The effects of melatonin and magnesium in a novel supplement delivery system on sleep scores, body composition and metabolism in otherwise healthy individuals with sleep disturbances.

The purpose of this study was to investigate the effects of a novel dietary supplement, including melatonin and magnesium, delivered via coffee pods on sleep quality, resting metabolic rate (RMR), and body composition in individuals with poor sleep quality disturbances. Using a double-blinded, randomized, crossover trial, we recruited 35 participants to a 4-week intervention with both supplements (1.9 mg melatonin + 200 mg elemental magnesium before sleep) and placebo conditions, considering a 7d washout period between treatments. The Pittsburgh Sleep Quality Index (PSQI) questionnaire was applied, RMR (kcal) was measured using indirect calorimetry (canopy ventilated open-circuit system) and body composition was assessed using dual-energy X-ray absorptiometry. Decreases in PSQI and anger - hostility scores, as well as in energy intake and fat mass, were observed (p < 0.05) for both conditions, from baseline to the end of each 4-week intervention. Differences between conditions were also observed for these parameters along with energy spent in activity, number of sedentary breaks, sleep efficiency, latency time, time in bed, total sleep time, awakening time, and movement index (p < 0.05) favouring the supplement condition. However, the final PSQI questionnaire scores still indicated poor sleep quality on average (PSQI > 5), in both conditions, with no changes regarding RMR. A melatonin-magnesium supplement, in a coffee pod format, showed improvements in sleep quality in otherwise healthy individuals with sleep disturbances, however PSQI questionnaire scores still indicated poor quality on average (PSQI > 5).

Intensity matters: impact of physical activity energy expenditure at moderate and vigorous intensity on total and abdominal obesity in children.

BACKGROUND/OBJECTIVES: Physical activity (PA) guidelines advocate that children should accumulate at least 60 min of moderate-to-vigorous PA daily. Still, it is not clear how body fat may differ if the same dose of PA is accumulated at different intensities. We aimed to determine the independent associations of energy expenditure (EE) at moderate (MPA) and vigorous (VPA) PA intensity on total and abdominal fat in children and if these associations were moderated by cardiorespiratory fitness (CRF). SUBJECTS/METHODS: A total of 326 children (girls = 171, boys = 151) aged 10-12 years had PA assessed with accelerometers. Total fat mass index (FMI) and abdominal FMI were assessed with DXA. CRF was assessed by a cycle ergometer test. Linear regression models were used to model the outcomes with the inclusion of an interaction term to test for moderation effects. RESULTS: An inverse association was found between VPA EE and FMI (ß = -0.013, p < 0.001) and abdominal FMI (ß = -0.0014, p < 0.001) independent of MPA EE. In contrast, MPA EE was not related to adiposity independent of VPA EE (p > 0.05). The relationships between the PA intensities and FMI and abdominal FMI were moderated by CRF. MPA EE was positively associated with adiposity in children with high levels of CRF, whereas VPA EE remained inversely associated with adiposity regardless of CRF level, although the strength of the association was lower in those with higher CRF levels. CONCLUSION: PA programs should provide opportunities for children to perform VPA in order to achieve healthier body fat profiles and avoid excess adiposity.

Development and Validation of an Anthropometric Equation to Predict Fat Mass Percentage in Professional and Semi-Professional Male Futsal Players.

This study aimed to (i) characterise the body composition of professional and semi-professional male futsal players, (ii) assess the validity of commonly used equations to estimate FM%, (iii) develop and cross-validate a futsal-specific FM% prediction equation. In a cross-sectional design, 78 adult male futsal players were assessed for body mass, stature, skinfolds, and girths as per the International Society for the Advancement of Kinanthropometry protocol and completed a dual-energy X-ray absorptiometry (DXA) scan for reference body composition data. Using paired-sample t-tests, the FM% from the DXA and nine published equations were compared. New sport-specific models were developed by stepwise multiple regression. Existing equations were cross-validated using the least squares regression, concordance correlation coefficient, and the Bland−Altman analyses. New equations were further cross-validated using the PRESS approach. None of the existing equations accurately predicted the DXA-derived FM% (p < 0.001; R2 ≤ 0.76, SEE ≥ 1.59; CCC ≤ 0.83; bias = −8.2% to −1.3%, limited agreement, and varying trends). The novel Bettery® equation: −0.620 + (0.159 ∗ Σ4SKF [triceps, abdominal, iliac crest, and front thigh (mm)]) + (0.120 ∗ waist girth (cm)), demonstrated a high accuracy (R2 = 0.85, SEE = 1.32%), a moderate strength of agreement (CCC = 0.92), no bias (0.2%), good agreement (±2.5%), and no trend (r = −0.157; p = 0.170) against the DXA. The Bettery® equation is the first to allow for a valid and sport-specific assessment of FM% in male futsal players.

