Impact of accelerometer wear time on physical activity data: a NHANES semisimulation data approach

Comparing national device-based physical activity surveillance systems: a systematic review

BACKGROUND

Physical activity surveillance systems are important for public health monitoring but rely mostly on self-report measurement of physical activity. Integration of device-based measurements in such systems can improve population estimates, however this is still relatively uncommon in existing surveillance systems. This systematic review aims to create an overview of the methodology used in existing device-based national PA surveillance systems.

METHODS

Four literature databases (PubMed, Embase.com, SPORTDiscus and Web of Science) were searched, supplemented with backward tracking. Articles were included if they reported on population-based (inter)national surveillance systems measuring PA, sedentary time and/or adherence to PA guidelines. When available and in English, the methodological reports of the identified surveillance studies were also included for data extraction.

RESULTS

This systematic literature search followed the PRISMA guidelines and yielded 34 articles and an additional 18 methodological reports, reporting on 28 studies, which in turn reported on one or multiple waves of 15 different national and 1 international surveillance system. The included studies showed substantial variation between (waves of) systems in number of participants, response rates, population representativeness and recruitment. In contrast, the methods were similar on data reduction definitions (e.g. minimal number of valid days, non-wear time and necessary wear time for a valid day).

CONCLUSIONS

The results of this review indicate that few countries use device-based PA measurement in their surveillance system. The employed methodology is diverse, which hampers comparability between countries and calls for more standardized methods as well as standardized reporting on these methods. The results from this review can help inform the integration of device-based PA measurement in (inter)national surveillance systems.

Does Wrist-Worn Accelerometer Wear Compliance Wane over a Free-Living Assessment Period? An NHANES Analysis

PURPOSE

Accelerometers are used to objectively measure physical behaviors in free-living environments, typically for seven consecutive days or more. We examined whether participants experience "wear fatigue," a decline in wear time day over day, during typical assessment period acquired in a nationally representative sample of 6- to 80-yr-olds in the United States.

METHODS

Participants were instructed to wear an ActiGraph GT3X+ on their nondominant wrist continuously for seven consecutive days. Participants with seven complete days of recorded data, regardless of wear status, were included in the analyses ( N = 13,649). Wear was scored with the sleep, wake, and nonwear algorithm.

RESULTS

Participants averaged 1248 ± 3.6 min·d -1 (mean ± SE) of wear over the assessment, but wear time linearly decreased from day 1 (1295 ± 3.2 min) to day 7 (1170 ± 5.3 min), resulting in a wear fatigue of -18.1 ± 0.7 min·d -1 ( β ± SE). Wear fatigue did not differ by sex but varied by age-group-highest in adolescents (-26.8 ± 2.4 min·d -1 ) and lowest in older adults (-9.3 ± 0.9 min·d -1 ). Wear was lower in evening (1800-2359 h) and early morning (0000-0559 h) compared with the middle of the day and on weekend days compared with weekdays. We verified similar wear fatigue (-23.5 ± 0.7 min·d -1 ) in a separate sample ( N = 14,631) with hip-worn devices and different wear scoring. Applying minimum wear criteria of ≥10 h·d -1 for ≥4 d reduced wear fatigue to -5.3 and -18.7 min·d -1 for the wrist and hip, respectively.

CONCLUSIONS

Patterns of wear suggest noncompliance may disproportionately affect estimates of sleep and sedentary behavior, particularly for adolescents. Further study is needed to determine the effect of wear fatigue on longer assessments.

The association between morning pleasant anticipation and daily positive incidental affect on adults' daily steps: An ecological momentary assessment study

OBJECTIVE

This study investigated the association between morning pleasant anticipation (i.e., how pleasant will the day be?) and daily positive incidental affect (PIA, e.g., feeling enjoyable, energetic) on daily steps as measured by ecological momentary assessment (EMA) and accelerometry.

METHODS

A total of 152 adults in Taiwan (female = 67.1 %, age range = 18-59, M = 24.97) completed smartphone-based surveys upon waking and at three quasi-random times during the day for seven days during the COVID-19 outbreak (February-July 2022). They also wore accelerometers for the same seven days to measure physical activity (daily steps). The morning survey asked participants to self-report pleasant anticipation throughout the day, and the three quasi-random time surveys assessed current PIA. Multilevel modeling was used to examine day-level associations between morning pleasant anticipation, PIA, and daily steps. A list of key covariates (i.e., age, sex, educational attainment, marital status, living arrangement, chronic disease, body mass index [BMI], smoking, drinking, wellbeing, daily sleep quality, daily sleep hours, and accelerometer wear time) were included in the models to adjust for the covariates' potential effects on the study outcomes.

RESULTS

The study sample consisted of 989 morning observations and 2714 quasi-random time observations (EMA response rate = 87.01 %). Findings suggest that higher-than-usual levels of pleasant anticipation in the morning were significantly associated with more same-day daily steps (b = 0.03, SD = 0.01, p = .03) after adjusting for covariates. In addition, daily PIA was a significant moderator between morning pleasant anticipation and daily steps (b = 0.02, SD = 0.01, p < .01), such that higher levels of daily PIA were associated with greater increases in daily steps in response to higher levels of morning pleasant anticipation.

CONCLUSION

On days when participants had higher levels of pleasant anticipation in the morning, they took more steps per day. In addition, the association between morning pleasant anticipation and steps per day was stronger on days when participants had higher levels of PIA. These findings have practical implications for future EMA studies investigating the "anticipatory" affective processes on movement behaviors with the goal of promoting physical activity in daily life.

Fundament for a methodological standard to process hip accelerometer data to a measure of physical activity intensity in middle-aged individuals

BACKGROUND

There is a lack of a methodological standard to process accelerometer data to measures of physical activity, which impairs data quality and comparability. This study investigated the effect of different combinations of settings of multiple processing components, on the measure of physical activity and the association with measures of cardiometabolic health in an unselected population of middle-aged individuals.

METHODS

Free-living hip accelerometer data, aerobic fitness, body mass index, HDL:total cholesterol ratio, blood glucose, and systolic blood pressure were achieved from 4391 participants 50-64 years old included in The Swedish CArdioPulmonary bioImage Study (SCAPIS) baseline measurement (cross-sectional). Lab data were also included for calibration of accelerometers to provide comparable measure of physical activity intensity and time spent in different intensity categories, as well as to enhance understanding. The accelerometer data processing components were hardware recalibration, frequency filtering, number of accelerometer axes, epoch length, wear time criterium, time composition (min/24 h vs. % of wear time). Partial least regression and ordinary least regression were used for the association analyses.

RESULTS

The setting of frequency filter had the strongest effect on the physical activity intensity measure and time distribution in different intensity categories followed by epoch length and number of accelerometer axes. Wear time criterium and recalibration of accelerometer data were less important. The setting of frequency filter and epoch length also showed consistent important effect on the associations with the different measures of cardiometabolic health, while the effect of recalibration, number of accelerometer axes, wear time criterium and expression of time composition was less consistent and less important. There was a large range in explained variance of the measures of cardiometabolic health depending on the combination of processing settings, for example, 12.1%-20.8% for aerobic fitness and 5.8%-14.0% for body mass index.

CONCLUSIONS

There was a large variation in the physical activity intensity measure and the association with different measures of cardiometabolic health depending on the combination of settings of accelerometer data processing components. The results provide a fundament for a standard to process hip accelerometer data to assess the physical activity in middle-aged populations.

Effectiveness of Non-pharmacologic Interventions on Device-measured Physical Activity in Adults With Cancer, and Methodology Used for Assessment: A Systematic Review and Meta-analysis

OBJECTIVE

To investigate the effectiveness of different types of interventions aimed at enhancing device-measured physical activity (PA) and summarize the devices and methodologies used to measure PA in adults with cancer.

DATA SOURCES

A systematic review was prospectively registered on PROSPERO (CRD42020199466). The search was conducted in PubMed, The Cochrane Library, EMBASE (via Ovid), and PEDro from 2005 onward.

STUDY SELECTION

Prospective interventional studies (randomized controlled trials [RCTs], non-randomized controlled trials, and single-group trials), that included adults within 12 months from cancer diagnosis, and device-measured PA before and after commencement of an intervention were included. Studies were excluded if PA was measured at a single time point. Two independent reviewers screened 3033 records and 30 articles met the inclusion criteria.

DATA EXTRACTION

Two reviewers independently extracted the data. PEDro scale and GRADE approach were used to assess methodological quality of RCTs and overall quality of evidence, respectively. A meta-analysis of relevant RCTs was conducted.

DATA SYNTHESIS

Thirty studies were identified, mainly including adults with multiple cancer types. Interventions were behavior change interventions (n=15), exercise training (n=13), neuromuscular electrostimulation (n=1), or a nutritional program (n=1). The meta-analysis showed improvements on moderate-to-vigorous intensity PA (MVPA) in the experimental group (8 studies; standardized mean difference (SMD)=0.23; 95% CI 0.06-0.39); with subgroup analysis showing that findings were mainly driven by behavior change interventions (5 studies; SMD=0.23, 95% CI 0.05-0.41). An uncertain effect on sedentary behavior, daily steps, and light intensity PA was found. PA was measured with medical devices and commercial wearables, quality of the methodology was variable.

CONCLUSIONS

Behavior change interventions increased device-derived MVPA in adult cancer patients who underwent the intervention within 12 months of the cancer diagnosis. Various devices and methodologies were used to assess PA, which limits comparisons across the studies.

Monitoring physical activity using wearable technology in people with Achilles tendinopathy undergoing physiotherapy treatment: A feasibility prospective cohort study

OBJECTIVES

Physical activity modification is an important part of the management of Achilles tendinopathy. However, to our knowledge, there is a lack of evidence on objective physical activity assessment in Achilles tendinopathy. The purpose of this study is to (1) assess feasibility of using an inertial measurement unit (IMU) to monitor physical activity and IMU-derived biomechanical measures over 12-week treatment course by a physiotherapist; (2) conduct a preliminary analysis of changes in physical activity over 12-weeks.

