Genetic predisposition to adiposity is associated with increased objectively assessed sedentary time in young children.

Increased sedentariness has been linked to the growing prevalence of obesity in children, but some longitudinal studies suggest that sedentariness may be a consequence rather than a cause of increased adiposity. We used Mendelian randomization to examine the causal relations between body mass index (BMI) and objectively assessed sedentary time and physical activity in 3-8 year-old children from one Finnish and two Danish cohorts [NTOTAL=679]. A genetic risk score (GRS) comprised of 15 independent genetic variants associated with childhood BMI was used as the instrumental variable to test causal effects of BMI on sedentary time, total physical activity, and moderate-to-vigorous physical activity (MVPA). In fixed effects meta-analyses, the GRS was associated with 0.05 SD/allele increase in sedentary time (P=0.019), but there was no significant association with total physical activity (beta=0.011 SD/allele, P=0.58) or MVPA (beta=0.001 SD/allele, P=0.96), adjusting for age, sex, monitor wear-time and first three genome-wide principal components. In two-stage least squares regression analyses, each genetically instrumented one unit increase in BMI z-score increased sedentary time by 0.47 SD (P=0.072). Childhood BMI may have a causal influence on sedentary time but not on total physical activity or MVPA in young children. Our results provide important insights into the regulation of movement behaviour in childhood

Cross-sectional and longitudinal associations between the 24-hour movement behaviours, including muscle and bone strengthening activity, with bone and lean mass from childhood to adolescence.

This is the final version. Available from BMC via the DOI in this record. Availability of data and materials: The data that support the findings of this study are available from University of Eastern Finland but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of University of Eastern Finland and PANIC study Principal Investigator ([email protected]).BACKGROUND: This study aimed to assess whether moderate-to-vigorous physical activity (MVPA), sport and exercise as a proxy measure of muscle and bone strengthening activity, sedentary behaviour, and sleep were associated with total-body-less-head (TBLH) bone mineral content (BMC) and TBLH lean mass cross-sectionally and longitudinally from age 6 to 9 years and age 9 to 11 years to age 15 to 17 years. METHODS: We used longitudinal data from a population sample of Finnish children from the Physical Activity and Nutrition in Children study (age 6 to 9 years: n = 478, 229 females; age 9 to 11 years: n = 384, 197 females; age 15 to 17 years: n = 222, 103 females). Linear regression analysed the cross-sectional and longitudinal associations between accelerometer-assessed MVPA, sedentary time and sleep, and questionnaire-assessed sport and exercise participation and screen time with dual-energy X-ray absorptiometry-assessed TBLH BMC and lean mass. RESULTS: In females, MVPA at age 6 to 9 years was positively associated with TBLH BMC at age 15 to 17 years (β = 0.008, p = 0.010). Sport and exercise at age 9 to 11 years was positively associated with TBLH BMC (β = 0.020, p = 0.002) and lean mass (β = 0.343, p = 0.040) at age 15 to 17 years. MVPA at age 9 to 11 years was positively associated with TBLH lean mass (β = 0.272, p = 0.004) at age 15 to 17 years. In males, sleep at age 6 to 9 years was positively associated with TBLH lean mass (β = 0.382, p = 0.003) at age 15 to 17 years. Sport and exercise at age 9 to 11 years was positively associated with TBLH BMC (β = 0.027, p = 0.012) and lean mass (β = 0.721, p < 0.001) at age 15 to 17 years. CONCLUSIONS: Promoting engagement in the 24-hour movement behaviours in childhood, particularly sport and exercise to strengthen muscle and bone, is important in supporting bone and lean mass development in adolescence. TRIAL REGISTRATION: NCT01803776; first trial registration date: 04/03/2013.Kuopio University HospitalMedical Research CouncilMedical Research CouncilNational Institute for Health ResearchMinistry of Education and Culture of FinlandAcademy of FinlandMinistry of Social Affairs and Health of FinlandFinnish Innovation Fund SitraSocial Insurance Institution of FinlandFinnish Cultural FoundationJuho Vainio FoundationFoundation for Paediatric ResearchDoctoral Programs in Public Health, Paavo Nurmi FoundationPaulo FoundationDiabetes Research FoundationThe Finnish Medical Society DuodecimOrion Research Foundatio

Physical activity volume and intensity distribution in relation to bone, lean and fat mass in children

