Cross-sectional and prospective associations between moderate to vigorous physical activity and sedentary time with adiposity in children.

BACKGROUND: Physical activity (PA) and sedentary time (SED) have both been suggested as potential risk factors for adiposity in children. However, there is paucity of data examining the temporal associations between these variables. OBJECTIVE: This study aimed to analyze the cross-sectional and prospective associations between PA, SED and body composition in children. METHODS: A total of 510 children (age at baseline 10.1±0.8, age at follow-up 11.8±0.9) from six Portuguese schools from the Oeiras Municipality participated in this study. PA and SED were measured by accelerometry and trunk fat mass (TFM) and body fat mass (BFM) were measured by dual energy X-ray absorptiometry. Fat mass index (FMI) was calculated as BFM divided by height squared. Several regression models adjusted for age, sex, maturity status, follow-up duration, baseline levels of the outcome variable and SED or moderate to vigorous PA (MVPA) were performed. RESULTS: MVPA (min per day) was cross-sectionally inversely associated with adiposity indexes (FMI, TFM and BFM). Adiposity indexes were inversely associated with time in MVPA. In prospective analyses, MVPA was associated with a lower levels of FMI (β=-0.37, 95% confidence interval (CI): -0.49 to -0.26, P<0.001), TFM (β=-0.20, 95% CI: -0.29 to -0.10, P<0.001) and BFM (β=-0.37, 95% CI: -0.49 to -0.26, P<0.001). When the model was adjusted for age, sex, maturity status and for baseline levels of the outcome variables MVPA remained a significant predictor of lower adiposity indexes (FMI: β=-0.09, 95% CI: -0.16 to -0.01, P<0.05; TFM: β=-0.08, 95% CI: -0.15 to -0.01, P<0.05; BFM: β=-0.07, 95% CI: -0.15 to 0.00, P<0.05). Adiposity was not associated with MVPA when modeled as the exposure in prospective analyses. SED was not related with adiposity indexes, except for the relationship with FMI. CONCLUSIONS: In cross-sectional and prospective analyses, MVPA is associated with lower adiposity independent of covariates and SED. Results suggest that promoting MVPA is important for preventing gain in adiposity in healthy children.The study was supported by the Portuguese Foundation of Science and Technology. Support/grant: PTDC/DES/108372/2008.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/ijo.2015.16

Associations between organized sports participation and objectively measured physical activity, sedentary time and weight status in youth

Objectives The purpose of this study was to examine whether participation in organized sports is related to achieving physical activity recommendations, body mass index (BMI), objectively measured PA intensity and time spent sedentary. Design Cross-sectional study. Methods The sample comprised 973 children and adolescents (427 boys, 546 girls) aged 10-18 years (Mage=14.1±2.4). Organized sport was self-reported. Physical activity and time spent in moderate and vigorous intensity PA (MVPA) and sedentary time was assessed with accelerometers. Results More boys (51.3%) than girls (28.3%) reported to be involved in organized sports participation (p<0.001). Those who were engaged in organized sports were more likely to achieve physical activity guidelines (OR=1.64, 95% CI: 1.14-2.35, p<0.01), spent more time in MPA (OR=1.01, 95% CI: 1.01-1.02, p<0.01), VPA (OR=1.09, 95% CI: 1.05-1.13, p<0.001), and MVPA (OR=1.01, 95% CI: 1.01-1.02, p<0.001) than those who did not participate in organized sports. No associations between organised sport participation and time spent sedentary or BMI was observed. Conclusions Engagement in organized sports is related to higher levels of objectively measured MPA, VPA and achieving the recommended levels of MVPA in youth; however participation in sports appears unrelated to time spent sedentary and BMI. Our results suggest that promoting organised sport may increase physical activity of at least moderate intensity in young people

Does Adaptive Thermogenesis occur after weight loss in adults? A systematic review