DESIGN

A feasibility prospective cohort study SETTING: A community setting.

PARTICIPANTS

People with Achilles tendinopathy who had recently commenced (≤2 sessions), or were about to commence, treatment with a physiotherapist MAIN OUTCOME MEASURES: Participants wore a shank-mounted IMU on the affected side for one week at baseline, 6-, and 12-week follow-ups. The outcomes were pain/symptom severity, IMU-derived physical activity and biomechanical measures (stride rate, peak shank angular velocity, and peak shank acceleration).

RESULTS

Thirty participants were recruited. There was a high retention rate (97%), response rate (97%), and IMU wear compliance at each timepoint (>93%). For pain/symptom severity, a significant time effect was observed between baseline and 12-week follow-up. Physical activity and IMU-derived biomechanical measures did not change over 12 weeks. Physical activity decreased at the 6-week follow-up but only returned to the baseline level at 12-week follow-up.

CONCLUSIONS

A larger-scale cohort study assessing clinical outcomes and physical activity appears feasible. Preliminary data indicate that physical activity may not change significantly over 12-weeks in people undergoing physiotherapy management for Achilles tendinopathy. CONTRIBUTION OF THE PAPER.

The Analytical and Clinical Validity of the pfSTEP Digital Biomarker of the Susceptibility/Risk of Declining Physical Function in Community-Dwelling Older Adults

Measures of stepping volume and rate are common outputs from wearable devices, such as accelerometers. It has been proposed that biomedical technologies, including accelerometers and their algorithms, should undergo rigorous verification as well as analytical and clinical validation to demonstrate that they are fit for purpose. The aim of this study was to use the V3 framework to assess the analytical and clinical validity of a wrist-worn measurement system of stepping volume and rate, formed by the GENEActiv accelerometer and GENEAcount step counting algorithm. The analytical validity was assessed by measuring the level of agreement between the wrist-worn system and a thigh-worn system (activPAL), the reference measure. The clinical validity was assessed by establishing the prospective association between the changes in stepping volume and rate with changes in physical function (SPPB score). The agreement of the thigh-worn reference system and the wrist-worn system was excellent for total daily steps (CCC = 0.88, 95% CI 0.83-0.91) and moderate for walking steps and faster-paced walking steps (CCC = 0.61, 95% CI 0.53-0.68 and 0.55, 95% CI 0.46-0.64, respectively). A higher number of total steps and faster paced-walking steps was consistently associated with better physical function. After 24 months, an increase of 1000 daily faster-paced walking steps was associated with a clinically meaningful increase in physical function (0.53 SPPB score, 95% CI 0.32-0.74). We have validated a digital susceptibility/risk biomarker-pfSTEP-that identifies an associated risk of low physical function in community-dwelling older adults using a wrist-worn accelerometer and its accompanying open-source step counting algorithm.

Physiologic and Behavioral Correlates of Energy Intake in Emerging Adulthood: Cross-Sectional Analysis of the RIGHT Track Health Study

BACKGROUND

Consistent findings have reported that FFM is associated with EI. However, conjoint assessments of physiologic (body composition, fasting serum leptin) and behavioral [eating behaviors and physical activity (PA)] correlates of EI during emerging adulthood have not been examined.

OBJECTIVES

We assessed associations between physiologic and behavioral correlates of EI within the context of one another in emerging adults (18-28 years old). We also assessed these associations in a subsample after the removal of probable EI underreporters.

METHODS

Cross-sectional data from 244 emerging adults (age = 19.6 ± 1.4 y; BMI = 26.4 ± 6.6 kg/m2; 56.6% female) from the RIGHT Track Health study were used. Measures included body composition (BOD POD), eating behaviors (Three-Factor Eating Questionnaire), objective and subjective PA (accelerometer-derived total activity counts and Godin-Shephard Leisure-Time Exercise Questionnaire), fasting serum leptin, and EI (three 24-hour dietary recalls). Correlates independently associated with EI were entered into a backward stepwise linear regression model. Correlates that met the criteria of P < 0.05 were retained. Analyses were repeated in a subsample after removing probable EI underreporters (n = 48). Effect modification by sex (male and female) and BMI (BMI < 25 kg/m2, BMI ≥ 25 kg/m2) categories was also assessed.

RESULTS

In the full sample, FFM (β: 18.4; 95% CI: 9.9, 26.8), leptin (β: -84.8; 95% CI: -154.3, -15.4), dietary restraint (β: -35.2; 95% CI: -59.1, -11.3), and subjective PA (β: 2.5; 95% CI: 0.04, 4.9) were significantly associated with EI. After the removal of probable underreporters, only FFM remained significantly associated with EI (β: 43.9; 95% CI: 27.2, 60.6). No evidence of effect modification by sex or BMI categories was noted.

CONCLUSIONS

Although physiologic and behavioral correlates were associated with EI in the full sample, only FFM remained a robust correlate of EI in a subsample of emerging adults after removing probable EI underreporters.

The feasibility of remotely monitoring physical, cognitive, and psychosocial function in individuals with stroke or chronic obstructive pulmonary disease

Objective

Clinical implementation of remote monitoring of human function requires an understanding of its feasibility. We evaluated adherence and the resources required to monitor physical, cognitive, and psychosocial function in individuals with either chronic obstructive pulmonary disease or stroke during a three-month period.

Methods

Seventy-three individuals agreed to wear a Fitbit to monitor physical function and to complete monthly online assessments of cognitive and psychosocial function. During a three-month period, we measured adherence to monitoring (1) physical function using average daily wear time, and (2) cognition and psychosocial function using the percentage of assessments completed. We measured the resources needed to promote adherence as (1) the number of participants requiring at least one reminder to synchronize their Fitbit, and (2) the number of reminders needed for each completed cognitive and psychosocial assessment.

Results

After accounting for withdrawals, the average daily wear time was 77.5 ± 19.9% of the day and did not differ significantly between months 1, 2, and 3 (p = 0.30). To achieve this level of adherence, 64.9% of participants required at least one reminder to synchronize their device. Participants completed 61.0% of the cognitive and psychosocial assessments; the portion of assessments completed each month didnot significantly differ (p = 0.44). Participants required 1.13 ± 0.57 reminders for each completed assessment. Results did not differ by disease diagnosis.

Conclusions

Remote monitoring of human function in individuals with either chronic obstructive pulmonary disease or stroke is feasible as demonstrated by high adherence. However, the number of reminders required indicates that careful consideration must be given to the resources available to obtain high adherence.

Preliminary results of the cross-sectional associations of sedentary behavior and physical activity with serum brain-derived neurotrophic factor in adults with coronary heart disease

This is the first study to analyze the association of accelerometer-measured patterns of habitual physical activity (PA) and sedentary behavior (SB) with serum BDNF in individuals with coronary heart disease. A total of 30 individuals (M = 69.5 years; 80% men) participated in this pre-post study that aimed to test a multi-behavioral intervention. All participants underwent standardized measurement of anthropometric variables, blood collection, self-administered survey, and accelerometer-based measurement of PA and SB over seven days. Serum BDNF concentrations were measured using enzyme-linked immunosorbent assay kit. We applied separate multiple linear regression analysis to estimate the associations of baseline SB pattern measures, light and moderate-to-vigorous PA with serum BDNF (n = 29). Participants spent 508.7 ± 76.5 min/d in SB, 258.5 ± 71.2 min/d in light PA, and 21.2 ± 15.2 min/d in moderate-to-vigorous PA. Per day, individuals had 15.5 ± 3.2 numbers of 10-to-30 min bouts of SB (average length: 22.2 ± 2.1 min) and 3.4 ± 1.2 numbers of > 30 min bouts of SB (average length: 43.8 ± 2.4 min). Regression analysis revealed no significant associations between any of the accelerometer-based measures and serum BDNF. The findings of this study did not reveal an association of accelerometer-measured PA and SB pattern variables with serum BDNF in individuals with coronary heart disease. In addition, our data revealed a considerable variation of PA and SB which should be considered in future studies.

Meeting 24-h movement guidelines and markers of adiposity in adults from eight Latin America countries: the ELANS study

This study aimed to compare compliance with 24-h movement guidelines across countries and examine the associations with markers of adiposity in adults from eight Latin American countries. The sample consisted of 2338 adults aged 18-65 years. Moderate-to-vigorous physical activity (MVPA) and sedentary behavior (SB) data were objectively measured using accelerometers. Sleep duration was self-reported using a daily log. Body mass index and waist circumference were assessed as markers of adiposity. Meeting the 24-h movement guidelines was defined as ≥ 150 min/week of MVPA; ≤ 8 h/day of SB; and between 7 and 9 h/day of sleep. The number of guidelines being met was 0.90 (95% CI 0.86, 0.93) with higher value in men than women. We found differences between countries. Meeting two and three movement guidelines was associated with overweight/obesity (OR: 0.75, 95% CI 0.58, 0.97 and OR: 0.69, 95% CI 0.51, 0.85, respectively) and high waist circumference (OR: 0.74, 95% CI 0.56, 0.97 and OR: 0.77, 95% CI 0.62, 0.96). Meeting MVPA and SB recommendations were related to reduced adiposity markers but only in men. Future research is needed to gain insights into the directionality of the associations between 24-h movement guidelines compliance and markers of adiposity but also the mechanisms underlying explaining differences between men and women.

