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Young athletes must contend with the constraints of elite sports on top of school commitments and the physiological processes associated with adolescence. This study assessed week and weekend sleep and schedule of activities in elite adolescent rugby players during the in-season competitive phase compared with age-matched non-athlete controls. 32 adolescents (GR: 16 elite rugby players, GC: 16 controls) from the same boarding school filled out a daily schedule of activities and a sleep diary, and wore a multichannel electroencephalogram for 14 days. They later filled out questionnaires on their sleep quality, sleepiness, and perceived stress. Both groups showed insufficient sleep duration during the week (<7 h). Only GC caught up on their sleep debt during the weekend (increased TIB, TST and time spent in REM sleep, all p < 0.001). Weekend TIB, TST and, N3 sleep remained similar to that for weekdays in GR. However, GR experienced lower sleep quality (decreased SE, increased WASO, all p < 0.01) and a decrease in REM sleep (p < 0.01). Schedules of activities showed an increase in time spent on overall activities during the weekend, mainly due to competition and sport-specific travel, which resulted in a decrease in sleep opportunity time compared with GC (p < 0.001). Δ sleep opportunity time (weekend-week) was associated with Δ TST (weekend-week), and Δ TST (weekend-week) was associated with sleepiness and perceived stress. Busy schedules during the competitive season decreased sleep opportunity time and prevented elite adolescent rugby players from catching up on their sleep at weekends. HIGHLIGHTS Adolescent rugby players have insufficient sleep during both week and weekend of the in-season competitive phase Congested schedule prevented elite adolescent rugby players from catching up on their sleep at weekends. Sleep considerations are necessary when planning the weekend sporting schedules [ABSTRACT FROM AUTHOR]

Aim: To assess muscle function and functional abilities in children with juvenile idiopathic arthritis (JIA).Methods: Fourteen children with JIA and 14 healthy controls matched for age and sex were included. Muscle characteristics, both structural (thickness, cross-sectional area (CSA) and fascicle angle) and qualitative (intermuscular adipose tissue; IMAT), were assessed in thigh muscles using ultrasound and peripheral quantitative computed tomography (pQCT). Muscle function and functional abilities were determined from the assessment of maximal voluntary isometric contraction (MVIC) knee extensors force and vertical jump performance.Results: No significant difference in MVIC force was observed between the two groups. However, squat jump height was significantly reduced in children with JIA (18.3 ± 5.4 vs 24.3 ± 7.9 cm, P < .05). No differences in structural parameters were observed, but IMAT/CSA (0.22 ± 0.02 vs 0.25 ± 0.03; P = .01) was significantly lower in children with JIA than in healthy children.Conclusion: Knee extensor muscle architecture and force were comparable between children with and without JIA, but functional abilities (vertical jump performance) were poorer in JIA. The lower IMAT area in JIA could result from a lower physical activity level compared with healthy children. [ABSTRACT FROM AUTHOR]

Summary: Background: Although adolescence and obesity are related to impaired sleep duration and quality, exercise was admitted as a nonpharmacological treatment for sleep and better control of energy balance. Objectives: To investigate the acute effects of intense exercise on sleep and subsequent dietary intake. Methods: Sixteen adolescent girls with obesity (age 13.7 ± 1.1 years, weight 82.7 ± 10.2 kg, body mass index (BMI) 30.5 ± 3.4 kg/m2, fat mass (FM) 39.2 ± 3.1%, Pittsburgh Sleep Quality Index (PSQI) 8.6 ± 2.8, paediatric daytime sleepiness scale (PDSS) 19.6 ± 5.9) took part in two experimental sessions in a random order: Control (CTL) and Exercise (EX). The two sessions were identical except for a continuous ergocycle exercise bout lasting 40 minutes and performed at 70% VO2max at the end of the morning of EX. Energy expenditure and sleep were measured by accelerometry and next‐morning dietary intake in an ad libitum meal. Results: Higher sleep duration (P < 0.03) and quality (decreased WASO: P < 0.02; increased SE%: P < 0.02) were observed in EX compared with CTL. This was associated with a nonsignificant decrease in caloric intake (−78 kcal) and a significant decrease in food energy density (P < 0.04), fat, and sugar consumption (respectively, P < 0.02 and P < 0.05) the following morning. Conclusions: Acute exercise efficaciously increased sleep duration and quality, resulting in a decrease in subsequent energy‐dense food consumption in adolescent girls with obesity. [ABSTRACT FROM AUTHOR]

