A Systematic Review of the Associations of Adiposity and Cardiorespiratory Fitness With Arterial Structure and Function in Nonclinical Children and Adolescents.

PURPOSE: To summarize the evidence on associations of adiposity and cardiorespiratory fitness (CRF) with arterial structure and function in nonclinical children and adolescents. METHODS: Two researchers conducted a search in 5 electronic databases in April 2022 to find studies in nonclinical youth (age 5-17.9 y) reporting multivariable associations. Studies were eligible if adiposity and/or CRF were used as the predictor and arterial structure and/or function was the outcome. The Quality Assessment Tool for Quantitative Studies was used to assess methodological quality for experimental studies, and a modified version was used for observational studies. RESULTS: Ninety-nine studies (72.7% cross-sectional) were included. Ninety-four assessed associations between adiposity and arterial outcomes, most using overall body proportion (n = 71), abdominal (n = 52), or whole-body adiposity (n = 40). Most evidence was inconsistent or nonsignificant, but 59 studies suggested higher abdominal adiposity and worse body proportion were associated with adverse arterial outcomes. Twenty-one assessed associations between CRF and arterial outcomes, with findings inconsistent. Most evidence was rated weak in quality. CONCLUSION: While high adiposity may contribute to poor arterial outcomes, evidence is limited regarding CRF. Future studies should disentangle these associations by studying youth with healthy adiposity but poor CRF, or vice versa, using longitudinal or experimental study designs.

Effects of interrupting daily sedentary behavior on children's glucose metabolism: A 6-day randomized controlled trial.

BACKGROUND: Metabolic disease risk in youth is influenced by sedentary behaviors. Acute in-lab studies show that, during a single day, interrupting a sedentary period with short bouts of physical activity improves glucometabolic outcomes. OBJECTIVE: To determine if acutely improved glucose metabolism persists after multi-day interruptions of sitting with walking brief bouts. We hypothesized that children who underwent interrupting sitting on multiple days would demonstrate lower insulin area under the curve during an oral glucose tolerance test compared to uninterrupted sitting. METHODS: Healthy, normoglycemic children (N = 109) ages 7-11 years were randomized to one of two conditions: Control (3 h of daily Uninterrupted Sitting) or Interrupted Sitting (3-min of moderate-intensity walking every 30 min for 3 h daily); with dietary intake controlled through provision of foodstuffs for the entire experiment. Participants attended six consecutive daily visits at a research ambulatory unit. The primary outcome was insulin area under the curve during the oral glucose tolerance test on day 6 during interrupted or uninterrupted sitting; secondary outcomes included glucose and c-peptide area under the curve, energy intake at a buffet meal on day 6, and free-living activity. RESULTS: Among 93 children (42 uninterrupted sitting, 51 interrupted sitting), daily interrupted sitting resulted in 21% lower insulin (ß = 0.102 CI:0.032-0.172, p = 0.005) and a 10% lower C-peptide (ß = 0.043, CI:0.001-0.084, p = 0.045) area under the curve. Matsuda and Glucose Effectiveness Indices were also improved (p's < 0.05). There were no group differences in energy intake or expenditure. CONCLUSIONS: Sustained behavioral change by interrupting sedentary behaviors is a promising intervention strategy for improving metabolic risk in children.

Interventions to Reduce Sedentary Behavior in Cancer Patients and Survivors: a Systematic Review.

