The Australian Schools Health and Fitness Survey. Physical fitness related to blood pressure but not lipoproteins

Determining pathways of effect between correlates and outcomes of transport-related physical activity at differing timepoints across the lifecourse: A structural equation modelling approach

Transport-related physical activity levels differ across the lifecourse; however, the nature of these differences is poorly understood. This study examined the relationship between correlates of transport-related physical activity and how they differ in strength, pathway, and direction across the lifecourse. Structural Equation Modelling assessed relationships between correlates (e.g., age, smoking, education) and transport-related physical activity (assessed via the International Physical Activity Questionnaire) at four timepoints of the Australian Childhood Determinants of Adult Health study: childhood (7-15y; n = 6302), early-adulthood (26-36y; n = 2700), early/mid-adulthood (31-41y; n = 1649), and mid-adulthood (36-49y; n = 1794). Several pathways were consistent across the lifecourse. Self-rated health directly associated with transport-related physical activity across all timepoints. During adulthood greater body mass index and smoking frequency were indirectly associated with lower levels of transport-related physical activity via self-rated health; similarly, lower educated adults, who smoked more frequently, and had poorer health, had lower transport-related physical activity. Urban residence was directly associated with greater transport-related physical activity in childhood and early-adulthood; having more children in early/mid- and mid-adulthood was directly associated with less transport-related physical activity. This is the first study to report pathways of direct and indirect association between correlates and transport-related physical activity at key lifecourse stages. The pathways highlighted can inform policy and practice to aid in the development of age-specific lifecourse interventions.

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.

Exploring the direct and indirect effects of cardiovascular disease risk factors on exercise blood pressure

OBJECTIVE

Exaggerated exercise blood pressure (BP) is independently associated with cardiovascular disease (CVD) outcomes. However, it is unknown how individual CVD risk factors may interact with one another to influence exercise BP. The aim of this study was to quantify direct and indirect associations between CVD risk factors and exercise BP, to determine what CVD risk factor/s most-strongly relate to exercise BP.

METHODS

In a cross-sectional design, 660 participants (44 ± 2.6 years, 54% male) from the population-based Childhood Determinants of Adult Health Study had BP measured during low-intensity fixed-workload cycling. CVD risk factors were measured, including body composition, clinic (rest) BP, blood biomarkers, and cardiorespiratory fitness. Associations between CVD risk factors and exercise BP were assessed using linear regression, with direct and indirect pathways of association assessed via structural equation model.

RESULTS

Sex, waist-to-hip ratio, fitness, and clinic BP were independently associated with exercise systolic BP (SBP), and along with age, had direct associations with exercise SBP (p < 0.05 all). Most CVD risk factors were indirectly associated with exercise SBP via a relation with clinic BP (p < 0.05 all). Clinic BP, waist-to-hip ratio, and fitness were most-strongly associated (direct and indirect association) with exercise SBP (β[95% CI]: 9.35 [8.04, 10.67], 4.91 [2.56, 7.26], and -2.88 [-4.25, -1.51] mm Hg/SD, respectively).

CONCLUSION

Many CVD risk factors are associated with exercise BP, mostly with indirect effects via clinic BP. Clinic BP, body composition, and fitness were most-strongly associated with exercise BP. These results may elucidate how lifestyle modification could be a primary strategy to decrease exaggerated exercise BP-related CVD risk.

Trajectory of metabolic syndrome and its association with knee pain in middle-aged adults

OBJECTIVE

Metabolic syndrome (MetS) is characterised by the clustering of central obesity with metabolic abnormalities. We aimed to describe the association of MetS and trajectories of MetS over 10-13 years with knee symptoms in general population-based middle-aged adults.

METHODS

Fasting blood biochemistry, waist circumference and blood pressure measures were collected during Childhood Determinants of Adult Health (CDAH)-1 study (year:2004-6; n = 2447; mean age:31.48 ± 2.60) and after 10-13 year at CDAH-3 (year:2014-2019; n = 1549; mean age:44 ± 2.90). Participants were defined as having MetS as per International Diabetes Federation (IDF) definition. Knee symptoms were assessed using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale at CDAH-3 (mid-adulthood).

RESULTS

The prevalence of MetS increased from 8 % at young adulthood (female:52.06 %) to 13 % in mid-adulthood (female:53.78 %) over 10-13 years. Presence of MetS at mid-adulthood was associated with knee symptoms at mid-adulthood [ratio of means (RoM): 1.33; 95%CI:1.27,1.39]. Four MetS trajectories were identified-'No MetS' (85.01 %); 'Improved MetS' (2.14 %), 'Incident MetS' (8.81 %), and 'Persistent MetS, (4.04 %). Compared to 'No MetS', 'Persistent MetS' [RoM:1.15; 95%CI:1.06,1.25], 'Incident MetS' [RoM:1.56; 95%CI:1.48,1.65], and 'Improved MetS' [RoM:1.22; 95%CI:1.05,1.41] was associated with higher knee symptoms. Notably, 'Incident MetS' was strongly associated with knee symptoms [RoM: 1.56; 95%CI:1.48,1.65] and pain [RoM:1.52; 95%CI:1.37,1.70] at mid-adulthood.

CONCLUSION

In this sample of middle-aged adults, there was a significant positive association between MetS and knee symptoms. Relative to those without MetS at either life stage, the elevation in mean knee pain scores was more pronounced for those who developed MetS after young adulthood than for those who had MetS in young adulthood.

Sex differences in the association between stroke risk factors and pre-clinical predictors of stroke in the childhood determinants of Adult Health study

BACKGROUND AND AIMS

It is unclear why blood pressure (BP), metabolic markers and smoking increase stroke incidence in women more than men. We examined these associations with carotid artery structure and function in a prospective cohort study.

METHODS

Participants in the Australian Childhood Determinants of Adult Health study at ages 26-36 years (2004-06) were followed-up at 39-49 years (2014-19). Baseline risk factors included smoking, fasting glucose, insulin, systolic and diastolic BP. Carotid artery plaques, intima-media thickness [IMT], lumen diameter and carotid distensibility [CD] were assessed at follow up. Log binomial and linear regression with risk factor × sex interactions predicted carotid measures. Sex-stratified models adjusting for confounders were fitted when significant interactions were identified.

RESULTS

Among 779 participants (50% women), there were significant risk factor × sex interactions with baseline smoking, systolic BP and glucose associated with carotid measures in women only. Current smoking was associated with incidence of plaques (RRunadjusted 1.97 95% CI 1.4, 3.39), which reduced when adjusted for sociodemographics, depression, and diet (RRadjusted 1.82 95% CI 0.90, 3.66). Greater systolic BP was associated with lower CD adjusted for sociodemographics (βadjusted -0.166 95% CI -0.233, -0.098) and hypertension with greater lumen diameter (βunadjusted 0.131 95% CI 0.037, 0.225), which decreased when adjusted for sociodemographics, body composition and insulin (βadjusted 0.063 95% CI -0.052, 0.178). Greater glucose (βunadjusted -0.212 95% CI -0.397, -0.028) was associated with lower CD, which decreased when adjusted for sociodemographics, BP, depression and polycystic ovary syndrome (βadjusted -0.023 95% CI -0.249, 0.201).

CONCLUSIONS

Smoking, SBP and glucose affect carotid structure and function more in women than men with some of this risk due to co-occurring risk factors.