Objective While indexes have been proposed to estimate total and abdominal adiposity in adults, the assessment of adiposity among obese adolescents remains difficult in clinical setting. The aim of this study was to evaluate the clinical applicability of total and visceral and fat mass indexes in obese adolescents. Methods One hundred and thirty, 12-16 year old obese adolescents were enrolled in the study. Anthropometric characteristics [Height, weight, waist (WC), and hip (HC) circumferences] were measured and body composition assessed by Dual X-Ray absorptiometry (DXA) assessed. High Density Lipoprotein-Cholesterol (HDL-C) and Triglycerides (TG) plasma concentrations were assessed from fasting blood samples. Body Adiposity indexes (BAI) were calculated from formulas taking into account, height, weight, and WC, and for the Visceral Adiposity indexes, a formula including WC, HDL-C, and TG. Results Both the BAI and Pediatric Body Adiposity Index (BAIp) were significantly correlated to the percentage of total body fat assessed by DXA (DXA %FM; P < 0.001; r = 0.67 and r = 0.64, respectively). The best concordance with DXA %FM was found using BAI. The Visceral Adiposity Index was only weakly associated with abdominal fat mass assessed by DXA ( r = 0.27, P < 0.01) and only significantly in boys ( r = 0.41, P < 0.01) when the analysis was performed by gender. Conclusion The BAI initially developed in adults presented a better but still weak association with DXA-%FM when compared with the BAIw and BAIp. The three indices thus do not provide better estimate of obese adolescents' adiposity than the widely used Body Mass Index. Am. J. Hum. Biol. 27:334-338, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The association between impairment in mitochondrial muscle fat oxidative capacity (OXFA) and occurrence of insulin resistance was examined in 14 healthy trained men (age, 24±4yr) submitted to 4weeks of training cessation. Training stop induced a significant decrease in mRNA levels of proteins involved in muscle fat metabolism, particularly PPARα (−58%, P <0.01) and PGC-1α (−30%, P <0.05), a 21% reduction in OXFA (P <0.01), and reduced fat oxidation during moderately intense exercise (P <0.05). In contrast, there was no significant alteration in insulin sensitivity. In conclusion, decline in OXFA is a rapid metabolic event following training cessation. It is involved in the regulation of whole body fat balance but not in the deterioration of insulin sensitivity. [Copyright &y& Elsevier]

Aim: To fight overweight and obesity in childhood, this study proposes an additional physical activity (PA) in young children aged 6–10 years. The objective was to evaluate the effect of school-based PA on the body composition according to body mass index (BMI) categories (nonobese vs. obese) and gender. Methods: This 6-month study examined the effect of this intervention on body composition in 425 children in 14 primary schools (2 weekly PA sessions of 1 h each) compared to 5 control schools. Adiposity indices were evaluated or calculated: BMI, BMI z-score, waist circumference, sum of skinfolds and fat-free mass. Results: No difference in the prevalence of obesity and anthropometric characteristics was found between the intervention and control groups at baseline. In girls, PA intervention had significant effect on all anthropometric variables (p < 0.05 to p < 0.001), except on BMI. In contrast, in boys only BMI z-score (p < 0.001) and fat-free mass (p < 0.001) were affected. Conclusions: Six months of preventive PA intervention offer an effective means to improve body composition in obese children. The pattern of response related to PA was similar between girls and boys. In contrast, the pattern was different according to BMI category, with a higher response in obese than nonobese children. [ABSTRACT FROM AUTHOR]

This commentary is on the original article by Eken et al. on pages 212–218 of this issue. [ABSTRACT FROM AUTHOR]