PURPOSE OF REVIEW: Sedentary behaviors (SB) after cancer diagnosis are associated with poor prognosis for certain cancers, and cancer patients and survivors report high levels of SB. Reducing SB may be a feasible and effective intervention strategy to improve outcomes. This systematic review aims to identify and evaluate the literature on interventions to reduce SB in cancer patients and survivors. RECENT FINDINGS: Studies were identified via database searches in December 2020. Two authors evaluated study eligibility. Data were extracted and checked, and risk of bias was assessed by the study team. Of 1401 records identified, nine studies involving 394 cancer patients or survivors were included in this review. Six were randomized trials, three were non-randomized intervention studies, and almost all (n = 8) focused on feasibility with small sample sizes. All studies were conducted within the previous 5 years in Canada, Australia, USA, and South Korea. Cancer types studied were breast (n = 3), prostate (n = 2), colorectal or peritoneal (n = 1), and mixed types (n = 3). Intervention duration of 12 weeks was most common (n = 7). Five studies had multiple intervention components, and six studies included wearable devices to measure and/or prompt behavior change. There was an overall trend where intervention groups reduced SB vs. control groups, often coupled with an increase in moderate-to-vigorous physical activity. This review suggests that there is some promise for intervention strategies to reduce SB in cancer patients and survivors. There is a need for more high-quality randomized controlled trials to understand how to best decrease SB in cancer patients and survivors.

Patterns of Objectively Measured Sedentary Time and Emotional Disorder Symptoms Among Youth.

OBJECTIVE: We examined the within-person longitudinal and bidirectional associations between patterns of sedentary time accumulation [alpha (sedentary bout duration/length), sedentary breaks (number of breaks in sedentary bouts)], and symptoms of major depressive disorder and generalized anxiety disorder. METHODS: Children [N = 167, 10.1(0.9) years old, 54.5% female, 59.3% Hispanic, 35.9% overweight/obese at baseline] participated in a 3-year longitudinal study that consisted of assessments of sedentary time, and depressive and anxiety symptoms. At each assessment, participants wore accelerometers and completed the Revised Child Anxiety and Depression Scale. Separate random intercept cross-lagged panel models estimated the within-person longitudinal and bidirectional associations between alpha, sedentary breaks, and symptoms of major depressive disorder and generalized anxiety disorder across chronological age intervals. RESULTS: Having greater than one's own usual depressive symptoms at age 11 was associated with fewer sedentary breaks 1 year later. Having greater than one's own usual generalized anxiety symptoms at age 11 was associated with longer sedentary bouts and fewer sedentary breaks 1 year later. In contrast, having greater than one's own usual sedentary breaks at age 10 was associated with fewer generalized anxiety symptoms 1 year later. All other associations, including at younger ages, were null. CONCLUSION: Deviations from one's usual levels of depressive or anxiety symptoms may be important for how sedentary time is subsequently accumulated. Intraindividual processes appear to be at play, therefore more within-person research is needed. Intervention strategies for promoting a healthier accumulation of sedentary time may consider targeting occasions when depressive and anxiety symptoms are greater than usual.

Day-level associations of physical activity and sedentary time in mother-child dyads across three years: a multi-wave longitudinal study using accelerometers.

Understanding associations between mothers' and children's physical activity and sedentary behavior on more fine-grained timescales can provide insights into real-time intervention opportunities. This study examined the extent to which mothers' and their children's device-measured moderate-to-vigorous physical activity (MVPA) and sedentary time (SDT) were associated at the day level during non-school time. Mother-child dyads (N = 193; baseline Mean ages = 40.69 ± 6.11 [mother] and 9.57 ± 0.89 [child] years) provided 3,135 paired days of accelerometry data from six bi-annual waves across three years. Controlling for covariates, multilevel models revealed that mothers' and their children's MVPA and SDT were positively associated at the day level during non-school time, both on weekdays and weekends. During weekdays, the day-level association for SDT was stronger for older than younger children, and the day-level association for MVPA was stronger for boys than girls. Designing family-based interventions targeting school-age children and their mothers during non-school time across the week may be useful for promoting active lifestyles.

Momentary intentions and perceived behavioral control are within-person predictors of sedentary leisure time: preliminary findings from an ecological momentary assessment study in adolescents.