This is the final version. Available on open access from Wiley via the DOI in this recordData availability statement: The datasets analyzed during the current study are not publicly available due to research ethical reasons and because the owner of the data is the University of Eastern Finland and not the research group. Requests to access the datasets should be directed to www.panicstudy.fi/en/etusivu.Considering physical activity (PA) volume and intensity may provide novel insights into the relationships of PA with bone, lean, and fat mass. This study aimed to assess the associations of PA volume, PA intensity distribution, including moderate-to-vigorous PA (MVPA) with total-body-less-head bone mineral content (BMC), lean, and fat mass in children. A population sample of 290 Finnish children (158 females) aged 9 to 11 years from the Physical Activity and Nutrition in Children (PANIC) Study was studied. PA, including MVPA, was assessed with a combined heart rate and movement sensor, and the uniaxial acceleration was used to calculate average-acceleration (a proxy metric for PA volume) and intensity-gradient (reflective of PA intensity distribution). Linear regression analysed the associations of PA volume, PA intensity and MVPA with BMC, lean mass, and fat mass assessed by dual-energy X-ray absorptiometry. PA volume was positively associated with BMC in females (unstandardised regression coefficient (ß) = 0.26) and males (ß = 0.47), and positively associated with lean (ß = 7.33) and negatively associated with fat mass in males (ß = -20.62). PA intensity was negatively associated with BMC in males (ß = -0.13). MVPA was positively associated with lean mass in females and males (ß = 0.007 to 0.012), negatively associated with fat mass in females and males (ß = -0.030 to -0.029). PA volume may be important for improving BMC in females and males, and increasing lean and reducing fat mass in males, whereas MVPA may be important for favourable lean and fat outcomes in both sexes.Ministry of Education and Culture of FinlandMinistry of Social Affairs and Health of FinlandFinnish Innovation Fund SitraSocial Insurance Institution of FinlandFinnish Cultural FoundationJuho Vainio FoundationFoundation for Pediatric ResearchPaavo Nurmi FoundationPaulo FoundationDiabetes Research FoundationFinnish Medical Society DuodecimOrion Research FoundationKuopio University HospitalCity of KuopioMedical Research Council (MRC)National Institute for Health Research (NIHR

Cross-Sectional Associations of Objectively-Measured Physical Activity and Sedentary Time with Body Composition and Cardiorespiratory Fitness in Mid-Childhood: The PANIC Study.

BACKGROUND: The minimum intensity of physical activity (PA) that is associated with favourable body composition and cardiorespiratory fitness (CRF) remains unknown. OBJECTIVE: To investigate cross-sectional associations of PA and sedentary time (ST) with body composition and CRF in mid-childhood. METHODS: PA, ST, body composition and CRF were measured in a population-based sample of 410 children (aged 7.6 ± 0.4 years). Combined heart-rate and movement sensing provided estimates of PA energy expenditure (PAEE, kJ/kg/day) and time (min/day) at multiple fine-grained metabolic equivalent (MET) levels, which were also collapsed to ST and light PA (LPA), moderate PA (MPA) and vigorous PA (VPA). Fat mass index (FMI, kg/m2), trunk fat mass index (TFMI, kg/m2) and fat-free mass index (FFMI, kg/m2.5) were derived from dual-energy X-ray absorptiometry. Maximal workload from a cycle ergometer test provided a measure of CRF (W/kg FFM). Linear regression and isotemporal substitution models were used to investigate associations. RESULTS: The cumulative time above 2 METs (221 J/min/kg) was inversely associated with FMI and TFMI in both sexes (p < 0.001) whereas time spent above 3 METs was positively associated with CRF (p ≤ 0.002); CRF increased and adiposity decreased dose-dependently with increasing MET levels. ST was positively associated with FMI and TFMI (p < 0.001) but there were inverse associations between all PA categories (including LPA) and adiposity (p ≤ 0.002); the magnitude of these associations depended on the activity being displaced in isotemporal substitution models but were consistently stronger for VPA. PAEE, MPA and to a greater extent VPA, were all positively related to CRF (p ≤ 0.001). CONCLUSIONS: PA exceeding 2 METs is associated with lower adiposity in mid-childhood, whereas PA of 3 METs is required to benefit CRF. VPA was most beneficial for fitness and fatness, from a time-for-time perspective, but displacing any lower-for-higher intensity may be an important first-order public health strategy. Clinical trial registry number (website): NCT01803776 ( https://clinicaltrials.gov/ct2/show/NCT01803776 ).This work has been financially supported by Grants from the Ministry of Social Affairs and Health of Finland, the Ministry of Education and Culture of Finland, the University of Eastern Finland, the Finnish Innovation Fund Sitra, the Social Insurance Institution of Finland, the Finnish Cultural Foundation, the Juho Vainio Foundation, the Foundation for Paediatric Research, the Paulo Foundation, the Paavo Nurmi Foundation, the Diabetes Research Foundation, the city of Kuopio, Kuopio University Hospital (EVO Funding Number 5031343), the Research Committee of the Kuopio University Hospital Catchment Area for the State Research Funding, the UK Medical Research Council [Grant MC_UU_12015/3], the Wellcome Trust [Grant 074296/Z/04/Z], the British Heart Foundation [Intermediate Basic Science Research Fellowship Grant FS/12/58/29709 to KWi], and the UK Clinical Research Collaboration Public Health Research [Grant RES-590-28- 0002]

