Waist-worn Accelerometer Research Articles

Establishing Accelerometer Cut-Points to Classify Walking Speed in People Post Stroke.

While accelerometers could be used to monitor important domains of walking in daily living (e.g., walking speed), the interpretation of accelerometer data often relies on validation studies performed with healthy participants. The aim of this study was to develop cut-points for waist- and ankle-worn accelerometers to differentiate non-ambulation from walking and different walking speeds in people post stroke. Forty-two post-stroke persons wore waist and ankle accelerometers (ActiGraph GT3x+, AG) while performing three non-ambulation activities (i.e., sitting, setting the table and washing dishes) and while walking in self-selected and brisk speeds. Receiver operating characteristic (ROC) curve analysis was used to define AG cut-points for non-ambulation and different walking speeds (0.41–0.8 m/s, 0.81–1.2 m/s and >1.2 m/s) by considering sensor placement, axis, filter setting and epoch length. Optimal data input and sensor placements for measuring walking were a vector magnitude at 15 s epochs for waist- and ankle-worn AG accelerometers, respectively. Across all speed categories, cut-point classification accuracy was good-to-excellent for the ankle-worn AG accelerometer and fair-to-excellent for the waist-worn AG accelerometer, except for between 0.81 and 1.2 m/s. These cut-points can be used for investigating the link between walking and health outcomes in people post stroke.

Affective judgments, environmental determinants, and physical activity in emerging and young adults

Objective Affective judgements represent a promising target for promoting physical activity among adults. This study examined whether relations between affective judgments and physical activity are robust after adjusting for social, built, and natural environmental determinants. Design Prospective cross-sectional study with 173 adults (70.1% female) aged 18–29 years who self-reported less than 90 minutes of moderate-to-vigorous physical activity. Main Outcome Measure Physical activity volume (total daily step count, total activity counts) and durations of intensity-specific physical activity (light-intensity activity and moderate-to-vigorous intensity) were assessed for a seven-day period via waist-worn ActiGraph wGT3X-BT accelerometer. Results Affective judgements were not statistically associated with measures of physical activity volume or intensity-specific physical activity after adjusting for environmental influences. Support for exercise from friends was positively associated with measures of physical activity volume and moderate-to-vigorous physical activity duration. More favorable perceptions of the built environment were positively associated with moderate-to-vigorous intensity physical activity and negatively associated with duration of light-intensity physical activity. Longer photoperiods were associated with more light-intensity physical activity. Conclusion Physical activity interventions for young and emerging adults reporting inactivity should target environmental determinants first and possibly wait until participants have a motivational stake in physical activity before targeting affective judgments.

Validation of a Modified Version of the German Sedentary Behavior Questionnaire.

Background: Physical inactivity and excessive sedentary behavior (SB) are growing public health issues that require surveillance, guidelines, and targeted interventions. In addition to a variety of sophisticated technical methods, questionnaires are still an attractive method for quick, easy, comprehensive, and cost-effective estimation of SB. The aim of this study was to validate a modified version of the widely used Sedentary Behavior Questionnaire (SBQ) compared to waist-worn accelerometers as an objective measurement. Contemporary explanations covering the use of smart devices have been added to the original instrument, and sitting while handwriting was explicated in more detail. Methods: Cross-sectional data from an adult sample (n = 64, 20–85 y, 25 m, 39 f) were used in this first validation study. Based on prior investigations of the SBQ, analyses were conducted in a gender-specific manner. Criterion validity was assessed using Spearman’s Rho coefficients. The Bland–Altman method was used to test the agreement between self-reported and accelerometer-measured SB time. Results: Using the modified SBQ (mSBQ), a significant gender difference in weekly sedentary time was found. Women estimated their sedentary time to be almost 50% higher than men (median 74.5 h vs. 51.0 h). No correlation was found between the questionnaire and accelerometer data for both subgroups (rho ≤ 0.281, p ≥ 0.174). Individual differences in daily SB estimation between both methods (in relation to accelerometry) were +3.82 h ± 4.36 h for women and +0.48 h ± 2.58 h for men (p < 0.001). Conclusion: The modifications to the SBQ did not improve the correlation between self-assessment of SB and objective determination. The reasons for the presented gender-specific overestimation of the participants’ own sedentary time, which contradicts the findings of other studies, remain unclear and need to be investigated further.

