Tracking of Cardiorespiratory Fitness from Childhood to Mid-adulthood.

High cardiorespiratory fitness (CRF) in adulthood is important for survival from major chronic diseases and preserving good health. We examined how childhood CRF tracks, or persists, into adulthood. Among a cohort of 748 school children followed over 34 years, we found child CRF correlated with young- (r = 0.30) and mid-adulthood (r = 0.16) CRF.

Muscular strength measured across the life-course and the metabolic syndrome.

BACKGROUND AND AIMS: Low muscular strength associates with the metabolic syndrome (MetS). However, how muscular strength measured at different life stages contribute to the development of MetS is unknown. This study compared the contribution of muscular strength measured in youth, young- and mid-adulthood with MetS in midlife. METHODS AND RESULTS: Prospective longitudinal study of 267 Childhood Determinants of Adult Health Study participants who between 1985 and 2019 had measures of muscular strength (dominant grip strength) at three life stages (youth = 9-15 years, young adulthood = 26-36 years, mid-adulthood = 36-49 years) and had their MetS status assessed in mid-adulthood. Bayesian relevant life-course exposure models quantified associations between muscular strength at each life stage with MetS and estimated the maximum accumulated effect of lifelong muscular strength. The contribution of muscular strength at each life stage with MetS was equal (youth = 38%, young adulthood = 28%, mid-adulthood = 34%). A one standard deviation increase in cumulative muscular strength was associated with 46% reduced odds of MetS. Of all MetS components, muscular strength was most strongly negatively associated with high waist circumference. CONCLUSION: A life-course approach demonstrated reduced odds of MetS in midlife was associated with cumulatively high muscular strength since youth. This supports efforts to promote physical fitness throughout life.

At-home testing to mitigate community transmission of SARS-CoV-2: protocol for a public health intervention with a nested prospective cohort study.

BACKGROUND: The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve as a global health crisis. Although highly effective vaccines have been developed, non-pharmaceutical interventions remain critical to controlling disease transmission. One such intervention-rapid, at-home antigen self-testing-can ease the burden associated with facility-based testing programs and improve testing access in high-risk communities. However, its impact on SARS-CoV-2 community transmission has yet to be definitively evaluated, and the socio-behavioral aspects of testing in underserved populations remain unknown. METHODS: As part of the Rapid Acceleration of Diagnostics-Underserved Populations (RADx-UP) program funded by the National Institutes of Health, we are implementing a public health intervention titled "Say Yes! COVID Test" (SYCT) involving at-home self-testing using a SARS-CoV-2 rapid antigen assay in North Carolina (Greenville, Pitt County) and Tennessee (Chattanooga City, Hamilton County). The intervention is supported by a multifaceted communication and community engagement strategy to ensure widespread awareness and uptake, particularly in marginalized communities. Participants receive test kits either through online orders or via local community distribution partners. To assess the impact of this intervention on SARS-CoV-2 transmission, we will conduct a non-randomized, ecological study using community-level outcomes. Specifically, we will evaluate trends in SARS-CoV-2 cases and hospitalizations, SARS-CoV-2 viral load in wastewater, and population mobility in each community before, during, and after the SYCT intervention. Individuals who choose to participate in SYCT will also have the option to enroll in an embedded prospective cohort substudy gathering participant-level data to evaluate behavioral determinants of at-home self-testing and socio-behavioral mechanisms of SARS-CoV-2 community transmission. DISCUSSION: This is the first large-scale, public health intervention implementing rapid, at-home SARS-CoV-2 self-testing in the United States. The program consists of a novel combination of an at-home testing program, a broad communications and community engagement strategy, an ecological study to assess impact, and a research substudy of the behavioral aspects of testing. The findings from the SYCT project will provide insights into innovative methods to mitigate viral transmission, advance the science of public health communications and community engagement, and evaluate emerging, novel assessments of community transmission of disease.

Exercise effects on arterial stiffness and heart health in children with excess weight: The SMART RCT.

