Longitudinal Mediating Effect of Fat Mass and Lipids on Sedentary Time, Light PA, and MVPA with Inflammation in Youth

Associations of Sedentary Time and Physical Activity From Childhood With Lipids: A 13-Year Mediation and Temporal Study

CONTEXT

Among children, evidence on long-term longitudinal associations of accelerometer-measured sedentary time, light physical activity (LPA), and moderate to vigorous PA (MVPA) with lipid indices are few. The mediating role of body composition and other metabolic indices in these associations remains unclear and whether poor movement behavior precedes altered lipid levels is unknown.

OBJECTIVE

This study examined the associations of sedentary time, LPA, and MVPA from childhood through young adulthood with increased lipids, the mediating role of body composition, and whether temporal interrelations exist.

METHODS

Data from 792 children (58% female; mean [SD] age at baseline, 11.7 [0.2] years), drawn from the Avon Longitudinal Study of Parents and Children (ALSPAC) UK birth cohort, who had at least 2 time-point measures of accelerometer-based sedentary time, LPA, and MVPA during clinic visits at ages 11, 15, and 24 years and complete fasting plasma high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, and total cholesterol measured during follow-up visits at ages 15, 17, and 24 years were analyzed.

RESULTS

Total fat mass partly mediated the inverse associations of LPA with low-density lipoprotein cholesterol by 13%, triglyceride by 28%, and total cholesterol by 6%. Total fat mass mediated the inverse associations of MVPA with low-density lipoprotein cholesterol by 37% and total cholesterol by 48%, attenuating the effect on total cholesterol to nonsignificance (P = .077). In the temporal path analyses, higher MVPA at age 15 years was associated with lower low-density lipoprotein cholesterol at 24 years (β = -0.08, SE, 0.01, P = .022) but not vice versa.

CONCLUSION

Sedentary time worsens lipid indices, but increased LPA had a 5- to 8-fold total cholesterol-lowering effect and was more resistant to the attenuating effect of fat mass than MVPA.

Independent and Combined Associations of Physical Activity and Screen Time With Biomarkers of Inflammation in Children and Adolescents With Overweight/Obesity

PURPOSE

Inflammation regulation is important for obesity management and prevention of obesity-related diseases. This cross-sectional study aimed to analyze the independent and combined associations of physical activity and screen time with biomarkers of inflammation in children and adolescents with overweight/obesity.

METHOD

A total of 1289 children and adolescents with overweight/obesity were included from the 2015 to 2018 National Health and Nutrition Examination Survey. Multivariable linear regressions were conducted for the association analyses.

RESULTS

For the independent associations, a negative dose-dependent relationship was demonstrated between physical activity and inflammatory biomarker high-sensitivity C-reactive protein (hsCRP) in adolescents with overweight/obesity (P < .001) but not children; screen time was not associated with hsCRP in both children and adolescents. No significant association was found between physical activity or screen time with other inflammatory biomarkers. For the combined associations, there was an interaction between physical activity and screen time on hsCRP in adolescents with overweight/obesity (P = .014). In addition, the negative association between physical activity and hsCRP was greater in boys compared with girls and in Hispanic and non-Hispanic Black individuals compared with non-Hispanic White individuals.

CONCLUSION

This study demonstrated a combined association of physical activity and screen time with inflammatory biomarker hsCRP in adolescents with overweight/obesity.

Accelerometer-based sedentary time and physical activity from childhood through young adulthood with progressive cardiac changes: a 13-year longitudinal study

AIMS

Longitudinal evidence on the relationship of sedentary time (ST), light-intensity physical activity (LPA), and moderate-to-vigorous-intensity physical activity (MVPA) with changes in cardiac structure and function in the paediatric population is scarce. This evidence is clinically important due to the impact ST can have on the long-term prognosis of healthy young population in the lifetime continuum. This prospective observational study examined the relationships of cumulative ST, LPA, and MVPA from childhood with longitudinal changes in cardiac structure and function.

