are at high risk for long-term positive energy balance and weight gain.

Leisure activities following a lower limb amputation

PURPOSE

The aim of this study was to describe leisure activities, leisure satisfaction and constraints on participation in leisure following a unilateral lower limb amputation due to vascular disease.

METHOD

This study used a mixed-method approach where 15 individuals with lower limb amputation completed the individual leisure profile 2-3 months post-discharge from rehabilitation. A subsample (n = 8) also participated in semi-structured interviews analysed using the Miles and Huberman analytic method.

RESULTS

Results show that participants were involved in 12 different leisure activities on average. Compared to before the amputation, a decrease in participation was observed in all categories of leisure activity, and especially crafts, nature and outdoor activities, mechanics, sports and physical activities. Nonetheless, overall satisfaction was high. The most important constraints on participation in leisure were lack of accessibility, material considerations, functional abilities, affective constraints and social constraints.

CONCLUSION

A decrease in leisure activity participation and the presence of constraints do not automatically translate into low levels of leisure satisfaction.

Day-to-Day Variability of Physical Activity of Older Adults Living in the Community

The purpose of the study was to investigate whether a 24-hr recording period is sufficient to describe physical activity (PA) of 1 week for intraindividual comparison in older adults. Furthermore, the authors analyzed whether physical performance can be used as a surrogate marker of PA. PA was captured on 7 consecutive days by a body-fixed sensor in 44 community-dwelling older adults (80.75 ± 4.05 yr). Mean times of walking and of “time on feet” of the group were 10.2 hr (± 3.5) and 35.1 hr (± 9.43), respectively. Intraindividual variabilities of walking and of time on feet were 31.9% ± 10.79% and 19.4% ± 8.76%, respectively. Accumulated time of variables of PA showed no differences between weekdays, with variabilities of 3.8% and 1.8% for walking and time on feet, respectively. Association between Short Physical Performance Battery and PA was limited (walkingr= .397, time on feetr= .41).

Resting energy expenditure in subjects with and without intermittent claudication

Subjects with peripheral arterial disease and intermittent claudication have ischemia of the lower extremities, but little is known how this influences resting energy expenditure. The objective of the study was to compare the resting energy expenditure of subjects with and without intermittent claudication. One hundred six subjects limited by intermittent claudication and 77 controls who did not have peripheral arterial disease and intermittent claudication participated in this study. Subjects were assessed on resting energy expenditure, body composition, ankle/brachial index (ABI), and calf blood flow. Subjects with intermittent claudication had a lower resting energy expenditure (1585 +/- 251 vs 1716 +/- 277 kcal/d, P = .019), higher body fat percentage (33.4% +/- 10.7% vs 29.6% +/- 7.7%, P = .016), higher fat mass (29.6 +/- 10.6 vs 24.2 +/- 8.9 kg, P = .011), and lower ABI (0.66 +/- 0.20 vs 1.19 +/- 0.12, P < .001). Resting energy expenditure was predicted by fat-free mass (P < .001), ABI (P = .027), and calf blood flow (P = .040). Resting energy expenditure remained lower in the subjects with intermittent claudication after adjusting for clinical characteristics plus fat-free mass (1611 +/- 171 vs 1685 +/- 209 kcal/d, P = .035), but was no longer different between groups after further adjustment for ABI and calf blood flow (1622 +/- 165 vs 1633 +/- 185 kcal/d, P = .500). Subjects with intermittent claudication have lower resting energy expenditure than controls, which is partially explained by ABI and calf blood flow.

Patterns of ambulatory activity in subjects with and without intermittent claudication

PURPOSE

This study compared the patterns of ambulatory activity in subjects with and without intermittent claudication.

METHODS

The study participants were 98 subjects limited by intermittent claudication and 129 controls who were matched for age, gender, and race. Subjects were assessed on their ambulatory activity patterns for 1 week with a small, lightweight step activity monitor attached to the ankle using elastic Velcro (Velcro Industries BV, Manchester, NH) straps above the lateral malleolus of the right leg. The step activity monitor recorded the number of strides taken on a minute-to-minute basis, the time spent ambulating, and the time and number of strides measured at low (<15 strides/min), medium (15 to 30 strides/min), and high (>30 strides/min) cadences.

RESULTS

Subjects with intermittent claudication took fewer total strides each day than the controls (3149 +/- 1557 strides/d vs 4230 +/- 1708 strides/d; P < .001) and fewer strides at medium (1228 +/- 660 strides/day vs 1638 +/- 724 strides/day; P = .001) and high (766 +/- 753 strides/day vs 1285 +/- 1029 strides/day; P < .001) cadences. Subjects with intermittent claudication also had a lower daily average cadence than the controls (11.8 +/- 2.9 strides/min vs 13.5 +/- 3.1 strides/min; P < .001) and spent less total time ambulating each day (264 +/- 109 min/day vs 312 +/- 96 min/day; P = .034), primarily at medium (58 +/- 30 min/day vs 75 +/- 32 min/day; P < .001) and at high (19 +/- 17 min/day vs 30 +/- 22 min/day; P = .001) cadences.