Fat-free Mass Bioelectrical Impedance Analysis Predictive Equation for Athletes using a 4-Compartment Model.

Bioelectrical impedance analysis equations for fat-free mass prediction in healthy populations exist, nevertheless none accounts for the inter-athlete differences of the chemical composition of the fat-free mass. We aimed to develop a bioimpedance-based model for fat-free mass prediction based on the four-compartment model in a sample of national level athletes; and to cross-validate the new models in a separate cohort of athletes using a 4-compartment model as a criterion. There were 142 highly trained athletes (22.9±5.0 years) evaluated during their respective competitive seasons. Athletes were randomly split into development (n=95) and validation groups (n=47). The criterion method for fat-free mass was the 4-compartment model. Resistance and reactance were obtained with a phase-sensitive 50 kHz bioimpedance device. Athletic impedance-based models were developed (fat-free mass=- 2.261+0.327*Stature2/Resistance+0.525*Weight+5.462*Sex, where stature is in cm, Resistance is in Ω, Weight is in kg, and sex is 0 if female or 1 if male). Cross validation revealed R2 of 0.94, limits of agreement around 10% variability and no trend, as well as a high concordance correlation coefficient. The new equation can be considered valid thus affording practical means to quantify fat-free mass in elite adult athletes.

Impact of combined training with different exercise intensities on inflammatory and lipid markers in type 2 diabetes: a secondary analysis from a 1-year randomized controlled trial.

BACKGROUND: Exercise is a well-accepted strategy to improve lipid and inflammatory profile in individuals with type 2 diabetes (T2DM). However, the exercise intensity having the most benefits on lipids and inflammatory markers in patients with T2DM remains unclear. We aimed to analyse the impact of a 1-year combined high-intensity interval training (HIIT) with resistance training (RT), and a moderate continuous training (MCT) with RT on inflammatory and lipid profile in individuals with T2DM. METHODS: Individuals with T2DM (n = 80, aged 59 years) performed a 1-year randomized controlled trial and were randomized into three groups (control, n = 27; HIIT with RT, n = 25; MCT with RT, n = 28). Exercise sessions were supervised with a frequency of 3 days per week. Inflammatory and lipid profiles were measured at baseline and at 1-year follow-up. Changes in inflammatory and lipid markers were assessed using generalized estimating equations. RESULTS: After adjusting for sex, age and baseline moderate-to-vigorous physical activity (MVPA), we observed a time-by-group interaction for Interleukin-6 (IL-6) in both the MCT with RT (ß = - 0.70, p = 0.034) and HIIT with RT (ß = - 0.62, p = 0.049) groups, whereas, only the HIIT with RT group improved total cholesterol (ß = - 0.03, p = 0.045) and LDL-C (ß = - 0.03, p = 0.034), when compared to control. No effect was observed for C-reactive protein (CRP), cortisol, tumour necrosis factor-α (TNF-α), soluble form of the haptoglobin-hemoglobin receptor CD163 (sCD163), triglycerides and HDL-C in both groups (p > 0.05). CONCLUSIONS: Favorable adaptations on IL-6 were observed in both the HIIT and MCT combined with RT groups following a long-term 1-year exercise intervention in individuals with T2DM. However, only the HIIT with RT prevented further derangement of total cholesterol and LDL-C, when compared to the control group. Therefore, in order to encourage exercise participation and improve inflammatory profile, either exercise protocols may be prescribed, however, HIIT with RT may have further benefits on the lipid profile. Trial registration Clinicaltrials.gov ID: NCT03144505.