METHODS AND RESULTS

This is a secondary analysis from the Avon Longitudinal Study of Parents and Children, UK birth cohort of 1682 children aged 11 years. Participants who had at least one follow-up timepoints accelerometer-measured ST, LPA, and MVPA over a period of 13 years and repeated echocardiography-measured cardiac structure and function at ages 17- and 24-year clinic visit were included. Left ventricular mass indexed for height2.7 (LVMI2.7) and left ventricular (LV) diastolic function from mitral E/A ratio (LVDF) were computed. Among 1682 children (mean [SD] age, 11.75 [0.24] years; 1054 [62.7%] females), the cumulative one-min/day increase in ST from ages 11 to 24 years was associated with progressively increased LVMI2.7 {effect estimate 0.002 g/m2.7 [confidence interval (CI) 0.001-0.003], P < 0.001}, irrespective of sex, obesity, and hypertensive status. Cumulative one-min/day increase in LPA was associated with a decreased LVMI2.7 (-0.005 g/m2.7 [-0.006 to -0.003], P < 0.0001) but an increased LVDF. Cumulative one-minute/day increase in MVPA was associated with progressively increased LVMI2.7 (0.003 g/m2.7 [0.001-0.006], P = 0.015).

CONCLUSION

ST contributed +40% to the 7-year increase in cardiac mass, MVPA increased cardiac mass by +5%, but LPA reduced cardiac mass by -49%. Increased ST may have long-term pathologic effects on cardiac structure and function during growth from childhood through young adulthood; however, engaging in LPA may enhance cardiac health in the young population.

Accelerometer-based sedentary time, light physical activity, and moderate-to-vigorous physical activity from childhood with arterial stiffness and carotid IMT progression: A 13-year longitudinal study of 1339 children

AIMS

We examined the longitudinal associations of sedentary time (ST), light physical activity (LPA), and moderate-to-vigorous PA (MVPA) from childhood with carotid-femoral pulse wave velocity (cfPWV), a measure of arterial stiffness and carotid intima-media thickness (cIMT).

METHODS

We studied 1339 children, aged 11 years from Avon Longitudinal Study of Parents and Children, UK, followed up for 13 years. Accelerometer-based ST, LPA, and MVPA were assessed at ages 11, 15, and 24 years clinic visits. cfPWV and cIMT were measured with Vicorder and ultrasound, respectively, at ages 17 and 24 years.

RESULTS

Among 1339 [56.4% female] participants, mean ST increased from ages 11 through 24 years, while mean LPA and MVPA decreased. Persistently high ST tertile from childhood was associated with increased cfPWV progression, effect estimate 0.047 m/s; [(95% CI 0.005 to 0.090); p = 0.030], but not cIMT progression. Persistently high LPA tertile category was associated with decreased cfPWV progression in males -0.022 m/s; [(-0.028 to -0.017); p < 0.001] and females -0.027 m/s; [(-0.044 to -0.010); p < 0.001]. Cumulative LPA exposure decreased the odds of progressively worsening cfPWV [Odds ratio 0.994 (0.994-0.995); p < 0.0001] and cIMT. Persistent exposure to ≥60 min/day of MVPA was paradoxically associated with increased cfPWV progression in males 0.053 m/s; [(0.030 to 0.077); p < 0.001] and females 0.012 m/s; [(0.002 to 0.022); p = 0.016]. Persistent exposure to ≥60 min/day of MVPA was inversely associated with cIMT progression in females -0.017 mm; [(-0.026 to -0.009); p < 0.001].

CONCLUSION

LPA >3 h/day from childhood may attenuate progressively worsening vascular damage associated with increased ST in youth.

Mediating effect of fat mass, lean mass, blood pressure and insulin resistance on the associations of accelerometer-based sedentary time and physical activity with arterial stiffness, carotid IMT and carotid elasticity in 1574 adolescents