Previous studies among adolescents conceptualize behavioral cognitions [e.g., intentions and perceived behavioral control (PBC)] as stable trait-like factors despite evidence suggesting they vary momentarily. We examined whether intentions and PBC momentarily relate to subsequent sedentary time during non-school periods. Healthy adolescents (N = 15, ages 11-15) reported their intentions and PBC regarding sedentary leisure behaviors via ecological momentary assessment (EMA) up to seven times/day for 14 days. Sedentary time in the two hours following each EMA prompt was measured by ActivPAL accelerometers. When participants reported greater sedentary intentions (within-person ß = 1.1, 95% CI 0.2, 2.1, p = 0.0213) and sedentary PBC (within-person ß = 1.7, 95% CI 0.6, 2.8, p = 0.0029), they accumulated greater sedentary time. This demonstrates that sedentary intentions and PBC are acutely associated with sedentary time among adolescents. Our findings highlight the potential for implementing just-in-time activity interventions among adolescents during at-risk periods within the day, characterized by deviations from one's usual intentions and PBC levels.

Associations among affect, diet, and activity and binge-eating severity using ecological momentary assessment in a non-clinical sample of middle-aged fathers.

PURPOSE: Knowledge of within-day factors associated with binge-eating severity among middle-aged fathers is limited. The purpose of the current report was to examine within-day associations of affect, diet, and activity in relation to binge-eating severity using ecological momentary assessment (EMA) in men. METHODS: Twenty-three middle-aged fathers completed 8 days of EMA and wore accelerometers to objectively assess activity. Generalized estimating equations assessed relationships among affect, diet, and activity and binge-eating severity. RESULTS: When positive affect was above average, men reported greater binge-eating severity in the next 2 h. Oppositely, when negative affect was above average, men reported less binge-eating severity in the next 2 h. At times when men reported consumption of sweets and fast food, they reported higher binge-eating severity during the same 2-h window. Men with greater average levels of light activity reported less overall binge-eating severity. CONCLUSIONS: Findings show that affect, unhealthy food intake, and light activity could be targeted among middle-aged fathers to reduce binge-eating severity and prevent eating disorders. LEVEL OF EVIDENCE: Level III: Evidence obtained from cohort or case-control analytic studies.

Examining the same-day relationship between morning cortisol after awakening, perceived stress in the morning, and physical activity in youth.

Most children in the United States currently do not meet physical activity (PA) guidelines, and perceived stress is a known barrier against PA. However, most studies have solely focused on the between-subject (BS) association of stress and PA, whereas the within-subject (WS) relationship remains under-studied in children. This limits our understanding of day-level psychosocial factors that influence children's PA engagement. This study assessed the same-day associations of the Morning Cortisol after Awakening (MCA) and morning perceived stress with moderate-to-vigorous physical activity (MVPA) in children using Ecological Momentary Assessment (EMA) methodologies. The analytic sample consisted of 143 children from Los Angeles in the Mothers and Their Children's Health (MATCH) study. Children collected four saliva samples and wore accelerometers to assess MVPA minutes across four days (two weekdays and two weekend days) during each data collection wave. On weekend days, they also answered a mobile phone EMA survey on perceived stress within 1 h of awakening. Data from four assessment waves, each approximately six months apart, were combined and analyzed cross-sectionally. Multilevel modeling, which adjusts for the nested data structure, was used to test the same-day associations of MCA and weekend morning perceived stress with MVPA. On weekend days when morning perceived stress was higher than usual, participants engaged in more MVPA on the same day (ß = 0.79, SE = 0.32, p = 0.02), but no association was found between MCA and MVPA. These findings elucidate same-day factors that predict MVPA in children and inform future WS studies on stress and PA.HighlightIt is unknown how stress influences children's daily activity levels. We tested if two types of stress (self-reported and saliva-measured) are related to children's daily activity. We found that self-reported stress is associated with physical activity, but saliva-measured stress is not.

Age-varying Bi-directional Associations Between Momentary Affect and Movement Behaviors in Children: Evidence From a Multi-wave Ecological Momentary Assessment Study.