CONCLUSION

Intermittent claudication is associated with lower total daily ambulatory activity owing both to less time ambulating and to fewer strides taken while ambulating, particularly at moderate and high cadences.

Physical activity assessment with accelerometers: an evaluation against doubly labeled water

This review focuses on the ability of different accelerometers to assess daily physical activity as compared with the doubly labeled water (DLW) technique, which is considered the gold standard for measuring energy expenditure under free-living conditions. The PubMed Central database (U.S. NIH free digital archive of biomedical and life sciences journal literature) was searched using the following key words: doubly or double labeled or labeled water in combination with accelerometer, accelerometry, motion sensor, or activity monitor. In total, 41 articles were identified, and screening the articles' references resulted in one extra article. Of these, 28 contained sufficient and new data. Eight different accelerometers were identified: 3 uniaxial (the Lifecorder, the Caltrac, and the CSA/MTI/Actigraph), one biaxial (the Actiwatch AW16), 2 triaxial (the Tritrac-R3D and the Tracmor), one device based on two position sensors and two motion sensors (ActiReg), and the foot-ground contact pedometer. Many studies showed poor results. Only a few mentioned partial correlations for accelerometer counts or the increase in R(2) caused by the accelerometer. The correlation between the two methods was often driven by subject characteristics such as body weight. In addition, standard errors or limits of agreement were often large or not presented. The CSA/MTI/Actigraph and the Tracmor were the two most extensively validated accelerometers. The best results were found for the Tracmor; however, this accelerometer is not yet commercially available. Of those commercially available, only the CSA/MTI/Actigraph has been proven to correlate reasonably with DLW-derived energy expenditure.

Exercise performance in patients with peripheral arterial disease who have different types of exertional leg pain

OBJECTIVE

This study compared the exercise performance of patients with peripheral arterial disease (PAD) who have different types of exertional leg pain.

METHODS

Patients with PAD were classified into one of four groups according to the San Diego Claudication Questionnaire: intermittent claudication (n = 406), atypical exertional leg pain causing patients to stop (n = 125), atypical exertional leg pain in which patients were able to continue walking (n = 81), and leg pain on exertion and rest (n = 103). Patients were assessed on the primary outcome measures of ankle-brachial index (ABI), treadmill exercise measures, and ischemic window.

RESULTS

All patients experienced leg pain consistent with intermittent claudication during a standardized treadmill test. The mean (+/- SD) initial claudication distance (ICD) was similar (P = .642) among patients with intermittent claudication (168 +/- 160 meters), atypical exertional leg pain causing patients to stop (157 +/- 130 meters), atypical exertional leg pain in which patients were able to continue walking (180 +/- 149 meters), and leg pain on exertion and rest (151 +/- 136 meters). The absolute claudication distance (ACD) was similar (P = .648) in the four respective groups (382 +/- 232, 378 +/- 237, 400 +/- 245, and 369 +/- 236 meters). Similarly, the ischemic window, expressed as the area under the curve (AUC) after treadmill exercise, was similar (P = .863) in these groups (189 +/- 137, 208 +/- 183, 193 +/- 143, and 199 +/- 119 AUC).

CONCLUSION

PAD patients with different types of exertional leg pain, all limited by intermittent claudication during a standardized treadmill test, were remarkably similar in ICD, ACD, and ischemic window. Thus, the presence of ambulatory symptoms should be of primary clinical concern in evaluating PAD patients regardless of whether they are consistent with classic intermittent claudication.