Earlier bedtimes and more sleep displace sedentary behavior but not moderate-to-vigorous physical activity in adolescents

ObjectivesCorrelational models suggest increased cardiometabolic risk when sleep replaces moderate-to-vigorous (but not sedentary or light) physical activity. This study tested which activity ranges are impacted by experimentally altering adolescents’ bedtime. MethodAdolescents completed a 3-week within-subjects crossover experiment with 5 nights of late bedtimes and 5 nights early bedtimes (6.5- and 9.5-hours sleep opportunity, respectively). Experimental condition order was randomized. Waketimes were held constant throughout to mimic school start times. Sleep and physical activity occurred in the natural environments, with lab appointments following each 5-day condition. Waist-worn accelerometers measured physical activity and sedentary behavior. Wrist-worn actigraphs confirmed sleep condition adherence. Wilcoxon tests and linear mixed effects models compared waking activity levels between conditions and across time. ResultsNinety healthy adolescents (14-17 years) completed the study. When in the early (vs. late) bedtime condition, adolescents fell asleep 1.96 hours earlier (SD = 1.08, d = 1.82, p < .0001) and slept 1.49 hours more (SD = 1.01, d = 1.74, p < .0001). They spent 1.68 and 0.32 fewer hours in sedentary behavior (SD = 1.67, d = 1.0, p < .0001) and light physical activity (SD = 0.87, d = 0.37, p = .0005), respectively. This pattern was reflected in increased proportion of waking hours spent in sedentary and light activity. Absolute and proportion of moderate-to-vigorous physical activity did not differ between conditions (d = 0.02, p = .89; d = 0.14, p = .05, respectively). ConclusionsInducing earlier bedtimes (allowing for healthy sleep opportunity) did not affect moderate-to-vigorous physical activity. Alternatively, later bedtimes (allowing for ≤ 6.5 hours of sleep opportunity, mimicking common adolescent school night sleep) increased sedentary behavior. Results are reassuring for the benefits of earlier bedtimes.

Physical Activity Patterns among Individuals with Prediabetes or Type 2 Diabetes across Two Years-A Longitudinal Latent Class Analysis.

Background: This study aimed to identify distinct profiles of physical activity (PA) patterns among individuals with prediabetes or type 2 diabetes participating in a two-year PA trial and to investigate predictors of the profiles. Methods: Data (n = 168, collected 2013–2020) from the cohort of a randomized trial aimed at increasing PA in individuals with prediabetes and type 2 diabetes were used. PA and sedentary behaviours were assessed by waist-worn ActiGraph GT1M accelerometers at baseline and at 6, 12, 18 and 24 months. Fifteen PA and sedentary variables were entered into a latent class mixed model for multivariate longitudinal outcomes. Multinominal regression analysis modelled profile membership based on baseline activity level, age, gender, BMI, disease status and group randomisation. Results: Two profiles of PA patterns were identified: “Increased activity” (n = 37, 22%) included participants increasing time in PA and decreasing sedentary time. “No change in activity” (n = 131, 78%) included participants with no or minor changes. “Increased activity” were younger (p = 0.003) and more active at baseline (p = 0.011), compared to “No change in activity”. No other predictor was associated with profile membership. Conclusions: A majority of participants maintained PA and sedentary patterns over two years despite being part of a PA intervention. Individuals improving PA patterns were younger and more active at baseline.