BACKGROUND: The bi-directional associations between affective states and movement behaviors (e.g., physical activity, sedentary behavior) have been observed in children. It is unclear if the strength of these bi-directional associations varies with age as children transition from childhood to adolescence. PURPOSE: This multi-wave ecological momentary assessment (EMA) study investigates the acute time-varying associations between affect and movement behaviors among youth. METHODS: Children (N = 195, baseline mean age = 10.72, range = 8-12 years, mean BMI-z = 0.49, 51% female) participated in a six-wave EMA study across three years. Each EMA survey captured momentary positive and negative affect. Time spent in moderate-to-vigorous physical activity (MVPA) and sedentary time in the 15-min window before and after each EMA survey was calculated using accelerometry data. Time-varying effect models (TVEM) examined the acute bi-directional associations between momentary positive/negative affect and MVPA/sedentary time across ages 8 to 14. RESULTS: Children provided 14,246 valid activity-matched EMA surveys across all waves. TVEM plots revealed that the directionality and the strength (time-varying slopes) of associations between momentary affect and activity levels vary across ages. Positive affect was associated with higher MVPA levels and lower sedentary time at younger ages, whereas negative affect linked to lower MVPA levels and more sedentary time at older ages. CONCLUSIONS: The acute associations between momentary affect and (in)activity levels may vary as a function of children's age. Applying TVEM to intensive longitudinal data could provide valuable information for developing age-tailored interventions that promote healthy lifestyles among children and adolescents.

Mother-child dyadic influences of affect on everyday movement behaviors: evidence from an ecological momentary assessment study.

BACKGROUND: Research has shown that affect is associated with everyday movement behaviors in children and adults. However, limited work to date has investigated dyadic influences of momentary affect on moderate-to-vigorous physical activity (MVPA) and sedentary time among children and their mothers using ecological momentary assessment (EMA). METHODS: Mothers and their children (eight to 12-years-old at baseline) from the Los Angeles metropolitan area participated in a longitudinal study with six semi-annual measurement waves across three years. During each measurement wave, mothers and children reported momentary negative and positive affect via a custom smartphone-based EMA application across seven days (randomly sampled up to eight times per day). Each dyad member's momentary affective states were used to predict their own and the other dyad member's accelerometer-measured MVPA and sedentary time in the prompt-matched 45-min time window. Multilevel modeling within the actor-partner interdependence model (APIM) framework was applied to accommodate the nested dyadic nature of the data. RESULTS: At the within-subject level, when children had higher-than-usual positive affect, they engaged in greater MVPA and less sedentary time in the prompt-matched 45-min window (actor effects; ps < .001). When mothers experienced higher-than-usual positive affect, they engaged in more sedentary time in the same 45-min window (actor effect; p < .001). Children's higher-than-usual positive affect also predicted more MVPA time of their mothers (partner effect; p < .05). At the between-subjects level, for mothers who reported higher average negative affect than other mothers, their children overall had less MVPA and more sedentary time (partner effects ps < .05). CONCLUSIONS: This study extends the literature by demonstrating that mothers' and children's everyday physical activity and sedentary time are not only associated with their own affective states, but also may be influenced by the affective states of each other. Our findings suggest that affective states have the potential to influence movement behaviors in mother-child dyads' everyday lives. Affective underpinnings of physical activity and sedentary behaviors should be further studied in order to develop family-based intervention strategies to influence these behaviors.

The relationship between screen-based sedentary behaviors and symptoms of depression and anxiety in youth: a systematic review of moderating variables.