The Baltimore activity scale for intermittent claudication: a validation study

The purpose of this study was to develop and cross-validate the Baltimore Activity Scale for Intermittent Claudication (BASIC) questionnaire in patients with peripheral arterial disease limited by intermittent claudication, and to determine whether the BASIC questionnaire score changed following a supervised program of exercise rehabilitation. A total of 702 consecutive patients with peripheral arterial disease and stable intermittent claudication were characterized on physical activity level using the BASIC questionnaire and an accelerometer. The first 351 patients tested were included in the validation group, whereas the final 351 patients were included in the cross-validation group. Subsequently, 61 of these patients participated in a randomized, controlled trial in which 28 patients completed 6 months of exercise rehabilitation and 24 patients completed usual care control. The sum of 5 questions from the BASIC questionnaire (0-10 point scale) was predictive of daily physical activity using the following regression equation: Daily Physical Activity (kcal/day) = 102.2 + (49.6 x BASIC score); R = 0.76, R(2) = 0.58, standard error of estimate = 52.0 kcal/day, P < .0001. This equation was successfully cross-validated on an independent group of patients, as the predicted daily physical activity (339 - 181 kcal/day, mean - SD) was similar (P = .501) to measured daily physical activity (347 - 266 kcal/day, mean - SD). Furthermore, the BASIC score increased 38% following 6 months of exercise rehabilitation (P < .01), whereas no change was observed in the control group (P > .05). A composite of 5 questions obtained from the self-administered BASIC questionnaire accurately estimates daily physical activity in patients with peripheral arterial disease limited by intermittent claudication, and is sensitive to change in physical activity following a program of exercise rehabilitation.

The relationship between ankle-brachial index and leisure-time physical activity in patients with intermittent claudication

The purpose of the study was to examine the relationship between ankle-brachial index (ABI) and leisure-time physical activity (LTPA) in patients with peripheral arterial disease limited by intermittent claudication. Patients included 342 sedentary men and women between the ages of 45 and 85 with intermittent claudication confirmed by a resting ABI of less than 0.90. Patients were categorized into either a low ABI group (ABI <0.50; n=84), a middle ABI group (ABI = 0.50 to 0.69; n=164), or a high ABI group (ABI = 0.70 to 0.89; n=94). The Minnesota LTPA questionnaire was used to estimate physical activity patterns, and a treadmill test, 6- minute walk test, and Walking Impairment Questionnaire were used to measure ambulatory function. A progressive decrease (p=0.030) in the total LTPA was observed among the high ABI (180 +/-131 kcal/day; mean +/- SD), middle ABI (138 +/-127 kcal/day), and low ABI (110 +/-89 kcal/day) groups. Progressive decrements in LTPA spent at moderate intensity (p=0.016) and high intensity (p=0.009), as well as the mean intensity of LTPA (p=0.024) were observed among the three respective ABI groups. Group differences in the LTPA measurements were no longer present (p>0.05) after adjusting for group differences in the absolute claudication distance during a treadmill test, and the 6-minute walk distance. The decline in total daily LTPA with progressively lower ABI in patients with intermittent claudication was due to their decreased participation in physical activities requiring moderate and high intensities. In addition, group differences in the LTPA measurements were explained by differences in ambulatory function.

Metabolic syndrome impairs physical function, health-related quality of life, and peripheral circulation in patients with intermittent claudication

PURPOSE

This study was conducted to (1) examine the effect of metabolic syndrome on intermittent claudication, physical function, health-related quality of life, and peripheral circulation in patients with peripheral arterial disease (PAD), and (2) determine whether peripheral vascular function was predictive of intermittent claudication and physical function in patients with metabolic syndrome.

METHODS

Patients limited by intermittent claudication and who had metabolic syndrome (n = 133) were compared with those without metabolic syndrome (n = 201). Patients were assessed on metabolic syndrome characteristics, PAD-specific measures consisting of ankle/brachial index and claudication distances, physical function measures, health-related quality of life, and calf blood flow and transcutaneous oxygen tension responses after 3 minutes of vascular occlusion.

RESULTS

Initial claudication distance (mean +/- SD) was 29% shorter (P = .018) in patients with metabolic syndrome than in the controls (128 +/- 121 meters vs 180 +/- 166 meters), and absolute claudication distance was 22% shorter (P = .025) in those with metabolic syndrome (319 +/- 195 meters vs 409 +/- 255 meters). Furthermore, patients with metabolic syndrome had lower peak oxygen uptake (P = .037), a shorter 6-minute walk distance (P = .027), lower values on six domains of health-related quality of life (P < .05), reduced calf hyperemia (P = .028), and greater calf ischemia (P < .001) after vascular occlusion. In the group with metabolic syndrome, calf ischemia was correlated with initial claudication distance (r = 0.30, P = .004), absolute claudication distance (r = 0.40, P < .001), and peak oxygen uptake (r = 0.52, P < .001).

CONCLUSION

Metabolic syndrome worsens intermittent claudication, physical function, health-related quality of life, and peripheral circulation in patients with PAD. Calf ischemia in those with metabolic syndrome was predictive of intermittent claudication and physical function. The additive burden of metabolic syndrome thus places patients who are limited by intermittent claudication at an even greater risk for living a functionally dependent lifestyle. Aggressive risk-factor modification designed to treat components of metabolic syndrome should be evaluated for efficacy in modifying physical and vascular function in patients with intermittent claudication.