Metabolic Syndrome and Inflammation from Young to Mid-Adulthood and Subclinical Kidney Damage in Middle-Aged Australians

Background: Relationships between metabolic syndrome (MetS), inflammation, and chronic kidney disease (CKD) have been reported, but long-term follow-up studies are limited. This study aimed to investigate whether MetS and C-reactive protein (CRP) from young adulthood associated with the risk of subclinical kidney damage (SKD), a surrogate measure for CKD, in mid-adulthood. Materials and Methods: One thousand fifteen participants from the Childhood Determinants of Adult Health study aged 26-36 years at baseline (2004-2006) were followed up at age 36-49 (2014-2019). Log-binomial regression was used to determine whether MetS and high CRP in young adulthood and from young to mid-adulthood predicted the risk of SKD (an estimated glomerular filtration rate [eGFR] of 30-60 mL/min/1.73 m2 or an eGFR >60 mL/min/1.73 m2 with a urine albumin-creatinine ratio ≥2.5 mg/mmol [males] or ≥3.5 mg/mmol [females]) in midlife. Results: Having MetS in young adulthood was associated with an increased risk of SKD in midlife (adjusted relative risk [aRR] = 2.67, 95% confidence interval [CI]: 1.24-5.76). Participants with MetS and high CRP as young adults had a greater risk of having SKD in midlife (aRR = 4.27, 95% CI: 1.61-11.30) compared with those without MetS and high CRP. Furthermore, for participants with persistent MetS, the aRR of SKD in midlife was 4.08 (95% CI: 1.84-9.05) compared with those without MetS from young to mid-adulthood. No significant associations were found between CRP in young adulthood, or change in CRP from young to mid-adulthood, and SKD in midlife. Conclusions: MetS in young adulthood, with and without high CRP, and persistent MetS were associated with an increased risk of SKD in middle midlife.

Distinct patterns of adult transport-related physical activity (TRPA) behaviour exist independent of the TRPA behaviours of childhood: the childhood determinants of adult health study

BACKGROUND

Transport-related physical activity (TRPA) is recognised as a potential means of increasing total physical activity participation that may yield substantial health benefits. Public health campaigns focusing on promoting TRPA from a young age aim to develop life-long healthy habits. However, few studies have examined how TRPA changes across the lifecourse and whether childhood TRPA levels influence those observed later in life.

METHODS

Using the Australian Childhood Determinants of Adult Health study (baseline, 1985), latent class growth mixture modelling with adjustment for time-varying covariates was performed using four timepoints (ranging from 7 to 49 years) to assess behavioural patterns and retention of TRPA across the lifecourse. As child and adult adjusted TRPA measures could not be harmonised, trajectories of adult TRPA (n = 702) were instead identified, and log-binomial regression analysis was performed to determine whether childhood levels of TRPA (high/medium/low) influenced these trajectories.

RESULTS

Two stable groups of adult TRPA trajectories were identified: persistently low (n = 520; 74.2%), and increasingly high TRPA (n = 181; 25.8%). There was no significant relationship between childhood TRPA levels and patterns in adulthood (relative risk of high childhood TRPA yielding high adult TRPA trajectory membership = 1.06; 95% confidence interval = 0.95-1.09).

CONCLUSION

This study found childhood TRPA levels were not associated with TRPA patterns in adulthood. These findings suggest that while TRPA in childhood may have health, social, and environmental benefits, it does not appear to impact adult TRPA directly. Therefore, further intervention is required beyond childhood to promote the implementation of healthy TRPA behaviours into adulthood.

Association Between Risk Factors in Childhood and Sex Differences in Prevalence of Carotid Artery Plaques and Intima-Media Thickness in Mid-Adulthood in the Childhood Determinants of Adult Health Study

Background The origins of sex differences in cardiovascular diseases are not well understood. We examined the contribution of childhood risk factors to sex differences in adult carotid artery plaques and intima-media thickness (carotid IMT). Methods and Results Children in the 1985 Australian Schools Health and Fitness Survey were followed up when they were aged 36 to 49 years (2014-19, n=1085-1281). Log binomial and linear regression examined sex differences in adult carotid plaques (n=1089) or carotid IMT (n=1283). Childhood sociodemographic, psychosocial, and biomedical risk factors that might contribute to sex differences in carotid IMT/plaques were examined using purposeful model building with additional adjustment for equivalent adult risk factors in sensitivity analyses. Women less often had carotid plaques (10%) than men (17%). The sex difference in the prevalence of plaques (relative risk [RR] unadjusted 0.59 [95% CI, 0.43 to 0.80]) was reduced by adjustment for childhood school achievement and systolic blood pressure (RR adjusted 0.65 [95% CI, 0.47 to 0.90]). Additional adjustment for adult education and systolic blood pressure further reduced sex difference (RR adjusted 0.72 [95% CI, 0.49 to 1.06]). Women (mean±SD 0.61±0.07) had thinner carotid IMT than men (mean±SD 0.66±0.09). The sex difference in carotid IMT (β unadjusted -0.051 [95% CI, -0.061 to -0.042]) reduced with adjustment for childhood waist circumference and systolic blood pressure (β adjusted -0.047 [95% CI, -0.057 to -0.037]) and further reduced with adjustment for adult waist circumference and systolic blood pressure (β adjusted -0.034 [95% CI, -0.048 to -0.019]). Conclusions Some childhood factors contributed to adult sex differences in plaques and carotid IMT. Prevention strategies across the life course are important to reduce adult sex differences in cardiovascular diseases.

Use of clinical scores in young Australian adults for prediction of atherosclerosis in middle age

We sought to apply a simple cardiovascular health tool not requiring laboratory tests (the Fuster-BEWAT score, FBS) to predict subclinical atherosclerosis. This study included 2657 young adults (< 40 years of age). In the prognostic group (n = 894, followed for 13 years until aged 40-50 years at follow-up), the primary outcome was presence of carotid plaque measured by carotid ultrasound at follow-up. Of these 894 participants, 86 (9.6%) had unilateral, and 23 participants (2.6%) had bilateral, carotid plaques at follow-up. The baseline FBS was predictive of carotid plaque at follow-up [odds ratio OR = 0.86 (95% CI 0.77-0.96) per 1-SD increase in FBS], similar to prediction from Pooled Cohort Equation [PCE, OR = 0.72 (0.61-0.85) per 1-SD decrease in PCE]. Risk scores at baseline predicted outcomes more strongly than those at follow-up, and did so independently of any changes over 13 years of follow-up. Similar discrimination for predicting carotid plaque after 13 years was found for both baseline FBS [C-statistic = 0.68 (95% CI 0.62-0.74)] and PCE [C-statistic = 0.69 (95% CI 0.63-0.75)]. Application of this FBS prognostic information to a contemporary cohort of 1763 young adults anticipates the future development of plaque in 305 (17.3%), especially in the 1494 participants (85%) with ≤ 2 metrics of ideal health. In conclusions, FBS measured in young adulthood predicted atherosclerosis 13 years later in middle age, independent of score changes over the follow-up period, emphasizing the importance of early damage to vascular health. FBS may be a simple and feasible risk score for engaging low-risk young people with reduction of future cardiovascular risk.