INTRODUCTION: Childhood obesity and inactivity are associated with cardiovascular risk. Evidence is limited for exercise effects on arterial health in children. METHODS: One hundred and seventy-five inactive children with overweight or obesity (8-11 years, ≥85th percentile BMI, 61% female, 87% Black, 73% with obesity) were randomized to an 8-month daily after-school aerobic exercise program (40 min/day, n = 90) or a sedentary control condition (n = 85). Carotid-femoral pulse wave velocity (PWV, primary outcome, arterial stiffness), fitness, adiposity, blood pressure (BP), glucose, insulin resistance, lipids, and C-reactive protein were measured at baseline and posttest (8 months). Adiposity, fitness, and BP were measured again at follow-up, 8-12 months later. Intent-to-treat analyses were conducted using mixed models. RESULTS: The study had 89% retention, with attendance of 59% in exercise and 64% in the control condition, and vigorous exercise participation (average heart rate 161 ± 7 beats/min). Compared with controls, the exercise group had twice the improvement in fitness (VÈ®2 peak, 2.7 (95% CI 1.8, 3.6) vs. 1.3 (0.4, 2.3) mL/kg/min) and adiposity (-1.8 (-2.4, -1.1) vs. -0.8 (-1.5, -0.1)%), each p = 0.04, and a large improvement in HDL-cholesterol (0.13 (0.075, 0.186) vs. -0.028 (-0.083, 0.023) mmol/L, p < 0.0001). There was no group × time effect on other outcomes at 8 months, or on any outcomes at follow-up. The change in PWV at 8 months correlated with changes in insulin and insulin resistance (both r = 0.32), diastolic BP (r = 0.24), BMI (r = 0.22), and adiposity (r = 0.18). CONCLUSIONS: Eight months of aerobic exercise training improved fitness, adiposity, and HDL-cholesterol levels, but did not reduce arterial stiffness in children with excess weight. PWV improved as a function of insulin resistance, BP, BMI, and adiposity. Weight loss may be required to improve arterial stiffness. Exercise benefits waned after discontinuing the program.

Factors associated with muscular fitness phenotypes in Australian children: A cross-sectional study.

To help inform strategies aimed at increasing muscular fitness levels, we examined factors associated with childhood muscular fitness (strength and power) that preceded the recently observed secular decline. Data were available from a nationally representative sample of Australian children aged 7-15 years in 1985 (n = 8469). Muscular fitness measures included strength (right and left grip, shoulder extension and flexion, and leg strength) and power (standing long jump distance). Anthropometric (adiposity, fat-free mass), cardiorespiratory fitness (CRF), flexibility, speed capability, physical activity (individual and parental), dietary quality and intake (fruit, vegetable, protein) and sociodemographic (area-level socioeconomic status (SES), school type) data were available. Statistical analyses included sex-stratified linear regression. Of all examined factors, measures of adiposity, fat-free mass, CRF, flexibility and speed capability were associated with muscular fitness at levels that met Cohen's threshold for important effects (r-squared = 0.02 to 0.28). These findings highlight the multifactorial relationship between muscular fitness and its determinants. Collectively, these factors were powerful in explaining muscular strength (females: r-squared = 0.32; males: r-squared = 0.41) and muscular power (females: r-squared = 0.36; males: r-squared = 0.42). These findings highlight modifiable and environmental factors that could be targeted to increase childhood muscular fitness.

The association between muscular power from childhood to adulthood and adult measures of glucose homeostasis.