Promoting Health-Related Cardiorespiratory Fitness in Physical Education: The Role of Class Intensity and Habitual Physical Activity.

Physical education (PE) has the potential to promote health-related fitness, however, its contribution is still not clear. The aim of this study was to assess whether students' health-related cardiorespiratory fitness (CRF) improved from the beginning to the end of the school year, and to examine the role of PE class intensity and habitual physical activity (PA) in promoting students' CRF. This observational study employed a longitudinal design. Participants were 212 7th and 8th grade students (105 boys), mean age 12.9 years old, followed during one school year, from September 2017 to June 2018. The Progressive Aerobic Cardiovascular Endurance Run (PACER) was used to assess CRF at baseline and follow-up. PA was measured using accelerometers. PE class intensity was assessed using the System for Observing Fitness Instruction Time. Findings indicated that from the beginning to the end of the school year, a greater percentage of participants were in the CRF healthy fitness zone (73.1% to 79.7%, p = 0.022). Among boys, participating in organized sports (B = 4.61, 95% confidence interval [CI]: 0.33, 8.88) and the percentage of PE time being very active (B = 0.90, 95% CI: 0.44, 1.35) were positively associated with the change in PACER laps. Among girls, daily vigorous PA (B = 0.38, 95% CI: 0.15, 0.60) and participating in organized sports (B = 4.10, 95% CI: 0.93, 7.27) were also positively associated with PACER change, while being overweight or obese (B = -5.11, 95% CI: -8.28, -1.93) was negatively associated. In conclusion, PE was demonstrated to have a positive role in the promotion of CRF, especially among boys, while for girls, habitual PA seems to have a greater contribution. Nevertheless, results and conclusions should be considered carefully, taking into account study limitations, such as the non-direct measures of PE class intensity, CRF, and school setting.

Physical Fitness and Bone Health in Young Athletes and Nonathletes.

BACKGROUND: Physical activity (PA) and physical fitness (PF) are crucial for bone health. However, children participating in competitive sports with high PA are at a greater risk of fracture from trauma or overuse. Given the importance of bone development during adolescence, associations between commonly used physical fitness tests with distal third radius (R-SoS) and midshaft tibia (T-SoS) speed of sound by quantitative ultrasound were assessed in adolescent athletes and nonathletes. HYPOTHESIS: The relationship between physical fitness tests and R-SoS and T-SoS will differ depending on sex and athletic status. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Physical fitness of 285 boys (156 athletes) and 311 girls (74 athletes) aged 10 to 18 years was assessed through strength, speed, agility, and cardiorespiratory tests. Linear regression was used to assess the associations of physical fitness tests with R-SoS and T-SoS. RESULTS: For boys, favorable associations were observed between physical fitness tests with R-SoS in athletes and T-SoS in both athletes and nonathletes (P < 0.05). For nonathlete girls, favorable associations were found for handgrip (R-SoS and T-SoS, both P < 0.05), whereas the progressive aerobic cardiovascular endurance run, vertical jump, speed at 20 m and 40 m were only favorably associated with T-SoS. For athlete girls, the association between handgrip (P = 0.03), vertical jump, and 4 × 10 m shuttle run (P < 0.05) with T-SoS was significantly related to a bone outcome. CONCLUSION: The handgrip test and vertical jump were associated with T-SoS in boys and girls independent of sport status. These results suggest that physical fitness is associated with bone health in adolescents, particularly boys, and that the relationship between physical fitness and bone may differ depending on sex and athletic status. CLINICAL RELEVANCE: Physical fitness tests are simple, easy-to-use tools for monitoring bone health and should be used by sport and health professsionals to promote healthy sport participation and prevent bone injuries.

The Predictive Role of Raw Bioelectrical Impedance Parameters in Water Compartments and Fluid Distribution Assessed by Dilution Techniques in Athletes.