Associations between childhood to adulthood socio-economic mobility and adult diet quality

The impact of change in socio-economic status (SES) from childhood to adulthood (SES mobility) on adult diet is not well understood. This study examined associations between three SES mobility variables (area disadvantage, education, occupation) and adult diet quality. 1482 Australian participants reported childhood area-level SES in 1985 (aged 10-15 years) and retrospectively reported highest parental education and main occupation (until participant age 12) and own area-level SES, education, occupation and dietary intake in 2004-2006 (aged 26-36 years). A Dietary Guidelines Index (DGI) was calculated from food frequency and habit questionnaires. A higher score (range 0-100) indicated better diet quality. Sex-stratified linear regression models adjusted for confounders. Area-level SES mobility was not associated with diet quality. Compared with stable high (university) education, stable low (school only) was associated with lower DGI scores (males: β = -5·5, 95 % CI: -8·9, -2·1; females: β = -6·3, 95 % CI: -9·3, -3·4), as was downward educational mobility (participant's education lower than their parents) (males: β = -5·3, 95 % CI: -8·5, -2·0; females: β = -4·5, 95 % CI: -7·2, -1·7) and stable intermediate (vocational) education among males (β = -3·9, 95 % CI: -7·0, -0·7). Compared with stable high (professional/managerial) occupation, stable low (manual/out of workforce) males (β = -4·9, 95 % CI: -7·6, -2·2), and participants with downward occupation mobility (males: β = -3·2, 95 % CI: -5·3, -1·1; females: β = -2·8, 95 % CI: -4·8, -0·8) had lower DGI scores. In this cohort, intergenerational low education and occupation, and downward educational and occupational mobility, were associated with poor adult diet quality.

Associations of a healthy lifestyle score from childhood to adulthood with subclinical kidney damage in midlife: a population-based cohort study

Background

The relationships of healthy lifestyle scores (HLS) of various kinds in adulthood with the risk of chronic kidney disease (CKD) have been reported, but little is known about the association of childhood lifestyle with later life CKD. This study examined the relationship of HLS from childhood to adulthood with subclinical kidney damage (SKD) in midlife, a surrogate measure for CKD.

Methods

Data were collected in an Australian population-based cohort study with 33 years follow-up. 750 participants with lifestyle information collected in childhood (ages 10–15 years) and midlife (ages 40–50 years), and measures of kidney function in midlife were included. The HLS was generated from the sum scores of five lifestyle factors (body mass index, smoking, alcohol consumption, physical activity, and diet). Each factor was scored as poor (0 point), intermediate (1 point), or ideal (2 points). Log-binomial regression was used to investigate the relationship of HLS in childhood and from childhood to adulthood with SKD defined as either 1) estimated glomerular filtration rate (eGFR) 30–60 mL/min/1.73m² or 2) eGFR> 60 mL/min/1.73m² with urine albumin-creatinine ratio ≥ 2.5 mg/mmol (males) or 3.5 mg/mmol (females), adjusting for socio-demographic factors and the duration of follow-up.

Results

The average HLS was 6.6 in childhood and 6.5 in midlife, and the prevalence of SKD was 4.9% (n = 36). Neither HLS in childhood nor HLS from childhood to adulthood were significantly associated with the risk of SKD in midlife.

Conclusions

A HLS from childhood to adulthood did not predict SKD in this middle-aged, population-based Australian cohort.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02627-0.

Risk factors for left ventricular dysfunction in adulthood: role of low birth weight

Aims

This study aimed to determine the relationship of low birth weight (LBW) with adult cardiac structure and function and investigate potential causal pathways.

Methods and results

A population‐based sample of 925 Australians (41.3% male) were followed from childhood (aged 7–15 years) to young adulthood (aged 26–36 years) and mid‐adulthood (aged 36–50 years). Left ventricular (LV) global longitudinal strain (GLS, %), LV mass index (LVMi, g/m^2.7), LV filling pressure (E/e′), and left atrial volume index (g/m²) were measured by transthoracic echocardiography in mid‐adulthood. Birth weight category was self‐reported in young adulthood and classified as low (≤5 lb or ≤2270 g), normal (5–8 lb or 2271–3630 g), and high (>8 lb or >3630 g). Of the 925 participants, 7.5% (n = 69) were classified as LBW. Compared with participants with normal birth weight, those with LBW had 2.01‐fold (95% confidence interval: 1.19, 3.41, P = 0.009) higher risks of impaired GLS (GLS > −18%) and 2.63‐fold (95% confidence interval: 0.89, 7.81, P = 0.08) higher risks of LV hypertrophy (LVMi > 48 g/m^2.7 in men or >44 g/m^2.7 in women) in adulthood, independent of age, sex, and any socio‐economic factors. Participants with LBW significantly increased body fat from childhood to adulthood relative to their peers and had greater levels of triglycerides, fasting glucose, and arterial stiffness in adulthood. These risk factors were the strongest mediators and explained 54% of the LBW effect size on adult GLS and 33% of the LBW effect size on LVMi. The remaining of these associations was independent of any of the measured risk factors.

Conclusions

Low birth weight was associated with impaired cardiac structure and function in mid‐adulthood. This association was only partially explained by known risk factors.

Retrospectively Estimating Energy Intake and Misreporting From a Qualitative Food Frequency Questionnaire: An Example Using Australian Cohort and National Survey Data

Qualitative food frequency questionnaires (Q-FFQ) omit portion size information from dietary assessment. This restricts researchers to consumption frequency data, limiting investigations of dietary composition (i.e., energy-adjusted intakes) and misreporting. To support such researchers, we provide an instructive example of Q-FFQ energy intake estimation that derives typical portion size information from a reference survey population and evaluates misreporting. A sample of 1,919 Childhood Determinants of Adult Health Study (CDAH) participants aged 26-36 years completed a 127-item Q-FFQ. We assumed sex-specific portion sizes for Q-FFQ items using 24-h dietary recall data from the 2011-2012 Australian National Nutrition and Physical Activity Survey (NNPAS) and compiled energy density values primarily using the Australian Food Composition Database. Total energy intake estimation was daily equivalent frequency × portion size (g) × energy density (kJ/g) for each Q-FFQ item, summed. We benchmarked energy intake estimates against a weighted sample of age-matched NNPAS respondents (n = 1,383). Median (interquartile range) energy intake was 9,400 (7,580-11,969) kJ/day in CDAH and 9,055 (6,916-11,825) kJ/day in weighted NNPAS. Median energy intake to basal metabolic rate ratios were 1.43 (1.15-1.78) in CDAH and 1.35 (1.03-1.74) in weighted NNPAS, indicating notable underreporting in both samples, with increased levels of underreporting among the overweight and obese. Using the Goldberg and predicted total energy expenditure methods for classifying misreporting, 65 and 41% of CDAH participants had acceptable/plausible energy intake estimates, respectively. Excluding suspected CDAH misreporters improved the plausibility of energy intake estimates, concordant with expected body weight associations. This process can assist researchers wanting an estimate of energy intake from a Q-FFQ and to evaluate misreporting, broadening the scope of diet-disease investigations that depend on consumption frequency data.

Association of body composition, physical activity and physical performance with knee cartilage thickness and bone area in young adults

OBJECTIVE

To describe associations of body composition, physical activity and physical performance with knee cartilage thickness and subchondral bone area in young adults.

METHODS

Body composition, physical activity and physical performance were measured 4-5 years prior to knee MRI. Cartilage thickness and bone area were measured quantitatively from MRI. Associations were assessed using linear regression analysis, with mediators being identified using mediation analysis.

RESULTS

Participants (n = 186) were 31-41 years of age when the MRI was acquired and 48% were female. Greater lean mass was positively associated with cartilage thickness [β = 6.52 μm/kg (95% CI 0.86, 12.18)] and bone area [β = 13.37 mm2/kg (95% CI 5.43, 21.31)]. Physical performance measures were positively associated with cartilage thickness [long jump: β = 2.44 μm/cm (95% CI 0.70, 4.18); hand grip strength: 7.74 μm/kg (95% CI 1.50, 13.98); physical work capacity: 1.07 μm/W (95% CI 0.29, 1.85)] and bone area [long jump: β = 3.99 mm2/cm (95% CI 0.64, 7.34); hand grip strength: 19.06 mm2/kg (95% CI 7.21, 30.92); leg strength: 3.18 mm2/kg (95% CI 1.09, 5.28); physical work capacity: 3.15 mm2/W (95% CI 1.70, 4.60)]. Mediation analysis suggested these associations were mediated by lean mass (effect mediated: 27-95%).