This study aimed to assess whether the longitudinal association between childhood muscular fitness and adult measures of glucose homeostasis persist despite changes in muscular fitness across the life course. This prospective longitudinal study included 586 participants who had their muscular power (standing long jump distance), cardiorespiratory fitness (CRF), and waist circumference measured as children (aged 9, 12, 15 years) and again 20 years later as adults. In adulthood, these participants also provided a fasting blood sample which was tested for glucose and insulin. Glucose homeostasis measures including insulin resistance (HOMA2-IR) and beta cell function (HOMA2-ß) were estimated. Child and adult muscular power levels were separated into thirds, and tracking groups (persistently low, decreasing, persistently moderate, increasing, and persistently high) were created. Sex-stratified multivariable linear regression models were used to examine the association between muscular power tracking groups and adult measures of glucose homeostasis. Compared with males with persistently high muscular power, males with increasing and persistently low muscular power had higher fasting insulin (increasing: ß = 1.12 mU/L, P = .04; persistently low: ß = 2.12 mU/L, P = .001) and HOMA2-ß (increasing: ß = 8.50%, P = .03; persistently low: ß = 11.27%, P = .01) independent of CRF and males with persistently low muscular power had greater fasting insulin (ß = 1.22 mU/L, P = .02) and HOMA2-IR (ß = 0.14, P = .02) independent of waist circumference. Non-significant associations were present for females. For males, maintaining persistently high muscular power between childhood and adulthood could lead to a healthier adult glucose homeostasis profile.

Predictive utility of childhood anthropometric measures on adult glucose homeostasis measures: a 20-year cohort study.

BACKGROUND/OBJECTIVES: Childhood body mass index (BMI) predicts adult glucose homeostasis measures and type 2 diabetes mellitus, but little is known about the predictive utility of other anthropometric measures in childhood. We aimed to identify the anthropometric measure in childhood that best predicts adult glucose homeostasis measures and examine if the combination of additional anthropometric measures further improves predictive utility. METHODS: A 20-year follow-up of children participating in the Childhood Determinants of Adult Health Study (n = 2345, aged 7-15 years at baseline). Baseline anthropometric measures were waist circumference (WC), WC adjusted for height, weight adjusted for height, hip circumference, waist-hip-ratio, waist-height-ratio, BMI, conicity index, abdominal volume index (AVI), body adiposity index, and a body shape index. Fasting glucose and insulin levels measured at follow-up were used to define insulin resistance (HOMA2-IR), low beta-cell function (HOMA2-ß), high fasting insulin, and impaired fasting glucose (IFG). RESULTS: All child anthropometric measures were significantly associated with HOMA2-IR, HOMA2-ß, and high fasting insulin (relative risk = 1.12-1.55), but not IFG. AVI had the largest area under receiver-operating curve (AUC) in predicting adult HOMA2-IR (AUC, 95% confidence interval: 0.610, 0.584-0.637), HOMA2-ß (0.615, 0.588-0.642) and high fasting insulin (0.613, 0.587-0.639). Combining each additional anthropometric measure with AVI did not appreciably increase predictive utility (an increase of 0.001-0.002 in AUC, p > 0.05 for all). CONCLUSIONS: Anthropometric measures from a single time-point in childhood are associated with insulin-related outcomes 20-year later in adulthood. However, overall predictive utility was low and was not substantially enhanced by combining multiple different child anthropometric measures.

Longitudinal associations between TV viewing and BMI not explained by the 'mindless eating' or 'physical activity displacement' hypotheses among adults.

BACKGROUND: The mechanisms explaining the positive relationship between television (TV) viewing and body mass index (BMI) are unclear. 'Mindless eating' and 'physical activity displacement' theories have been suggested, but have not been tested longitudinally among young adults. This study aimed to determine whether longitudinal associations between young adults' TV viewing and BMI are explained by changes in TV-related food and beverage consumption (FBC) and/or leisure-time physical activity (LTPA) over 5 years among young adults. METHODS: A cohort of young Australian adults (n = 1068) was assessed in 2004-6 (T1) and 2009-2011 (T2), height and weight were measured (T1) or self-reported (T2), and participants self-reported TV viewing time (hours/day), weekly TV-related FBC and LTPA (mins/week). Linear regression was used to examine direct pathways between TV viewing and BMI, adjusting for TV-related FBC and LTPA to examine indirect pathways. RESULTS: The association between TV viewing time and BMI (ß: 0.41, 95% CI 0.03, 0.78 for > 1-h increase in TV viewing/day) was not explained by TV-related FBC (ß: 0.37, 95% CI -0.18, 0.91) or LTPA (ß: 0.38, 95% CI -0.17, 0.93) hypotheses. Increased TV-related FBC was associated with increased TV viewing (0.39 ± 1.54 h/day) and greater increases in BMI (0.92 ± 2.28 kg/m2, p = 0.16). LTPA increases were not associated with changes in TV viewing (- 0.07 ± 1.42 h/day), and increases in BMI were smallest when LTPA increased (0.44 ± 2.25 kg/m2) and greatest when LTPA decreased (0.82 ± 2.30 kg/m2) (p = 0.13). CONCLUSIONS: Factors other than changes in TV-related FBC or LTPA may explain the longitudinal relationship between TV viewing and increasing BMI among young adults. Findings confirm that TV viewing is a risk factor for weight gain in young adults but the underlying causal mechanisms remain unclear.