The Mediating Role of Endocrine Factors in the Positive Relationship Between Fat Mass and Bone Mineral Content in Children Aged 9–11 Years: The Physical Activity and Nutrition in Children Study

This is the final version. Available on open access from Frontiers Media via the DOI in this recordData Availability Statement: The datasets presented in this article are not readily available because of research ethical reasons and because the owner of the data is the University of Eastern Finland and not the research group. Requests to access the datasets should be directed to www.panicstudy.fi/en/etusivu.Introduction: We aimed to investigate whether the relationship between fat mass and bone mineral content (BMC) is mediated by insulin, leptin, adiponectin, dehydroepiandrosterone sulphate, testosterone and estradiol in children aged 9-11 years. Materials and Methods: We utilised cross-sectional data from the Physical Activity and Nutrition in Children study (n = 230 to 396; 112 to 203 girls). Fat mass and BMC were assessed with dual-energy X-ray absorptiometry. Endocrine factors were assessed from fasted blood samples. We applied the novel 4-way decomposition method to analyse associations between fat mass, endocrine factors, and BMC. Results: Fat mass was positively associated with BMC in girls (ß = 0.007 to 0.015, 95% confidence interval (CI) 0.005 to 0.020) and boys (ß = 0.009 to 0.015, 95% CI 0.005 to 0.019). The relationship between fat mass and BMC was mediated by free leptin index in girls (ß = -0.025, 95% CI -0.039 to -0.010) and boys (ß = -0.014, 95% CI -0.027 to -0.001). The relationship between fat mass and BMC was partially explained by mediated interaction between fat mass and free leptin index in boys (ß = -0.009, 95% CI -0.013 to -0.004) and by interaction between fat mass and adiponectin in girls (ß = -0.003, 95% CI -0.006 to -0.000). Conclusion: At greater levels of adiponectin and free leptin index, the fat mass and BMC relationship becomes less positive in girls and boys respectively. The positive association between fat mass with BMC was largely not explained by the endocrine factors we assessed. Clinical Trial Registration: [https://clinicaltrials.gov/ct2/show/NCT01803776], identifier NCT01803776.Ministry of Social Affairs and Health of FinlandMinistry of Education and Culture of FinlandFinnish Innovation Fund SitraSocial Insurance Institution of FinlandFinnish Cultural FoundationJuho Vainio FoundationFoundation for Paediatric ResearchDoctoral Programs in Public HealthPaavo Nurmi FoundationPaulo FoundationDiabetes Research FoundationFinnish Medical Society DuodecimOrion Research FoundationResearch Committee of the Kuopio University Hospital Catchment AreaKuopio University HospitalCity of Kuopi

Cardiorespiratory Fitness, Physical Activity, and Insulin Resistance in Children

This is the author accepted manuscript. The final version is available from Lippincott, Williams & Wilkins via the DOI in this record.Purpose: Few studies have investigated the independent and joint associations of cardiorespiratory fitness (CRF) and body fat percentage (BF%) with insulin resistance in children. We investigated the independent and combined associations of CRF and BF% with fasting glycaemia and insulin resistance and their interactions with physical activity (PA) and sedentary time among 452 children aged 6¬–8 years. Methods: We assessed CRF with a maximal cycle ergometer exercise test and used allometrically scaled maximal power output (Wmax) for lean body mass (LM1.13) and body mass (BM1) as measures of CRF. BF% and LM were measured by dual-energy X-ray absorptiometry, fasting glycaemia by fasting plasma glucose, and insulin resistance by fasting serum insulin and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). PA energy expenditure (PAEE), moderate-to-vigorous PA (MVPA), and sedentary time were assessed by combined movement and heart rate sensor. Results: Wmax/LM1.13 was not associated with glucose (β=0.065, 95% CI=-0.031 to 0.161), insulin (β=-0.079, 95% CI=-0.172 to 0.015), or HOMA-IR (β=-0.065, 95% CI=-0.161 to 0.030). Wmax/BM1 was inversely associated with insulin (β=-0.289, 95% CI=-0.377 to -0.200) and HOMA-IR (β=-0.269, 95% CI=-0.359 to -0.180). BF% was directly associated with insulin (β=0.409, 95% CI=0.325 to 0.494) and HOMA-IR (β=0.390, 95% CI=0.304 to 0.475). Higher Wmax/BM1, but not Wmax/LM1.13, was associated with lower insulin and HOMA-IR in children with higher BF%. Children with higher BF% and who had lower levels of MVPA or higher levels of sedentary time had the highest insulin and HOMA-IR. Conclusion: Children with higher BF% together with less MVPA or higher levels of sedentary time had the highest insulin and HOMA-IR. CRF appropriately controlled for body size and composition using LM was not related to insulin resistance among children.Medical Research CouncilNIH