BACKGROUND: To elucidate the populations and conditions where screen-based sedentary behaviors (SB) and internalizing symptoms are coupled, this review synthesized the evidence for factors that may moderate the associations between screen-based SB, depressive symptoms, and anxiety symptoms among youth. METHODS: Two independent researchers conducted a systematic literature search of the Medline, psycINFO, and Scopus electronic databases in late 2018 for observational studies assessing moderators of the association between screen-based SB and depressive and anxiety symptoms. Studies among children and adolescents were eligible if moderation was assessed by statistical test (interaction) or stratification; and a narrative synthesis of eligible studies was conducted in accordance with PRISMA guidelines. RESULTS: Seventy empirical studies (46 cross-sectional, 19 longitudinal, and 5 both) of 13 different moderating variables of screen-based SB-internalizing symptom associations met the eligibility criteria. Of these, 40 studies were of depressive symptoms, 2 were of anxiety symptoms, and 28 studies assessed symptoms of both. The most consistent evidence of moderation was for screen-type, such that TV viewing was not as strongly associated with internalizing symptoms compared to other forms of screen-based SB. There was also inconsistent evidence for physical activity buffering screen-based SB-internalizing symptom associations and for female sex amplifying screen-based SB-internalizing symptom associations. In general, the body of evidence for anxiety symptoms was more limited than that for depressive symptoms, and were therefore more inconsistent. CONCLUSIONS: Screen-type, physical activity, and sex may influence the magnitude of screen-based SB-internalizing symptom coupling; highlighting potential sources of heterogeneity of screen-based SB-internalizing symptom associations. Additional studies aimed at understanding potential mechanistic explanations for the above moderators are needed prior to the development of tailored intervention strategies designed to decouple screen-based SB and internalizing symptoms among youth.

Doing exercise or sport together with one's child is positively associated with mothers' momentary affect in daily life, but not with higher levels of overall physical activity.

BACKGROUND: Physical inactivity is a widespread problem with a great need for innovative intervention concepts to overcome it. Epidemiological studies have identified working women in high-income Western countries to be at greater risk for physical inactivity. The current study included working mothers and examined within-subject associations between doing exercise/sport together with one's child and five different affective states, and with light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). METHOD: During 1 week, mothers (N = 192) completed up to eight ecological momentary assessment (EMA) surveys a day to assess momentary affect and certain situational circumstances (e.g., doing exercise/sport, being together with child). Physical activity was assessed objectively with waist-worn accelerometers. RESULTS: Multilevel analysis showed that doing exercise/sport together with one's child was associated with higher positive affect and lower negative affect compared to being active alone. However, greater frequency of doing exercise/sport together with children was negatively associated with MVPA. CONCLUSION: Due to the positive effect on momentary affect, combining spending time together with one's child and simultaneously doing exercise/sport might be a good strategy of pairing two relevant personal goals. However, this strategy was not associated with sufficient MVPA.

The Effects of Interrupting Sitting Time on Affect and State Anxiety in Children of Healthy Weight and Overweight: A Randomized Crossover Trial.

PURPOSE: Sedentary time relates to higher anxiety and more negative affect in children. This study assessed whether interrupting sitting over 3 hours is sufficient to influence state anxiety, positive affect, or negative affect, and tested weight status as a moderator. METHODS: Analyses were the second (preplanned) purpose of a larger study. Children (N = 61; age: mean [SD] = 9.5 [1.3]; 43% healthy weight) completed 2 experimental conditions: continuous sitting for 3 hours and sitting for 3 hours interrupted with walking for 3 minutes in every 30 minutes. State anxiety, positive affect, and negative affect were reported at pretest and posttest. Multilevel models for repeated measures assessed whether experimental condition predicted posttest scores. RESULTS: Experimental condition was unrelated to posttest state anxiety or positive affect. Weight status moderated how experimental condition influenced posttest negative affect (P = .003). Negative affect was lower in the children of healthy weight after interrupted sitting (vs continuous sitting; ß = -0.8; 95% confidence interval, -1.5 to 0.0, P = .05), but it was higher in the children with overweight/obesity after interrupted sitting (vs continuous sitting; ß = 0.6; 95% confidence interval, 0.0 to 1.2, P = .06). CONCLUSIONS: Interrupting sitting acutely reduced negative affect in children of healthy weight, but not in children with overweight. Further research is needed to better understand the potential emotional benefits of sitting interruptions in youth.

