Energy and Macronutrient Intakes in Young Athletes: A Systematic Review and Meta-analysis.

The aim of this study was to conduct a systematic review and meta-analysis of differences in energy and macronutrient intakes between young athletes and non-athletes, considering age, gender and sport characteristics. The study included original research articles that compared energy and macronutrient intakes of 8 to 18-year-old athletes to non-athletes. Mean difference (MD) meta-analyses were performed to quantify energy and macronutrient intake differences between athletes and non-athletes. Eighteen observational studies were included. Results revealed that the energy and carbohydrate consumption of athletes was higher than that of non-athletes (MD=4.65kcal/kg/d, p<0.01 and MD=1.65% of total energy intake, p<0.01, respectively). Subgroup analyses revealed a significant effect of total training time on the observed mean differences between athletes and non-athletes. As practice time increased, the differences between athletes and non-athletes increased for carbohydrate and decreased for protein. Sport type analysis revealed a higher protein intake by mixed sport athletes compared to endurance and power sports. Analyses also indicated an age effect: the older the athletes, the smaller the differences between athletes and non-athletes for energy intake. However, the methods used to match groups and estimate dietary intakes forced us to moderate the results. More rigorous research methods are needed to define the dietary intakes of athletes and non-athletes.

Effect of maturity status on force-velocity relationships in a ballistic lower limb test in high-level soccer players.

This study aimed to investigate the effect of maturity status on force-velocity relationships in a ballistic lower limb (BLL) test in high-level soccer adolescents and young adults. The population was 61 adolescents (13.0-17.9 years) and 23 young adults (18.0-26.2 years). Subjects completed the BLL test on a ballistic ergometer equipped with two force plates and a linear encoder. Following Samozino's method, maximal power output (Pmax), force (F0) and velocity (v0) were determined. An allometric model was applied to Pmax and F0 with body mass (BM) and fat-free mass (FFM). Significant effects of maturity status were found for absolute Pmax, F0, relative Pmax to BM and FFM, relative F0 to FFM and F0 allometrically scaled to BM and FFM (p = 0.02 to p < 0.001; η = 0.10 to η = 0.49). There was no significant effect for Pmax allometrically scaled to BM and FFM, F0 relative to BM and v0. Body dimensions explain group differences in Pmax whereas for F0, qualitative factors explain the differences between the groups. As maturity status and body dimensions influence Pmax, these factors should be considered when assessing explosive short efforts. This could help to better identify potential athletic talent and adapt training content.

Influence of Growth, Maturation, and Sex on Maximal Power, Force, and Velocity During Overground Sprinting.

ABSTRACT: Sudlow, A, Galantine, P, Del Sordo, G, Raymond, J-J, Dalleau, G, Peyrot, N, and Duché, P. Influence of growth, maturation, and sex on maximal power, force, and velocity during overground sprinting. J Strength Cond Res 38(3): 491-500, 2024-In pediatric populations maximal anaerobic power, force, and velocity capabilities are influenced by changes in body dimensions and muscle function. The aim of this study was to investigate the influences of growth, maturation, and sex on short-term anaerobic performance. One hundred forty children pre-, mid-, and postpeak height velocity performed two 30-m sprints concurrently measured using a radar device. Maximal power (Pmax), force (F0), and velocity (v0) were calculated from sprint velocity-time data and normalized using sex-specific, multiplicative, allometric models containing body mass, fat-free mass (FFM), or height, and chronological age. Absolute values for Pmax, F0, and v0 were higher with increasing maturity (p < 0.01; d ≥ 0.96), and boys had greater outputs than girls (p < 0.01; d ≥ 1.19). When Pmax and v0 were scaled all maturity-related and sex-related differences were removed. When F0 was scaled using models excluding age, all maturity-related differences were removed except for the least mature group (p < 0.05; d ≥ 0.88) and boys maintained higher values than girls (p < 0.05; d ≥ 0.92). All maturity-related and sex-related differences were removed when F0 was scaled using models including age. Maturity-related and sex-related variance in Pmax and v0 can be entirely explained when FFM, height, and chronological age are accounted for. Regarding F0, there seems to be a threshold after which the inclusion of age is no longer necessary to account for maturity-related differences. In young prepubertal children, the inclusion of age likely accounts for deficits in neuromuscular capacities and motor skills, which body dimensions cannot account for. Practitioners should focus on eliciting neural adaptations and enhancing motor coordination in prepubertal children to improve anaerobic performance during overground sprinting.

Fitness and metabolic response to exercise in young adult survivors of childhood lymphoma.