Association of cardiac autonomic modulation with different intensities of physical activity in a small Brazilian inner city: A gender analysis

ABSTRACT Physical activity has been linked to higher cardiac autonomic modulation. However, it is not clear in the literature which type of intensity of physical activity (sedentary, light, moderate, or vigorous) could be related to better cardiac autonomic modulation and whether this relationship is similar in men and women. The aim of this study was to analyze the relationship between cardiac autonomic modulation and the different intensities of physical activity in men and women. The sample included 100 men and 131 women. Cardiac autonomic modulation was obtained by heart rate variability (SDNN, RMSSD, LF un, HF un, SD1, and SD2). Time spent in different intensities (sedentary, light, moderate, and vigorous intensity physical activity) was measured using a waist-worn accelerometer for seven days. Linear regression was used to verify the relationship between physical activity and cardiac autonomic modulation, considering the adjustment for age, ethnicity, and socioeconomic level. Among men, a significant relationship of moderate intensity was observed with SDNN (β = 2.442; p = 0.021) and SD2 (β = 2.936, p = 0.028), and of vigorous intensity with SDNN (β = 12.826, p = 0.028), RMSSD (β = 16.370, p = 0.018), and SD1 (β = 12.344, p = 0.025) indices. Among women, light-intensity physical activity was significantly related with LFnu (β = .655, p = 0.005) and HFnu (β = -.590, p = 0.010). Moderate and vigorous physical activity was associated with better cardiac autonomic modulation in men. Light physical activity was associated with lower sympathetic modulation in women.

Measuring sedentary behavior using waist- and thigh-worn accelerometers and inclinometers - are the results comparable?

Background:Objective sensor-based quantification of sedentary behavior is an important tool for planning and evaluating interventions for excessive sedentary behavior in patients with musculoskeletal diseases. Although waist-worn accelerometers are the standard for physical activity (PA) assessment, only thigh-worn inclinometers can clearly distinguish sedentary behavior from any light PA or standing activity.Methods:In this study, 53 adults (ages 20–85 years) wore two ActiGraph wGT3X-BT monitors, each containing an inclinometer and accelerometer (set for acquisition of slow movements in all three planes), attached to the right waist and thigh for a period of about 4 days. Both monitors recorded total sedentary time and continuous sedentary 10-min bouts by synchronous accelerometry and inclinometry. Differences and correlations between methods and wearing positions were evaluated against participant age, body mass index (BMI), and number of steps taken. Thigh-worn inclinometry was used as reference.Results:Data from thigh-worn inclinometry and waist-worn accelerometry were highly correlated for total sedentary time [rho = 0.888; intraclass correlation coefficient (ICC) = 0.937] and time in sedentary bouts (rho = 0.818; ICC = 0.848). Nevertheless, accelerometry at the waist underestimated sedentary time by ≈17% (p < 0.001) and time in sedentary bouts by ≈54% (p < 0.001). A satisfactory concordance thus could be demonstrated only for total sedentary time, based on the Bland–Altmann method (≈96% of data within the limits of agreement). The differences between waist-worn accelerometry and thigh-worn inclinometry did not correlate with age but did correlate with BMI and PA for both sedentary behavior parameters (r ⩾ 0.240, p ⩽ 0.043).Conclusion:A waist-worn accelerometer can be used to determine total sedentary time under free-living conditions with sufficient accuracy if the correct settings are chosen. Further investigations are necessary to investigate why short sedentary bouts cannot be reliably assessed.Trial registration:DRKS00024060 (German Clinical Trials Register)

Change in Objectively Measured Activity Levels Resulting from the EMPOWER Study Lifestyle Intervention.