CONCLUSION

Greater lean mass and better physical performance measured 4-5 years prior were associated with greater knee cartilage thickness and subchondral bone area in young adults, and the associations of physical performance were largely mediated by lean mass. These findings suggest lean mass may play an important role in maintaining knee joint health in young adults.

Non-HDL Cholesterol Levels in Childhood and Carotid Intima-Media Thickness in Adulthood

BACKGROUND

Elevated non-high-density lipoprotein cholesterol (HDL-C) levels are used to identify children at increased cardiovascular risk, but the use of non-HDL-C in childhood to predict atherosclerosis is unclear. We examined whether the National Heart, Lung, and Blood Institute classification of youth non-HDL-C status predicts high common carotid artery intima-media thickness in adulthood.

METHODS

We analyzed data from 4 prospective cohorts among 4582 children aged 3 to 19 years who were remeasured as adults (mean follow-up of 26 years). Non-HDL-C status in youth and adulthood was classified according to cut points of the National Heart, Lung, and Blood Institute and the National Cholesterol Education Program Adult Treatment Panel III. High carotid intima-media thickness (cIMT) in adulthood was defined as at or above the study visit-, age-, sex-, race-, and cohort-specific 90th percentile of intima-media thickness.

RESULTS

In a log-binomial regression analysis adjusted with age at baseline, sex, cohort, length of follow-up, baseline BMI, and systolic blood pressure, children with dyslipidemic non-HDL-C were at increased risk of high cIMT in adulthood (relative risk [RR], 1.29; 95% confidence interval [CI], 1.07-1.55). Compared with the persistent normal group, the persistent dyslipidemia group (RR, 1.80; 95% CI, 1.37-2.37) and incident dyslipidemia (normal to dyslipidemia) groups (RR, 1.45; 95% CI, 1.07-1.96) had increased risk of high cIMT in adulthood, but the risk was attenuated for the resolution (dyslipidemia to normal) group (RR, 1.17; 95% CI, 0.97-1.41).

CONCLUSIONS

Dyslipidemic non-HDL-C levels predict youth at risk for developing high cIMT in adulthood. Those who resolve their non-HDL-C dyslipidemia by adulthood have normalized risk of developing high cIMT in adulthood.

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 great leap backward: changes in the jumping performance of Australian children aged 11-12-years between 1985 and 2015

Previous data have indicated relative stability over time of paediatric jumping performance, but few data exist since the early 2000s. This study quantified the 30-year secular changes in jumping performance of Australian children aged 11-12-years using data from the Australian Schools Health and Fitness Survey (1985, n = 1967) and Growing Up in Australia's Child Health CheckPoint (2015, n = 1765). Both cohorts measured jumping performance (standing long jump distance), anthropometric and demographic data. Secular changes in jumping performance means and quantiles were examined using multivariable linear and quantile regression. Between 1985 and 2015, jumping performance declined by 16.4 cm or by 11.2% (standardised change 0.66 SD, 95%CI 0.60 to 0.73). Adjustment for body mass reduced the effect by 32%, although the decline remained (absolute change - 11.1 cm, 95%CI -12.5 to -9.7; percent change 7.7%, 95%CI 6.7 to 8.6; standardised change 0.51 SD, 95%CI 0.44 to 0.57). This decline was evident across all quantiles. The jumping performance of Australian children aged 11-12-years has declined between 1985 and 2015, with body mass changes accounting for only part of the decline. Efforts should continue to promote paediatric muscular fitness, reduce adiposity, and aim to reverse this decline in jumping performance.

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-β), high fasting insulin, and impaired fasting glucose (IFG).

RESULTS

All child anthropometric measures were significantly associated with HOMA2-IR, HOMA2-β, 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-β (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.

Cross-Sectional Associations between Dietary Fat-Related Behaviors and Continuous Metabolic Syndrome Score among Young Australian Adults

Dietary guidelines recommend removing visible fat from meat, choosing low-fat options and cooking with oil instead of butter. This study examined cross-sectional associations between fat-related eating behaviors and a continuous metabolic syndrome (cMetSyn) score among young adults. During 2004–2006, 2071 participants aged 26–36 years reported how often they trimmed fat from meat, consumed low-fat dairy products and used different types of fat for cooking. A fasting blood sample was collected. Blood pressure, weight and height were measured. To create the cMetSyn score, sex-specific principal component analysis was applied to normalized risk factors of the harmonized definition of metabolic syndrome. Higher score indicates higher risk. For each behavior, differences in mean cMetSyn score were calculated using linear regression adjusted for confounders. Analyses were stratified by weight status (Body mass index (BMI) < 25 kg/m² or ≥ 25 kg/m²). Mean cMetSyn score was positively associated with consumption of low-fat oily dressing (P_Trend = 0.013) among participants who were healthy weight and frequency of using canola/sunflower oil for cooking (P_Trend = 0.008) among participants who were overweight/obese. Trimming fat from meat, cooking with olive oil, cooking with butter, and consuming low-fat dairy products were not associated with cMetSyn score. Among young adults, following fat-related dietary recommendations tended to not be associated with metabolic risk.

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 (β: 0.41, 95% CI 0.03, 0.78 for > 1-h increase in TV viewing/day) was not explained by TV-related FBC (β: 0.37, 95% CI -0.18, 0.91) or LTPA (β: 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.

Impact of Lipid Measurements in Youth in Addition to Conventional Clinic-Based Risk Factors on Predicting Preclinical Atherosclerosis in Adulthood: International Childhood Cardiovascular Cohort Consortium

BACKGROUND

Data suggest that the prediction of adult cardiovascular disease using a model comprised entirely of adult nonlaboratory-based risk factors is equivalent to an approach that additionally incorporates adult lipid measures. We assessed and compared the utility of a risk model based solely on nonlaboratory risk factors in adolescence versus a lipid model based on nonlaboratory risk factors plus lipids for predicting high-risk carotid intima-media thickness (cIMT) in adulthood.

METHODS

The study comprised 2893 participants 12 to 18 years of age from 4 longitudinal cohort studies from the United States (Bogalusa Heart Study and the Insulin Study), Australia (Childhood Determinants of Adult Health Study), and Finland (The Cardiovascular Risk in Young Finns Study) and followed into adulthood when cIMT was measured (mean follow-up, 23.4 years). Overweight status was defined according to the Cole classification. Hypertension was defined according to the Fourth Report on High Blood Pressure in Children and Adolescents from the National High Blood Pressure Education Program. High-risk plasma lipid levels were defined according to the National Cholesterol Education Program Expert Panel on Cholesterol Levels in Children. High cIMT was defined as a study-specific value ≥90th percentile. Age and sex were included in each model.

RESULTS

In univariate models, all risk factors except for borderline high and high triglycerides in adolescence were associated with high cIMT in adulthood. In multivariable models (relative risk [95% confidence interval]), male sex (2.7 [2.0-2.6]), prehypertension (1.4 [1.0-1.9]), hypertension (1.9 [1.3-2.9]), overweight (2.0 [1.4-2.9]), obesity (3.7 [2.0-7.0]), borderline high low-density lipoprotein cholesterol (1.6 [1.2-2.2]), high low-density lipoprotein cholesterol (1.6 [1.1-2.1]), and borderline low high-density lipoprotein cholesterol (1.4 [1.0-1.8]) remained significant predictors of high cIMT (P<0.05). The addition of lipids into the nonlaboratory risk model slightly but significantly improved discrimination in predicting high cIMT compared with nonlaboratory-based risk factors only (C statistics for laboratory-based model 0.717 [95% confidence interval, 0.685-0.748] and for nonlaboratory 0.698 [95% confidence interval, 0.667-0.731]; P=0.02).