This study examined the mediating effect of total body fat mass, lean mass, blood pressure (BP) and insulin resistance on the associations of sedentary time (ST), light physical activity (LPA) and moderate-to-vigorous PA (MVPA) with carotid-femoral pulse wave velocity (cfPWV), carotid intima-media thickness (cIMT) and carotid elasticity in 1574 adolescents from the Avon Longitudinal Study of Parents and Children birth cohort, UK. ST, LPA and MVPA were assessed with ActiGraph accelerometer. ST and LPA were sex-categorised in tertiles as low (reference), moderate and high, while MVPA was categorised as <40 min/day (reference), 40-<60 min/day and ≥60 min/day. cfPWV, cIMT and carotid elasticity were measured with Vicorder and ultrasound. Fat mass and lean mass were assessed with dual-energy X-ray absorptiometry and homeostatic model assessment of insulin resistance (HOMA-IR) was computed. Mediation analyses structural equation models and linear mixed-effect models adjusted for cardiometabolic and lifestyle factors were conducted. Among 1574 adolescents [56.2% female; mean (SD) age 15.4 (0.24) years], 41% males and 17% females accumulated ≥60 min/day of MVPA. Higher ST was associated with lower cIMT partly mediated by lean mass. Higher LPA (standardized β = -0.057; [95% CI -0.101 to -0.013; p = 0.014]) and the highest LPA tertile were associated with lower cfPWV. BP had no significant mediating effect movement behaviour relations with vascular indices. Lean mass partially mediated associations of higher MVPA with higher cIMT (0.012; [0.007-0.002; p = 0.001], 25.5% mediation) and higher carotid elasticity (0.025; [0.014-0.039; p = 0.001], 28.1% mediation). HOMA-IR mediated the associations of higher MVPA with higher carotid elasticity (7.7% mediation). Engaging in ≥60 min/day of MVPA was associated with higher carotid elasticity. In conclusion, higher LPA was associated with lower arterial stiffness, but higher MVPA was associated with thicker carotid wall explained by higher lean mass.

Waist-circumference-to-height-ratio had better longitudinal agreement with DEXA-measured fat mass than BMI in 7237 children

BACKGROUND

The absolute agreement of surrogate measures of adiposity with dual-energy X-ray absorptiometry (DEXA)-measured body composition was examined.

METHODS

Over a 15-year follow-up, 7237 (3667 females) nine-year-old children from the Avon Longitudinal Study of Parents and Children (ALSPAC) UK birth cohort were included. Total fat mass (FM) and trunk FM were serially measured with DEXA at ages 9, 11, 15, 17, and 24 years. BMI and waist circumference-to-height ratio (WHtR) were computed. Pearson's correlations, intraclass correlations (ICC), and area under curve (AUC) analyses were conducted.

RESULTS

Over 15 years, BMI, total FM, and trunk FM, increased but WHtR was relatively stable. WHtR provided a better longitudinal absolute agreement [males ICC 0.84 (95% CI 0.84-0.85); females 0.81 (0.80-0.82)] than BMI [(males (0.65 (0.64-0.66); females 0.72 (0.71-0.73)] with total FM as well as trunk FM from ages 9-24 years. WHtR cut-point for predicting excess total FM (75th-95th percentile) was 0.50-0.53 in males [AUC 0.86-0.94, sensitivity 0.51-0.79 and specificity 0.93-0.95]. WHtR cut-point for predicting excess total FM (75th-95th percentile) was 0.52-0.54 in females [AUC 0.83-0.95, sensitivity 0.38-0.68 and specificity 0.92-0.95]. Results were similar with trunk FM.

CONCLUSION

WHtR is an inexpensive alternative to BMI for predicting FM in pediatrics.

IMPACT

Waist circumference-to-height ratio (WHtR) is a better adiposity surrogate measure than body mass index (BMI) in predicting fat mass and discriminating lean mass from childhood through young adulthood. BMI has been used as an inexpensive surrogate measure of adiposity in children for several decades. However, emerging findings suggest that BMI fails to discriminate between fat mass adiposity and lean mass. This is the first-ever longitudinal study in over 7000 children followed up for 15 years that identified WHtR as an inexpensive accurate measure that discriminates fat mass from lean mass that could replace BMI measure of obesity in pediatrics.

The cross-sectional and prospective associations of parental practices and environmental factors with 24-hour movement behaviours among school-aged Asian children

BACKGROUND

Parental practices and neighbourhood environmental factors may influence children's movement behaviours. We aimed to investigate the cross-sectional and prospective associations of parental practices and neighbourhood environmental factors with accelerometer-measured 24-hour movement behaviours (24 h-MBs) among school-aged children in Singapore.