Cross-Sectional Associations of Objectively-Measured Physical Activity and Sedentary Time with Body Composition and Cardiorespiratory Fitness in Mid-Childhood: The PANIC Study.

$\textit{Background}$ The minimum intensity of physical activity (PA) that is associated with favourable body composition and cardiorespiratory fitness (CRF) remains unknown. $\textit{Objective}$ To investigate cross-sectional associations of PA and sedentary time (ST) with body composition and CRF in mid-childhood. $\textit{Methods}$ PA, ST, body composition and CRF were measured in a population-based sample of 410 children (aged 7.6 ± 0.4 years). Combined heart-rate and movement sensing provided estimates of PA energy expenditure (PAEE, kJ/kg/day) and time (min/day) at multiple fine-grained metabolic equivalent (MET) levels, which were also collapsed to ST and light PA (LPA), moderate PA (MPA) and vigorous PA (VPA). Fat mass index (FMI, kg/ m$^2$ ), trunk fat mass index (TFMI, kg/m$^2$ ) and fat-free mass index (FFMI, kg/m$^{2.5}$) were derived from dual-energy X-ray absorptiometry. Maximal workload from a cycle ergometer test provided a measure of CRF (W/kg FFM). Linear regression and isotemporal substitution models were used to investigate associations. $\textit{Results}$ The cumulative time above 2 METs (221 J/min/ kg) was inversely associated with FMI and TFMI in both sexes ($p$<0.001) whereas time spent above 3 METs was positively associated with CRF ($p\leq$0.002); CRF increased and adiposity decreased dose-dependently with increasing MET levels. ST was positively associated with FMI and TFMI ($p$<0.001) but there were inverse associations between all PA categories (including LPA) and adiposity ($p\leq$0.002); the magnitude of these associations depended on the activity being displaced in isotemporal substitution models but were consistently stronger for VPA. PAEE, MPA and to a greater extent VPA, were all positively related to CRF ($p\leq$0.001). $\textit{Conclusions}$ PA exceeding 2 METs is associated with lower adiposity in mid-childhood, whereas PA of 3 METs is required to benefit CRF. VPA was most beneficial for fitness and fatness, from a time-for-time perspective, but displacing any lower-for-higher intensity may be an important first-order public health strategy. Clinical trial registry number (website): NCT01803776 (https://clinicaltrials.gov/ct2/show/NCT01803776).This work has been financially supported by Grants from the Ministry of Social Affairs and Health of Finland, the Ministry of Education and Culture of Finland, the University of Eastern Finland, the Finnish Innovation Fund Sitra, the Social Insurance Institution of Finland, the Finnish Cultural Foundation, the Juho Vainio Foundation, the Foundation for Paediatric Research, the Paulo Foundation, the Paavo Nurmi Foundation, the Diabetes Research Foundation, the city of Kuopio, Kuopio University Hospital (EVO Funding Number 5031343), the Research Committee of the Kuopio University Hospital Catchment Area for the State Research Funding, the UK Medical Research Council [Grant MC_UU_12015/3], the Wellcome Trust [Grant 074296/Z/04/Z], the British Heart Foundation [Intermediate Basic Science Research Fellowship Grant FS/12/58/29709 to KWi], and the UK Clinical Research Collaboration Public Health Research [Grant RES-590-28- 0002]

Physical activity and sedentary time in relation to academic achievement in children.