The effect of exercise intensity on the response to exercise rehabilitation in patients with intermittent claudication

PURPOSE

The purpose of this randomized trial was to compare the efficacy of a low-intensity exercise rehabilitation program vs a high-intensity program in changing physical function, peripheral circulation, and health-related quality of life in peripheral arterial disease (PAD) patients limited by intermittent claudication.

METHODS

Thirty-one patients randomized to low-intensity exercise rehabilitation and 33 patients randomized to high-intensity exercise rehabilitation completed the study. The 6-month exercise rehabilitation programs consisted of intermittent treadmill walking to near maximal claudication pain 3 days per week at either 40% (low-intensity group) or 80% (high-intensity group) of maximal exercise capacity. Total work performed in the two training regimens was similar by having the patients in the low-intensity group exercise for a longer duration than patients in the high-intensity group. Measurements of physical function, peripheral circulation, and health-related quality of life were obtained on each patient before and after the rehabilitation programs.

RESULTS

After the exercise rehabilitation programs, patients in the two groups had similar improvements in these measures. Initial claudication distance increased by 109% in the low-intensity group (P < .01) and by 109% in the high-intensity group (P < .01), and absolute claudication distance increased by 61% (P < 0.01) and 63% (P < .01) in the low-intensity and high-intensity groups, respectively. Furthermore, both exercise programs elicited improvements (P < .05) in peak oxygen uptake, ischemic window, and health-related quality of life.

CONCLUSION

The efficacy of low-intensity exercise rehabilitation is similar to high-intensity rehabilitation in improving markers of functional independence in PAD patients limited by intermittent claudication, provided that a few additional minutes of walking is accomplished to elicit a similar volume of exercise.

Indices de mesure de l'activité physique dans le domaine des affections cardiovasculaires

PURPOSE

To identify the more useful among many methods available for the measurement of physical activity in patients with cardiovascular disease. For practical and financial reasons only questionnaires and mechanical monitoring, which are appropriate for use in large studies, were assessed.

METHODS

To select tools valuable for clinical and epidemiological measurement of physical activity, with sufficient validity, reproducibility and sensitivity, we reviewed the literature in Medline with use of keywords: accelerometry, ambulatory accelerometry, ambulatory monitoring, cardiovascular diseases, daily activity, heart disease, pedometer, physical activity, questionnaire.

RESULTS

Considering appropriate level of reproducibility and validity, 15 questionnaires are available. For measuring postures and motions during daily life, activity monitor seems to be more valid than pedometers or single accelerometers.

CONCLUSION

At present the preferred method is a questionnaire, provided it is valid, repeatable, easy to use and inexpensive. In the future mechanical monitoring (especially activity monitor) will be probably a good alternative.

Accelerometer monitoring of home- and community-based ambulatory activity after stroke

OBJECTIVES

To investigate the utility of a novel microprocessor-linked Step Watch Activity Monitor (SAM) to quantify ambulatory activity after stroke and to evaluate the validity and reliability of conventional accelerometers to measure free-living physical activity in this population.

DESIGN

Cross-sectional with repeated measures of 2 separate 48-hour recordings in 17 persons wearing an ankle-mounted SAM and Caltrac, a hip-mounted mechanical accelerometer.

SETTING

Home and community.

PARTICIPANTS

Seventeen subjects with chronic hemiparetic gait after stroke.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The SAM derived stride counts per day and Caltrac estimated the daily caloric expenditure of physical activity.

RESULTS

SAM data revealed that stroke patients had a mean strides per day +/- standard deviation of 3035+/-1944 and demonstrated a broad range of daily activity profiles (400-6472 strides). SAM test-retest reliability was high across separate monitoring periods (r=.96, P<.001). Although Caltrac also revealed a broad range of daily activity calories (346+/-217 kcal/d; range, 83-1222 kcal/d), reliability was poor (r=.044, P=not significant) and Caltrac accounted for only 64% of the ambulatory activity quantified by the SAM.

CONCLUSIONS

Microprocessor-linked accelerometer monitoring, but not conventional accelerometers, are accurate and highly reliable for quantifying ambulatory activity levels in stroke patients. These findings support the utility of personal status monitoring of ambulatory activity as an outcomes instrument and metric in programs to increase physical activity and cardiovascular health after stroke.

Natural history of physical function in older men with intermittent claudication

PURPOSE

This study was undertaken to determine the natural history of physical function in older men limited by intermittent claudication.

METHODS

Forty-three men limited by intermittent claudication (mean age, 69 +/- 7 years) were recruited and followed up for 18 months. At baseline the patients reported a history of intermittent claudication for 6.1 +/- 6.1 years, and were able to walk for 1.9 +/- 1.6 blocks before experiencing claudication pain. Measurements during the 18-month study included ankle-brachial index (ABI), calf blood flow, 6-minute walk performance, monitored and self-reported physical activity, self-reported stability while walking, and summary performance score of physical function determined from a 4-m walk test, a chair stand test, and a tandem stand test.