METHODS

The Growing Up in Singapore Towards healthy Outcomes (GUSTO) study collected information on dimensions of parental practices and neighbourhood environment at age 5.5 years. Confirmatory factor analyses were performed to generate latent variables and used to compute overall parental practices [involvement in PA + support for PA + control of screen viewing context] and environmental scores [facilities for active play + active mobility facilitators + barriers*-1]. Children wore an accelerometer on their non-dominant wrist for seven consecutive days at ages 5.5 and 8 years. The R-package GGIR 2.6 was used to derive moderate-to-vigorous-intensity physical activity (MVPA), light-intensity physical activity (LPA), inactivity, and total-sleep (napping+night sleep) minutes per day. Associations were determined using compositional data analysis with multivariate linear regression models, taking into account potential confounders.

RESULTS

Among 425 children (48% girls, 59% Chinese), higher parental involvement in PA, parental support for PA and overall parental practices were associated with 24 h-MBs at ages 5.5 and 8 years, specifically with greater time spent in MVPA and less time being inactive relative to the remaining movement behaviours. The corresponding mean changes in the overall 24 h-MB for increasing parental practices from lowest to highest scores (- 2 to + 2 z-scores) indicated potential increases of up to 15-minutes in MVPA, 20-minutes in LPA, 5-minutes in sleep duration, and a reduction of 40-minutes in inactivity at age 5.5 years. At age 8 years, this could translate to approximately 15-minutes more of MVPA, 20-minutes more of LPA, a 20-minute reduction in sleep duration, and a 20-minute reduction in inactivity. Parental control of screen viewing contexts and neighbourhood environmental factors were not associated with 24 h-MBs.

CONCLUSIONS

Parental practices but not environmental factors were associated with higher MVPA and lower inactivity among Singaporean children, even at a later age. Further research may provide insights that support development of targeted public health strategies to promote healthier movement behaviours among children.

STUDY REGISTRATION

This study was registered on 4th August 2010 and is available online at ClinicalTrials.gov: NCT01174875.

Increasing lipids with risk of worsening cardiac damage in 1595 adolescents: A 7-year longitudinal and mediation study

BACKGROUND AND AIMS

Longitudinal evidence on the associations of changes in lipids level with changes in cardiac structure and function in youth is limited due to few repeated echocardiography measures. This study examined whether changes in lipid levels from adolescence through young adulthood associate with the risk of cardiac damage progression and potential mechanistic pathways.

METHODS

From the Avon Longitudinal Study of Parents and Children (ALSPAC), UK birth cohort, 1595 adolescents aged 17 years who had fasting plasma total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), and non-HDL-c measured at 17- and 24-year clinic visit were included. Echocardiography measured left ventricular mass indexed for height2.7 (LVMI2.7), and LV diastolic function from mitral E/A ratio (LVDF). LVMI2.7 ≥51 g/m2.7 and LVDF<1.5 were categorized as LV hypertrophy and LVD dysfunction, respectively. Multivariable adjusted associations were examined using generalized logit mixed-effect models and structural equation models for mediation analyses.

RESULTS

The prevalence of LV hypertrophy increased from 3.6% at baseline to 11.6% at follow-up in males and increased from 1.6% to 4.0% in females. The prevalence of LVD dysfunction increased from 7.8% at baseline to 16.6% at follow-up in males and increased from 10.3% to 15.4% in females. Each 1 mmol increase in total cholesterol (OR, 1.18; [95% CI, 1.09-1.27]), triglyceride (2.89; [1.54-5.43]), LDL-c (1.19; [1.08-1.32]), and non-HDL-c (1.21; [1.11-1.33]) was associated with higher odds of worsening LV hypertrophy progression over 7 years. Increased triglyceride was associated with the odds of progressively worsening LVD dysfunction (1.98; [1.06-3.71]). Increased HDL-c was not associated with the odds of cardiac structural and functional damage. Systolic blood pressure (12% mediation) and fat mass (25% mediation) partly mediated the associations of LDL-c with increased LVMI2.7.