To examine changes in physical activity (PA) during a behavioral weight-loss intervention and determine baseline factors associated with PA goal achievement. Overweight/obese community-dwelling adults with valid PA accelerometer data (N=116; mean age 51.7 years; 89% female; 83% non-Hispanic White) were recruited into a single-arm prospective cohort study examining the effects of a 12-month intervention that included 24 in-person group sessions, weight-loss, calorie, fat gram, and PA goals, self-monitoring, and feedback. Minutes of moderate-to-vigorous (MV) PA and steps were measured using a waist-worn accelerometer (ActiGraph GT3x) at baseline, 6 months, and 12 months. Achievement of the 150 minute/week MVPA goal was examined using total minutes and bout minutes (i.e., counting only PA occurring in bouts ≥10 minutes in length). Change in PA was analyzed using non-parametric tests for multiple comparisons. Associations of factors with meeting the PA goal were modeled using binary logistic regression. At 6 months, there were increases from baseline in MVPA (median [p25, p75]: 5.3 [-0.9, 17.6] minutes/day) and steps (863 [-145, 2790] steps/day), both p<0.001. At 12 months, improvements were attenuated (MVPA: 2.4 [-2.0, 11.4] minutes/day, p=0.047; steps: 374[-570, 1804] p=0.14). At 6 months, 33.6% of individuals met the PA goal (using total or bout minutes). At 12 months, the percent meeting the goal using total MVPA [31%] differed from bout MVPA [22.4%]. Male gender (OR=4.14, p=0.027) and an autumn program start (versus winter; OR=3.39, p=0.011) were associated with greater odds of goal achievement at 6 months. The intervention increased PA goal achievement at 6 and 12 months with many making clinically meaningful improvements. Our results suggest female participants may require extra support toward improving PA levels.

Parental-perceived home and neighborhood environmental correlates of accelerometer-measured physical activity among school-going children in Uganda.

The benefits of physical activity (PA) on children's health and well-being are well established. However, many children do not meet the PA recommendations, increasing their risk of being overweight, obese, and non-communicable diseases. Environmental characteristics of homes and neighborhoods may constrain a child's ability to engage in PA, but evidence is needed to inform country-specific interventions in understudied low-income countries. This study assessed the associations between parental-perceived home and neighbourhood, built environment characteristics, and moderate-to-vigorous physical activity (MVPA) among children in Kampala city, Uganda. In this cross-sectional study, data were obtained from 256 children (55.5% girls) aged between 10 and 12 years and their parents. Children's MVPA was measured using waist-worn ActiGraph accelerometers. The environments were assessed using a valid self-reported parent survey. Linear regression models with standard errors (clusters) were used to analyze the relationship between environmental variables and children's MVPA. Sex-specific relationships were assessed using sex-stratified models. Play equipment at home (β = -2.37, p <0.001; unexpected direction), residential density (β = 2.70, p<0.05), and crime safety (β = -5.29, p <0.05; unexpected direction) were associated with children's MVPA. The sex-specific analyses revealed more inconsistent patterns of results with a higher perception of land use mix associated with less MVPA in girls (irrespective of school type attended), and higher perceptions of sidewalk infrastructure (β = -12.01, p <0.05) and walking and cycling infrastructure (β = -14.72, p <0.05) associated with less MVPA in girls attending public schools only. A better perception of crime safety was associated with less MVPA among boys and girls attending private schools (β = -3.80, p <0.05). Few environmental characteristics were related to children's MVPA in Uganda, and findings were largely inconsistent, especially among girls. Future studies are needed to understand the ecological determinants of health-related PA behaviors among children in Uganda.

The Acute Relationship between Affective States and Stress Biomarkers in Ethnic Minority Youths.

Background: Whether affective states acutely predict the hypothalamic–pituitary–adrenal (HPA) axis activities and whether energy balance-related behaviors moderate the affect–HPA axis relationship in obese youths are not well-understood. Methods: 87 mostly obese (94.3% obese) minority adolescents (mean: 16.3 ± 1.2 years old; 56.8% Latino and 43.2% African American) participated in a randomized crossover trial in an observation laboratory, where they received either high-sugar/low-fiber (HSLF) or low-sugar/high-fiber (LSHF) meals first and then crossed over in the next visit 2–4 weeks later. During each visit, they rated five affective states and provided a saliva sample every 30 min for the first 5 h and wore a waist-worn accelerometer. The association between the affect ratings and cortisol levels in the subsequent 30 min and the moderation effect of energy balance-related behavior were examined using multilevel models. Results: Within-person negative affect (β = 0.02, p = 0.0343) and feeling of panic (β = 0.007, p = 0.004) were acutely related to the subsequent cortisol level only during the HSLF condition. The time spent in moderate-to-vigorous physical activity did not moderate the acute relationship between affect and the subsequent cortisol level. Conclusions: Negative affect could be acutely related to heightened HPA axis activities in youths, but only when they were exposed to meals with high sugar and low fiber content. These results suggest that the meals’ sugar and fiber content may modulate HPA axis reactivity to negative affect in youths.