RESULTS

Pain-free walking distance during the 6-minute walk test decreased by 22% (P <.05) from baseline (185 +/- 96 m) to follow-up (144 +/- 93 m), and the total 6-minute walk distance decreased by 9% (P <.05), from 368 +/- 106 m to 334 +/- 90 m. Furthermore, monitored physical activity decreased by 31% (P <.05), from 159 +/- 151 kcal/d to 110 +/- 137 kcal/d; self-reported physical activity declined by 27% (P <.05), from 1.5 +/- 1.0 units to 1.1 +/- 0.8 units; tandem stance time declined by 14% (P <.05), from 9.46 +/- 1.83 seconds to 8.12 +/- 2.10 seconds; summary performance score of physical function decreased by 12% (P <.05), from 6.8 +/- 2.4 units to 6.0 +/- 2.4 units; and the percentage of patients reporting ambulatory unsteadiness and stumbling increased from 28% to 43% (P <.05). Calf blood flow measured at rest declined by 18% (P <.05), from 3.72 +/- 1.81 (mL/100 mL(-1)/min(-1)) to 3.04 +/- 1.43 mL/100 mL(-1)/min(-1), whereas ABI did not change (P >.05).

CONCLUSION

Older men limited by intermittent claudication experienced decline in ambulatory function, physical activity, physical function, stability, and calf blood flow over 18 months of follow-up, despite no change in ABI.

Response to exercise rehabilitation in smoking and nonsmoking patients with intermittent claudication

BACKGROUND

The purpose was to compare the changes in claudication pain, ambulatory function, daily physical activity, peripheral circulation, and health-related quality of life following a program of exercise rehabilitation in smoking and nonsmoking patients with peripheral arterial disease (PAD) limited by intermittent claudication. Methods and results Thirty-nine smokers (63 +/- 4 pack-year smoking history; mean +/- SE) and 46 nonsmokers (former smokers who had a 51 +/- 7 pack-year smoking history who quit 14 +/- 2 years prior to investigation) completed the study. The 6-month exercise rehabilitation program consisted of intermittent treadmill walking to near maximal claudication pain 3 days per week, with progressive increases in walking duration and intensity during the program. Measurements were obtained on each patient before and after rehabilitation. Following exercise rehabilitation the smokers and nonsmokers had similar improvements in these measures, as initial claudication distance increased by 119% in the smokers (P <.001) and by 97% in the nonsmokers (P <.001), and absolute claudication distance increased by 82% (P <.001) and 59% (P <.001) in the smokers and nonsmokers, respectively. Furthermore, exercise rehabilitation improved (P <.05) ambulatory function, daily physical activity, peripheral circulation, and health-related quality of life in the smokers and nonsmokers.

CONCLUSION

Exercise rehabilitation is an effective therapy to improve functional independence in both smoking and nonsmoking patients with PAD limited by intermittent claudication. Therefore, smokers with intermittent claudication are prime candidates for exercise rehabilitation because their relatively low baseline physical function does not impair their ability to regain lost functional independence to levels similar to nonsmoking patients with PAD.

Utility of pedometers for assessing physical activity: convergent validity

Valid assessment of physical activity is important to researchers and practitioners interested in surveillance, screening, programme evaluation and intervention. The validity of an assessment instrument is commonly considered its most important attribute. Convergent validity is the extent to which an instrument's output is associated with that of other instruments intended to measure the same exposure of interest. A systematic review of the literature produced 25 articles directly relevant to the question of convergent validity of pedometers against accelerometers, observation, and self-reported measures of physical activity. Reported correlations were pooled and a median r-value was computed. Pedometers correlate strongly (median r = 0.86) with different accelerometers (specifically uniaxial accelerometers) depending on the specific instruments used, monitoring frame and conditions implemented, and the manner in which the outputs are expressed. Pedometers also correlate strongly (median r = 0.82) with time in observed activity. Time in observed inactivity correlated negatively with pedometer outputs (median r = -0.44). The relationship with observed steps taken depended upon monitoring conditions and speed of walking. The highest agreement was apparent during ambulatory activity (running, walking) or during sitting (when both observation and pedometers would register few steps taken). There was consistent evidence of reduced accuracy during slow walking. Pedometers correlate moderately with different measures of energy expenditure (median r = 0.68). The relationship between pedometer outputs and energy expenditure is complicated by the use of many different direct and indirect measures of energy expenditure and population samples. Concordance with self-reported physical activity (median r = 0.33) varied depending upon the self-report instrument used, individuals assessed, and how pedometer outputs are expressed (e.g. steps, distance travelled, energy expenditure). Pedometer output has an inverse relationship with reported time spent sitting (r = -0.38). The accumulated evidence herein provides ample support that the simple and inexpensive pedometer is a valid option for assessing physical activity in research and practice.