Within-Subject Associations of Maternal Physical Activity Parenting Practices on Children's Objectively Measured Moderate-to-Vigorous Physical Activity.

OBJECTIVE: Longitudinal within-subject (WS) associations of mothers' momentary assessed physical activity (PA) parenting practices were examined with children's objectively measured PA during the same 2-hr time frame. METHOD: Mother-child dyads (n = 189) completed five ecological momentary assessment (EMA) measurement bursts over 3 years. During each 7-day burst, mothers EMA-reported their past 2 hr PA parenting practices (i.e., encouraging their child to be physically active, taking their child someplace to be physically active), and children (Mage=9.6 years, SD = 0.9) wore an accelerometer to measure moderate-to-vigorous PA (MVPA). Two-part multilevel models were used, with zero portions representing not meeting MVPA and positive portions representing any MVPA, controlling for demographic covariates. Cross-level interaction terms of child sex and age with parenting were created to test moderation effects. RESULTS: When mothers reported taking their child to be physically active, children were more likely to get some MVPA (b = -0.56, p < .001). When mothers reported taking their child to be physically active more, children had higher levels of MVPA (b = 0.24, p < .001). When mothers reported encouraging their child to be physically active, children were less likely to get any MVPA (b = 0.27, p < .05). However, when mothers reported encouraging their child to be physically active more, children had higher levels of MVPA (b = 0.29, p < .001). These effects were not moderated by child sex or age. CONCLUSIONS: WS variations of mothers' support for PA across the day were associated with changes in children's MVPA. Future research should consider promoting mothers' provision of support for increasing children's PA.

Dual Versus Single Parental Households and Differences in Maternal Mental Health and Child's Overweight/Obesity.

Objectives Mothers report higher levels of psychological stress than fathers. s. Psychological stress is posited to influence parenting practices that could increase children's obesity risk. However, previous studies have not investigated several aspects of maternal mental health and the moderating role of household structure on children's obesity risk. The objective was to investigate associations of maternal mental health with child obesity risk, and whether these associations differed by household structure (single-parent vs. dual parent/multigenerational). Methods Mothers and their 8-12 year old children (N = 175 dyads) completed baseline questionnaires on mothers' mental health and child anthropometrics. Separate logistic regressions assessed associations of standardized maternal mental health indicators with the odds of child overweight/obesity, controlling for child age, and women's BMI, age, education, employment status, and annual income. Household structure was investigated as a moderator of these relationships.Results There were no statistically significant relationships between maternal mental health characteristics and odds of child overweight/obesity. Among single mothers only, greater anxiety was associated with higher risk of child overweight/obesity [OR (95% CI) = 3.67 (1.27-10.62); p = 0.0163]; and greater life satisfaction was marginally associated with lower risk of child overweight/obesity [OR (95% CI) = 0.44 (0.19-1.01); p = 0.0522]. Mothers' life satisfaction may lower risk for their children's overweight/obesity, whereas higher anxiety may increase this risk, particularly among children living in single-mother households. Conclusions for Practice Future interventions could increase resources for single mothers to buffer the effects of stress and lower pediatric obesity risk.

Parenting styles, food-related parenting practices, and children's healthy eating: A mediation analysis to examine relationships between parenting and child diet.