Abstract: The aims of this study were to analyze the usefulness of raw bioelectrical impedance (BI) parameters in assessing water compartments and fluid distribution in athletes. A total of 202 men and 71 female athletes were analyzed. Total body water (TBW) and extracellular water (ECW) were determined by dilution techniques, while intracellular water (ICW) was calculated. Fluid distribution was calculated as the ECW/ICW ratio (E:I). Phase angle (PhA), resistance (R) and reactance (Xc) were obtained through BI spectroscopy using frequency 50kHz. Fat (FM) and fat-free mass (FFM) were assessed by dual-energy X-ray absorptiometry. After adjusting for height, FM, FFM, age and sports category we observed that: PhA predicted ICW (females: ß = 1.62, p < 0.01; males: ß = 2.70, p < 0.01) and E:I (males and females: ß = -0.08; p < 0.01); R explained TBW (females: ß = -0.03; p < 0.01; males: ß = -0.06; p < 0.01) and ECW (females: ß = -0.02, p < 0.01; males: ß = -0.03, p < 0.01) and ICW (females: ß = -0.01, p < 0.053; males: ß = -0.03 p < 0.01); and Xc predicted ECW (females: ß = -0.06, p < 0.01; males: ß = -0.12, p < 0.01). A higher PhA is a good predictor of a larger ICW pool and a lower E:I, regardless of body composition, age, height, and sports category. Lower R is associated with higher water pools whereas ECW expansion is explained by lower Xc. Raw BI parameters are useful predictors of total and extracellular pools, cellular hydration and fluid distribution in athletes.

Usefulness of Reflection Scanning in Determining Whole-Body Composition in Broadly Built Individuals Using Dual-Energy X-ray Absorptiometry.

Whole-body composition analysis by dual-energy X-ray absorptiometry (DXA) requires subjects to fit within the width limits of the DXA bed. To overcome this limitation, the aim of this study was to validate a partial scanning technique at which the upper left limb is deliberately left unscanned and measurements are "reflected" from the right-side upper limb. A Hologic Explorer-W densitometer was used in a sample of 189 participants, including athletes and nonathletes, ranging from underweight to obese (body mass index: 17.0-40.1 kg/m2). A whole-body scan was analyzed as the reference procedure to determine bone mineral content (BMC), lean soft tissue (LST), and fat mass (FM), and reanalyzed using a partial reflection scanning (RS) technique. RS estimates of BMC were associated with athletic status and differed significantly from reference estimates (p < 0.05). Also, the RS estimates of LST and FM were different (p < 0.05) from those of the reference whole-body scan, although differences were small (0.17 kg, -0.02 kg, and -0.10% for BMC, LST, and FM, respectively). The alternative procedure explained more than 99% of the reference scan variance with low limits of agreement (BMC: -13.8 to 23.9 g [athletes] and -6.3 to 18.0 g [nonathletes]; LST: -0.11 to 0.45 kg; FM: -0.22 to 0.17 kg). Regardless of body mass index, athletic status, and gender, RS is a useful and simple solution to be used in individuals wider than the DXA scan area. However, individual errors for BMC may be higher in athletes engaged in lateral dominant sports practice.

Lack of agreement of in vivo raw bioimpedance measurements obtained from two single and multi-frequency bioelectrical impedance devices.

BACKGROUND: It is important for highly active individuals to accurately assess their hydration level. Bioelectrical impedance (BIA) can potentially meet these needs but its validity in active individuals is not well established. METHODS: We compared whole-body bioimpedance measurements obtained from multi-frequency bioelectrical impedance spectroscopy (BIS, Xitron 4200) at a 50 kHz frequency with those determined by a phase-sensitive single-frequency device (SF-BIA, BIA-101, RJL/Akern Systems) in two populations: active adults and elite athletes. RESULTS: One hundred twenty-six participants, including active males involved in recreational sports (N = 25, 20-39 yr) and elite athletes (females: N = 26, 18-35 yr; males: N = 75, 18-38 yr) participated in this study. Reactance (Xc), Resistance (R), Impedance (Z), and phase angle (PhA) were obtained by BIS and SF-BIA. Small but significant differences (R: -9.91 ± 15.09 Ω; Xc: -0.97 ± 2.56 Ω; Z: -9.96 ± 15.18 Ω; PhA: 0.12 ± 0.2°) were observed between the bioimpedance equipment in all measured variables (p < 0.05) though differences were within the devices' technical error of measurements. Device-specific values were highly (p < 0.0001) correlated [R2 ranged from 0.881 (Xc) to 0.833 (R)], but slopes and intercepts were different (p < 0.0001) from 1 and 0, respectively. Relatively large limits of agreement were observed for R (-40 to 21 Ω), Xc (-6 to 4 Ω), PhA (-0.4 to 0.5°), and impedance (-40 to 20 Ω). CONCLUSION: Bioimpedance measurements from the current single- and multi-frequency devices should not be used interchangeably. The of lack of agreement between devices was observed in determining individual values of R, Xc, Z and PhA of highly active populations possibly due to methodological and biological factors.