Sex differences in claudication pain in subjects with peripheral arterial disease

PURPOSES

To compare the claudication distances between men and women patients with peripheral arterial disease (PAD), and to determine whether sex differences in claudication pain persisted after controlling for potential confounders such as demographic, functional, and physiological measures.

METHODS

A total of 488 men and 72 women functionally limited by intermittent claudication were evaluated. Patients were characterized on PAD-specific measures consisting of ankle/brachial index (ABI) and treadmill claudication distances, physical function measures consisting of ambulatory function, monitored physical activity, balance, and strength, and demographic measures obtained during a medical history.

RESULTS

Initial claudication distance (ICD) was 33% shorter ( = 0.024) in women than in men (126 +/- 22 vs 189 +/- 13 m; mean +/- SEM), and absolute claudication distance (ACD) was 23% shorter ( = 0.022) in women (313 +/- 43 vs 407 +/- 18 m). These differences were present despite similar ( = 0.440) ABI values between women (0.63 +/- 0.02) and men (0.62 +/- 0.01). Peak oxygen uptake ( = 0.043) and self-perceived stair climbing ability ( = 0.020) were different between men and women, and were independently related to ICD (multiple R = 0.57, < 0.001) and to ACD (multiple R = 0.71, < 0.001). The sex differences in ICD ( = 0.524) and ACD ( = 0.722) were no longer present after controlling for peak oxygen uptake and self-perceived stair climbing ability.

CONCLUSION

Shorter treadmill claudication distances in women with PAD were explained by their lower cardiopulmonary fitness and poorer self-perceived ability to climb stairs than compared with men. Therefore, women with intermittent claudication represent a subgroup of PAD patients who should receive high priority for exercise rehabilitation to improve physical function.

Association between physical activity and endogenous fibrinolysis in peripheral arterial disease: a cross-sectional study

The purpose of this study was to determine whether daily physical activity was independently related to endogenous fibrinolysis in subjects with peripheral arterial disease (PAD). One hundred and six subjects with peripheral arterial disease (PAD) and intermittent claudication were characterized on the activity level of tissue plasminogen activator (tPA, the activator of fibrinolysis), the activity level of plasminogen activator inhibitor (PAI-1, the inhibitor of fibrinolysis), daily physical activity, ambulatory function, and demographic information. Subjects were separated into low (n = 36), moderate (n = 34), and high (n = 36) physical activity tertiles based on a 48-hour monitoring period with use of an accelerometer. The tPA activity of the low physical activity group (1.30 +/- 0.16 IU/mL) was 21% and 19% lower (p<0.05) than that of the moderate (1.65 +/- 0.18 IU/mL) and the high (1.61 +/- 0.15 IU/mL) physical activity groups, respectively. The PAI-1 activity of the low physical activity group (21.41 +/- 1.14 AU/mL) was 15% and 23% higher than that of the moderate (18.61 +/- 1.34 AU/mL) and the high (17.47 +/- 1.14 AU/mL) physical activity groups, respectively. Group differences in tPA activity and PAI-1 activity persisted after our controlling for group differences in measured and self-reported ambulatory measures. Daily physical activity is related to a more favorable endogenous fibrinolytic profile in PAD subjects with intermittent claudication. Subjects who expend fewer than 175 kcal/day in physical activities (approximately 35 minutes) are particularly susceptible to having a prothrombotic state. Subjects should be encouraged to participate in at least 35 minutes of physical activity each day to enhance fibrinolysis.

Effects of long-term exercise rehabilitation on claudication distances in patients with peripheral arterial disease: a randomized controlled trial

PURPOSE

To determine if improvements in physical function and peripheral circulation after 6 months of exercise rehabilitation could be sustained over a subsequent 12-month maintenance exercise program in older patients with intermittent claudication.

METHODS

Seventeen patients randomized to exercise rehabilitation and 14 patients randomized to usual care control completed this 18-month study. Patients exercised three times per week during the first 6 months of a progressive exercise program, followed by two times per week during the final 12 months of a maintenance program. Patients were studied at baseline, 6 months, and 18 months during the study.

RESULTS

Eighteen months of exercise rehabilitation increased the initial claudication distance by 373 meters (189%) (P <.001), the absolute claudication distance by 358 meters (80%) (P <.001), walking economy by 11% (P <.001), 6-minute walk distance by 10% (P <.001), daily physical activity by 31%, and maximal calf blood flow by 18% (P <.001). These changes were similar to those found after 6 months of exercise rehabilitation (P = NS), and were significantly greater than the changes in the control group throughout the study (P <.05).