OBJECTIVES: To investigate the independent and combined associations of objectively measured moderate-to-vigorous physical activity (MVPA) and sedentary time (ST) with reading and arithmetic skills. DESIGN: Cross-sectional/prospective. METHODS: Participants were 89 boys and 69 girls aged 6-8 years. MVPA and ST were measured using a combined heart rate and movement sensor and body fat percentage by dual-energy X-ray absorptiometry in Grade 1. Reading fluency, reading comprehension, and arithmetic skills were assessed using standardized tests in Grades 1-3. The data were analyzed using linear regression analyses and analyses of covariance with repeated measures. RESULTS: In boys, MVPA was directly and ST inversely associated with reading fluency in Grades 1-3 and arithmetic skills in Grade 1 (P<0.05). Higher levels of MVPA were also related to better reading comprehension in Grade 1 (P<0.05). Most of the associations of MVPA and ST with reading and arithmetic skills attenuated after mutual adjustment for MVPA or ST. Furthermore, boys with a combination of lower levels of MVPA and higher levels of ST had consistently poorer reading fluency (P=0.002) and reading comprehension (P=0.027) across Grades 1-3 than other boys. In girls, ST was directly associated with arithmetic skills in Grade 2 (P<0.05). However, this relationship of ST with arithmetic skills was no longer significant after adjustment for body fat percentage. CONCLUSIONS: Lower levels of MVPA and higher levels of ST and particularly their combination were related to poorer reading skills in boys. In girls, higher levels of ST were related to better arithmetic skills.Jenny and Antti Wihuri Foundation, Sinikka and Sakari Sohlberg Foundation, Ministry of Social Affairs and Health of Finland, Ministry of Education and Culture of Finland, Finnish Innovation Fund Sitra, Social Insurance Institution of Finland, Finnish Cultural Foundation, Juho Vainio Foundation, Yrjö Jahnsson Foundation, Foundation for Paediatric Research, Paavo Nurmi Foundation, Paulo Foundation, Diabetes Research Foundation, city of Kuopio, Kuopio University Hospital (EVO-funding number 5031343), Research Committee of the Kuopio University Hospital Catchment Area (the State Research Funding), UK Medical Research Council (MC_UU_12015/3

The independent and interactive associations of physical activity intensity and vitamin D status with bone mineral density in prepubertal children: the PANIC Study.

UNLABELLED: It is unclear how physical activity intensity and vitamin D status are related to bone health in prepubertal children. We found positive associations between vitamin D status and moderate-to-vigorous physical activity with bone in boys and girls. This highlights the importance of lifestyle factors for skeletal health prepuberty. INTRODUCTION: The sex-specific independent and interactive associations of physical activity (PA) intensity and serum 25-hydroxyvitamin D (25(OH)D) levels with areal bone mineral density (aBMD) were investigated in prepubertal children. METHODS: The participants were 366 prepubertal Finnish children (190 boys, 176 girls) aged 6-8 years. Linear regression analysed the associations of sedentary time (ST), light PA (LPA), moderate PA (MPA), moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) measured by accelerometery, and serum 25(OH)D with total body less head (TBLH) and lower-limb aBMD, measured by dual-energy X-ray absorptiometry. RESULTS: There was no interaction between PA intensity or serum 25(OH)D and sex with aBMD. MPA and MVPA were positively associated with TBLH and lower-limb aBMD (β = 0.11, 95% CI 0.02-0.20, p = 0.01). Serum 25(OH)D was positively associated with TBLH and lower-limb aBMD (β = 0.09, 95% CI 0.01-0.18, p = 0.03). There were no interactions between PA intensity and serum 25(OH)D with aBMD. CONCLUSION: Vitamin D status, MPA and MVPA levels in active prepubertal children were positively associated with aBMD. The influence of MVPA is due to the MPA component, though our findings regarding the role of VPA should be interpreted with caution, as shorter accelerometer epochs are needed to more accurately assess VPA. This study adds evidence to the promotion of MPA and behaviours to encourage optimal vitamin D status in supporting skeletal health in childhood, though these need not be used in conjunction to be beneficial, and a sex-specific approach is not necessary in prepubertal children. TRIAL REGISTRATION NUMBER: NCT01803776 . Date of registration: 4/03/2013.This work was financially supported by grants from Ministry of Social Affairs and Health of Finland, Ministry of Education and Culture of Finland, Finnish Innovation Fund Sitra, Social Insurance Institution of Finland, Finnish Cultural Foundation, Juho Vainio Foundation, Foundation for Paediatric Research, Doctoral Programs in Public Health, Paavo Nurmi Foundation, Paulo Foundation, Diabetes Research Foundation, The Finnish Medical Society Duodecim, Orion Research Foundation sr, Research Committee of the Kuopio University Hospital Catchment Area (State Research Funding), Kuopio University Hospital (previous state research funding (EVO), funding number 5031343) and the city of Kuopio. S. B. and K. W. were supported by the UK Medical Research Council (MC_UU_12015/3) and the NIHR Cambridge Biomedical Research Centre (IS-BRC-1215-20014)