Assessment of Physical Activity Using Waist-Worn Accelerometers in Hospitalized Heart Failure Patients and Its Relationship with Kansas City Cardiomyopathy Questionnaire.

The health benefits of physical activity have been widely recognized, yet there is limited information on associations between accelerometer-related parameters and established patient-reported health status. This study investigated the association between the waist-worn accelerometer measurements, cardiopulmonary exercise testing (CPX), and results of the Kansas City Cardiomyopathy Questionnaire (KCCQ) in heart failure (HF) patients hospitalized for acute decompensation. A total of 31 patients were enrolled and wore a validated three-axis accelerometer for 2 weeks and completed the short version of the KCCQ after removing the device. Daily step counts, exercise time (metabolic equivalents × hours), and %sedentary time (sedentary time/device-equipped time) were measured. Among the measured parameters, the best correlation was observed between %sedentary time and the KCCQ overall and clinical summary scores (r = −0.65 and −0.65, each p < 0.001). All of the individual domains of the KCCQ (physical limitation, symptom frequency, and quality of life), with the exception of the social limitation domain, showed moderate correlations with %sedentary time. Finally, oxygen consumption assessed by CPX demonstrated only weak associations with the accelerometer-measured parameters. An accelerometer could complement the KCCQ results in accurately assessing the physical activity in HF patients immediately after hospitalization, albeit its correlation with CPX was at most moderate.

Exploring Feelings of Pleasure and Purpose Associated With Older People’s Activities Using Ecological Momentary Analysis: An Observational Study

Momentary feelings of pleasure and purpose can be sources of intrinsic motivation, but momentary purpose is rarely studied. Activities, contexts, and feelings of retired/semiretired adults (n = 67, aged 50-78 years) were captured using ecological momentary assessment. Participants provided 2,065 valid responses to six daily smartphone surveys for 7 days. Physical activity was measured by waist-worn ActiGraph accelerometer. Pleasure (measured by affective happiness) and purpose outcomes were regressed on activities, context, and potential confounding variables. Interactions between activities and contexts were explored. Participants were highly active: 98.5% met physical activity guidelines. Sedentary activities were negatively associated with sense of purpose, especially when indoors. However, social sedentary activities were positively associated with feelings of happiness. Active, social outdoor activities were positively associated with both outcomes. Less sedentary participants experienced greater happiness and purpose during all their activities. Context matters: active, social, and outdoor activities seem to be more appealing to older adults.

Sex Differences In Physical Activity And Sedentary Behaviors Between Traditional And Nature-based Pre-kindergarten Program Settings