CONCLUSIONS

Nonlaboratory-based risk factors and lipids measured in adolescence independently predicted preclinical atherosclerosis in young adulthood. The addition of lipid measurements to traditional clinic-based risk factor assessment provided a statistically significant but clinically modest improvement on adolescent prediction of high cIMT in adulthood.

Association between childhood health, socioeconomic and school-related factors and effort-reward imbalance at work: a 25-year follow-up study

OBJECTIVES

Stress pathways can have origins in childhood, but few early predictors have been explored in relation to adult job stress. This study examined whether childhood school, health or socioeconomic factors were associated with adult job stress.

METHODS

Data came from the Childhood Determinants of Adult Health study that began in 1985 with children aged 7-15 years who reported effortreward imbalance (ERI) scales at ages 31-41 years. Linear regression assessed the association between childhood factors and adult ERI adjusted for age and socioeconomic position (SEP) in childhood and adulthood.

RESULTS

There were between 999 and 1390 participants in each analysis. Lower adulthood ERI, indicating less job stress, was predicted by several school-related factors in men. For example, each higher category of learner self-concept was associated with a 19% (95% CI - 32% to 6%) reduction in adult ERI, and each unit increase in academic attainment was associated with a 15% (95% CI -28% to 3%) reduction in adult ERI. Childhood health was associated with adult ERI. For example, in women, overweight children had 14% (95% CI 5% to 22%) higher adult ERI scores compared with healthy weight children, and each unit of negative affect was associated with 2% (95% CI 1% to 4%) increase in adult ERI. Adult SEP had no effect on these associations for men but explained some of the effect in women. Childhood SEP had inconsistent associations with adult ERI.

CONCLUSION

Our findings suggest that a range of childhood socioeconomic, school- and health-related factors might contribute to the development of job stress in adulthood.

Physical activity stages of change surveillance data shows that the majority of Hawai'i's Keiki (Children) meet the guidelines

Targeting Native Hawaiian and other Pacific Islander (NHOPI) children based on their physical activity (PA) stages of change (SOC) may improve intervention effectiveness. No known SOC surveillance system exists for NHOPI jurisdictions. The purpose was to determine the PA SOC prevalence over 5 years in children living in Hawai'i. Self-reported PA SOC from 5 cohorts (3-6 grade students) in Hawai'i were compared between cohorts and sex. The combined PA SOC distribution (n = 1726, 50.7% female) was: Precontemplation, 7.5%; Contemplation, 7.6%; Preparation, 9.9%; Action, 33.4%; Maintenance, 41.5%. There were no significant difference between cohorts 1 and 2 (n = 258), χ² (16) = 21.75, p = 0.15; 2 and 3 (n = 129), χ² (16) = 17.51, p = 0.35; 3 and 4 (n = 171), χ² (16) = 17.28, p = 0.77; 4 and 5 (n = 129), χ² (16) = 17.51, p = 0.35; and for all cohorts between males and females (p > 0.05). Most participants were in Action and Maintenance. Prevention efforts should emphasize maintaining PA levels. Extending PA behavior surveillance systems to include intention in NHOPI jurisdictions is warranted.

Tracking of muscular strength and power from youth to young adulthood: Longitudinal findings from the Childhood Determinants of Adult Health Study

OBJECTIVES

Low muscular fitness levels have previously been reported as an independent risk factor for chronic disease outcomes. Muscular fitness tracking, the ability to maintain levels measured at one point in time to another point in time, was assessed from youth to adulthood to provide insight into whether early identification of low muscular fitness in youth is possible.

DESIGN

Prospective longitudinal study.

METHODS

Study including 623 participants who had muscular fitness measures in 1985 (aged 9, 12 or 15 years) and again 20 years later in young adulthood. Measures of muscular fitness were strength (right and left grip, leg, shoulder extension and flexion measured by dynamometer, and a combined strength score) and power (standing long jump distance).

RESULTS

Strength and power were relatively stable between youth and adulthood; the strongest tracking correlations were observed for the combined strength score (r=0.47, p≤0.001), right grip strength (r=0.43, p≤0.001) and standing long jump (r=0.43, p≤0.001). Youth in the lowest third of muscular fitness had an increased risk of remaining in the lowest third of muscular fitness in adulthood (strength: relative risk (RR)=4.70, 95% confidence interval (CI) (3.19, 6.92); power: RR=4.06 (2.79, 5.90)).

CONCLUSIONS

Youth with low muscular fitness are at increased risk of maintaining a low muscular fitness level into adulthood. These findings warrant investigation into the long term effects of early interventions that focus on improving low muscular fitness levels in youth which could potentially improve adult muscular fitness and reduce future chronic disease outcomes.

Childhood fitness reduces the long-term cardiometabolic risks associated with childhood obesity

OBJECTIVE

The objective of this study was to examine whether childhood cardiorespiratory fitness attenuates or modifies the long-term cardiometabolic risks associated with childhood obesity.

DESIGN AND METHODS

The study consisted of a 20-year follow-up of 1792 adults who participated in the 1985 Australian Schools Health and Fitness Survey when they were 7-15 years of age. Baseline measures included a 1.6-km run to assess cardiorespiratory fitness and waist circumference to assess abdominal adiposity. At follow-up, participants attended study clinics where indicators of Metabolic Syndrome (MetS) (waist circumference, blood pressure, fasting blood glucose and lipids) were measured and cardiorespiratory fitness was reassessed using a submaximal graded exercise test.

RESULTS

Both high waist circumference and low cardiorespiratory fitness in childhood were significant independent predictors of MetS in early adulthood. The mutually adjusted relative risk of adult MetS was 3.00 (95% confidence interval: 1.85-4.89) for children in the highest (vs lowest) third of waist circumference and 0.64 (95% confidence interval: 0.43-0.96) for children with high (vs low) cardiorespiratory fitness. No significant interaction between waist circumference and fitness was observed, with higher levels of childhood fitness associated with lower risks of adult MetS among those with either low or high childhood waist circumference values. Participants who had both high waist circumference and low cardiorespiratory fitness in childhood were 8.5 times more likely to have MetS in adulthood than those who had low waist circumference and high cardiorespiratory fitness in childhood. Regardless of childhood obesity status, participants with low childhood fitness who increased their relative fitness by adulthood had a substantially lower prevalence of MetS than those who remained low fit.

CONCLUSIONS

Childhood waist circumference and cardiorespiratory fitness are both strongly associated with cardiometabolic health in later life. Higher levels of cardiorespiratory fitness substantially reduce the risk of adult MetS, even among those with abdominal obesity in childhood.