CONCLUSIONS

Increased lipids may independently associate with the risk of progressively worsening structural and functional cardiac damage in youth but increased systolic blood pressure and fat mass explained circa forty percent of the relationship.

A natural experiment to assess recess frequency on children's physical activity in Arizona (U.S.) elementary schools

BACKGROUND

In the United States, the number of state policies mandating recess in schools has rapidly increased over the past decade; however, few policies specify recess frequency. Informed by an ecological model of physical activity (PA) policy, this study examined and compared total amounts and intensity of PA expended during recess among children attending schools in compliance with Arizona recess policy ARS§ 15-118 mandating 2 + daily recess periods versus not.

METHODS

PA during recess was measured among grade three children (ages 8-10) in four randomly selected elementary schools (two complying averaging 30 daily recess minutes; two non-complying averaging 15 daily recess minutes) in Maricopa County, Arizona. Group-level PA was assessed by direct observation using the System for Observing Play and Leisure (137 observations). A subset of students (N = 134) from all schools wore ActiGraph GT3X + devices during recess to measure individual PA. General linear mixed effects models were used to analyze the impact of recess frequency on group and individual PA during recess.

RESULTS

Students attending complying schools spent significantly greater proportions of time in moderate-to-vigorous PA (MVPA) based on direct observation (5%) and accelerometry (15%) and less time being sedentary based on accelerometry (14%) during recess. Across the school day, this would equate to 5.1 more MVPA minutes based on systematic direct observation and 9.5 more MVPA minutes based on accelerometry, and 4.1 less minutes being sedentary based on accelerometry if students received two daily 15-minute recess periods compared to one.

CONCLUSIONS

Students attending elementary schools implementing 2 + recesses, in accordance with state policy, demonstrated greater MVPA and less sedentary time, providing preliminary evidence that recess frequency is associated with greater PA intensity among children during recess. Schools that adhere to state-level PA policies may provide a more supportive environment for PA, resulting in increased movement among students. Specifying recess frequency should be considered in statewide recess policy.

DEXA-based Fat Mass with the Risk of Worsening Insulin Resistance in Adolescents: A 9-Year Temporal and Mediation Study

CONTEXT

Surrogate measures of childhood and adolescent obesity have impaired the understanding of body composition's relationship with insulin resistance in the young population.

OBJECTIVES

We aim to examine the longitudinal associations of directly measured total fat mass, trunk fat mass, and lean mass with the risk of hyperglycaemia, hyperinsulinemia, and insulin resistance from ages 15-24 years, the mediation path through which lipids and inflammation influence insulin resistance and whether increased fat mass temporally precede insulin resistance.

METHODS

We studied 3160 adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC), UK birth cohort, who had complete dual-energy Xray absorptiometry measure and fasting blood samples at age 15 years and repeated measures at ages 17- and 24-years clinic visit. Fasting glucose >6.1 mmol/L, insulin >11.78 mU/L, and homeostatic model assessment for insulin resistance (HOMA-IR) ≥75th percentile were categorized as hyperglycaemia, hyperinsulinemia, and high insulin resistance, respectively. Longitudinal associations were examined with generalized logit-mixed effect models, whilst mediation and temporal path analyses were examined using structural equation models, adjusting for cardiometabolic and other lifestyle factors.

RESULTS

Among 3160 participants (51% female), fat mass and lean mass increased linearly in both males and females while glucose, insulin, and HOMA-IR had a U-shaped course from age 15 through 24 years. After full adjustment, each 1 kg cumulative increase in total fat mass [odds ratio 1.12 (95% confidence interval 1.11-1.13)] and trunk fat mass [1.21 (1.19-1.23)] from ages 15 through 24 years were associated with a progressively worsening risk of high insulin resistance as well as hyperglycaemia and hyperinsulinemia. The association of increased total fat mass with increased insulin resistance was partly mediated by triglycerides (9% mediation). In the temporal path analysis, higher total fat mass at age 15 years was associated with higher insulin resistance at 17 years, but not vice versa. Higher total fat mass at 17 years was bi-directionally associated with higher insulin resistance at 24 years.