Across all age groups, boys tend to engage in more physical activity (PA) than girls. Previous research has shown that the school setting may have a stronger influence on boys PA and sedentary behavior (SB) than girls, while it has also been suggested that as early as preschool, the school a child attends acts as a strong predictor of moderate- to vigorous-intensity PA (MVPA). PURPOSE: The purpose of this study was to compare sex differences in Pre-Kindergarten (Pre-K) children’s PA and SB between a nature-based or traditional classroom setting. METHODS: 18 boys and 7 girls from one Pre-K program enrolled in this study. Data was collected using waist-worn accelerometers for 4 days (2h45min/day) across one week in the winter. Participants spent two days in a traditional classroom setting, and two days in a nature-based setting. Accelerometer data was analyzed using Butte (2014) cutpoints. Mann-Whitney U Tests were used to detect significant differences (p < 0.05) in PA and SB between boys and girls across school settings. RESULTS: Compared to a traditional setting, boys and girls averaged significantly more MVPA in a nature-based setting (Boys: 6.3 ± 6.3 minutes, p < .001; Girls: 5.8 ± 5.0 minutes, p < .001). The change in MVPA between educational settings was not significantly different between boys and girls (p = .790). In a nature-based setting boys spent significantly more time in moderate-intensity PA (MPA) than girls (Diff: 2.9 ± 1.2% of Wear Time [WT]; p = .047), averaging 20- and 17-minutes of MPA per class period, respectively. There were no significant differences in the PA or SB levels of boys and girls in the traditional classroom setting. CONCLUSIONS: Early education is a period during which children begin forming the PA habits they will follow through K-12 schooling and into adulthood. Therefore, any intervention which can promote higher levels of PA at this age should be explored. Boys and girls experienced similar benefits to PA when attending school in a nature-based compared to a traditional setting, therefore this pilot study suggests that educating children in a nature-based setting may promote greater levels of PA in both boys and girls. Due to the pilot nature of this study however, further research examining the potential factors that may explain the sex differences found in a nature-based setting is needed.

Physical Activity Recognition Based on a Parallel Approach for an Ensemble of Machine Learning and Deep Learning Classifiers.

Human activity recognition (HAR) by wearable sensor devices embedded in the Internet of things (IOT) can play a significant role in remote health monitoring and emergency notification to provide healthcare of higher standards. The purpose of this study is to investigate a human activity recognition method of accrued decision accuracy and speed of execution to be applicable in healthcare. This method classifies wearable sensor acceleration time series data of human movement using an efficient classifier combination of feature engineering-based and feature learning-based data representation. Leave-one-subject-out cross-validation of the method with data acquired from 44 subjects wearing a single waist-worn accelerometer on a smart textile, and engaged in a variety of 10 activities, yielded an average recognition rate of 90%, performing significantly better than individual classifiers. The method easily accommodates functional and computational parallelization to bring execution time significantly down.

Comparison of Classroom-Based Sedentary Time and Physical Activity in Conventional Classrooms and Open Learning Spaces Among Elementary School Students.

European children and adolescents spend most of their daily life and especially their school hours being sedentary which may increase their risk for chronic non-communicable diseases later in life. After the curriculum reform of Finnish basic education in 2014, most of the new or renovated comprehensive schools in Finland incorporate open and flexible classroom designs. Their open learning spaces may provide students opportunities to reduce sedentary behavior during school hours. Thus, waist-worn accelerometers were used to assess classroom-based sedentary time (ST), the number of breaks from sedentary time (BST), and physical activity (PA) among cross-sectional samples of 3rd and 5th grade students during two separate academic years in a school that underwent a renovation from conventional classrooms to open learning spaces. The cohort of 5th grade students before renovation had a smaller proportion of ST from total classroom time (56.97 ± 12.24%, n = 42 vs. 67.68 ± 5.61%, n = 28, mean difference = 10.71%-points, 95%CI = −15.65 to−5.77, p < 0.001), a greater number of BST per 60 min of classroom time (7.41 ± 1.16 breaks/h vs. 9.19 ± 1.59 breaks/h, mean difference = −1.78 breaks/h, 95%CI = −2.486 to −1.079, p < 0.001) and a greater proportion of light intensity PA (28.66 ± 9.99% vs. 22.56 ± 4.59%, mean difference = 6.10%, 95%CI = 2.56 to 9.64, p = 0.001) than the 5th grade cohort assessed after renovation. The cohort of 3rd grade student had a greater proportion of moderate-to-vigorous intensity PA (MVPA) after the renovation compared to the cohort assessed before the renovation [Mean Rank (Before) = 27.22, Mean Rank (After) = 37.58, U =524.0, p = 0.033]. Despite the greater ST found in 5th graders, schools with open learning spaces may facilitate BST or MVPA as observed in the 5th and 3rd grade cohorts in open learning spaces compared to the cohorts in conventional classrooms, respectively. Future studies should seek to investigate and develop teacher practices to capitalize the potential of open classrooms to reduce ST, since classroom renovation alone may not be a sufficient intervention as of itself. Longitudinal studies utilizing randomized controlled trials are warranted.