Acculturation is Not Related to Physical Activity Stage of Change for Children in Hawai'i

The relationship between acculturation and physical activity stages of change is unexplored. Stages of change conceptualize behavior change as a progression through a series of five stages indicating the readiness to change behavior. The level of acculturation can be assessed using the Ethnocultural Identity Behavioral Index (EIBI) which is based on three factors: Cultural Activities, Social Interaction and Language Opportunities. The purpose of this project was to explore the relationship between parental acculturation and physical activity stages of change in Hawai'i children. Participants (N = 85; 62% female; aged 5-8 years; 22% Native Hawaiian or Other Pacific Islanders, 42% Asian, 25% White, and 11% Other) completed the EIBI and a physical activity stages of change measure. Acculturation factor means were: Cultural Activities = 4 (SD = 1.26), Social Interaction = 3 (SD = 1.04), and Language Opportunities = 4 (SD = 1.29). The physical activity stages of change distribution was Precontemplation = 11 (13%), Contemplation/Preparation = 15 (18%), and Action/Maintenance = 59 (69%). Analysis of covariance (ANCOVA) for Cultural Activities F(3, 81) = 0.77, P = .47, Social Interaction F(3, 81) = 0.93, P = .40; and Language Opportunities F(3, 81) = 1.34, P = .27 showed no significant differences between physical activity stages of change. The results of our study do not show an association between acculturation and readiness to change for physical activity. The lack of differences may be due to participants being moderately acculturated, possibly lessening the differentiation of acculturation by physical activity stages of change.

Correlates of knee bone marrow lesions in younger adults

BACKGROUND

Subchondral bone marrow lesions (BMLs) play a key role in the pathogenesis of osteoarthritis (OA) and are associated with pain and structural progression in knee OA. However, little is known about clinical significance and determinants of BMLs of the knee joint in younger adults. We aimed to describe the prevalence and environmental (physical activity), structural (cartilage defects, meniscal lesions) and clinical (pain, stiffness, physical dysfunction) correlates of BMLs in younger adults and to determine whether cholesterol levels measured 5 years prior were associated with current BMLs in young adults.

METHODS

Subjects broadly representative of the Australian young adult population (n = 328, aged 31-41 years, female 48.7 %) underwent T1- and proton density-weighted fat-suppressed magnetic resonance imaging (MRI) in their dominant knee. BMLs, cartilage defects, meniscal lesions and cartilage volume were measured. Knee pain was assessed by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and physical activity was measured by the International Physical Activity Questionnaire (IPAQ). Cholesterol levels including high-density lipoprotein (HDL) were assessed 5 years prior to MRI.

RESULTS

The overall prevalence of BML was 17 % (grade 1: 10.7 %, grade 2: 4.3 %, grade 3: 1.8 %). BML was positively associated with increasing age and previous knee injury but not body mass index. Moderate physical activity (prevalence ratio (PR):0.93, 95 % CI: 0.87, 0.99) and HDL cholesterol (PR:0.36, 95 % CI: 0.15, 0.87) were negatively associated with BML, while vigorous activity (PR:1.02, 95 % CI: 1.01, 1.03) was positively associated with medial tibiofemoral BMLs. BMLs were associated with more severe total WOMAC knee pain (>5 vs ≤5, PR:1.05, 95 % CI: 1.02, 1.09) and WOMAC dysfunction (PR:1.75, 95 % CI: 1.07, 2.89), total knee cartilage defects (PR:2.65, 95 % CI: 1.47, 4.80) and total meniscal lesion score (PR:1.92, 95 % CI: 1.13, 3.28).

CONCLUSIONS

BMLs in young adults are associated with knee symptoms and knee structural lesions. Moderate physical activity and HDL cholesterol are beneficially associated with BMLs; in contrast, vigorous physical activity is weakly but positively associated with medial tibiofemoral BMLs.

Vigorous physical activity and carotid distensibility in young and mid-aged adults

Although physical activity (PA) improves arterial distensibility, it is unclear which type of activity is most beneficial. We aimed to examine the association of different types of PA with carotid distensibility (CD) and the mechanisms involved. Data included 4503 Australians and Finns aged 26-45 years. Physical activity was measured by pedometers and was self-reported. CD was measured using ultrasound. Other measurements included resting heart rate (RHR), cardiorespiratory fitness (CRF), blood pressure, biomarkers and anthropometry. Steps/day were correlated with RHR (Australian men r = -0.10, women r = - 0.14; Finnish men r = -0.15, women r = -0.11; P<0.01), CRF and biochemical markers, but not with CD. Self-reported vigorous leisure-time activity was more strongly correlated with RHR (Australian men r = -0.23, women r = -0.19; Finnish men r = -0.20, women r = -0.13; P < 0.001) and CRF, and was correlated with CD (Australian men r = 0.07; Finnish men r = 0.07, women r = 0.08; P < 0.05). This relationship of vigorous leisure-time activity with CD was mediated by RHR independently of potential confounders. In summary, vigorous leisure-time PA but not total or less intensive PA was associated with arterial distensibility in young to mid-aged adults. Promotion of vigorous PA is therefore recommended among this population. RHR was a key intermediary factor explaining the relationship between vigorous PA and arterial distensibility.

Self-recalled Youth Physical Activity and Postmenopausal Cardiovascular Disease

OBJECTIVES

To evaluate the association between childhood physical activity and incident cardiovascular disease (CVD) during postmenopausal years.

METHODS

Proportional hazards and logistic regression were used describe the association between self-reported childhood physical activity and CVD incidence and mortality in 36,741 postmenopausal women.

RESULTS

Older women, African-Americans, or nondrinkers or past drinkers self-reported the highest levels of youth physical activity and women with a history of diabetes, hypertension, overweight or obesity, or current smoking reported the highest youth physical activity dose. Youth physical activity was not associated with CVD incidence (HR=1.11; 0.93, 1.34) or mortality (HR=1.2; 0.9, 1.73).

CONCLUSIONS

Self-reported youth activity was not associated with postmenopausal CVD incidence or mortality.

Impact of adiposity on cardiac structure in adult life: the Childhood Determinants of Adult Health (CDAH) study

BACKGROUND

We have examined the association between adiposity and cardiac structure in adulthood, using a life course approach that takes account of the contribution of adiposity in both childhood and adulthood.

METHODS

The Childhood Determinants of Adult Health study (CDAH) is a follow-up study of 8,498 children who participated in the 1985 Australian Schools Health and Fitness Survey (ASHFS). The CDAH follow-up study included 2,410 participants who attended a clinic examination. Of these, 181 underwent cardiac imaging and provided complete data. The measures were taken once when the children were aged 9 to 15 years, and once in adult life, aged 26 to 36 years.

RESULTS

There was a positive association between adult left ventricular mass (LVM) and childhood body mass index (BMI) in males (regression coefficient (β) 0.41; 95% confidence interval (CI): 0.14 to 0.67; p = 0.003), and females (β = 0.53; 95% CI: 0.34 to 0.72; p < 0.001), and with change in BMI from childhood to adulthood (males: β = 0.27; 95% CI: 0.04 to 0.51; p < 0.001, females: β = 0.39; 95% CI: 0.20 to 0.58; p < 0.001), after adjustment for confounding factors (age, fitness, triglyceride levels and total cholesterol in adulthood). After further adjustment for known potential mediating factors (systolic BP and fasting plasma glucose in adulthood) the relationship of LVM with childhood BMI (males: β = 0.45; 95% CI: 0.19 to 0.71; p = 0.001, females: β = 0.49; 95% CI: 0.29 to 0.68; p < 0.001) and change in BMI (males: β = 0.26; 95% CI: 0.04 to 0.49; p = 0.02, females: β = 0.40; 95% CI: 0.20 to 0.59; p < 0.001) did not change markedly.

CONCLUSIONS

Adiposity and increased adiposity from childhood to adulthood appear to have a detrimental effect on cardiac structure.

The cross-sectional association of sitting time with carotid artery stiffness in young adults

OBJECTIVES

Physical activity is negatively associated with arterial stiffness. However, the relationship between sedentary behaviour and arterial stiffness is poorly understood. In this study, we aimed to investigate the association of sedentary behaviour with arterial stiffness among young adults.

DESIGN

Cross-sectional.