The Potential for Bias across GPS-Accelerometer Combined Wear Criteria among Adolescents

Physical activity has many health benefits, yet a large portion of our population is not meeting recommendations. Using accelerometry and global positioning systems (GPS) to accurately measure where people are active and to identify barriers and facilitators of activity across various settings will inform evidence-based policies and interventions to improve activity levels. Criteria for sufficient accelerometry data (e.g., number of days, minimum hours in a day) to accurately monitor free-living physical activity in adults and children have been widely studied, implemented, and reported by researchers. However, few best practice recommendations for researchers using GPS have been established. Therefore, this paper examined the impact of three co-wear criteria of varying stringency among a sample of children aged 10 to 16 years in Baton Rouge, Louisiana. Overall and location-based physical activity was consistent across the samples even within sociodemographic subgroups. Despite the lack of significant subgroup-specific mean differences in physical activity across the three samples, associations between sociodemographics and weight status and physical activity were significantly different depending on the device time-matching "co-wear" criteria applied. These differences demonstrate the critical impact co-wear criteria may have on conclusions drawn from research examining health disparities. There is a need for additional research and understanding of ideal co-wear criteria that reduce bias and accurately estimate free-living location-based physical activity across diverse populations.

Evaluating daily physical activity and biomechanical measures using wearable technology in people with Achilles tendinopathy: A descriptive exploratory study

BACKGROUND

Load management is considered an important factor for prevention and treatment of Achilles tendinopathy. However, little attention has been given to monitoring daily load objectively in this population.

OBJECTIVES

We aimed to explore patterns in proxies of daily load derived from a six-axis inertial measurement unit (IMU) over a one-week period and the concordance between day-to-day fluctuation in pain intensity and IMU measures.

DESIGN

Descriptive exploratory study.

METHOD

Ten participants with Achilles tendinopathy (age: 53.00 ± 12.37) wore an IMU on the affected ankle for one week. Participants were contacted via text message three times daily to rate their worst pain intensity. Physical activity and biomechanical measures derived from the IMU signals including daily number of steps, peak stride rate, peak shank acceleration, and peak shank angular velocity were calculated.

RESULTS

The relationship between weekly worst pain and physical activity levels appeared modest; with increased steps not seeming to be linked to increased or reduced pain levels. According to the daily pain and daily IMU measures, a concordant pattern was evident in younger, highly active participants. However, in the middle-aged/older less active participants, there was either a fluctuation in pain intensity without fluctuation in the IMU measures, or a stable pattern of both pain and IMU measures.

CONCLUSIONS

Our exploratory study results suggest that continuous monitoring of proxies of daily load measures in parallel with pain may provide information about load management strategies in people with Achilles tendinopathy. Monitoring of these proxies may ultimately have a role in improving Achilles tendinopathy management.

An investigation into the optimal wear time criteria necessary to reliably estimate physical activity and sedentary behaviour from ActiGraph wGT3X+ accelerometer data in older care home residents

Background

Research protocols regarding the use of ActiGraph wGT3X+ accelerometers in care home residents are yet to be established. The purpose of this study was to identify the minimal wear time criteria required to achieve reliable estimates of physical activity (PA) and sedentary behaviour (SB) in older care home residents.

Methods

Ninety-four older adults from 14 care homes wore an ActiGraph wGT3X+ accelerometer on the right hip for 7 consecutive days. A pragmatic, staged approach was adopted in order to explore the effect of: monitoring day; minimum daily wear time and number of wear days on estimates of four outcomes derived from the accelerometer data: counts^.day^− 1, counts^.minute^− 1, PA time and SB time.

Results

Data from 91 participants (mean age: 84 ± 9 years, 34% male) was included in the analysis. No effect of monitoring day was observed. Lowering the daily wear time to ≥ 8 h (compared to ≥10 h) had no effect on the outcomes of interest. Four days of monitoring was sufficient to provide reliable estimates of all four outcomes.

Conclusion

In this study, a minimum wear time criterion of ≥ 8 h on any 4 days was required to derive reliable estimates of PA and SB from ActiGraph wGT3X+ accelerometer data in older care home residents.

Usefulness of wearable fitness tracking devices in patients undergoing esophagectomy

BACKGROUND

Esophageal cancer surgery requires maintenance and enhancement of perioperative nutritional status and physical function to prevent postoperative complications. Therefore, awareness of the importance of preoperative patient support is increasing. This study examined the usefulness of using a diary in combination with a wearable fitness tracking device (WFT) in patients undergoing surgery for esophageal cancer.

METHODS

Ninety-four patients who underwent esophagectomy between February 2019 and April 2021 were included. Physicians, nurses, dietitians, and physical therapists provided diary-based education for the patients. In addition, a WFT was used by some patients. The perioperative outcomes of patients who used both the diary and WFT (WFT group) and those who used the diary alone (non-WFT group) were compared. In addition, propensity score matching was performed to improve comparability between the two groups.

RESULTS

After the propensity score matching, the rate of postoperative pneumonia was significantly lower in the WFT group (0% vs. 22.6%, P = 0.005). The postoperative hospital stay was shorter in the WFT group (P = 0.012). Nutritional status indices, such as the prognostic nutritional index, also improved significantly in the WFT group at 1 month after surgery (P = 0.034). The rate of diary entries was significantly higher in the WFT group (72.3% vs. 28.3%, P < 0.001).

CONCLUSION

The use of a WFT reduced the incidence of postoperative pneumonia and improved postoperative nutritional status and rates of diary entries after esophagectomy, suggesting that its use may be useful for promoting recovery after esophagectomy.

Considerations to address missing data when deriving clinical trial endpoints from digital health technologies

Digital health technologies (DHTs) enable us to measure human physiology and behavior remotely, objectively and continuously. With the accelerated adoption of DHTs in clinical trials, there is an unmet need to identify statistical approaches to address missing data to ensure that the derived endpoints are valid, accurate, and reliable. It is not obvious how commonly used statistical methods to handle missing data in clinical trials can be directly applied to the complex data collected by DHTs. Meanwhile, current approaches used to address missing data from DHTs are of limited sophistication and focus on the exclusion of data where the quantity of missing data exceeds a given threshold. High-frequency time series data collected by DHTs are often summarized to derive epoch-level data, which are then processed to compute daily summary measures. In this article, we discuss characteristics of missing data collected by DHT, review emerging statistical approaches for addressing missingness in epoch-level data including within-patient imputations across common time periods, functional data analysis, and deep learning methods, as well as imputation approaches and robust modeling appropriate for handling missing data in daily summary measures. We discuss strategies for minimizing missing data by optimizing DHT deployment and by including the patients' perspective in the study design. We believe that these approaches provide more insight into preventing missing data when deriving digital endpoints. We hope this article can serve as a starting point for further discussion among clinical trial stakeholders.

Effect of self-regulatory behaviour change techniques and predictors of physical activity maintenance in cancer survivors: a 12-month follow-up of the Phys-Can RCT

Background

Current knowledge about the promotion of long-term physical activity (PA) maintenance in cancer survivors is limited. The aims of this study were to 1) determine the effect of self-regulatory BCTs on long-term PA maintenance, and 2) identify predictors of long-term PA maintenance in cancer survivors 12 months after participating in a six-month exercise intervention during cancer treatment.

Methods

In a multicentre study with a 2 × 2 factorial design, the Phys-Can RCT, 577 participants with curable breast, colorectal or prostate cancer and starting their cancer treatment, were randomized to high intensity exercise with or without self-regulatory behaviour change techniques (BCTs; e.g. goal-setting and self-monitoring) or low-to-moderate intensity exercise with or without self-regulatory BCTs. Participants’ level of PA was assessed at the end of the exercise intervention and 12 months later (i.e. 12-month follow-up), using a PA monitor and a PA diary. Participants were categorized as either maintainers (change in minutes/week of aerobic PA ≥ 0 and/or change in number of sessions/week of resistance training ≥0) or non-maintainers. Data on potential predictors were collected at baseline and at the end of the exercise intervention. Multiple logistic regression analyses were performed to answer both research questions.

Results

A total of 301 participants (52%) completed the data assessments. A main effect of BCTs on PA maintenance was found (OR = 1.80, 95%CI [1.05–3.08]) at 12-month follow-up. Participants reporting higher health-related quality-of-life (HRQoL) (OR = 1.03, 95%CI [1.00–1.06] and higher exercise motivation (OR = 1.02, 95%CI [1.00–1.04]) at baseline were more likely to maintain PA levels at 12-month follow-up. Participants with higher exercise expectations (OR = 0.88, 95%CI [0.78–0.99]) and a history of tobacco use at baseline (OR = 0.43, 95%CI [0.21–0.86]) were less likely to maintain PA levels at 12-month follow-up. Finally, participants with greater BMI increases over the course of the exercise intervention (OR = 0.63, 95%CI [0.44–0.90]) were less likely to maintain their PA levels at 12-month follow-up.

Conclusions

Self-regulatory BCTs improved PA maintenance at 12-month follow-up and can be recommended to cancer survivors for long-term PA maintenance. Such support should be considered especially for patients with low HRQoL, low exercise motivation, high exercise expectations or with a history of tobacco use at the start of their cancer treatment, as well as for those gaining weight during their treatment. However, more experimental studies are needed to investigate the efficacy of individual or combinations of BCTs in broader clinical populations.

Trial registration

NCT02473003 (10/10/2014).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08996-x.

Physical activity in the early postpartum period in primiparous women

Little is known about early postpartum physical activity (PA).

OBJECTIVES

We aimed to describe PA amount and types and compare moderate-vigorous PA (MVPA) at 12-25 (T1) and 33-46 days (T2) postpartum.

DESIGN

Cross-sectional study.

METHODS

Participants, primiparas delivered vaginally, wore wrist accelerometers and completed questionnaires. Median and interquartile range (IQR) describe minutes/day of PA intensities in total minutes, 5- and 10-minute bouts. Wilcoxon Signed Rank test compared MVPA.