Moderate, but not vigorous, intensity exercise training reduces C-reactive protein.

BACKGROUND: Sprint interval cycle training is a contemporary popular mode of training but its relative efficacy, under conditions of matched energy expenditure, to reduce risk factors for cardiometabolic disease is incompletely characterised, especially in young women. The purpose of this investigation was to determine the relative efficacy of six weeks of moderate-intensity cycling (MOD-C) and vigorous sprint-interval cycling (VIG-SIC) on lipid profile, insulin (INS) and insulin resistance using the homeostatic model assessment (HOMA-IR) and C-reactive protein (CRP) in inactive, overweight/obese (OW/OB) young women. METHODS: Participants (BMI ≥25 kg/m2, waist circumference ≥88 cm) were randomly assigned to MOD-C (20-30 min at 60-70% of heart rate reserve(HRR)) or VIG-SIC (5-7 repeated bouts 30-second maximal effort sprints, followed by four minutes of active recovery) supervised training three days/week for six weeks, with each group matched on energy expenditure. Adiposity (%Fat) was measured using dual x-ray absorptiometry. RESULTS: Forty-four participants (20.4 ± 1.6 years, 65.9% Caucasian, 29.8 ± 4.1 kg/m2) were included in the analysis. The improvement in CRP observed in the MOD-C group was larger than the VIG-C group (p = .034). Overall, high-density lipoprotein (HDL-C) and low-density lipoprotein (LDL-C) levels improved following training (p < .05); however, total cholesterol, triglyceride, INS and HOMA-IR did not improve (p > .05). CONCLUSION: These results indicate MOD-C training may be more effective in reducing CRP than VIG-SIC.

Interactive associations of physical activity, adiposity, and oral contraceptive use on C-reactive protein levels in young women.

Oral contraceptives (OCs) are the most frequently used type of birth control among young women. OC-users have higher C-reactive protein (CRP) values, an indicator of systemic inflammation, than do non-OC-users. In addition, adiposity (percent fat) is positively associated with CRP, and physical activity (PA) is inversely associated with CRP. The present study determined the interactive associations of PA, percent fat, and OC-use with CRP. Data were collected during 2012-2015 at the University of Georgia. Objective PA was measured via pedometers. Percent fat was measured via dual X-ray absorptiometry. The current OC-use was self-reported. High-sensitivity (hs) CRP was determined using venipuncture. Multivariate linear regression determined the interactive associations of percent fat, OC-use, and PA with hs-CRP. Participants (n = 247; mean age 18.9 ± 1.4 years, 60.7 percent white) accumulated a mean of 10,075.7 ± 3,593.4 steps/day. One-third of participants were categorized as overweight/obese by BMI (mean = 24.5 ± 4.8 kg/m2, mean percent fat = 35.2 ± 6.8). The current OC-use was reported by 26.2 percent of the sample (n = 61). A significant three-way interaction (ß = 0.01, p = .03) indicated that higher PA was associated with lower hs-CRP in non-OC-users with higher percent fat, but not among OC-users with higher percent fat. These results highlight the need to measure and account for the current OC-use in studies examining the relationship between PA and CRP.

Dose-response association of physical activity with HbA1c: Intensity and bout length.