SETTING

34 study clinics across Australia during 2004-2006.

PARTICIPANTS

2328 participants (49.4% male) aged 26-36 years who were followed up from a nationally representative sample of Australian schoolchildren in 1985.

MEASUREMENTS

Arterial stiffness was measured by carotid ultrasound. Sitting time per weekday and weekend day, and physical activity were self-reported by questionnaire. Cardiorespiratory fitness was estimated as physical work capacity at a heart rate of 170 bpm. Anthropometry, blood pressure, resting heart rate and blood biochemistry were measured. Potential confounders, including strength training, education, smoking, diet, alcohol consumption and parity, were self-reported. Rank correlation was used for analysis.

RESULTS

Sitting time per weekend day, but not per weekday, was correlated with arterial stiffness (males r=0.11 p<0.01, females r=0.08, p<0.05) and cardiorespiratory fitness (males r = -0.14, females r = -0.08, p<0.05), and also with fatness and resting heart rate. One additional hour of sitting per weekend day was associated with 5.6% (males p=0.046) and 8.6% (females p=0.05) higher risk of having metabolic syndrome. These associations were independent of physical activity and other potential confounders. The association of sitting time per weekend day with arterial stiffness was not mediated by resting heart rate, fatness or metabolic syndrome.

CONCLUSIONS

Our study demonstrates a positive association of sitting time with arterial stiffness. The greater role of sitting time per weekend day in prediction of arterial stiffness and cardiometabolic risk than that of sitting time per weekday may be due to better reflection of discretionary sitting behaviour.

Resting heart rate and the association of physical fitness with carotid artery stiffness

BACKGROUND

Physical fitness is known to influence arterial stiffness. Resting heart rate is reduced by exercise and positively associated with arterial stiffness. This study aimed to investigate the role of resting heart rate in the relationship of physical fitness with arterial stiffness.

METHODS

Subjects were 2,328 young adults from the Childhood Determinants of Adult Health study. Cardiorespiratory fitness was estimated as physical work capacity at a heart rate of 170 bpm. Muscular strength was estimated by hand-grip (both sides), shoulder (pull and push), and leg strength. Arterial stiffness was measured using carotid ultrasound.

RESULTS

Arterial stiffness was negatively associated with cardiorespiratory fitness (men P < 0.001; women P = 0.002), and positively associated with muscular strength in women (P = 0.002) but not in men. Resting heart rate was positively associated with arterial stiffness (P < 0.001 both men and women). Adjustment for resting heart rate reduced the inverse association of arterial stiffness with cardiorespiratory fitness by 93.7% (men) and 67.6% (women) but substantially increased the positive association of arterial stiffness with muscular strength among women and revealed a positive association of arterial stiffness with muscular strength among men. These findings were independent of body size, blood pressure, biochemical markers, socioeconomic status, smoking, and alcohol consumption.

CONCLUSIONS

Our findings attribute a key intermediary role for resting heart rate in the relationship between fitness and arterial stiffness, whereby higher cardiorespiratory fitness may reduce arterial stiffness mainly through resting heart rate, and higher muscular strength might have deleterious effects on arterial stiffness that are partially offset by lower resting heart rate.

Cohort Profile: the international childhood cardiovascular cohort (i3C) consortium

This is a consortium of large children's cohorts that contain measurements of major cardiovascular disease (CVD) risk factors in childhood and had the ability to follow those cohorts into adulthood. The purpose of this consortium is to enable the pooling of data to increase power, most importantly for the follow-up of CVD events in adulthood. Within the consortium, we hope to be able to obtain data on the independent effects of childhood and early adult levels of CVD risk factors on subsequent CVD occurrence.

Sugar-Added Beverages and Adolescent Weight Change

OBJECTIVE

The increase in consumption of sugar-added beverages over recent decades may be partly responsible for the obesity epidemic among U.S. adolescents. Our aim was to evaluate the relationship between BMI changes and intakes of sugar-added beverages, milk, fruit juices, and diet soda.

RESEARCH METHODS AND PROCEDURES

Our prospective cohort study included >10,000 boys and girls participating in the U.S. Growing Up Today Study. The participants were 9 to 14 years old in 1996 and completed questionnaires in 1996, 1997, and 1998. We analyzed change in BMI (kilograms per meter squared) over two 1-year periods among children who completed annual food frequency questionnaires assessing typical past year intakes. We studied beverage intakes during the year corresponding to each BMI change, and in separate models, we studied 1-year changes in beverage intakes, adjusting for prior year intakes. Models included all beverages simultaneously; further models adjusted for total energy intake.

RESULTS

Consumption of sugar-added beverages was associated with small BMI gains during the corresponding year (boys: +0.03 kg/m2 per daily serving, p = 0.04; girls: +0.02 kg/m2, p = 0.096). In models not assuming a linear dose-response trend, girls who drank 1 serving/d of sugar-added beverages gained more weight (+0.068, p = 0.02) than girls drinking none, as did girls drinking 2 servings/d (+0.09, p = 0.06) or 3+ servings/d (+0.08, p = 0.06). Analyses of year-to-year change in beverage intakes provided generally similar findings; boys who increased consumption of sugar-added beverages from the prior year experienced weight gain (+0.04 kg/m2 per additional daily serving, p = 0.01). Children who increased intakes by 2 or more servings/d from the prior year gained weight (boys: +0.14, p = 0.01; girls +0.10, p = 0.046). Further adjusting our models for total energy intake substantially reduced the estimated effects, which were no longer significant.

DISCUSSION

Consumption of sugar-added beverages may contribute to weight gain among adolescents, probably due to their contribution to total energy intake, because adjustment for calories greatly attenuated the estimated associations.

Daily eating frequency and cardiometabolic risk factors in young Australian adults: cross-sectional analyses

Eating frequency may be important in the development of overweight and obesity and other cardiometabolic risk factors; however, the evidence is inconsistent. The aim of the present study was to examine the associations between the number of eating occasions and cardiometabolic risk factors in a national population-based sample of young adults. A cohort of 1273 men and 1502 women, aged 26–36 years, completed a meal pattern chart to record when they had eaten during the previous day (in hourly intervals). The total number of eating occasions was calculated. Diet quality was assessed, waist circumference was measured and a fasting blood sample was taken. Dietary intake was compared with the Australian Guide to Healthy Eating. The associations between the number of eating occasions and cardiometabolic risk factors were calculated using linear regression. Analyses were adjusted for age, education and physical activity. Most men ate three to five times per d and most women ate four to six times. The proportion of participants meeting dietary recommendations increased with the number of eating occasions. For men, an additional eating occasion was associated with reductions in mean values for waist circumference ( − 0·75 cm), fasting glucose ( − 0·02 mmol/l), fasting insulin ( − 0·34 mU/l; 2·04 pmol/l), TAG ( − 0·03 mmol/l), total cholesterol ( − 0·08 mmol/l) and LDL-cholesterol ( − 0·06 mmol/l). Adjustment for waist circumference attenuated the results. Significant trends were not observed for women. In conclusion, a higher number of eating occasions were associated with reduced cardiometabolic risk factors in men. Many associations were mediated by waist circumference.

Takeaway food consumption and cardio-metabolic risk factors in young adults

BACKGROUND/OBJECTIVES

Takeaway food consumption is positively associated with adiposity. Little is known about the associations with other cardio-metabolic risk factors. This study aimed to determine whether takeaway food consumption is associated with fasting glucose, insulin, lipids, homeostasis model assessment (HOMA) and blood pressure.