PURPOSE: Childhood lymphoma survivors (CLSs) are at high risk of reduced daily activity. This work studied metabolic substrate use and cardiorespiratory function in response to exercise in CLSs. METHODS: Twenty CLSs and 20 healthy adult controls matched for sex, age, and BMI took an incremental submaximal exercise test to determine fat/carbohydrate oxidation rates. Resting echocardiography and pulmonary functional tests were performed. Physical activity level, and blood metabolic and hormonal levels were measured. RESULTS: CLSs reported more physical activity than controls (6317 ± 3815 vs. 4268 ± 4354 MET-minutes/week, p = 0.013), had higher resting heart rate (83 ± 14 vs. 71 ± 13 bpm, p = 0.006), and showed altered global longitudinal strain (- 17.5 ± 2.1 vs. - 19.8 ± 1.6%, p = 0.003). We observed no difference in maximal fat oxidation between the groups, but it was reached at lower relative exercise intensities in CLSs (Fatmax 17.4 ± 6.0 vs. 20.1 ± 4.1 mL/kg, p = 0.021). At V̇O2 peak, CLSs developed lower relative exercise power (3.2 ± 0.9 vs. 4.0 ± 0.7 W/kg, p = 0.012). CONCLUSION: CLSs reported higher levels of physical activity but they attained maximal fat oxidation at lower relative oxygen uptake and applied lower relative power at V̇O2 peak. CLSs may thus have lower muscular efficiency, causing greater fatigability in response to exercise, possibly related to chemotherapy exposure during adolescence and childhood. Long-term follow-up is essential and regular physical activity needs to be sustained.

Force-velocity profile in sprinting: sex effect.

The ability to produce muscle power during sprint acceleration is a major determinant of physical performance. The comparison of the force-velocity (F-v: theoretical maximal force, F0; velocity, v0 and maximal power output, Pmax) profile between men and women has attracted little attention. Most studies of sex differences have failed to apply a scaling ratio when reporting data. The present study investigated the sex effect on the F-v profile using an allometric model applied with body mass (BM), fat-free mass (FFM), fat-free mass of the lower limb (FFMLL), cross-sectional area (CSA) and leg length (LL) to mechanical parameters. Thirty students (15 men, 15 women) participated. Raw velocity-time data for three maximal 35 m sprints were measured with a radar. Mechanical parameters of the F-v relationship were calculated from the modelling of the velocity-time curve. When F0 and Pmax were allometrically scaled with BM (p = 0.538; ES = 0.23) and FFM (p = 0.176; ES = 0.51), there were no significant differences between men and women. However, when the allometric model was applied to Pmax with FFMLL (p = 0.015; ES = 0.52), F0 with CSA (p = 0.016; ES = 0.93) and v0 with LL (p ≤ 0.001; ES = 1.98) differences between men and women persisted. FFM explained 83% of the sex differences in the F-v profile (p ≤ 0.001). After applying an allometric model, sex differences in the F-v profile are explained by other factors than body dimensions (i.e., physiological qualitative differences).

A Delayed Evening Meal Enhances Sleep Quality in Young Rugby Players.

The aim of this study was to examine the effect of delayed evening mealtime on sleep quality in young athletes. Twelve rugby players (age 15.8 ± 0.7 years) participated in a crossover within-participant design. Adolescents spent five consecutive days in each of two conditions, separated by a 2-week washout period: routine dinner (3.5 hr before bedtime) and late dinner (LD, 1.5 hr before bedtime). Other mealtimes as well as bedtime and wake-up time were usual and remained the same in both conditions. Their schedules, dietary intakes, and physical activity were controlled and kept constant throughout the study. Sleep was assessed using polysomnography on the first and the last nights in the individual rooms of the boarding school. An increase in total sleep time by 24 min (p = .001, d = 1.24) and sleep efficiency by 4.8% was obtained during LD (p = .001, d = 1.24). Improvement in sleep efficiency was mainly due to a lower wake after sleep onset (-25 min, p = .014, d = -3.20), a decrease of microarousals (-25%, p = .049, d = -0.64), and awakenings ≥90 s (-30%, p < .01, d = -0.97) in LD compared to routine dinner. There were no significant differences in sleep architecture except for a shorter slow-wave sleep (N3) latency (-6.9 min, p = .03, d = -0.778) obtained during LD. In this study, evening dinner 1.5 hr before bedtime leads to better quality and less fragmented sleep compared to evening dinner 3.5 hr before bedtime in young athletes.

Muscle function and architecture in children with juvenile idiopathic arthritis.

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.

Metabolic response to exercise in childhood brain tumor survivors: A pilot controlled study.