OBJECTIVE: The aims of this study were to characterize the dose-response relationship between moderate-to-vigorous intensity physical activity (MVPA), and light-intensity activity with HbA1c in adults at low, moderate, and high risks of type 2 diabetes, and to compare the relationship of short (1 to 9min) versus long (10+min) bouts of MVPA with HbA1c. METHODS: Data from 2707 participants from the 2003-2006 National Health And Nutrition Examination Survey were analyzed in 2014-2015. Type 2 diabetes risk was classified into three groups based upon age (<40years; ≥40years) and BMI (<30; ≥30). The relationship between HbA1c and accelerometer-based physical activity variables was assessed using multiple regression models. RESULTS: There was a curvilinear dose-response relationship between HbA1c with total activity and MVPA in adults at moderate or high risk for type 2 diabetes: higher amounts of physical activity were associated with lower HbA1c. The association of physical activity on HbA1c was stronger at lower levels of physical activity. There was no dose-response relationship in adults at low risk for type 2 diabetes. The relationship between short bouts with HbA1c was stronger than for bouts≥10min. CONCLUSIONS: In adults at risk for type 2 diabetes, there is a dose-response relationship between physical activity and HbA1c levels such that the relationship: (1) is curvilinear; (2) is stronger when a higher percent of total activity comes from MVPA; and (3) is more potent with short bouts of MVPA. Fractionalized physical activity of at least moderate-intensity may contribute to long-term glucose control.

Physical activity patterns and risk of depression in young adulthood: a 20-year cohort study since childhood.

PURPOSE: Little is known about how physical activity patterns during childhood and adolescence are associated with risk of subsequent depression. We examined prospective and retrospective associations between leisure physical activity patterns from childhood to adulthood and risk of clinical depression in young adulthood. METHODS: Participants (759 males, 871 females) in a national survey, aged 9-15 years, were re-interviewed approximately 20 years later. Leisure physical activity was self-reported at baseline (1985) and follow-up (2004-2006). To bridge the interval between the two time-points, historical leisure activity from age 15 years to adulthood was self-reported retrospectively at follow-up. Physical activity was categorized into groups that, from a public health perspective, compared patterns that were least beneficial (persistently inactive) with those increasingly beneficial (decreasing, increasing and persistently active). Depression (major depressive or dysthymic disorder) was assessed using the Composite International Diagnostic Interview. RESULTS: Compared with those persistently inactive, males who were increasingly and persistently active had a 69 and 65 % reduced risk of depression in adulthood, respectively (all p < 0.05). In retrospective analyses, females who were persistently active had a 51 % reduced risk of depression in adulthood (p = 0.01). Similar but non-significant trends were observed for leisure physical activity in females and historical leisure activity in males. Results excluded those with childhood onset of depression and were adjusted for various sociodemographic and health covariates. CONCLUSIONS: Findings from both prospective and retrospective analyses indicate a beneficial effect of habitual discretionary physical activity since childhood on risk of depression in young adulthood.

Harmonization of three different accelerometers to classify the 24 h activity cycle.

Increasing interest in measuring key components of the 24 h activity cycle (24-HAC) [sleep, sedentary behavior (SED), light physical activity (LPA), and moderate to vigorous physical activity (MVPA)] has led to a need for better methods. Single wrist-worn accelerometers and different self-report instruments can assess the 24-HAC but may not accurately classify time spent in the different components or be subject to recall errors.Objective. To overcome these limitations, the current study harmonized output from multiple complimentary research grade accelerometers and assessed the feasibility and logistical challenges of this approach.Approach. Participants (n= 108) wore an: (a) ActiGraph GT9X on the wrist, (b) activPAL3 on the thigh, and (c) ActiGraph GT3X+ on the hip for 7-10 d to capture the 24-HAC. Participant compliance with the measurement protocol was compared across devices and an algorithm was developed to harmonize data from the accelerometers. The resulting 24-HAC estimates were described within and across days.Main results. Usable data for each device was obtained from 94.3% to 96.7% of participants and 89.4% provided usable data from all three devices. Compliance with wear instructions ranged from 70.7% of days for the GT3X+ to 93.2% of days for the activPAL3. Harmonized estimates indicated that, on average, university students spent 34% of the 24 h day sleeping, 41% sedentary, 21% in LPA, and 4% in MVPA. These behaviors varied substantially by time of day and day of the week.Significance. It is feasible to use three accelerometers in combination to derive a harmonized estimate the 24-HAC. The use of multiple accelerometers can minimize gaps in 24-HAC data however, factors such as additional research costs, and higher participant and investigator burden, should also be considered.