Adaptive thermogenesis (AT) has been proposed to be a compensatory response that may resist weight loss(WL) and promote weight regain. This systematic review examined the existence of AT in adults after a period of negative energy balance with or without a weight stabilization phase. Studies published until May 15th, 2020 were identified from PubMed, Cochrane Library, EMBASE, MEDLINE, SCOPUS and Web of Science. Inclusion criteria included: statistically significant WL; observational with follow-up or experimental studies; age>18years; sample size≥10 participants; intervention period ≥1week; published in English; objective measures of total daily energy expenditure(TDEE), resting energy expenditure(REE) and sleeping energy expenditure(SEE). The systematic review was registered at PROSPERO(2020 CRD42020165348). A total of 33 studies comprising 2528 participants, were included. AT was observed in 27 out of 33 studies. Twenty-three studies showed significant values for AT for REE(82.8%), 4 studies for TDEE(80.0%) and 2 studies for SEE(100%). A large heterogeneity in the methods used to quantify AT and between subjects and among studies regarding the magnitude of WL and/or of AT was reported. Well-designed studies reported lower or non-significant values for AT. Overall, these findings suggest that although WL may lead to AT in some of the EE components, these values may be small or non-statistically significant when higher-quality methodological designs are used. Furthermore, AT seems to be attenuated, or non-existent, after periods of weight stabilization/neutral energy balance. Therefore, more high-quality studies are warranted not only to disclose the existence of AT, but to understand its clinical implications on weight management outcomes

Changes in total and segmental bioelectrical resistance are correlated with whole-body and segmental changes in lean soft tissue following a resistance training intervention

Background Raw bioelectrical values can be used to assess physiological outcomes, though limited information is available concerning the relationships between changes in these values and changes in other variables of interest. Methods This investigation quantified the relationships between total and segmental changes in raw bioelectrical variables (i.e., resistance, reactance, and phase angle) and corresponding whole-body and segmental changes in independently assessed body composition. Resistance-trained females (n = 31, body mass index: 22.8 ± 2.6 kg/m2, body fat: 28 ± 6%) completed eight weeks of supervised resistance training. Before and after the intervention, body composition was assessed via dual-energy x-ray absorptiometry (GE® Lunar Prodigy), and raw bioelectrical variables were assessed via 8-point multi-frequency bioelectrical impedance analysis (Seca® mBCA 515/514) at 19 frequencies ranging from 1 to 1000 kHz. Results Lean soft tissue of the whole body (+ 3.2% [2.1, 4.4]; mean [95% confidence interval]) and each body segment (+ 2.8 to 6.3%) increased as a result of the intervention. Group-level changes in total (− 2.4% [− 5.2, 0.3]) and segmental fat mass were not statistically significant. Significant decreases in total resistance (− 2.1% [− 3.7, − 0.6] at 50 kHz) and increases in phase angle (+ 4.2% [2.5, 5.9] at 50 kHz) were observed, with minimal changes in reactance and varying changes in segmental values. Moderate to strong negative correlations (0.63 ≤ |r| ≤ 0.83, p ≤ 0.001) were found between changes in lean soft tissue and changes in resistance for the whole body, trunk, and arms. No significant correlations were identified between changes in fat mass or bone mineral content and changes in any bioelectrical variable. Conclusions Total and segmental changes in resistance were associated with corresponding total and segmental changes in lean soft tissue following a resistance training intervention, while fewer associations were identified between changes in other bioelectrical parameters (i.e., reactance and phase angle) and body composition variables (e.g., fat mass and bone mineral content). Measurement frequency and body segment appeared to influence the presence and strength relationships between bioelectrical and body composition variables. These findings suggest that researchers and practitioners utilizing bioimpedance technology may benefit from examining raw resistance values to enhance detection of physiological adaptations to exercise interventions

Sedentary Time and Physical Activity Surveillance Through Accelerometer Pooling in Four European Countries.