Parents exert a strong influence on their children's diet. While authoritative parenting style is linked to healthier weight and dietary outcomes in children, and authoritarian and permissive parenting styles with unhealthy eating, little is known about the mechanisms that mediate these relationships. Feeding styles are often examined in relation to child diet, but they do not consider the social and physical environmental contexts in which dietary behaviors occur. Therefore, this study examined whether parenting styles (authoritative, authoritarian, and permissive) were associated with three specific food-related parenting practices - mealtime structural practices (e.g., eating meals as a family), parent modeling of healthy food, and household food rules and whether these parenting practices mediated the association between parenting styles and children's diet. Participants were 174 mother-child dyads. Mothers (68% married, 58% college graduates, Mage = 41 years [SD = 6.2]) reported on their parenting practices using validated scales and parenting style using the Parenting Styles and Dimensions Questionnaire. Children (52% female, Mage = 10 years [SD = 0.9]) completed two telephone-based 24-hour dietary recalls. Dietary outcomes included the Healthy Eating Index (HEI)-2010 score, and fruit and vegetables and added sugar intake. Using PROCESS, multiple mediation cross-sectional analyses with parallel mediators using 10,000 bootstraps were performed. Significant indirect effects were observed with mealtime structure and the relationships between authoritative parenting and HEI-2010 score (b = 0.045, p < .05, CI = [0.006, 0.126]), authoritarian parenting and HEI-2010 score (b = -0.055, p < .05, CI = [-0.167, -0.001]), and permissive parenting and HEI-2010 score (b = -0.093, p < .05, CI = [-0.265, -0.008]). Child diet quality is affected by mealtime structural practices. Further examination of the features by which mealtime structural practices serve as a mechanism for parents to support healthy eating among their children may improve children's diet quality.

Double jeopardy: metabolic syndrome leads to increased sedentary behavior in peri-pubertal minority females.

While most studies have focused on investigating the preventive effects of physical activity on metabolic risk, the longitudinal impacts of metabolic syndrome (MetS) on activity levels is poorly understood. This study aims to examine the influence of MetS on initial activity levels and the trajectory of activity levels in Latina and African American female children over 12 months (n = 55, 9 ± 1 years). Metabolic measures, including fat and lean tissue mass by BodPod, fasting glucose, lipids, blood pressure, and waist circumference, were collected at baseline. Moderate-to-vigorous physical activity and sedentary behavior by accelerometry were collected on a quarterly basis. There were no significant differences in either initial activity levels by MetS status (Moderate-to-vigorous physical activity: 33 ± 12 mins/day for MetS, 48 ± 28 mins/day for Non-MetS, p = .12; sedentary behavior: 408 ± 57 mins/day for MetS, 421 ± 72 mins/day for Non-MetS, p = .67). Longitudinal declines in moderate-to-vigorous physical activity (p = .038) and increases in sedentary behavior (p = .003) were found. Daily sedentary behavior increased by 82.64 more minutes in youth with MetS than in those without over one year (p = .015). This study yields the first evidence of the adverse effect of MetS on sedentary behavior. Targeted intervention strategies to reduce progressive sedentariness evident in minority youth with MetS are warranted.

Long-term effects of the COVID-19 pandemic on children's physical activity and sedentary behavior.

Background: During the early months of the COVID-19 pandemic, decreases in physical activity (PA) and increases in sedentary behavior (SB) were reported among children in the United States (U.S.). This follow-up analysis examines 13-month effects of the COVID-19 pandemic on children's PA and SB one year into the pandemic. Methods: Parents of 5-13-year-old children in the U.S. (N = 71) reported on their child's PA and SB during the early COVID-19 period (April-May 2020) and again 12-14 months later (June-July 2021). Results: Paired t-tests showed significant within-subject reductions in SB minutes per day (M diff = -86.20, t = 3.26, p < 0.01) but no changes in PA minutes per day. Separate mixed-model repeated-measures analysis of covariance procedures found that within-subject changes in PA and SB did not differ by child sex or age. Conclusion: As COVID-19 restrictions lessened, there were more opportunities for children to reduce SB, but there were still barriers to engage in PA.

Perceived stress and associations between physical activity, sedentary time, and interstitial glucose in healthy adolescents.