CONCLUSION

Improvements in claudication distances, walking economy, 6-minute walk distance, physical activity level, and peripheral circulation after 6 months of exercise rehabilitation are sustained for an additional 12 months in older patients with intermittent claudication using a less frequent exercise maintenance program.

The relationship between history of falling and physical function in subjects with peripheral arterial disease

The purpose of this study was to determine whether peripheral arterial disease (PAD) subjects with a history of falling had more impaired physical function than their non-falling counterparts. A total of 120 PAD subjects (26%) who had fallen over the past year and 346 PAD subjects (74%) who had not fallen were evaluated. Additionally, subjects were characterized on physical function, consisting of balance, strength, ambulatory function, and monitored physical activity, as well as PAD-specific measures of ankle/brachial pressure index (ABPI) and treadmill claudication distances. Full-tandem stance time was 19% shorter (p < 0.001) in the fallers than in the non-fallers (7.2 +/- 0.3 vs 8.9 +/- 0.1 s; mean +/- SEM), and the self-reported ability to climb stairs was 36% lower (27 +/- 4 vs 42 +/- 2%). Furthermore, the fallers were 126% more likely (p < 0.001) to report ambulatory stumbling and unsteadiness, took 14% longer (p = 0.022) to perform five sequential sit-to-stand transfers using an armless chair, covered 16% shorter distance (p < 0.001) during a 6-min walk test, and were 25% less physically active than the non-fallers. The groups had similar ABPI and treadmill claudication distances (p < 0.05). A history of falling was independently related to the self-reported ability to climb stairs, the full-tandem stance time, self-reported ambulatory stumbling and unsteadiness, and daily physical activity (multiple R = 0.47, p < 0.001). In conclusion, impairments in multiple domains of physical function were associated with a history of falling in PAD subjects with intermittent claudication. Furthermore, the link between poor physical function and falling was independent of PAD severity.

Impaired balance and higher prevalence of falls in subjects with intermittent claudication

BACKGROUND

The purpose of this study was to determine whether peripheral arterial disease (PAD) subjects have impaired balance and a higher prevalence of falls than non-PAD controls and to determine whether balance and falls are related to the severity of PAD and functional status.

METHODS

A total of 367 PAD subjects (aged 68 +/- 1 years; mean +/- SEM) and 458 non-PAD controls (aged 67 +/- 1 years) were recruited. Unipedal stance time, history of ambulatory stumbling and unsteadiness, and history of falling were recorded. Additionally, subjects were characterized on age, ankle/brachial index (ABI), anthropometry, measured and self-reported ambulatory function, and monitored daily physical activity.

RESULTS

Unipedal stance time was 28% shorter ( p <.001) in the PAD subjects than in the non-PAD controls (15.9 +/- 0.9 vs 22.1 +/- 1.0). History of ambulatory stumbling and unsteadiness was 86% more prevalent ( p <.001) in the PAD group (150/367 = 41%) than in the controls (101/458 = 22%), and history of falling was 73% more prevalent ( p <.001) in the PAD subjects (95/367 = 26%) than in the controls (69/458 = 15%). Within the PAD group, 6-minute walk distance, self-reported ambulatory function, and daily physical activity were significantly related to the balance and falling measures ( p <.05), whereas ABI was unrelated ( p >.05).

CONCLUSIONS

Compared with the controls, PAD subjects with intermittent claudication had impaired balance and a greater likelihood of falling, both of which were associated with ambulatory function and daily physical activity.

Exercise rehabilitation improves functional outcomes and peripheral circulation in patients with intermittent claudication: a randomized controlled trial

OBJECTIVE

To determine the effects of a 6-month exercise program on ambulatory function, free-living daily physical activity, peripheral circulation, and health-related quality of life (QOL) in disabled older patients with intermittent claudication.

DESIGN

Prospective, randomized controlled trial.

SETTING

University Medical (Center and Veterans Affairs Medical Center, Baltimore, Maryland.

PARTICIPANTS

Thirty-one of 61 patients with Fontaine stage II peripheral arterial occlusive disease (PAOD) were randomized to exercise rehabilitation and 30 to usual-care control. Three patients from the exercise group and six patients from the control group dropped out, leaving 28 and 24 patients, respectively, completing the study in each group.

INTERVENTION

Six months of exercise rehabilitation.

MEASUREMENTS

Treadmill distance walked to onset of claudication and to maximal claudication, ambulatory function, peripheral circulation, perceived QOL, and daily physical activity.