Virtual fitness buddy ecosystem: a mixed reality precision health physical activity intervention for children.

6-11-year-old children provide a critical window for physical activity (PA) interventions. The Virtual Fitness Buddy ecosystem is a precision health PA intervention for children integrating mixed reality technology to connect people and devices. A cluster randomized, controlled trial was conducted across 19 afterschool sites over two 6-month cohorts to test its efficacy in increasing PA and decreasing sedentary behavior. In the treatment group, a custom virtual dog via a mixed reality kiosk helped children set PA goals while sharing progress with parents to receive feedback and support. Children in the control group set PA goals using a computer without support from the virtual dog or parents. 303 children had 8+ hours of PA data on at least one day of each of the 3 intervention time intervals. Conversion of sedentary time was primarily to light-intensity PA and was strongest for children with low baseline moderate-to-vigorous PA than children above 45 min of baseline moderate-to-vigorous PA. Findings suggest that the VFB ecosystem can promote sustainable PA in children and may be rapidly diffused for widespread public health impact.

Physical activity and depression symptom profiles in young men and women with major depression.

OBJECTIVE: This study explored whether young adults with major depression who are physically active differ in their depression symptom profile from those physically inactive. METHODS: Analyses included data from 950 (47.6%) men and 1045 women (mean [standard deviation] age = 31.5 [2.6] years) participating in a national study. Participants reported leisure physical activity (International Physical Activity Questionnaire) and ambulatory activity (pedometer steps per day). Diagnosis and symptoms of major depression were assessed using the Composite International Diagnostic Interview. RESULTS: Prevalence of major depression was 5.5% (n = 52) for men and 11.6% (n = 121) for women. Interactions between physical activity and sex were observed for depressed mood, appetite changes, vacillating thoughts, and suicidality (all, p < .050). Among those with major depression, physically active men were significantly less likely to endorse the presence of insomnia (prevalence ratio [PR] = 0.78, 95% confidence interval [CI] = 0.63-0.96), fatigue (PR = 0.82, 95% CI = 0.69-0.99), and suicidality (PR = 0.69, 95% CI = 0.49-0.96) compared with inactive men. Physically active women were significantly less likely to endorse hypersomnia (PR = 0.50, 95% CI = 0.27-0.95), excessive/irrational guilt (PR = 0.76, 95% CI = 0.59-0.97), vacillating thoughts (PR = 0.74, 95% CI = 0.58-0.95), and suicidality (PR = 0.43, 95% CI = 0.20-0.89) compared with inactive women. Associations were adjusted for age, physical health, educational attainment, depression severity, and other depressive symptoms. CONCLUSIONS: Among adults with major depression, those physically active seem to differ in their depression symptom profile from those physically inactive.

Agreement between Fitbit and ActiGraph Estimates of Physical Activity in Young Children.

Physical activity (PA) estimates from the Fitbit Flex 2 were compared to those from the ActiGraph GT9X Link in 123 elementary school children. Steps and intensity-specific estimates of PA and 3-month PA change were calculated using two different ActiGraph cut-points (Evenson and Romanzini). Fitbit estimates were 35% higher for steps compared to the ActiGraph. Fitbit and ActiGraph intensity-specific estimates were closest for sedentary and light PA while estimates of moderate and vigorous PA varied substantially depending upon the ActiGraph cut-points used. Spearman correlations between device estimates were higher for steps (rs=.70) than for moderate (rs =.54 to .55) or vigorous (rs =.29 to .48) PA. There was low concordance between devices in assessing PA changes over time. Agreement between Fitbit Flex 2 and ActiGraph estimates may depend upon the cut-points used to classify PA intensity. However, there is fair to good agreement between devices in ranking children's steps and MVPA.