BACKGROUND/OBJECTIVES: Survival rates in children diagnosed with malignant brain tumors exceed 70%. A higher risk of dyslipidemia, central obesity, and insulin resistance has been reported among these children. We investigated substrate utilization during submaximal exercise. DESIGN/METHODS: Ten brain tumor survivors and 10 healthy children were matched by sex, age, and Tanner stage. Participants completed a submaximal incremental exercise test to determine their fat and carbohydrate oxidation rates. RESULTS: The relative oxygen volume (VO2 ) peak was significantly higher in the control group than in the survivors of childhood brain tumors (43.3 ± 11.9 and 32.4 ± 10.2 mL/kg /min, P = .04). At the same relative exercise intensity, there was no difference in the carbohydrate or lipid oxidation rate between the two groups, or in the maximal fat oxidation (MFO) rate, or in the heart rate or percentage of VO2 peak to reach MFO. Healthy children achieved MFO at significantly higher muscular power than did brain tumor survivors (47.9 ± 20.8 and 21.8 ± 9.6 W, P = .003). CONCLUSION: Because child brain tumor survivors are less physically fit than healthy children, and substrate utilization during submaximal exercise is not different, physical activity should be promoted for child brain tumor survivors.

Effects of timing of moderate exercise in the evening on sleep and subsequent dietary intake in lean, young, healthy adults: randomized crossover study.

PURPOSE: This work studied the acute effects in healthy adults of evening exercise timing on their quality of sleep and dietary intake over the following 12 h. METHODS: Sixteen men and women, (age: 22.3 ± 1.4 years; BMI: 20.8 ± 1.4 kg/m2, intermediate chronotype) took part in three randomized crossover sessions spread over three consecutive weeks: control session (CTL), 1 h exercise session at 6:30 pm (E6:30) and 1 h exercise session at 8:30 pm (E8:30), in which exercise finished 4 h and 2 h before habitual bedtime, respectively. Exercise was an outdoor run at 60% HRmaxth. Energy expenditure and sleep were ambulatories monitored by accelerometry under free-living condition. Ad-libitum dinner and breakfast were used to measure subsequent energy intake and proportion of that energy derived from each macronutrient. RESULTS: Evening exercise did not disrupt sleep. Improvement in sleep quality compared to the control condition was observed only when exercise was performed 4 h before habitual bedtime (WASO: p < 0.01; SE: p < 0.02). Interestingly, our results give insight into differences in sleep parameters response to evening exercise between habitually poor and good sleepers mainly when it comes to sleep efficiency and wake after sleep onset (all p < 0.01). There was no difference in calorie intake from ad-libitum dinner and breakfast. However, an association between improvement in sleep efficiency from acute exercise and reduction of energy intake the following morning was found. CONCLUSION: Early evening exercise could offer a useful alternative for achieving better sleep in healthy young adults especially when it comes to poor sleepers.

Effect of Drop Height on Vertical Jumping Performance in Pre-, Circa-, and Post-Pubertal Boys and Girls.

PURPOSE: To examine the effect of drop height on vertical jumping performance in children with respect to sex and maturity status. METHODS: Thirty-seven pre-pubertal, 71 circa-pubertal, and 69 post-pubertal boys and girls performed, in a randomized order, 2 squat jumps, 2 countermovement jumps, and 2 drop jumps (DJ) from heights of 20, 30, 40, 50, 60, and 70 cm. The trial with the best jump height in each test was used for analysis. RESULTS: No significant sex × maturity status × jump type interaction for jump height was observed. However, on average, the children jumped higher in the countermovement jump than in squat jump and DJs (+1.2 and +1.6 cm, P < .001, respectively), with no significant differences between DJs and squat jumps or between DJs when increasing drop heights. Regarding DJs, 59.3% of the participants jumped higher from drop heights of 20 to 40 cm. CONCLUSIONS: Children, independent of sex and maturity status, performed best in the countermovement jump, and no performance gain was obtained by dropping from heights of 20 to 70 cm. During maturation, the use of drop heights between 20 and 40 cm may be considered in plyometric training, but the optimum height must be obtained individually.

La santé des enfants en France : un enjeu négligé ?

INTRODUCTION: As part of the National Health Strategy, the High Council for Public Health (HCSP) was tasked with leading a reflection on a “comprehensive and concerted child health policy”. Policy-making requires relevant knowledge and statistical benchmarks. It therefore seemed useful to examine the French statistical system and active research topics. This assessment is expected to provide a current portrait of the priorities and implicit health choices for the children. It also aims to reveal insufficiently explored aspects of children’s health. METHODS: The inventory of this system was carried out on the basis of several methods, hearings, work of two documentalists, and analysis of the published and grey literature. RESULTS: The emphasis is on pathologies, medical prevention and behaviors conceived primarily as individual. The idea that the health of tomorrow’s adults is built up behind this apparent good health and its inequalities does not appear, or only marginally. The elements on affective, cognitive or relational development are not sufficiently analyzed, for lack of data. The living conditions of children, especially poverty and violence in all its forms, are not sufficiently considered as health issues. Research is developing today with a hospital-centric vision, without a real strategy of research on children’s health. DISCUSSION: Given the dispersion of data, publishing a summary report on children’s health on a regular basis is essential, as enriching the system with data on the environment, poverty and psychomotor, psychosocial and cognitive development. There is an urgent need to develop research on children’s health and to define a research strategy that does not exist today.