RESULTS

577 (age: 28.3 (SD: 5.1)) had accelerometry or questionnaire at either time-point. 405 had accelerometry at both time-points. Median (IQR) total minutes/day for light, moderate, vigorous and MVPA were 295.8 (256.1-331.7), 54.6 (40-72.7), 0.4 (0.2-0.8), and 55.5 (40.4-74.3), respectively, at T1 and 329 (289.4-367.1), 63.6 (46.9-82.2), 0.6 (0.3-1.3), and 64.5 (47-84.8), respectively, at T2. Median (IQR) minutes/day for MVPA in 5- and 10-minute bouts were 1.6 (0-5.5) and 0 (0-3.8) at T1, and 3 (0-9.2) and 0 (0-5.5) at T2. At T1, 75% (406/541) and at T2, 72.4% (397/548) reported non-impact activities. At T1, 4% and at T2, 13% reported impact/straining activities. MVPA was greater at T2 than T1 (p < 0.0001) with medians (IQR) of: total: 64.7 (47-84.6) vs 56.5 (41-74.9) minutes; 5-minute bouts: 3 (0-9.8) vs 1.7 (0-5.6) minutes; and 10-minute bouts: 1.3(0-6) vs 0(0-3.8) minutes.

CONCLUSIONS

Women had high daily MVPA, though MVPA in bouts remained low. Significant increases in MVPA from T1 to T2 were small, few women reported impact/straining activities. Realistic return to pre-pregnancy PA levels should recognize the relative lack of sustained/strenuous activity in early postpartum.

School-based physical activity interventions in rural and urban/suburban communities: A systematic review and meta-analysis

Disparities in physical activity and health outcomes exist between urban and rural youth. School settings can be utilized to promote physical activity in youth regardless of urban-rural status. This systematic review and meta-analysis aimed to assess and compare the effect of rural and urban/suburban school-based physical activity programs on total physical activity in youth. A search of five databases was conducted. A total of 33 studies remained after the exclusion process, 28 of which took place in urban/suburban schools and five of which took place in rural schools. The DerSimonian and Laird random effects model was employed with the estimates of heterogeneity taken from the inverse-variance fixed-effect model. For rural studies, the Hartung-Knapp-Sidak-Jonkman method was used to obtain error estimates. Results from the total sample indicated a significant but small pooled increase in daily physical activity (Hedge's g = 0.12, 95% confidence interval [CI]: 0.06-0.18), which held for interventions conducted in urban/suburban schools (Hedge's g = 0.12, 95% CI: 0.06-0.19). For rural school-based interventions, there was no significant pooled effect (Hedge's g = 0.06, 95% CI: -0.50 to 0.61). This meta-analysis provides evidence that school-based interventions can be marginally effective for increasing daily physical activity in children and adolescents; however, no effect was observed for interventions implemented in rural settings.

Free-Living Physical Activity and Sedentary Behaviour in Autoimmune Myasthenia Gravis: A Cross-Sectional Study

BACKGROUND

Muscle weakness and fatigability, the prominent symptoms of autoimmune myasthenia gravis (MG), negatively impact daily function and quality of life (QoL). It is currently unclear as to what extent symptoms limit activity and whether physical activity (PA) behaviours are associated with reduced QoL.

OBJECTIVES

This study aimed to describe habitual PA patterns and explore relationships between PA metrics, clinical MG characteristics, and health-related QoL (HRQoL).

METHODS

PA data from a tri-axial trunk accelerometer worn for seven days, was collected from females with generalized, stable MG and compared to control subjects. MG-specific evaluations, the six-minute walk test and knee extension strength were assessed in individuals with MG (IwMG). Mann-Whitney tests were used to study between-group differences. Spearman rank correlation coefficient was performed to explore relationships between variables.

RESULTS

Thirty-three IwMG (mean (SD) age 45 (11) years) and 66 control subjects were included. IwMG perform less vigorous-intensity PA than control subjects (p = 0.001), spend more time sedentary (p = 0.02) and engage in less and shorter durations of moderate-vigorous-intensity PA (MVPA). For IwMG, habitual PA correlated positively with 6 min walking distance (rho = 0.387, p = 0.029) and negatively with body mass index (rho = -0.407, p = 0.019). We did not find any association between PA or sedentary behaviour and; HRQoL, symptom severity nor lower limb strength.

CONCLUSIONS

Individuals with stable MG perform less PA, at lower intensities, and are more inactive than control individuals. Further research is warranted to understand factors influencing PA patterns in MG and whether interventions could be successful in increasing PA quantity and intensity in IwMG.

Influence of the Duration and Timing of Data Collection on Accelerometer-Measured Physical Activity, Sedentary Time and Associated Insulin Resistance

Accelerometry is a commonly used method to determine physical activity in clinical studies, but the duration and timing of measurement have seldom been addressed. We aimed to evaluate possible changes in the measured outcomes and associations with insulin resistance during four weeks of accelerometry data collection. This study included 143 participants (median age of 59 (IQR9) years; mean BMI of 30.7 (SD4) kg/m²; 41 men). Sedentary and standing time, breaks in sedentary time, and different intensities of physical activity were measured with hip-worn accelerometers. Differences in the accelerometer-based results between weeks 1, 2, 3 and 4 were analyzed by mixed models, differences during winter and summer by two-way ANOVA, and the associations between insulin resistance and cumulative means of accelerometer results during weeks 1 to 4 by linear models. Mean accelerometry duration was 24 (SD3) days. Sedentary time decreased after three weeks of measurement. More physical activity was measured during summer compared to winter. The associations between insulin resistance and sedentary behavior and light physical activity were non-significant after the first week of measurement, but the associations turned significant in two to three weeks. If the purpose of data collection is to reveal associations between accelerometer-measured outcomes and tenuous health outcomes, such as insulin sensitivity, data collection for at least three weeks may be needed.

Effect of Linear and Nonlinear Pedagogy Physical Education Interventions on Children's Physical Activity: A Cluster Randomized Controlled Trial (SAMPLE-PE)

Background: School-based interventions are a key opportunity to improve children’s physical activity (PA); however, there is lack of evidence about how pedagogical approaches to motor learning in physical education (PE) might affect PA in children. Therefore, this study aimed to assess how different pedagogical approaches in PE might affect children’s PA. Methods: Participants (n = 360, 5–6 years) from 12 primary schools within the SAMPLE-PE randomized controlled trial were randomly allocated to either Linear Pedagogy (LP: n = 3) or Nonlinear Pedagogy (NP: n = 3) interventions, where schools received a 15-week PE intervention delivered by trained coaches, or to a control group (n = 6), where schools followed usual practice. ActiGraph GT9X accelerometers were used to assess PA metrics (moderate-to-vigorous PA, mean raw acceleration and lowest acceleration over the most active hour and half hour) over whole and segmented weeks at baseline, immediately post-intervention and 6 months follow-up. Intention to treat analysis employing multilevel modelling was used to assess intervention effects. Results: LP and NP interventions did not significantly affect children’s PA levels compared to the control group. Conclusion: PE interventions based on LP and NP alone might not be effective in improving habitual PA in children.

Measurement Reactivity of Accelerometer-Based Sedentary Behavior and Physical Activity in 2 Assessment Periods

BACKGROUND

The purposes of this study were to examine accelerometer measurement reactivity (AMR) in sedentary behavior (SB), physical activity (PA), and accelerometer wear time in 2 measurement periods and to quantify AMR as a human-related source of bias for the reproducibility of SB and PA estimates.

METHODS

In total, 136 participants (65% women, mean age = 54.6 y) received 7-day accelerometry at the baseline and after 12 months. Latent growth models were used to identify AMR. Intraclass correlations were calculated to examine the reproducibility using 2-level mixed-effects linear regression analyses.

RESULTS

Within each 7-day accelerometry assessment, the participants increased their time spent in SB (b = 2.4 min/d; b = 3.8 min/d) and reduced their time spent in light PA (b = -2.0 min/d; b = -3.2 min/d), but did not change moderate to vigorous PA. The participants reduced their wear time (b = -5.2 min/d) only at the baseline. The intraclass correlations ranged from .42 for accelerometer wear time to .74 for SB. The AMR was not identified as a source of bias in any regression model.

CONCLUSIONS

AMR may influence SB and PA estimates differentially. Although 7-day accelerometry seems to be a reproducible measure, our findings highlight accelerometer wear time as a crucial confounder in analyzing SB and PA data.

The effect of a video-supported assessment to increase the accuracy of self-reported physical activity

Self-reported physical activity differs from activity levels measured by device. We tested the effect of a video that visualizes the intensity levels of physical activity to increase the agreement between self-reported and accelerometer-based moderate-to-vigorous physical activity (MVPA) within a single-blinded, randomized study. Participants (N = 378, 40-75 years) wore an accelerometer for seven days. Prior to the collection of self-reported data by the IPAQ-SF, participants were randomly assigned (1:1) to a control group (CG) or a video group (VG). The outcome was the absolute difference between self-reported and accelerometer-based time spent in MVPA (Δ MVPA_{IPAQ-Accelerometry} ). To examine the agreement, we used Spearman correlation coefficients and Bland-Altman analysis. To test the video effect, we used Wilcoxon signed-rank test, Bayes factor, and simultaneous-quantile regression. In total, 302 participants fulfilled the accelerometer wear time criteria (≥10 hours/day; ≥6 days) and completed self-reports within three days after the wearing period. The median of Δ MVPA_{IPAQ-Accelerometry} was -9.0 min/day (IQR: -32.0 to 66.6) for CG and -11.5 min/day (IQR: -29.9 to 14.3) for VG. Wilcoxon signed-rank test revealed no differences in Δ MVPA_{IPAQ-Accelerometry} between study groups whereas Bayes factor indicated insensitivity of the data. Simultaneous-quantile regression revealed no relationship between video presentation and Δ MVPA_{IPAQ-Accelerometry} in the 25th percentile. In the 50th (b = -12.4 [95% CI = -23.2 to -1.5] and 75th percentile (b = -45.7 [95% CI = -70.5 to -20.9]), Δ MVPA_{IPAQ-Accelerometry} was negatively associated with video presentation. To conclude, video-supported assessment may increase the accuracy of self-reported MVPA among individuals who slightly underestimated and those who overestimated their MVPA.