Validity and Test-Retest Reliability of a Thai Stroke Physical Activity Questionnaire

Background and objectivesThis study evaluated the validity and reliability of the Stroke Physical Activity Questionnaire (SPAQ), a Thai self-report questionnaire for assessing physical activity (PA) in participants with chronic stroke. MethodsThe validity of the SPAQ was tested by correlating PA data from the SPAQ with data obtained from a waist worn accelerometer which participants wore for seven days. The participants completed the SPAQ twice, one week apart and test-retest reliability was calculated using intraclass correlation coefficient. ResultsForty-one participants, at least 3 months post-stroke (24 men and 17 women) were enrolled. The average age was 55.3 years (SD 11.9). Correlation coefficients of 0.58 and 0.57 were found between SPAQ and the accelerometer data for moderate PA and moderate to vigorous PA (MVPA), respectively. There was no significant correlation between light PA determined from SPAQ and accelerometer. The intraclass correlation coefficients were 0.56, 0.91 and 0.90 for light, moderate PA and MVPA, respectively. ConclusionsThe validity of the SPAQ for moderate and MVPA was acceptable and the test-retest reliability of the SPAQ was excellent. This suggests the SPAQ is a useful tool for assessing moderate PA and MVPA among chronic stroke participants. However, it cannot be used to quantify light PA.

Effect of Reducing Sedentary Behavior on Blood Pressure (RESET BP): Rationale, design, and methods

Sedentary behavior (SB) has recently been recognized as a strong risk factor for cardiovascular disease, with new guidelines encouraging adults to ‘sit less, move more.’ Yet, there are few randomized trials demonstrating that reducing SB improves cardiovascular health. The Effect of Reducing Sedentary Behavior on Blood Pressure (RESET BP) randomized clinical trial addresses this gap by testing the effect of a 3-month SB reduction intervention on resting systolic BP. Secondary outcomes include other BP measures, pulse wave velocity, plasma renin activity and aldosterone, and objectively-measured SB (via thigh-mounted activPAL) and physical activity (via waist-worn GT3X accelerometer). RESET BP has a targeted recruitment of 300 adults with desk jobs, along with elevated, non-medicated BP (systolic BP 120–159 mmHg or diastolic BP 80–99 mmHg) and physical inactivity (self-reported aerobic physical activity below recommended levels). The multi-component intervention promotes 2–4 fewer hours of SB per day by replacing sitting with standing and light-intensity movement breaks. Participants assigned to the intervention condition receive a sit-stand desk attachment, a wrist-worn activity prompter, behavioral counseling every two weeks (alternating in-person and phone), and twice-weekly automated text messages. Herein, we review the study rationale, describe and evaluate recruitment strategies based on enrollment to date, and detail the intervention and assessment protocols. We also document our mid-trial adaptations to participant recruitment, intervention deployment, and outcome assessments due to the intervening COVID-19 pandemic. Our research methods, experiences to date, and COVID-specific accommodations could inform other research studying BP and hypertension or targeting working populations, including those seeking remote methods.

Cross-Sectional and Longitudinal Associations between Non-School Time Physical Activity, Sedentary Time, and Adiposity among Boys and Girls: An Isotemporal Substitution Approach.