CONCLUSION

Mid-adolescence may be an optimal time for interrupting the worsening fat mass-insulin resistance pathologic cycle and attenuating the risk of progressively worsening metabolic dysfunction before young adulthood.

Effects of accelerometer-based sedentary time and physical activity on DEXA-measured fat mass in 6059 children

Globally, childhood obesity is on the rise and the effect of objectively measured movement behaviour on body composition remains unclear. Longitudinal and causal mediation relationships of accelerometer-based sedentary time (ST), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with dual-energy X-ray absorptiometry-measured fat mass were examined in 6059 children aged 11 years followed-up until age 24 years from the Avon Longitudinal Study of Parents and Children (ALSPAC), UK birth cohort. Over 13-year follow-up, each minute/day of ST was associated with 1.3 g increase in fat mass. However, each minute/day of LPA was associated with 3.6 g decrease in fat mass and each minute/day of MVPA was associated with 1.3 g decrease in fat mass. Persistently accruing ≥60 min/day of MVPA was associated with 2.8 g decrease in fat mass per each minute/day of MVPA, partly mediated by decrease insulin and low-density lipoprotein cholesterol. LPA elicited similar and potentially stronger fat mass-lowering effect than MVPA and thus may be targeted in obesity and ST prevention in children and adolescents, who are unable or unwilling to exercise.

Arterial stiffness but not carotid intima-media thickness progression precedes premature structural and functional cardiac damage in youth: A 7-year temporal and mediation longitudinal study

BACKGROUND AND AIMS

The longitudinal relations of cardiac indices with the aorta and carotid vessel and the time sequence for early cardiac disease development are uncharacterized in youth. We examined the temporal longitudinal associations of carotid-femoral pulse wave velocity (cfPWV) and carotid intima-media thickness (cIMT) with left ventricular hypertrophy (LVH) and diastolic dysfunction (LVDD).

METHODS

From the Avon Longitudinal Study of Parents and Children, UK birth cohort, 1856 adolescents (1011 females) at a mean (SD) age 17.7 (0.3) years were followed up for 7 years. Vicorder-measured cfPWV and ultrasound-measured cIMT were grouped in tertiles as low (reference), moderate, and high. Echocardiography measured cardiac abnormalities are left ventricular mass indexed for height2.7 (LVMI2.7) ≥51 g/m2.7 as LVH; relative wall thickness ≥44 as hiRWT; LVD function E/A <1.5 as LVD dysfunction (LVDD); and LV filling pressure E/e' ≥8 as hiLVFP. Data were analysed with generalized logit mixed-effect models, cross-lagged path, and mediation structural equation models adjusting for cardiometabolic and lifestyle factors.

RESULTS

Over follow-up, LVH prevalence increased from 3.6% to 7.2% and LVDD from 11.1 to 16.3%. High cfPWV progression was associated with worsening LVH [Odds ratio 1.23 (1.13-1.35); p < 0.001] in the total cohort, males, overweight/obese, and normotensive. High cfPWV progression was associated with worsening hiLVFP in the total cohort, females, and normal weight. Likewise, high cIMT progression was associated with worsening LVH [1.27 (1.26-1.27); p < 0.0001] in the total cohort, overweight/obese and elevated BP/hypertensive. Neither cfPWV nor cIMT progression was associated with worsening hiRWT in the total cohort. In cross-lagged models, higher baseline cfPWV was associated with future LVMI2.7 (β = 0.06, SE, 5.14, p = 0.035), RWT, LVDF, and LVFP. However, baseline LVMI2.7, RWT, LVDF, and LVFP were not associated with follow-up cfPWV. Baseline cIMT was not associated with follow-up cardiac indices and vice versa. Cumulative increased systolic blood pressure (34.3% mediation) and insulin resistance (15.1% mediation) mediated the direct associations of cumulative cfPWV with cumulative LVMI2.7.

CONCLUSIONS

Arterial stiffness progression temporally preceded worsening structural and functional cardiac damage in youth with increased systolic blood pressure and insulin resistance partly mediating the relationships. Future interventions aimed at attenuating premature cardiac damage in adolescents and young adults may consider a simultaneous treatment of both arterial stiffness, elevated blood pressure and insulin resistance.