Maternal body mass index, change in weight status from childhood to late adulthood and physical activity in older age

This study aimed to examine the longitudinal associations of maternal body mass index (BMI), weight status in childhood and late adulthood and device-measured total physical activity (TPA) in older age. The study involves 552 participants from Helsinki Birth Cohort Study who were born in Helsinki, Finland, in 1934-1944. TPA was measured with a multisensory body monitor at a mean age of 70 years and expressed in metabolic equivalent of task hours/day (METh/d). Childhood overweight (BMI > 85th percentile) was based on school health records at 6-7 years of age, and late adulthood overweight (BMI ≥ 25 kg/m² ) was based on clinical measurements at the mean age of 61 years. Childhood overweight was associated with lower TPA, particularly in older women (mean difference -3.2 METh/d, 95% confidence interval (CI) -4.6 - -1.9), and late adulthood overweight was associated with lower TPA both in older women (mean difference -6.2, 95% CI (-7.2 - -5.1) and in older men (mean difference -2.6 METh/d, 95% CI -3.7 - -1.5). TPA in older age was highest in participants who were normal weight both in childhood and adulthood and lowest in participants who were overweight in childhood and adulthood. In participants with childhood overweight, TPA was lower in participants who were overweight both in childhood and adulthood compared to those who were overweight only in childhood. There was a U-shaped distribution of TPA according to maternal BMI in older women (P = .002), but not in older men. In conclusion, reaching normal weight after childhood predicted higher physical activity levels in older age.

Both sedentary time and physical activity are associated with cardiometabolic health in overweight adults in a 1 month accelerometer measurement

The aim of this study was to examine the associations of cardiometabolic health markers with device-measured sedentary behavior (SB) duration and different intensities of physical activity (PA) among overweight working-aged adults with low self-reported PA levels. This cross-sectional analysis included 144 subjects (42 men) with mean age of 57 (SD 6.5) years and mean BMI of 31.7 (SD 4) kg/m². SB and standing time, breaks in sedentary time, light PA (LPA) and moderate-to-vigorous PA (MVPA) were measured for 4 consecutive weeks (mean 25 days, SD 4) with hip-worn accelerometers. Fasting plasma glucose, insulin, HbA_1c, triglycerides and total cholesterol, HDL and LDL were measured from venous blood samples. HOMA-IR index was calculated as a surrogate of insulin resistance. The associations were examined using linear models. LPA, MVPA, and daily steps associated with better insulin sensitivity and favorable plasma lipid profile, when adjusted for age, sex and BMI, whereas greater proportion of SB associated with insulin resistance and unfavorable lipid profile. As all PA intensities associated with better cardiometabolic health, the total daily duration of PA may be more relevant than intensity in maintaining metabolic health in overweight adults, if the current guidelines for PA are not met.

Trial Registration: ClinicalTrials.gov NCT03101228, registered 05/04/2017, https://clinicaltrials.gov/show/NCT03101228.

A comparison of total and domain-specific sedentary time in breast cancer survivors and age-matched healthy controls

Breast cancer survivors (BCS) engage in more sedentary behavior (SED) than those without cancer. However, the context in which SED is accrued is unknown. The purpose of this study is to examine differences in total and domain-specific SED of BCS and healthy controls. 20 BCS and 20 age-matched, healthy controls wore ActiGraph GT3X + accelerometers to measure SED and activity. Participants self-reported SED for transportation, occupational, screen time and leisure purposes. Multiple linear regressions were used to estimate differences in SED between BCS and controls. BCS spent significantly more time watching TV (152.4 vs. 60.3; p < 0.01) and less time in total SED (490.8 vs. 587.4; p = 0.046) and other leisure activities (57.6 vs. 106.9; p < 0.01) than healthy controls. BCS engage in more TV watching and less time in other leisure activities than controls, thus interventions should focus on reducing TV time. Understanding facilitators of TV viewing is needed to determine specific intervention targets.

Development and Evaluation of an Accelerometer-Based Protocol for Measuring Physical Activity Levels in Cancer Survivors: Development and Usability Study

Background

The collection of self-reported physical activity using validated questionnaires has known bias and measurement error.

Objective

Accelerometry, an objective measure of daily activity, increases the rigor and accuracy of physical activity measurements. Here, we describe the methodology and related protocols for accelerometry data collection and quality assurance using the Actigraph GT9X accelerometer data collection in a convenience sample of ovarian cancer survivors enrolled in GOG/NRG 0225, a 24-month randomized controlled trial of diet and physical activity intervention versus attention control.

Methods

From July 2015 to December 2019, accelerometers were mailed on 1337 separate occasions to 580 study participants to wear at 4 time points (baseline, 6, 12, and 24 months) for 7 consecutive days. Study staff contacted participants via telephone to confirm their availability to wear the accelerometers and reviewed instructions and procedures regarding the return of the accelerometers and assisted with any technology concerns.

Results

We evaluated factors associated with wear compliance, including activity tracking, use of a mobile app, and demographic characteristics with chi-square tests and logistic regression. Compliant data, defined as ≥4 consecutive days with ≥10 hours daily wear time, exceeded 90% at all study time points. Activity tracking, but no other characteristics, was significantly associated with compliant data at all time points (P<.001). This implementation of data collection through accelerometry provided highly compliant and usable activity data in women who recently completed treatment for ovarian cancer.

Conclusions

The high compliance and data quality associated with this protocol suggest that it could be disseminated to support researchers who seek to collect robust objective activity data in cancer survivors residing in a wide geographic area.

Opposing associations between sedentary time and decision-making competence in young adults revealed by functional connectivity in the dorsal attention network

How daily physical activity and sedentary time relate to human judgement and functional connectivity (FC) patterns that support them remains underexplored. We investigated the relationships between accelerometer-measured moderate-to-vigorous physical activity (MVPA) and sedentary time to decision-making competence (DMC) in young adults using a comprehensive Adult-Decision Making Competence battery. We applied graph theory measures of global and local efficiency to test the mediating effects of FC in cognitively salient brain networks (fronto-parietal; dorsal attention, DAN; ventral attention; and default mode), assessed from the resting-state fMRI. Sedentary time was related to lower susceptibility to a framing bias. However, once global and local efficiency of the DAN were considered we observed (1) higher susceptibility to framing with more sedentary time, mediated through lower local and global efficiency in the DAN, and (2) lower susceptibility to framing with more sedentary time. MVPA was not related to DMC or graph theory measures. These results suggest that remaining sedentary may reduce neurofunctional readiness for top-down control and decrease engagement of deliberate thought, required to ignore irrelevant aspects of a problem. The positive effect suggests that the relationship between sedentary time and DMC may be moderated by unmeasured factors such as the type of sedentary behavior.

Determining Minimum Wear Time for Mobile Sensor Technology

Part 1 in the DIA Study Endpoint Community Working Group on Mobile Sensor Technology (MST) series addresses considerations that may be useful when determining the minimum wear time associated with mobile sensor use to ensure reliable estimation of the clinical endpoint under consideration. What constitutes a minimum valid data set is a dilemma facing those using MSTs in clinical studies. If this alignment does not occur, the integrity of the data collected and conclusions drawn from these data may be in incorrect. While study participants should consent to engage with MSTs as defined in a protocol, participant behavior or technology lapses may result in capturing incomplete data. Drawing from the literature, we review what constitutes a minimum data set, the risks associated with missing data, alignment with the clinical endpoint(s) and goals of a study, as well as managing patient burden.

Semisupervised Physical Exercise and Lifestyle Counseling in Cardiometabolic Risk Management in Sedentary Adults: Controlled Randomized Trial (BELLUGAT)

BACKGROUND

The purpose of this study was to evaluate the feasibility and effectiveness of a high-intensity semisupervised exercise program alongside lifestyle counseling as an intervention for managing cardiometabolic risk in sedentary adults.

METHODS

A 40-week 3-arm randomized controlled clinical trial (16-wk intervention and 24-wk follow-up) was used. Seventy-five sedentary adults (34-55 y) with at least 1 cardiometabolic risk factor were randomized into one of the following arms: (1) aerobic interval training (AIT) plus lifestyle counseling (n = 25), (2) low- to moderate-intensity continuous training plus lifestyle counseling (traditional continuous training, TCT) (n = 27), or (3) lifestyle counseling alone (COU) (n = 23). Metabolic syndrome severity scores, accelerometer-based physical activity, and self-reported dietary habits were assessed at baseline, after the intervention, and at follow-up.

RESULTS

AIT was well accepted with high enjoyment scores. All groups showed similar improvements in metabolic syndrome severity scores (standardized effect size = 0.46) and dietary habits (standardized effect size = 0.30). Moderate to vigorous physical activity increased in all study groups, with the number of responders higher in AIT and TCT groups (50%) than in COU group (21%). Both AIT and TCT had a greater impact on sedentary behavior than COU (63.5% vs 30.4% responders).

CONCLUSIONS

AIT appears to be a feasible and effective strategy in sedentary individuals with cardiometabolic risk factors. AIT could be included in intervention programs tackling unhealthy lifestyles.

Total energy expenditure in patients with colorectal cancer: associations with body composition, physical activity, and energy recommendations

BACKGROUND

Total energy expenditure (TEE) data in patients with early-stage cancer are scarce, precluding an understanding of energy requirements.

OBJECTIVE

The objective was to cross-sectionally characterize TEE in patients with colorectal cancer (CRC) and to compare measured TEE with energy recommendations. It was hypothesized that TEE would differ according to body mass, body composition, and physical activity level (PAL) and current energy recommendations would have poor individual-level accuracy.

METHODS

Patients with newly diagnosed CRC had resting energy expenditure (REE) measured by indirect calorimetry and TEE by doubly labeled water. Hypermetabolism was defined as REE > 110% of that predicted from the Mifflin St.-Jeor equation. Body composition was assessed via DXA. Physical activity was determined as the ratio of TEE to REE (TEE:REE) (PAL) and residual activity energy expenditure (RAEE). TEE was compared with energy recommendations of 25-30 kcal/d and Dietary Reference Intakes (DRIs) using Bland-Altman analyses. Patients were stratified according to median BMI, PAL, and sex-specific ratio of fat mass (FM) to fat-free mass (FFM).