This study investigated the cross-sectional and longitudinal associations of the substitution of non-school time light physical activity (LPA), moderate-to-vigorous physical activity (MVPA), and sedentary time (ST) with adiposity in boys and girls. Boys (n = 65, baseline Mage= 9.93 ± 0.86 years) and girls (n = 77, baseline Mage = 10.17 ± 0.95 years) wore waist-worn accelerometers (ActiGraph GT3X) at baseline and at a 30-month follow-up, from which non-school time LPA, MVPA, ST, and total device wear were quantified. Body mass index (BMI) and waist-to-height-ratio (WHR) were measured at baseline and follow-up. Body fat percent (BF%) was obtained at follow-up only. Isotemporal substitution models assessed the cross-sectional and longitudinal associations of reallocating non-school time activity with BMI, WHR and BF%. In boys, replacing 30 min/day of LPA with MVPA was cross-sectionally (β = −8.26, p < 0.05) associated with a lower BF%. Replacing 30 min/day of ST with MVPA was cross-sectionally (β = −6.02, p < 0.05) associated with a lower BF% in boys. Longitudinally in boys, replacing 30 min of change in LPA with MVPA (β = −7.42, p < 0.10) and replacing 30 min of change in MVPA with ST (β = 5.78, p < 0.10) over 30 months was marginally associated with less BF%. Associations were null in girls (p > 0.05). These results may support targeting activity reallocation during non-school time for the purposes of adiposity improvement in boys. A multi-behavioral approach may be more appropriate for girls, as non-school time activity may not be driving adiposity status.

Momentary associations between stress and physical activity among children using ecological momentary assessment

Chronic and acute stress may have a detrimental effect on children's physical activity. Research on stress as a predictor of children's physical activity has mostly focused on stress between children, rather than how children's within-day variation in stress may predict physical activity. The current study assessed the within- and between-effects of stress on subsequent physical activity in three different time windows using ecological momentary assessment (EMA) and accelerometry. Children (N = 190; MBaseline Age = 10.1 ± 0.9, 53% female, 56% self-identified Hispanic/Latino) completed six semi-annual assessment bursts across three years. During each burst, participants responded to up to seven (weekend) or three (weekday) randomly prompted EMA surveys on smartphones for seven days and wore a waist-worn accelerometer. Multi-level structural equation modeling examined within- and between-subjects effects of stress as a predictor of children's subsequent moderate-to-vigorous physical activity (MVPA) in the 15, 30, and 60 min following the EMA prompt. Latent variables were created for within- and between-subjects stress were comprised of three EMA stress items. Higher than average levels of stress (within-subjects) significantly predicted lower MVPA in the subsequent 15, 30 and 60 min (ps < .05). Between-subjects stress was not significantly associated with subsequent MVPA (ps > .05). Results indicate that elevated momentary stress predicts less subsequent MVPA. These findings suggest that within-day fluctuations in stress may be a barrier for children engaging in physical activity. Childhood physical activity promotion and interventions should consider the role of children's stress, aim to reduce the stress children experience throughout the day, and incorporate stress coping strategies.

Association of daily step count and serum testosterone among men in the United States

PurposeTo describe the association between daily activity (i.e., daily step counts and accelerometer intensity measures) and serum TT levels in a representative sample of US adults aged 18 years or older.MethodsA retrospective cohort study was carried out utilizing the NHANES (National Health and Nutrition Examination Survey) 2003–2004 cycle. Physical activity was measured with a waist-worn uniaxial accelerometer (AM-7164; ActiGraph) for up to 7 days using a standardized protocol. Using linear and multivariable logistic regression controlling for relevant social, demographic, lifestyle, and comorbidity characteristics, we assessed the association between daily step counts and TT.ResultsA total of 279 subjects with a median age 46 (IQR: 33–56) were included in the analysis. 23.3% of the cohort had a low serum TT level (TT < 350 ng/dl). Compared to men who took <4000 steps per day, men who took >4000 or >8000 steps/day had a lower odd of being hypogonadal (OR 0.14, 95% CI: 0.07–0.49 and 0.08, 95%CI: 0.02–0.44, respectively). While a threshold effect was noted on average, TT increased 7 ng/dL for each additional 1000 steps taken daily (β-estimate: 0.007, 95% CI: 0.002–0.013).ConclusionsPatients with the lowest daily step counts had higher odds of being hypogonadal. The current work supports a possible association between daily steps, total testosterone, and hypogonadism for men in the US.