RESULTS

Compliance with the exercise program was 73% of the possible sessions. Exercise rehabilitation increased treadmill distance walked to onset of claudication by 134% (P < .001) and to maximal claudication by 77% (P < .001), walking economy by 12% (P = .003), 6-minute walk distance by 12% (P < .001), and maximal calf blood flow by 30% (P < .001). Changes in distance walked to maximal pain correlated with changes in walking economy (r = -.50, P = .013) and changes in maximal calf blood flow (r = .38, P = .047). Exercise rehabilitation increased accelerometer-derived daily physical activity by 38% (P < .001); this change correlated with the change in distance walked to maximal pain (r = .45, P = .020). These improvements were significantly better than the changes in the control group (P < .05).

CONCLUSION

Improvements in claudication following exercise rehabilitation in older PAOD patients are dependent on improvements in peripheral circulation and walking economy. Improvement in treadmill claudication distances in these patients translated into increased accelerometer-derived physical activity in the community, which enabled the patients to become more functionally independent.

Simultaneous validation of ten physical activity questionnaires in older men: a doubly labeled water study

OBJECTIVE

The purpose of this study was to simultaneously validate 10 physical activity (PA) questionnaires in a homogenous population of healthy elderly men against the reference method: doubly labeled water (DLW).

DESIGN

Cross-sectional study.

SETTING

Community-based sample from Lyon, France.

PARTICIPANTS

Nineteen healthy old men (age 73.4 +/- 4.1 years), recruited from various associations for elderly people in Lyon, agreed to participate in the study.

MEASUREMENTS

The questionnaire-derived measures (scores) were compared with two validation measures: DLW and maximal oxygen uptake (VO2max). With the DLW method three parameters were calculated: (1) total energy expenditure (TEE), (2) physical activity level (PAL), i.e., the ratio of TEE to resting metabolic rate, (3) energy expenditure of PA.

RESULTS

Relative validity. Correlation between the questionnaires and TEE ranged from 0.11 for the Yale Physical Activity Survey (YPAS) total index to 0.63 for the Stanford usual activity questionnaire. This questionnaire also gave the best correlation coefficients with PAL (0.75), and with VO2max (0.62). Significant results with TEE measured by the DLW method were also obtained for college alumni sports score, Seven Day Recall moderate activity, and Questionnaire d'Activité Physique Saint-Etienne sports activity (r = 0.54, r = 0.52, and r = 0.54, respectively). Absolute validity. No difference was found between PA measured by the Seven Day Recall or by the YPAS and DLW, on a group basis. The limits of agreement were wide for all the questionnaires.

CONCLUSIONS

Only a few questionnaires demonstrated a reasonable degree of reliability and could be used to rank healthy older men according to PA. Correlation coefficients were best when the Stanford Usual Activity Questionnaire was compared with all the validation measures. The two questionnaires reporting recent PA, the Seven Day Recall, and YPAS accurately assessed energy expenditure for the group. The individual variability was high for all the questionnaires, suggesting that their use as a proxy measure of individual energy expenditure may be limited.

Improved functional outcomes following exercise rehabilitation in patients with intermittent claudication

BACKGROUND

The purposes of this study were to identify predictors of increased claudication distances following exercise rehabilitation in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication and determine whether improved claudication distances translated into increased free-living daily physical activity in the community setting.

METHODS

Sixty-three patients were recruited (age, 68+/-1 years, mean +/- standard error). Patients were characterized on treadmill claudication distances, walking economy, peripheral circulation, cardiopulmonary function, self-perceived ambulatory function, body composition, baseline comorbidities, and free-living daily physical activity before and after a 6-month treadmill exercise program.

RESULTS

Exercise rehabilitation increased distance to onset of claudication pain by 115% (178+/-22 m to 383+/-34 m; p < .001) and distance to maximal claudication pain by 65% (389+/-29 m to 641+/-34 m; p < .001). The increased distance to onset of pain was independently related to a 27% increase in calf blood flow (r = .42, p < .001) and to baseline age (r = -.26, p < .05), and the increased distance to maximal pain was predicted by a 10% increase in peak oxygen uptake (r = .41, p < .001) and by a 10% improvement in walking economy (r = -.34, p < .05). Free-living daily physical activity increased 31% (337+/-29 kcal/day to 443+/-37 kcal/day; p < .001) and was related to the increases in treadmill distances to onset (r = .24, p < .05) and to maximal pain (r = .45, p < .001).

CONCLUSIONS

Increased claudication distances following exercise rehabilitation are mediated through improvements in peripheral circulation, walking economy, and cardiopulmonary function, with younger patients having the greatest absolute ambulatory gains. Furthermore, improved symptomatology translated into enhanced community-based ambulation.