RESULTS

Twenty-one patients (M:F 14:7; mean ± SD BMI: 28.3 ± 4.9 kg/m2, age: 57 ± 12 y) were included. Most (n = 20) had stage II-III disease; 1 had stage IV. Approximately half (n = 11) were hypermetabolic; TEE was not different in those with hypermetabolism and REE as a percentage of predicted was not correlated with TEE. Mean ± SD TEE was 2473 ± 499 kcal/d (range: 1562-3622 kcal/d), or 29.7 ± 6.3 kcal/kg body weight (range: 20.4-48.5 kcal/kg body weight). Mean ± SD PAL was 1.43 ± 0.27. The energy recommendation of 25 kcal/kg underestimated TEE (-12.6% ± 16.5%, P = 0.002); all energy recommendations had wide limits of agreement (the smallest was DRI with measured PAL: -21.2% to 29.3%). Patients with higher BMI and FM:FFM had higher bias using kilocalories per kilogram recommendations; bias from several recommendations was frequently lower (i.e. underestimation) in patients with higher PAL and RAEE.

CONCLUSIONS

TEE variability was not reflected in energy recommendations and error was related to body weight, body composition, and physical activity. This trial was registered at clinicaltrials.gov as NCT03131921.

Neighborhood Recreation Facilities and Facility Membership Are Jointly Associated with Objectively Measured Physical Activity

Efforts to increase physical activity have traditionally included either individual-level interventions (e.g., educational campaigns) or neighborhood-level interventions (e.g., additional recreational facilities). Little work has addressed the interaction between spatial proximity and individual characteristics related to facility use. We aimed to better understand the synergistic impact of both physical activity environments and recreational facility membership on objectively measured physical activity. Using the New York City Physical Activity and Transit (PAT) survey (n = 644), we evaluated associations between counts of commercial physical activity facilities within 1 km of participants' home addresses with both facility membership and accelerometry-measured physical activity. Individuals living near more facilities were more likely to report membership (adjusted odds ratio for top versus bottom quartile of facility count: 3.77 (95% CI 1.54-9.20). Additionally, while amount of facilities within a neighborhood was associated with more physical activity, this association was stronger for individuals reporting gym membership. Interventions aiming to increase physical activity should consider both neighborhood amenities and potential barriers, including the financial and social barriers of membership. Evaluation of neighborhood opportunities must expand beyond physical presence to consider multiple dimensions of accessibility.

Training-induced changes in daily energy expenditure: Methodological evaluation using wrist-worn accelerometer, heart rate monitor, and doubly labeled water technique

INTRODUCTION

Wrist-mounted motion sensors can quantify the volume and intensity of physical activities, but little is known about their long-term validity. Our aim was to validate a wrist motion sensor in estimating daily energy expenditure, including any change induced by long-term participation in endurance and strength training. Supplemental heart rate monitoring during weekly exercise was also investigated.

METHODS

A 13-day doubly labeled water (DLW) measurement of total energy expenditure (TEE) was performed twice in healthy male subjects: during two last weeks of a 12-week Control period (n = 15) and during two last weeks of a 12-week combined strength and aerobic Training period (n = 13). Resting energy expenditure was estimated using two equations: one with body weight and age, and another one with fat-free mass. TEE and activity induced energy expenditure (AEE) were determined from motion sensor alone, and from motions sensor combined with heart rate monitor, the latter being worn during exercise only.

RESULTS

When body weight and age were used in the calculation of resting energy expenditure, the motion sensor data alone explained 78% and 62% of the variation in TEE assessed by DLW at the end of Control and Training periods, respectively, with a bias of +1.75 (p <.001) and +1.19 MJ/day (p = .002). When exercise heart rate data was added to the model, the combined wearable device approach explained 85% and 70% of the variation in TEE assessed by DLW with a bias of +1.89 and +1.75 MJ/day (p <.001 for both). While significant increases in TEE and AEE were detected by all methods as a result of participation in regular training, motion sensor approach underestimated the change measured by DLW: +1.13±0.66 by DLW, +0.59±0.69 (p = .004) by motion sensor, and +0.98±0.70 MJ/day by combination of motion sensor and heart rate. Use of fat-free mass in the estimation of resting energy expenditure removed the biases between the wearable device estimations and the golden standard reference method of TEE and demonstrated a training-induced increase in resting energy expenditure by +0.18±0.13 MJ/day (p <.001).

CONCLUSIONS

Wrist motion sensor combined with a heart rate monitor during exercise sessions, showed high agreement with the golden standard measurement of daily TEE and its change induced by participation in a long-term training protocol. The positive findings concerning the validity, especially the ability to follow-up the change associated with a lifestyle modification, can be considered significant because they partially determine the feasibility of wearable devices as quantifiers of health-related behavior.

Comparison of Two Models of Family-Based Treatment for Childhood Obesity: A Pilot Study

BACKGROUND

Family-based weight loss treatment (FBT) for childhood obesity, the current "gold standard," is typically provided in weekly groups for 6 months. Although this program is considered effective, it poses limitations to treatment engagement, due to time commitment and lack of widespread availability. A guided self-help version of FBT (gshFBT; eleven 20-minute sessions and one 1-hour over 5 months) was developed to circumvent such limitations. The current study examined the comparative efficacy of a 5-month FBT and gshFBT program.

METHODS

Participants included 50 parent-child dyads enrolled in FBT between 2011 and 2013 and 50 parent-child dyads enrolled in gshFBT between 2009 and 2010. Data were collected at baseline, posttreatment, and 6-month follow-up. Noninferiority analyses were conducted to assess comparative efficacy of changes in parent and child weight status, child nutrition, child physical activity, and drop-out.

RESULTS

Results indicated that gshFBT was noninferior to FBT in changes in child BMI z-score, overweight parent BMI, child nutritional intake, child vigorous physical activity, and drop-out. Results did not support noninferiority for changes in moderate to vigorous physical activity.

CONCLUSIONS

gshFBT is less intensive, more flexible, and may be similarly effective to FBT and could reach a greater proportion of the pediatric overweight population. Further research, including a randomized clinical trial, is needed to confirm these results.

Sickness absence in pregnancy and sedentary behavior: a population-based cohort study from Norway

Background

Sickness absence in pregnancy accounts for a large part of sickness-related absenteeism among women. Exercise in pregnancy is associated with a lower level of sickness absence, however little is known about how sedentary behaviour is related to sickness absence in pregnancy. In the current study, we hypothesize a positive association between sedentary hours/day and the risk of long-term sickness absence.

Methods

Population-based cohort study of pregnant women attending three Child Health Clinics in Groruddalen, Oslo, 823 Women (74% of those eligible) were included between 2008 and 2010. Questionnaire data were collected at gestational weeks 10–20 (visit 1) and 28 (visit 2). Sedentary time and physical activity were objectively recorded at visit 1 with the multi-sensor SenseWear™ Pro3 Armband (SWA). Long-term sickness absence was self-reported at visit 2. We explored the association between sedentary time and long-term sickness absence in pregnancy using multiple logistic regression analysis.

Results

The odds of long-term sickness absence was significantly increased per one-hour increase in daily sedentary time (odds ratio 1.45 [95% confidence interval 1.13–1.84]), providing support for our hypothesis that sedentary time is positively associated with long-term sickness absence.

Conclusions

Pregnant women with a sedentary lifestyle have a higher risk of long-term sickness absence from work. Reducing sedentary time in pregnancy may improve health, and may, in turn reduce sickness absence in pregnancy.

How Well iPhones Measure Steps in Free-Living Conditions: Cross-Sectional Validation Study

Background

Smartphones have great potential for monitoring physical activity. Although a previous laboratory-based study reported that smartphone apps were accurate for tracking step counts, little evidence on their accuracy in free-living conditions currently exists.

Objective

We aimed to investigate the accuracy of step counts measured using iPhone in the real world.

Methods

We recruited a convenience sample of 54 adults (mean age 31 [SD 10] years) who owned an iPhone and analyzed data collected in 2016 and 2017. Step count was simultaneously measured using a validated pedometer (Kenz Lifecorder) and the iPhone. Participants were asked to carry and use their own iPhones as they typically would while wearing a pedometer on the waist for 7 consecutive days during waking hours. To assess the agreement between the two measurements, we calculated Spearman correlation coefficients and prepared a Bland-Altman plot.

Results

The mean step count measured using the iPhone was 9253 (3787) steps per day, significantly lower by 12% (1277/10,530) than that measured using the pedometer, 10,530 (3490) steps per day (P<.001). The Spearman correlation coefficient between devices was 0.78 (P<.001). The largest underestimation of steps by the iPhone was observed among those who reported to have seldom carried their iPhones (seldom carry: mean −3036, SD 2990, steps/day; sometimes carry: mean −1424, SD 2619, steps/day; and almost always carry: mean −929, SD 1443, steps/day; P for linear trend=.08).

Conclusions

Smartphones may be of practical use to individuals, clinicians, and researchers for monitoring physical activity. However, their data on step counts should be interpreted cautiously because of the possibility of underestimation due to noncarrying time.

Moderate increases in daily step count are associated with reduced IL6 and CRP in women with PCOS

Aims Physical activity has been proposed to be an effective non-pharmacological method of reducing systemic inflammation and therefore may prove particularly efficacious for women with polycystic ovary syndrome (PCOS) who have been shown to have high levels of inflammation and an increased risk of type 2 diabetes (T2DM) and cardiovascular disease (CVD). Therefore, the aim of the present study was to assess whether modest changes in daily step count could significantly reduce levels of inflammatory markers in women with PCOS. Subjects and Methods Sixty-five women with PCOS were assessed at baseline and again at 6 months. All had been provided with an accelerometer and encouraged to increase activity levels. Multivariate linear regression analyses (adjusted for age, ethnicity, baseline step count, change in BMI and change in accelerometer wear-time) were used to assess changes in daily step count against clinical and research biomarkers of inflammation, CVD and T2DM. Results Mean step count/day at baseline was 6337 (±270). An increase in step count (by 1000 steps) was associated with a 13% reduction in IL6 (β: -0.81 ng/L; 95% CI, -1.37, -0.25, P = 0.005) and a 13% reduction in CRP (β: -0.68 mg/L; 95% CI, -1.30, -0.06, P = 0.033). Additionally, there was a modest decrease in BMI (β: 0.20 kg/m2; 95% CI, -0.38, -0.01, P = 0.038). Clinical markers of T2DM and CVD were not affected by increased step count. Conclusions Modest increases in step count/day can reduce levels of inflammatory markers in women with PCOS, which may reduce the future risk of T2DM and CVD.