Fitness Mediates Activity and Sedentary Patterns Associations with Adiposity in Youth.

PURPOSE: We aimed to examine the cross-sectional associations of patterns of sedentary time (ST) and moderate-to-vigorous physical activity (MVPA) with total fat mass index (FMI) and abdominal FMI (FMIabd) in children, and additionally, to analyze if cardiorespiratory fitness (CRF) mediated these associations. METHODS: Fat mass index and FMIabd were assessed with dual-energy X-ray absorptiometry in 333 participants (172 girls) age 9 to 11 yr. MVPA, ST, breaks in ST per sedentary hour (BST/ST) and the number of daily sedentary bouts with various lengths (1-4, 5-9, 10-14, and ≥15 min) were assessed with accelerometry and CRF using a maximal cycle test. Hayes' PROCESS macro for SPSS was used for mediation analysis. RESULTS: The number of shorter sedentary bouts (1-4 min) was inversely associated with FMI (ß = -0.108), whereas longer sedentary bouts (5-9 min, ß = 0.169; 10-14 min, ß = 0.193; ≥15 min, ß = 0.377) had a positive association, independent of MVPA (P < 0.05). A similar trend was found for FMIabd. Moderate-to-vigorous physical activity was negatively related to FMI (ß = -0.029) and to FMIabd (ß = -0.003). There were no main associations for ST and BST/ST (P > 0.05). Cardiorespiratory fitness was inversely related to total and abdominal adiposity, and a large portion (40.9-65.7%) of the associations of MVPA and sedentary bouts with both FMI and FMIabd were mediated by CRF. CONCLUSIONS: Time in MVPA and accumulating ST in shorter sedentary bouts is inversely related to adiposity. However, these associations may be mediated by CRF. Emphasis should be given to programs that target increases in MVPA, which may influence CRF while reducing sedentary recreational behaviors.

Characterization and Comparison of Nutritional Intake between Preparatory and Competitive Phase of Highly Trained Athletes.

Background and objective: For a high level athlete, it is essential to ensure optimal energy as well as macro- and micro-nutrient and fluid intakes, in order to improve their performance during training and competition. Protein intake should be 1.2⁻2.1 g/kg/d, whereas the requirements for carbohydrate and fat intakes should be >5g/kg/d and 20⁻35% of energy, respectively. The micronutrient and fluid intakes in athletes were compared to the Dietary Reference Intake (DRI) and European Food Safety Authority (EFSA) recommendations, respectively. This study aimed to characterize and compare the nutritional habits of athletes at the preparatory and competitive phase, and to test if their nutritional intakes were in accordance with the recommendations. Materials and methods: A total of 276 professional athletes were assessed. To evaluate their nutritional intake, the athletes completed a 7 days food record. Under reporting was defined using a ratio of energy intake to basal metabolic rate (BMR) of 1.1. Body composition was assessed using dual energy X-ray absorptiometry (DXA). Results: Almost half (49%) of the athletes from the final sample reported lower measured intakes of carbohydrates and 27% reported a higher consumption of proteins than what was recommended. In both the preparatory and competitive phases, the micronutrients with a higher mismatch between the actual and recommended intakes were vitamins D and E, magnesium, folate, calcium, and zinc for both sexes, and iron intake for females. A large proportion of athletes reported a lower water intake. Compared to the recommendations, males reported a higher intake of carbohydrates, lipids, vitamins E, calcium, and magnesium (p <0.05) in the competitive phase, while females reported a lower ingestion of water, vitamins A and D, and calcium (p <0.05) in the preparatory phase. Conclusions: Overall, in the preparatory and competitive phases of the season, athletes reported a macro- and micro-nutrient intake below the recommendations, especially in the female athletic population. Dietary intakes in athletes need to be optimized and adjusted to their requirements, according to sex and sport, so as to avoid compromising health and performance.