BACKGROUND: Less moderate to vigorous physical activity (MVPA), more sedentary time (ST), and higher perceived stress are related to type 2 diabetes mellitus (T2DM) occurrence, but observational evidence addressing the interaction of these factors is lacking in youth. This pilot study investigated momentary stress as a moderator in the acute associations of MVPA and ST with subsequent glucose in healthy adolescents. METHODS: Participants (N=15, Mage=13.1±1.0 years, 10 girls, 5 with overweight/obesity) simultaneously wore a continuous glucose monitor (CGM), thigh-mounted accelerometer, and reported momentary stress via random ecological momentary assessments (EMA; Time T) for 7-14 days. MVPA and ST (min) were calculated for 60- and 120-minute time windows before each EMA prompt (Time T-1). Mean CGM-measured interstitial glucose (mg/dL) was calculated after each prompt (Mmin=120.0±25.4; Time T+1). Multilevel models assessed whether within-subject MVPA and ST (Time T-1) predicted mean glucose (Time T+1), with momentary stress as a moderator (Time T). RESULTS: There were 513 time-matched EMA reports of stress, accelerometer, and CGM data. Momentary stress moderated the effects of MVPA 60 (ß=-0.22, p=.001) and 120 min (ß=-0.08, p=.02) before the prompt on subsequent glucose levels. When youth spent more time in MVPA than their average and when momentary stress was higher than their average, subsequent glucose was lower. Stress did not moderate associations of ST with glucose (p>.05). CONCLUSIONS: Higher momentary stress may interact with higher MVPA to lower subsequent glucose in youth. Accelerometers, EMA, and CGMs can be integrated in future studies to further understand these associations in free-living environments.

Investigating the day-level associations between affective variability and physical activity using ecological momentary assessment.

BACKGROUND: Understanding affect as a determinant of physical activity has gained increased attention in health behavior research. Fluctuations in affect intensity from moment-to-moment (i.e., affective variability) may interfere with cognitive and regulatory processes, making it difficult to engage in goal-directed behaviors such as physical activity. Preliminary evidence indicates that those with greater trait-level affective variability engage in lower levels of habitual physical activity. However, the extent to which daily fluctuations in affect variability are associated with same-day physical activity levels is unknown. This study used ecological momentary assessment (EMA) to investigate day-level associations between affective variability (i.e., within-subject variance) and physical activity. METHODS: Young adults (N = 231, M = 23.58 ± 3.02 years) provided three months of smartphone-based EMA and smartwatch-based activity data. Every two weeks, participants completed a 4-day EMA measurement burst (M = 5.17 ± 1.28 bursts per participant). Bursts consisted of hourly randomly-prompted EMA surveys assessing momentary positive-activated (happy, energetic), positive-deactivated (relaxed), negative-activated (tense, stressed), and negative-deactivated (sad, fatigued) affect. Participants continuously wore a smartwatch to measure physical activity across the three months. Mixed-effects location scale modeling examined the day-level associations of affective variability (i.e., positive-activated, positive-deactivated, negative-activated, and negative-deactivated) and physical activity, controlling for covariates such as mean levels of affect, between-subject effects of physical activity, time of day, day of week, day in study, and smartwatch wear time. RESULTS: There were 41,546 completed EMA surveys (M = 182.22 ± 69.82 per participant) included in the analyses. Above and beyond mean levels of affect, greater day-level variability in positive-activated affect was associated with greater physical activity on that same day compared to other days (τ = 0.01, p < .001), whereas greater day-level variability in negative-deactivated affect was associated with less physical activity on that same day compared to other days (τ = -0.01, p < .001). Day-level variability in positive-deactivated affect or negative-activated affect were not associated with day-level physical activity (ps > .05) CONCLUSIONS: Individuals were less active on days with greater variability in feeling sad and fatigued but more active on days with greater variability in feeling happy and energetic. Understanding the dynamic relationships of affective variability with day-level physical activity can strengthen physical activity interventions by considering how these processes differ within individuals and unfold within the context of daily life. Future research should examine causal pathways between affective variability and physical activity across the day.