Dietary Intake and Physical Activity Assessment: Current Tools, Techniques, and Technologies for Use in Adult Populations

Accurate assessment of dietary intake and physical activity is a vital component for quality research in public health, nutrition, and exercise science. However, accurate and consistent methodology for the assessment of these components remains a major challenge. Classic methods use self-report to capture dietary intake and physical activity in healthy adult populations. However, these tools, such as questionnaires or food and activity records and recalls, have been shown to underestimate energy intake and expenditure as compared with direct measures like doubly labeled water. This paper summarizes recent technological advancements, such as remote sensing devices, digital photography, and multisensor devices, which have the potential to improve the assessment of dietary intake and physical activity in free-living adults. This review will provide researchers with emerging evidence in support of these technologies, as well as a quick reference for selecting the "right-sized" assessment method based on study design, target population, outcome variables of interest, and economic and time considerations.

THEME INFORMATION

This article is part of a theme issue entitled Innovative Tools for Assessing Diet and Physical Activity for Health Promotion, which is sponsored by the North American branch of the International Life Sciences Institute.

Physical activity in pregnancy and postpartum depressive symptoms in a multiethnic cohort

INTRODUCTION

There is strong evidence that postpartum depression is associated with adverse health effects in the mother and infant. Few studies have explored associations between physical activity in pregnancy and postpartum depression. We aimed to investigate whether physical activity during pregnancy was inversely associated with postpartum depressive symptoms, PPDS in a multiethnic sample.

METHOD

Population-based, prospective cohort of 643 pregnant women (58% ethnic minorities) attending primary antenatal care from early pregnancy to postpartum in Oslo between 2008 and 2010. Data on demographics and health outcomes were collected during standardized interviews. PPDS was defined by a sum score ≥10 from the Edinburgh Postnatal Depression Scale (EPDS), 3 months after birth. Physical activity was recorded with Sense Wear™ Pro3 Armband (SWA) in gestational week 28 and defined as moderate-to-vigorous intensity physical activity (MVPA) accumulated in bouts ≥10 min.

RESULTS

Women who accumulated ≥150 MVPA minutes/week had significantly lower risk (OR = 0.2, 95% CI: 0.06-0.90), for PPDS compared to those who did not accumulate any minutes/week of MVPA, adjusted for ethnic minority background, depressive symptoms in the index pregnancy and self-reported pelvic girdle syndrome. The results for MVPA persisted in the sub-sample of ethnic minority women.

LIMITATIONS

Numbers of cases with PPDS were limited. The SWA does not measure water activities. Due to missing data for SWA we used multiple imputations.

CONCLUSION

Women meeting the physical activity recommendation (>150 MVPA min/week) during pregnancy have a lower risk of PPDS compared to women who are not active during pregnancy.

Children's Compliance With Wrist-Worn Accelerometry Within a Cluster-Randomized Controlled Trial: Findings From the Healthy Lifestyles Programme

PURPOSE

The purpose of this study was to assess children's compliance with wrist-worn accelerometry during a randomized controlled trial and to examine whether compliance differed by allocated condition or gender.

METHODS

A total of 886 children within the Healthy Lifestyles Programme trial were randomly allocated to wear a GENEActiv accelerometer at baseline and 18-month follow-up. Compliance with minimum wear-time criteria (≥10 h for 3 weekdays and 1 weekend day) was obtained for both time points. Chi-square tests were used to determine associations between compliance, group allocation, and gender.

RESULTS

At baseline, 851 children had usable data, 830 (97.5%) met the minimum wear-time criteria, and 631 (74.1%) had data for 7 days at 24 hours per day. At follow-up, 789 children had usable data, 745 (94.4%) met the minimum wear-time criteria, and 528 (67%) had complete data. Compliance did not differ by gender (baseline: χ² = 1.66, P = .2; follow-up: χ² = 0.76, P = .4) or by group at follow-up (χ² = 2.35, P = .13).

CONCLUSION

The use of wrist-worn accelerometers and robust trial procedures resulted in high compliance at 2 time points regardless of group allocation, demonstrating the feasibility of using precise physical activity monitors to measure intervention effectiveness.

Domain-Specific Adult Sedentary Behaviour Questionnaire (ASBQ) and the GPAQ Single-Item Question: A Reliability and Validity Study in an Asian Population

This study examined the validity and reliability of a domain-specific Adult Sedentary Behaviour Questionnaire (ASBQ) and the Global Physical Activity Questionnaire (GPAQ) single-item sitting question using self- and interviewer-administered modes of administration against the triaxial ActiGraph wGT3X-BT accelerometer. The ASBQ and the GPAQ were administered twice, seven days apart. Participants were asked to put on the waist-worn accelerometer for seven days. Convergent validity was assessed using Spearman’s rho, mean absolute error (MAE), and Bland-Altman analysis (n = 78). Reliability was assessed using the Spearman’s rho and intraclass correlation coefficient (ICC) (n = 84). Participants were adults aged 20–65 years and identifying as Chinese, Malay, or Indian. Only the self-administered GPAQ was significantly correlated with accelerometry-based measures (rho: 0.46), but not the interviewer-administered version (rho: 0.12). MAE for GPAQ was 207.5–218.3 min/day in relation to the accelerometer and for ASBQ was 154.7–174.6 min/day. Bland-Altman plots demonstrated large limits of agreement between questionnaire and accelerometry-based measures. While the self-administered GPAQ demonstrated a moderate correlation with accelerometry, the mean bias and the limits of agreement were large. The GPAQ (rho: 0.68–0.79; ICC: 0.68–0.78) and the ASBQ (rho: 0.53–0.64; ICC: 0.66–0.74) showed moderate-to-good reliability for total sedentary time using either self- or interviewer-administration. Future research should incorporate accelerometers to generate useful sedentary behaviour measures.

A comparison of 10 accelerometer non-wear time criteria and logbooks in children

BACKGROUND

There are many unresolved issues regarding data reduction algorithms for accelerometry. The choice of criterion for removal of non-wear time might have a profound influence on physical activity (PA) and sedentary time (SED) estimates. The aim of the present study was to compare 10 different non-wear criteria and a log of non-wear periods in 11-year-old children.

METHODS

Children from the Active Smarter Kids study performed 7-days of hip-worn accelerometer monitoring (Actigraph GT3X+) and logged the number of non-wear periods each day, along with the approximate duration and reason for non-wear. Accelerometers were analyzed using 10 different non-wear criteria: ≥ 10, 20, 30, 45, 60, and 90 min of consecutive zero counts without allowance for interruptions, and ≥60 and 90 min with allowance for 1 and 2 min of interruptions.

RESULTS

891 children provided 5203 measurement days, and reported 1232 non-wear periods ranging from 0 to 3 periods per day: on most days children reported no non-wear periods (77.1% of days). The maximum number of non-wear periods per day was 2 for the 90-min criterion, 3 to 5 for most criteria, 7 for the 20-min criterion, and 20 for the 10-min criterion. The non-wear criteria influenced overall PA (mean values across all criteria: 591 to 649 cpm; 10% difference) and SED time (461 to 539 min/day; 17% difference) estimates, especially for the most prolonged SED bouts. Estimates were similar for time spent in intensity-specific (light, moderate, vigorous, and moderate-to-vigorous) PA, but varied 6-9% among the non-wear criteria for proportions of time spent in intensity-specific PA (% of total wear time).

CONCLUSIONS

Population level estimates of PA and SED differed between different accelerometer non-wear criteria, meaning that non-wear time algorithms should be standardized across studies to reduce confusion and improve comparability of children's PA level. Based on the numbers and reasons for non-wear periods, we suggest a 45 or 60-min consecutive zero count-criterion not allowing any interruptions to be applied in future pediatric studies, at least for children older than 10 years.

TRIAL REGISTRATION

The study is registered in Clinicaltrials.gov with identification number NCT02132494 . Registered 7 April 2014.

Neighborhood-based PA and its environmental correlates: a GIS- and GPS based cross-sectional study in the Netherlands

Background

To improve our understanding of the neighborhood environment – physical activity (PA) relationship, it is of importance to assess associations between neighborhood environmental characteristics and neighborhood-based PA.

Methods

Participants’ (N = 308; 45–65 years) light PA (LPA) and moderate-vigorous PA (MVPA) within a 400, 800, and 1600 m buffer around adults’ homes was measured using accelerometers and GPS-devices. Land use data in ArcGIS provided neighborhood characteristics for the same buffers. Multilevel linear regression models, adjusted for socio-demographic variables and attitude towards PA, were used to assess associations of objective neighborhood characteristics with neighborhood-based LPA and MVPA.

Results

LPA was positively associated with the proportions of roads (within a 400 m buffer), and negatively associated with the proportions of recreational areas (within an 800 m buffer), and the proportion of green space (within the 800 m and 1600 m buffers). Multiple characteristics of 400 m buffers were positively associated with MVPA, i.e. proportions of green space, blue space, residences, shops and foodservice industry, sports terrain, and public social-cultural facilities. Also, characteristics of larger buffers were positively associated with MVPA, i.e. the proportions of shops and foodservice industry, sports terrain, and blue space (within an 800 m buffer), and the proportion of public social-cultural facilities (within the 800 m and 1600 m buffers).