OBJECTIVE: The objective of this study was to pool, harmonise and re-analyse national accelerometer data from adults in four European countries in order to describe population levels of sedentary time and physical inactivity. METHODS: Five cross-sectional studies were included from England, Portugal, Norway and Sweden. ActiGraph accelerometer count data were centrally processed using the same algorithms. Multivariable logistic regression analyses were conducted to study the associations of sedentary time and physical inactivity with sex, age, weight status and educational level, in both the pooled sample and the separate study samples. RESULTS: Data from 9509 participants were used. On average, participants were sedentary for 530 min/day, and accumulated 36 min/day of moderate to vigorous intensity physical activity. Twenty-three percent accumulated more than 10 h of sedentary time/day, and 72% did not meet the physical activity recommendations. Nine percent of all participants were classified as high sedentary and low active. Participants from Norway showed the highest levels of sedentary time, while participants from England were the least physically active. Age and weight status were positively associated with sedentary time and not meeting the physical activity recommendations. Men and higher-educated people were more likely to be highly sedentary, while women and lower-educated people were more likely to be inactive. CONCLUSIONS: We found high levels of sedentary time and physical inactivity in four European countries. Older people and obese people were most likely to display these behaviours and thus deserve special attention in interventions and policy planning. In order to monitor these behaviours, accelerometer-based cross-European surveillance is recommended.The original studies were funded by the Norwegian Directorate of Health and the Norwegian School of Sport Sciences; the Portuguese Institute of Sport; a grant from the Stockholm County Council; and grants from the Swedish Council for Working Life and Social Research, and The Swedish Research Council for Environment, Agricultural Sciences, and Spatial Planning. AL, JL, JB and HvdP were supported by the Netherlands Organisation for Health Research and Development (Grant no. 200.600.001). KS was supported by the National Heart, Lung, And Blood Institute of the National Institutes of Health (award no. R01HL116381). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. KW was supported by the British Heart Foundation (Grant FS/12/58/29709). KW and SB were supported by the UK Medical Research Council (Grant MC_UU_12015/3)

Cross-Sectional Associations of Reallocating Time Between Sedentary and Active Behaviours on Cardiometabolic Risk Factors in Young People: An International Children's Accelerometry Database (ICAD) Analysis.

INTRODUCTION: Sedentary time and time spent in various intensity-specific physical activity are co-dependent, and increasing time spent in one behaviour requires decreased time in another. OBJECTIVE: The aim of the present study was to examine the theoretical associations with reallocating time between categories of intensities and cardiometabolic risk factors in a large and heterogeneous sample of children and adolescents. METHODS: We analysed pooled data from 13 studies comprising 18,200 children and adolescents aged 4-18 years from the International Children's Accelerometry Database (ICAD). Waist-mounted accelerometers measured sedentary time, light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). Cardiometabolic risk factors included waist circumference (WC), systolic blood pressure (SBP), fasting high- and low-density lipoprotein cholesterol (HDL-C and LDL-C), triglycerides, insulin, and glucose. Associations of reallocating time between the various intensity categories with cardiometabolic risk factors were explored using isotemporal substitution modelling. RESULTS: Replacing 10 min of sedentary time with 10 min of MVPA showed favourable associations with WC, SBP, LDL-C, insulin, triglycerides, and glucose; the greatest magnitude was observed for insulin (reduction of 2-4%), WC (reduction of 0.5-1%), and triglycerides (1-2%). In addition, replacing 10 min of sedentary time with an equal amount of LPA showed beneficial associations with WC, although only in adolescents. CONCLUSIONS: Replacing sedentary time and/or LPA with MVPA in children and adolescents is favourably associated with most markers of cardiometabolic risk. Efforts aimed at replacing sedentary time with active behaviours, particularly those of at least moderate intensity, appear to be an effective strategy to reduce cardiometabolic risk in young people

Physical activity moderates the effect of sedentary time on an older adult's physical independence

Background/objectives: Moderate-to-vigorous physical activity (MVPA) and breaks in sedentary time (BST) have been proposed as viable solutions to improve an older adult's physical independence, whereas sedentary time (ST) has been associated with detrimental effects. We sought to assess the joint effects of ST, BST, and MVPA on the physical independence of older adults and determine whether and to what extent the ST relationship with physical independence is moderated by MVPA and/or BST. Design: Cross-sectional. Setting: Laboratory of Exercise and Health, Faculty of Human Kinetics. Participants: Older adults (≥65 years old) from the national surveillance sys tem in Portugal (n = 821). Measurements: Physical activity and ST were assessed by accelerometry. Physi cal independence was assessed using a 12-item composite physical function (CPF) questionnaire. Multiple linear regression was used to model the outcomes. Results: Higher ST was related to lower CPF score (β = −0.01, p < 0.0001), whereas higher MVPA was related to better CPF score (β = 0.02, p < 0.0001). BST was not related to physical independence after accounting for MVPA and ST (β = 0.03, p = 0.074). MVPA had a moderating effect on the relationship of ST with CPF score (p < 0.0001), where MVPA ≥36.30 min/day ameliorated the significant inverse relationship between ST and CPF. Engaging in ≥107.78 of MVPA resulted in ST having a significant positive relationship with CPF score. No moderation effect was found for BST (p > 0.05). Conclusion: Regardless of the time spent in MVPA and BST, ST was inversely related to CPF. However, MVPA was found to be a moderator of the relationship between ST and physical independence, such that engaging in at least 36 min/day of MVPA may blunt the negative effects of ST. At high levels of MVPA (≥108 min/day), having some ST may actually provide some benefit to an older adult's ability to maintain physical independence