SUBJECTS/METHODS

A national sample of 1896, 26-36 year olds completed a questionnaire on socio-demographics, takeaway food consumption, physical activity and sedentary behaviour. Waist circumference and blood pressure were measured, and a fasting blood sample was taken. For this analysis, takeaway food consumption was dichotomised to once a week or less and twice a week or more. Linear regression was used to calculate differences in the adjusted mean values for fasting lipids, glucose, insulin, HOMA and blood pressure. Models were adjusted for age, employment status, leisure time physical activity and TV viewing.

RESULTS

Compared with women who ate takeaway once a week or less, women who ate takeaway twice a week or more had significantly higher adjusted mean fasting glucose (4.82 vs 4.88 mmol/l, respectively; P=0.045), higher HOMA scores (1.27 vs 1.40, respectively, P=0.034) and tended to have a higher mean fasting insulin (5.95 vs 6.45 mU/l, respectively, P=0.054). Similar associations were observed for men for fasting insulin and HOMA score, but the differences were not statistically significant. For both women and men adjustment for waist circumference attenuated the associations.

CONCLUSION

Consuming takeaway food at least twice a week was associated with cardio-metabolic risk factors in women but less so in men. The effect of takeaway food consumption was attenuated when adjusted for obesity.

Correlates of pedometer-measured and self-reported physical activity among young Australian adults

Accurately quantifying physical activity is important for investigating relations with potential correlates, but past studies have mostly relied on self-report measures, which may be susceptible to error and biases, limiting interpretability. This study aimed to examine correlates of pedometer-determined physical activity and compare them with correlates of self-reported physical activity. Cross-sectional data were taken from 2017 Australian adults (aged 26-36 years) who were involved in the Childhood Determinants of Adult Health follow-up study during 2004-2006. Daily steps were recorded for seven days using Yamax pedometers and physical activity (total min/week) was reported via the long International Physical Activity Questionnaire. Demographic, biological, behavioral, psychological, social and environmental factors were assessed. Lower education, blue collar occupation and higher mental health score (men) and low-moderate alcohol intake (women) were positively associated with self-report and pedometer-measured activity. Among men, body mass index (BMI) was inversely and physical health score was positively associated with pedometer-measured activity while smoking, low to moderate alcohol intake, higher general health and urban area of residence were positively associated with self-reported activity. Among women, age and general health status were positively associated and number of live births inversely associated with pedometer-measured activity, while lower education, blue collar occupation, part time employment, smoking, diet, higher physical health score and higher mental health score were positively associated and white collar occupation inversely associated with self-reported activity. Many physical activity correlates differed depending on the measure employed; researchers should be mindful of these differences when selecting measures of physical activity.

Oral contraceptive use and bone mass in women aged 26-36 years

INTRODUCTION

The association between hormonal contraceptive use and bone mineral density remains controversial.

HYPOTHESIS

Hormonal contraceptive use is positively associated with bone mass in young premenopausal women.

METHODS

Cross-sectional analysis of data collected from women aged 26-36 years (n = 687) in the Childhood Determinants of Adult Health study-a longitudinal study investigating childhood determinants of cardiovascular disease, diabetes, and other chronic diseases in adulthood. Participants were not currently pregnant or breast-feeding. Contraceptive use was obtained by self-administered questionnaire. Women were categorized as combined oral contraceptive users (n = 219), progestogen-only contraceptive users (n = 43), and non-users of hormonal contraceptives (n = 425). Bone mass was measured by quantitative ultrasound.

RESULTS

Compared with women who were not using any hormonal contraceptives, women using combined oral contraceptives had significantly higher values of broadband ultrasound attenuation (BUA), speed of sound, and quantitative ultrasound index. These associations remained after adjustment for confounders. Progestogen-only contraceptive users had higher BUA than non-users, but the differences were not statistically significant in this small group.

CONCLUSION

Combined oral contraceptive use was associated with higher bone mass measured by quantitative ultrasound in this population-based sample of premenopausal women aged 26-36 while progestogen-only contraceptives appeared to have no deleterious effect on bone mass.

Menstrual irregularity and bone mass in premenopausal women: cross-sectional associations with testosterone and SHBG

Background

There have been few studies examining the associations between menstrual irregularity, androgens and bone mass in population-based samples of premenopausal women. This study aimed to describe the associations between menstrual pattern, testosterone, sex hormone binding globulin (SHBG) and bone mass in a population-based sample of premenopausal women.

Methods

Cross-sectional study (N = 382, mean age 31.5 years). Menstrual pattern was assessed by questionnaire, bone mass measured by quantitative ultrasound (QUS) and androgen status was assessed by levels of serum testosterone, SHBG and the free androgen index (FAI).

Results

Women with irregular cycles (n = 41, 11%) had higher free androgen index (FAI, P = 0.01) and higher QUS measurements including speed of sound (SOS, 1%, P < 0.05), quantitative ultrasound index (QUI, 7%, p < 0.05), and broadband ultrasound attenuation (BUA, 7%, p = 0.10). These associations persisted after adjustment for age and body mass index (BMI). After further adjustment for hormonal factors (either testosterone, SHBG or FAI), the strength of the associations was moderately attenuated, however, women with irregular cycles still had a 6% increase in mean QUS. Total testosterone, FAI and SHBG were also associated with QUS measures (testosterone and FAI, r +0.11 to +0.21, all p < 0.05; SHBG r -0.14 to -0.16, all p < 0.05) and the associations remained significant after adjustment.

Conclusion

Irregular menstrual cycles were associated with higher bone mass in this population-based sample of premenopausal women suggesting menstrual disturbance should continue to be evaluated but may be less harmful for bone mass. The association between menstrual irregularity and bone mass was partially mediated by markers of androgen status especially free testosterone.

Skipping breakfast: longitudinal associations with cardiometabolic risk factors in the Childhood Determinants of Adult Health Study

BACKGROUND

The long-term effects of skipping breakfast on cardiometabolic health are not well understood.

OBJECTIVE

The objective was to examine longitudinal associations of breakfast skipping in childhood and adulthood with cardiometabolic risk factors in adulthood.

DESIGN

In 1985, a national sample of 9-15-y-old Australian children reported whether they usually ate breakfast before school. During follow-up in 2004-2006, 2184 participants (26-36 y of age) completed a meal-frequency chart for the previous day. Skipping breakfast was defined as not eating between 0600 and 0900. Participants were classified into 4 groups: skipped breakfast in neither childhood nor adulthood (n = 1359), skipped breakfast only in childhood (n = 224), skipped breakfast only in adulthood (n = 515), and skipped breakfast in both childhood and adulthood (n = 86). Diet quality was assessed, waist circumference was measured, and blood samples were taken after a 12-h fast (n = 1730). Differences in mean waist circumference and blood glucose, insulin, and lipid concentrations were calculated by linear regression.

RESULTS

After adjustment for age, sex, and sociodemographic and lifestyle factors, participants who skipped breakfast in both childhood and adulthood had a larger waist circumference (mean difference: 4.63 cm; 95% CI: 1.72, 7.53 cm) and higher fasting insulin (mean difference: 2.02 mU/L; 95% CI: 0.75, 3.29 mU/L), total cholesterol (mean difference: 0.40 mmol/L; 95% CI: 0.13, 0.68 mmol/L), and LDL cholesterol (mean difference: 0.40 mmol/L; 95% CI: 0.16, 0.64 mmol/L) concentrations than did those who ate breakfast at both time points. Additional adjustments for diet quality and waist circumference attenuated the associations with cardiometabolic variables, but the differences remained significant.

CONCLUSIONS

Skipping breakfast over a long period may have detrimental effects on cardiometabolic health. Promoting the benefits of eating breakfast could be a simple and important public health message.