Patterns of accelerometer-derived sedentary time across the lifespan.

We aimed to describe ST and its patterns on a national level. A hip-worn accelerometer (ActiGraph GT1M) was used to collect data during waking hours from 4575 Portuguese' participants from 2007-2009 (2683 females) aged 10-102 years old. Data was presented by sex, in 5-years age intervals, and by adolescents (n=2833), adults (n=1122), and older adults (n=620). Lambda-mu-sigma (LMS) smoothed percentile curves were estimated. Girls, women, and older women spent 61, 57, and 64% of wear time in ST, respectively. In males, ST represented 57, 60, and 62% of wear time respectively for boys, men, and older men. Comparing to other age groups, older adults spent a larger amount of ST in bouts ≥30-min (women: 33%, men: 39% of total ST). The number of breaks/ST hour were: 10.6 in girls, 11.7 in women, and 9.6 in older women. In males, the number of breaks/ST hour were: 11.2, 10.5, and 8.5 for boys, men, and older men. In conclusion, ST was not consistently higher at older ages. Instead, we found that the potential critical moments in which ST may be higher are during adolescence and in the transition from adulthood into older adulthood, which represents critical periods for interventions.

Regular physical activity eliminates the harmful association of television watching with multimorbidity. A cross-sectional study from the European Social Survey.

The aims of the study were to analyse the association of television viewing, physical activity (PA), and multimorbidity; and to understand if PA attenuates or eliminates the detrimental associations between television viewing and multimorbidity. This is a cross-sectional study based on data from the European Social Survey round 7, 2014. Participants were 32,931 adults (15,784 men), aged 18-114 years old, from 18 European countries. Self-reported information regarding chronic diseases (CD), PA and time watching television were collected through interview. Logistic regression analysis was conducted to analyse the association between watching television and PA with the presence of multimorbidity (≥1 CD). Men and women who watched television had increased odds of having multimorbidity. When considering PA it was observed that, independently of television viewing, compared to engaging in PA for ≤1 day/week, engaging in 2-4 days/week and in ≥5 days/week was inversely associated with multimorbidity. Increased odds of multimorbidity were observed for men spending >3 h/day watching television in the 2-3 days/week and ≤1 day/week categories of PA. For women engaged in 30 min of physical activity 2-3 days/week, spending >3 h/day watching television was associated with higher odds for multimorbidity. For adults who practiced physical activity on ≥ 5 days/week watching television was not associated with multimorbidity. Time spent watching television is associated with multimorbidity. However, physical activity participation can attenuate or even eliminate this association.

Pulse pressure tracking from adolescence to young adulthood: contributions to vascular health.

PURPOSE: We examined whether exposure to high PP in adolescence predicts carotid artery intima-media thickness (IMT) and stiffness indices at young adulthood. METHODS: Seventy-nine participants had their brachial systolic (SBP) and diastolic blood (DBP) pressures taken at the age of 15-16 years and later at young adulthood (29-31 years). Carotid IMT, distensibility and stiffness index ß were measured at young adulthood. Linear and logistical regression analysis were performed. RESULTS: PP at adolescence and at young adulthood predicted vascular health independently of sex, body mass index, and mean arterial pressure, explaining up to 37% of the variance. When analyzing its single constituents, at adolescence DBP was more predictive of vascular health, whereas DBP and SBP were equally important at young adulthood. Adolescents with high PP were at risk for increased carotid IMT (OR: 4.04-4.09), even if PP decreased at young adulthood. Young adults with high PP were at risk for increased stiffness regardless of adolescence PP (OR: 4.64-7.35). CONCLUSION: PP at adolescence and young adulthood may be a better predictor of early pathological changes in carotid artery structure and stiffness. Whereas carotid IMT in young adults appears to be influenced by PP at adolescence, carotid stiffness depends primarily on current PP.

A cross-sectional and prospective analyse of reallocating sedentary time to physical activity on children's cardiorespiratory fitness.