Relative sit-to-stand power: aging trajectories, functionally relevant cut-off points, and normative data in a large European cohort

Background A validated, standardized, and feasible test to assess muscle power in older adults has recently been re ported: the sit-to-stand (STS) muscle power test. This investigation aimed to assess the relationship between relative STS power and age and to provide normative data, cut-off points, and minimal clinically important differences (MCID) for STS power measures in older women and men. Methods A total of 9320 older adults (6161 women and 3159 men) aged 60–103 years and 586 young and middle-aged adults (318 women and 268 men) aged 20–60 years were included in this cross-sectional study. Relative (normalized to body mass), allometric (normalized to height squared), and specific (normalized to legs muscle mass) muscle power values were assessed by the 30 s STS power test. Body composition was evaluated by dual energy X-ray absorptiometry and bioelectrical impedance analysis, and legs skeletal muscle index (SMI; normalized to height squared) was calculated. Habitual and maximal gait speed, timed up-and-go test, and 6 min walking distance were col lected as physical performance measures, and participants were classified into two groups: well-functioning and mobility-limited older adults. Results Relative STS power was found to decrease between 30–50 years ( 0.05 W·kg 1 ·year 1 ; P > 0.05), 50–80 years ( 0.10 to 0.13 W·kg 1 ·year 1 ; P < 0.001), and above 80 years ( 0.07 to 0.08 W·kg 1 ·year 1 ; P < 0.001). A total of 1129 older women (18%) and 510 older men (16%) presented mobility limitations. Mobility-limited older adults were older and exhibited lower relative, allometric, and specific power; higher body mass index (BMI) and legs SMI (both only in women); and lower legs SMI (only in men) than their well-functioning coun terparts (all P < 0.05). Normative data and cut-off points for relative, allometric, and specific STS power and for BMI and legs SMI were reported. Low relative STS power occurred below 2.1 W·kg 1 in women (area under the curve, AUC, [95% confidence interval, CI] = 0.85 [0.84–0.87]) and below 2.6 W·kg 1 in men (AUC [95% CI] = 0.89 [0.87–0.91]). The age-adjusted odds ratios [95% CI] for mobility limitations in older women and men with low relative STS power were 10.6 [9.0–12.6] and 14.1 [10.9–18.2], respectively. MCID values for relative STS power were 0.33 W·kg 1 in women and 0.42 W·kg 1 in men. Conclusions Relative STS power decreased significantly after the age of 50 years and was negatively and strongly as sociated with mobility limitations. Our study provides normative data, functionally relevant cut-off points, and MCID values for STS power for their use in daily clinical practice

Objective and Self-Rated Sedentary Time and Indicators of Metabolic Health in Dutch and Hungarian 10–12 Year Olds: The ENERGY-Project

Background: The association between objectively assessed sedentary time and metabolic risk factors in childhood have rarely been studied. Therefore, we examined the independent relationship between objectively assessed and self-rated sedentary time and indicators of metabolic health in Dutch and Hungarian 10–12 year olds. Methodology/Principal Findings: We performed a cross-sectional survey in primary schools. Participants were Dutch and Hungarian girls (n = 73, aged 12.260.6 years, 18 % overweight/obese) and boys (n = 69, aged 12.260.7 years, 38% overweight/obese). Sedentary time and physical activity were assessed by the Actigraph accelerometer. TV and PC time were assessed by self-report. Adiposity indicators included body weight, height, and waist circumference (WC). Fasting plasma glucose, C-peptide, total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol, and triglycerides were determined in capillary blood and summed into a metabolic risk score. Linear regression analyses were adjusted for physical activity, number of sedentary bouts and WC. Children spent on average 7.6 hours of their daily waking time in sedentary behavior and self-reported 116664 min/day watching TV and 85657 min/day using the computer. Comparing the 1 st and 4 th quartile of objectively assessed sedentary time, C-Peptide levels, WC and BMI were significantly higher in the most sedentary quartile, while the difference in metabolic risk score was borderline significant (p = 0.09). Comparing the 1 st and 4 th quartile of TV time, BMI was significantly higher in the most sedentary quartile, while th