Conclusions

Objective neighborhood characteristics of smaller as well as larger sized buffers were associated with neighborhood-based LPA and MVPA. Green and blue spaces seem to be of particular importance for PA in the smallest buffer, i.e. in the direct surrounding of adults’ homes.

Measuring Children's Physical Activity: Compliance Using Skin-Taped Accelerometers

INTRODUCTION

Accelerometer-based physical activity monitoring has become the method of choice in many large-scale physical activity (PA) studies. However, there is an ongoing debate regarding the placement of the device, the determination of device wear time, and how to solve a lack of participant compliance. The aim of this study was to assess the compliance of Axivity AX3 accelerometers taped directly to the skin of 9- to 13-yr-old children.

METHODS

Children in 46 school classes (53.4% girls, age 11.0 ± 1.0 yr, BMI 17.7 ± 2.8 kg·m) across Denmark wore two Axivity AX3 accelerometers, one taped on the thigh (n = 903) and one on the lower back (n = 856), for up to 10 consecutive days. Participants were instructed not to reattach an accelerometer should it fall off. Simple and multiple linear regressions were used to determine associations between accelerometer wear time and age, sex, BMI percentiles, and PA level.

RESULTS

More than 65% had >7 d of uninterrupted, 24-h wear time for the thigh location and 59.5% for the lower back location. From multiple linear regressions, PA levels showed the strongest association with lower wear time (thigh: β = -0.231, R = 0.066; lower back: β = -0.454, R = 0.126). In addition, being a boy, being older (only for lower back), and having higher BMI percentile were associated with lower wear time.

CONCLUSION

Using skin-taped Axivity accelerometers, we obtained 7 d of uninterrupted accelerometer data with 24-h wear time per day with a compliance rate of more than 65%. Thigh placement resulted in higher compliance than lower back placement. Achieving days with 24-h wear time reduces the need for arbitrary decisions regarding wear time validation and most likely improves the validity of daily life PA measurements.

Pitfalls in accelerometer-based measurement of physical activity: The presence of reactivity in an adult population

When a behavior is monitored, it is likely to change, even if no change may be intended. This phenomenon is known as measurement reactivity. We investigated systematic changes in accelerometer-based measures over the days of monitoring as an indicator of measurement reactivity in an adult population. One hundred seventy-one participants from the general population (65% women; mean age = 55 years, range: 42-65 years) wore accelerometers for 7 consecutive days to measure sedentary behavior and physical activity (PA). Latent growth models were used (a) to investigate changes in accelerometer wear time over the measurement days and (b) to identify measurement reactivity indicated by systematic changes in sedentary time (ST), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). Over the measurement days, participants reduced accelerometer wear time by trend (rate of change [b] = -4.7 min/d, P = .051, Cohen's d = .38), increased ST (b = 2.4 min/d, P = .018, d = .39), and reduced LPA (b = -2.4 min/d, P = .015, d = .38). Participants did not significantly reduce MVPA (P = .537). Our data indicated that accelerometry might generate reactivity. Small effects on ST and LPA were found. Thus, the validity of accelerometer-based data on ST and LPA may be compromised. Systematic changes observed in accelerometer wear time may further bias accelerometer-based measures. MVPA seems to be less altered due to the presence of an accelerometer.

The Impact of Low Accelerometer Wear Time on the Estimates and Application of Sedentary Behavior and Physical Activity Data in Adults

BACKGROUND

This investigation sought to determine how accelerometer wear (1) biased estimates of sedentary behavior (SB) and physical activity (PA), (2) affected misclassifications for meeting the Physical Activity Guidelines for Americans, and (3) impacted the results of regression models examining the association between moderate to vigorous physical activity (MVPA) and a clinically relevant health outcome.

METHODS

A total of 100 participants [age: 20.6 (7.9) y] wore an ActiGraph GT3X+ accelerometer for 15.9 (1.6) hours per day (reference dataset) on the hip. The BOD POD was used to determine body fat percentage. A data removal technique was applied to the reference dataset to create individual datasets with wear time ranging from 15 to 10 hours per day for SB and each intensity of PA.

RESULTS

Underestimations of SB and each intensity of PA increased as accelerometer wear time decreased by up to 167.2 minutes per day. These underestimations resulted in Physical Activity Guidelines for Americans misclassification rates of up to 42.9%. The regression models for the association between MVPA and body fat percentage demonstrated changes in the estimates for each wear-time adherence level when compared to the model using the reference MVPA data.

CONCLUSIONS

Increasing accelerometer wear improves daily estimates of SB and PA, thereby also improving the precision of statistical inferences that are made from accelerometer data.

Association between Objectively Measured Physical Activity and Mortality in NHANES

PURPOSE

We examined total activity, light activity, and moderate-to-vigorous physical activity (MVPA) as predictors of mortality in a nationally representative sample of older adults. Then we explored the theoretical consequences of replacing sedentary time with the same duration of light activity or MVPA.

METHODS

Using accelerometer-measured activity, the associations between total activity, light activity (100-2019 counts per minute), and MVPA (>2019 counts per minute) counts and mortality were examined in adults age 50 to 79 yr in the National Health and Nutrition Examination Survey, 2003-2006 (n = 3029), with mortality follow-up through December 2011. Cox proportional hazard models were fitted to estimate mortality risks. An isotemporal substitution model was used to examine the theoretical consequences of replacing sedentary time with light activity or MVPA on mortality.

RESULTS

After adjusting for potential confounders, including age, sex, race/ethnicity, education, BMI, and the presence of comorbid conditions, those in the highest tertile of total activity counts had one fifth the risk of death of those in the lowest tertile (hazard ratio [HR] = 0.21, 95% confidence interval [CI] = 0.12-0.38), and those in the middle tertile had one third the risk of death (HR = 0.36, 95% CI = 0.30-0.44). In addition, replacing 30 min of sedentary time with light activity was associated with significant reduction in mortality risk (after 5 yr of follow-up: HR = 0.80, 95% CI = 0.75-0.85). Replacing 30 min of sedentary time with MVPA was also associated with reduction in mortality risk (HR = 0.49, 95% CI = 0.25-0.97).

CONCLUSIONS

Greater total activity is associated with lower all-cause mortality risk. Replacing sedentary time with light activity or MVPA may reduce mortality risk for older adults.

Context matters! sources of variability in weekend physical activity among families: a repeated measures study

Background

Family involvement is an essential component of effective physical activity (PA) interventions in children. However, little is known about the PA levels and characteristics of PA among families. This study used a repeated measures design and multiple data sources to explore the variability and characteristics of weekend PA among families.

Methods

Families (including a ‘target’ child aged 9–11 years, their primary caregiver(s) and siblings aged 6–8 years) were recruited through primary schools in Liverpool, UK. Participants completed a paper-based PA diary and wore an ActiGraph GT9X accelerometer on their left wrist for up to 16 weekend days. ActiGraph.csv files were analysed using the R-package GGIR version 1.1–4. Mean minutes of moderate-to-vigorous PA (MVPA) for each weekend of measurement were calculated using linear mixed models, and variance components were estimated for participant (inter-individual), weekend of measurement, and residual error (intra-individual). Intraclass correlation coefficients (ICC) were calculated from the proportion of total variance accounted for by inter-individual sources, and used as a measure of reliability. Diary responses were summed to produce frequency counts. To offer contextual insight into weekend PA among family units, demographic, accelerometer, and diary data were combined to form two case studies representative of low and high active families.

Results

Twenty-five participants from 7 families participated, including 7 ‘target’ children (mean age 9.3 ± 1.1 years, 4 boys), 6 siblings (mean age 7.2 ± 0.7 years; 4 boys) and 12 adults (7 mothers and 5 fathers). There was a high degree of variability in target children’s (ICC = 0.55), siblings (ICC = 0.38), and mothers’ MVPA (ICC = 0.58), but not in fathers’ MVPA (ICC = 0.83). Children’s weekend PA was mostly unstructured in nature and undertaken with friends, whereas a greater proportion of parents’ weekend PA was undertaken alone in structured settings. The family case studies demonstrated that in the selected cases MVPA levels and variability across weekends were contingent on mode of PA participation.

Conclusions

These novel findings enhance understanding of the variability and characteristics of weekend PA among family units. The study demonstrates the utility of PA diaries in conjunction with accelerometers to provide understanding of the mode and contexts of out-of-school and family-based PA.

Reproducibility of Accelerometer-Assessed Physical Activity and Sedentary Time

INTRODUCTION

Accelerometers are used increasingly in large epidemiologic studies, but, given logistic and cost constraints, most studies are restricted to a single, 7-day accelerometer monitoring period. It is unknown how well a 7-day accelerometer monitoring period estimates longer-term patterns of behavior, which is critical for interpreting, and potentially improving, disease risk estimates in etiologic studies.

METHODS

A subset of participants from the Women's Health Study (N=209; mean age, 70.6 [SD=5.7] years) completed at least two 7-day accelerometer administrations (ActiGraph GT3X+) within a period of 2-3 years. Monitor output was translated into total counts, steps, and time spent in sedentary, light-intensity, and moderate to vigorous-intensity activity (MVPA) and bouted-MVPA (i.e., 10-minute bouts). For each metric, intraclass correlations (ICCs) and 95% CIs were calculated using linear-mixed models and adjusted for wear time, age, BMI, and season. The data were collected in 2011-2015 and analyzed in 2015-2016.

RESULTS

The ICCs ranged from 0.67 (95% CI=0.60, 0.73) for bouted-MVPA to 0.82 (95% CI=0.77, 0.85) for total daily counts and were similar across age, BMI, and for less and more active women. For all metrics, classification accuracy within 1 quartile was >90%.

CONCLUSIONS

These data provide reassurance that a 7-day accelerometer-assessment protocol provides a reproducible (and practical) measure of physical activity and sedentary time. However, ICCs varied by metric; therefore, future prospective studies of chronic diseases might benefit from existing methods to adjust risk estimates for within-person variability in activity to get a better estimate of the true strength of association.