Cardiorespiratory fitness (CRF) is associated with health benefits in children, improving cardiac morphology, cardiovascular disease risk factors, and biological outcomes. This study aimed to examine the substitution effects of displaying a fixed duration of sedentary time with a fixed duration of physical activity (PA) at different intensities on children's CRF. A total of 315 children (136 boys) were assessed (age: 10.6 ± 0.6 years old). Outcomes at baseline and follow-up (16-months) were CRF determined using a maximal cycle test and sedentary time and PA measured with accelerometers. Data were analysed by isotemporal substitution analyses estimating the effect of reallocating 30 min/day of sedentary time by light (LPA), moderate (MPA) and vigorous physical activity (VPA) on CRF. VPA was positively and significantly associated with CRF cross-sectional (ß = 0.026, p < 0.001) and prospectively (ß = 0.010, p < 0.001). Reallocating 30 min/day of sedentary time into VPA was positively cross-sectionally (ß = 0.780, p < 0.001) and prospectively (ß = 0.303, p < 0.05) associated with CRF. Conversely, relocating 30-minutes of sedentary time into 30 minutes of LPA and MPA was not associated with CRF. These results suggest that reallocating an equal amount of time from sedentary into VPA is cross-sectional and prospectively associated with a favourable CRF.

How does academic achievement relate to cardiorespiratory fitness, self-reported physical activity and objectively reported physical activity: a systematic review in children and adolescents aged 6-18 years.

OBJECTIVE: This report aimed to systematically review the evidence for a differential association between objective and self-reported physical activity and cardiorespiratory fitness on academic achievement. DESIGN: Systematic review. DATA SOURCES: Studies were identified from searches in Embase, Education Resources Information Center, PubMed, PsycINFO, SPORTdiscus and Web of Science databases from January 2000 to December 2016. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Eligibility criteria included cross-sectional, longitudinal and interventional study designs. Outcomes included students' school grade or a standardised test or measure of academic achievement. Explanatory variables were cardiorespiratory fitness and objective and self-reported physical activity. Inclusion criteria included school-aged children and adolescents aged-18 years (or students from primary to secondary school when student's participants age was not described) and articles published in English, Portuguese or Spanish. RESULTS: A total of 51 articles met inclusion criteria: 41 cross-sectional, 2 intervention and 8 longitudinal studies. Results from 11 studies were inconsistent regarding the relationship between objectively measured physical activity and academic achievement. Ten of the 16 articles reported positive associations between self-reported physical activity and academic achievement. From the 22 studies that analysed the relationship between cardiorespiratory fitness and academic achievement, it was verified that they all generally support the beneficial effect of cardiorespiratory fitness on students' academic achievement. CONCLUSION: Higher cardiorespiratory fitness may be important to enhance children and adolescents' health and, additionally, academic achievement. Due to a lack of consensus across studies, methodological issues associated with the assessment of physical activity should be considered when investigating physical activity and academic achievement.

Abdominal obesity in adolescents: Development of age-specific waist circumference cut-offs linked to adult IDF criteria.

OBJECTIVES: The purpose of this study was to develop age- and sex-specific waist circumference (WC) cut-off points, linked to older adolescent and adult criteria for abdominal obesity, to be applied to children in the clinical setting. METHODS: A total of 16,788 adolescents aged 10 to 16 years were assessed for WC. Smoothed age and sex-specific WC curves were obtained using Cole's LMS method. RESULTS: Percentiles that corresponded to the International Diabetes Federation (IDF) recommendations used for older adolescents and adults (16+ years old) were the 97th percentile for boys and the 87th percentile for girls. Using these cutoffs, a total of 368 boys and 1138 girls were categorized as abdominally obese, in contrast to 1654 boys and 987 girls that were identified using the current IDF pediatric criteria (90th percentile). CONCLUSIONS: We provide age- and sex-specific cut-off points that can be used to identify abdominal obesity in adolescents. The present findings provide a tool that can be used in the clinical setting for the early detection and prevention of adult obesity. Population-specific cutoffs may be required for pediatric ages to diagnose children at risk.

Sedentary Patterns, Physical Activity, and Cardiorespiratory Fitness in Association to Glycemic Control in Type 2 Diabetes Patients.