Muscular fitness and clustered cardiovascular disease risk in Australian youth.

Low cardiorespiratory fitness (CRF) is a risk factor for cardiovascular disease (CVD) but the association of muscular fitness phenotypes (strength, endurance and power) on CVD risk in youth has not been examined. We examined the cross-sectional association between muscular fitness phenotypes with individual and clustered CVD risk factors and determined if any potential associations are independent of CRF. Participants were 1,642 youth aged 9, 12, and 15 years from the Australian Schools Health and Fitness Survey that had muscular strength (dynamometer), power (standing long-jump), and endurance (push-ups) as well as CRF (1.6 km run-time) measured. Outcomes included established risk factors (body mass index, waist circumference, blood lipids and blood pressure) and a clustered CVD risk-score. Muscular strength, endurance, and power were inversely associated with clustered CVD risk (all P < 0.05). After adjustment for body mass index, the association remained for muscular endurance and power (all P ≤ 0.001), but not strength. Muscular power was inversely related to prevalence of clustered CVD risk (≥80th percentile) within low (P trend < 0.001), moderate (Ptrend < 0.001), and high (Ptrend = 0.001) CRF categories. Among youth, low muscular fitness levels as well as low CRF should be avoided for primary CVD prevention.

Childhood Factors Associated with Muscular Strength Trajectories between Childhood and Mid-Adulthood.

PURPOSE: To promote greater muscular strength across the life course and, in turn, help improve long-term health outcomes, strategies aimed at increasing muscular strength are required. To inform these strategies, this study identified childhood factors associated with muscular strength trajectories. METHODS: Prospective longitudinal study of 1280 Childhood Determinants of Adult Health participants who had a range of potentially modifiable factors (e.g., anthropometric measures, physical activity) and health and risk motivation items (e.g., attitudes, beliefs, and intentions on health-related actions) measured in childhood and had their muscular strength assessed up to three times between childhood and midlife. Associations between childhood factors and three predetermined life course muscular strength trajectories (identified previously using group-base trajectory modeling as follows: above average and increasing, average, and below average and decreasing) were examined using log multinomial regression. RESULTS: Greater physical fitness, physical activity, fat-free mass, enjoyment of physical activity, physical education, and school sports, and positive attitudes regarding the importance of exercising, staying fit, and body image were associated with a lower likelihood of being in the below average and decreasing muscular strength trajectory (relative risk range, 0.45-0.98). Greater physical fitness, physical activity, and fat-free mass, and attending an independent school were associated with a higher likelihood of being in the above average and increasing muscular strength trajectory (relative risk range, 1.03-1.93). CONCLUSIONS: In addition to providing health benefits in the short term, physical activity, physical fitness, positive health attitudes, and healthy weight in childhood may lead to better muscular strength in the long term.

Scaling the Virtual Fitness Buddy Ecosystem as a School-Based Physical Activity Intervention for Children.

Childhood obesity is a growing concern as it can lead to lifelong health problems that carry over into adulthood. A substantial contributing factor to obesity is the physical activity (PA) habits that are formed in early childhood, as these habits tend to sustain throughout adulthood. To aid children in forming healthy PA habits, we designed a mixed reality system called the Virtual Fitness Buddy ecosystem, in which children can interact with a virtual pet agent. As a child exercises, their pet becomes slimmer, faster, and able to play more games with them. Our initial deployment of this project showed promise but was only designed for a short-term intervention lasting three days. More recently, we have scaled it from a pilot grade study to a 9-month intervention comprised of 422 children. Ultimately, our goal is to scale this project to be a nationwide primary prevention program to encourage moderate to vigorous PA in children. This article explores the challenges and lessons learned during the design and deployment of this system at scale in the field.