Background: Sedentary behavior has been considered an independent risk factor for type-2 diabetes (T2D), with a negative impact on several physiological outcomes, whereas breaks in sedentary time (BST) have been proposed as a viable solution to mitigate some of these effects. However, little is known about the independent associations of sedentary pursuits, physical activity, and cardiorespiratory fitness (CRF) variables with glycemic control. We investigated the independent associations of total sedentary time, BST, moderate-to-vigorous physical activity (MVPA), and CRF with glycemic outcomes in patients with T2D. Methods: Total sedentary time, BST, and MVPA were assessed in 66 participants (29 women) with T2D, using accelerometry. Glucose and insulin were measured during a mixed meal tolerance test, with the respective calculations of HOMA-IR and Matsuda index. Glycated hemoglobin (HbA1c) was also analyzed. CRF was measured in a maximal treadmill test with breath-by-breath gases analysis. Multiple regressions were used for data analysis. Results: Regardless of CRF, total sedentary time was positively associated with HbA1c (ß = 0.25, p = 0.044). Adjusting for MVPA, total sedentary time was related to fasting glucose (ß = 0.32, p = 0.037). No associations between total sedentary time and the remaining glycemic outcomes, after adjusting for MVPA. BST had favorable associations with HOMA-IR (ß = -0.28, p = 0.047) and fasting glucose (ß = -0.25, p = 0.046), when adjusted for MVPA, and with HOMA-IR (ß = -0.25, p = 0.036), Matsuda index (ß = 0.26, p = 0.036), and fasting glucose (ß = -0.22, p = 0.038), following adjustment for CRF. When adjusting for total sedentary time, only CRF yielded favorable associations with HOMA-IR (ß = -0.29, p = 0.039), fasting glucose (ß = -0.32, p = 0.012), and glucose at 120-min (ß = -0.26, p = 0.035), and no associations were found for MVPA with none of the metabolic outcomes. Conclusion: The results from this study suggest that sedentary time and patterns are relevant for the glycemic control in patients with T2D. Still, MVPA and CRF counteracted most of the associations for total sedentary time but not for the BST. MVPA was not associated with metabolic outcomes, and CRF lost some of the associations with glycemic indicators when adjusted for total sedentary time. Future interventions aiming to control/improve T2D must consider reducing and breaking up sedentary time as a viable strategy to improve glycemic control.

Energy Balance over One Athletic Season.

INTRODUCTION: Magnitude and variation in energy balance (EB) components over an athletic season are largely unknown. PURPOSE: We investigated the longitudinal changes in EB over one season and explored the association between EB variation and change in the main fat-free mass (FFM) components in highly trained athletes. METHODS: Eighty athletes (54 males; handball, volleyball, basketball, triathlete, and swimming) were evaluated from the beginning of the season to the main competition stage. Resting and total energy expenditure (REE and TEE, respectively) were assessed by indirect calorimetry and doubly labeled water, respectively. Physical activity energy expenditure was calculated as TEE - 0.1 TEE - REE. Fat mass (FM), FFM, and bone mineral were evaluated with dual-energy x-ray absorptiometry; changed body energy stores were calculated as 1.0(ΔFFM/Δtime) + 9.5(ΔFM/Δtime). Total-body water (TBW) and its compartments were assessed through dilution techniques, and total-body protein was calculated from a four-compartment model, with body volume assessed by air displacement plethysmography. RESULTS: Although a negative EB of -17.4 ± 72.7 kcal·d was observed (P < 0.05), EB varied widely among sports and across sex groups resulting in a net weight increase (0.7 ± 2.3 kg) that is attributable to significant changes in FFM (1.2 ± 1.6 kg) and FM (-0.7 ± 1.5 kg) (P < 0.05). EB was related with TBW and intracellular water (r = 0.354, r = 0.257, P < 0.05, respectively), regardless of sex, sports, and age. CONCLUSIONS: The mean negative EB observed over the season resulted from the rate of FM use and FFM accretion, but with a large variation by sex and sports. TBW, but not total-body protein or mineral balance, explained the magnitude of EB, which means that athletes under a positive or a negative EB showed a TBW expansion or shrinkage, respectively, specifically within the cells, over one athletic season.