Physical activity and sedentary levels in children with juvenile idiopathic arthritis and inflammatory bowel disease. A systematic review and meta-analysis.

BACKGROUND: Physical activity (PA) is essential for children throughout their growth and maturation. It improves physiological and psychological health and limits the risk of developing metabolic disorders. However, some chronic physiological and metabolic diseases may lead to decreased PA. The diversity of outcomes in the literature offers no consensus for physical activity and sedentary levels in children with juvenile idiopathic arthritis (JIA) or inflammatory bowel disease (IBD). METHODS: A literature review and a meta-analysis were carried out with original studies from a Medline database search. Only high-quality studies (STROBE checklist) written in English comparing PA level or sedentary behavior (SB) between children with the disorders and their healthy peers were considered. The aim was to examine PA and SB in children with JIA or IBD compared to their healthy peers. RESULTS: The literature review and meta-analysis identified decreased PA and increased time spent in SB in these populations, which may exacerbate both their lower physical fitness and the symptoms of their health disorders. CONCLUSION: Results nevertheless show discrepancies due to the different materials and methods used and the variables measured. Further studies are needed to establish a gold standard method for assessing PA level in these populations.

Acute effect of an intensified exercise program on subsequent sleep, dietary intake, and performance in junior rugby players.

The effect of exercise on sleep remains controversial in athletes especially in junior athletes. This study tested the acute effect of additional intense rugby training on sleep, next-day dietary intake, and physical performances in adolescent rugby players compared to a day with regular exercise. 17 male rugby players in the national under-17 category (age: 15.7 ± 1.1 years, height: 1.78 ± 0.1 m, weight: 84.4 ± 13.6 kg, BMI: 26.6 ± 3.8 kg/m2, fat mass: 14.5 ± 3.4%, VO2max Yo-Yo test: 52.1 ± 4.4 mL/min/kg, evening chronotype) took part in this study. The athletes completed two 36-h experimental sessions in random order: a regular exercise program (REP) vs. an intensified exercise program (IEP) at a 1-week interval. Physical activity and sleep data were collected using accelerometers. Performance tests were conducted the next morning after an ad libitum breakfast. Sleep improved during intensive training (TST: + 26 min, SL: - 4%, WASO: - 39%, SE: + 8.5%) with moderate effect size. There was no next-day difference in calorie intake from breakfast, but macronutrient composition shifted toward proteins (regular: 15.4 ± 6.1% vs. intensive: 18.9 ± 7.4%, ES = - 0.650 [- 1.13; - 0.18]). There were no significant differences in Wingate test performance or spatial awareness task time. However, performance in submaximal tests improved. Acute intensified training results in increased sleep duration and quality without disturbing next-day performance or dietary intake in young rugby players.

Corrigendum to "Single Bout Exercise in Children with Juvenile Idiopathic Arthritis: Impact on Inflammatory Markers".

[This corrects the article DOI: 10.1155/2018/9365745.].

Inflammatory Response 24 h Post-Exercise in Youth with Juvenile Idiopathic Arthritis.

The aim of this study was to measure the impact, at 24 h post-exercise, of a single exercise bout on plasma inflammatory markers such as calprotectin, IL-6, sIL-6 R, sgp130 and the hypothalamic-pituitary-adrenal (HPA) axis in children with juvenile idiopathic arthritis (JIA).Twelve children with JIA attended the laboratory on three consecutive days (control day, exercise day and 24 h post-exercise), including a 20-min exercise bout on a cycle-ergometer at 70% of max. HR at 8:30 a.m. on day 2. Plasma concentrations of calprotectin, IL-6, sIL-6 R, sgp130, cortisol, ACTH and DHEA were measured on venous blood samples taken every day.at rest and at 8:30, 8:50, 9:30, 10:30 a.m. and 12:00, 3:00, 5:30 p.m.A single exercise bout increased plasma calprotectin 1.7-fold (p<0.001) but did not increase IL-6 and soluble IL-6 receptors in short-term post-exercise recovery. However, at 24 h post-exercise, calprotectin, IL-6 and its receptors had decreased compared to control-day levels. There was a transient 2-fold increase in post-exercise self-evaluated pain (p=0.03) that disappeared in the evening without repercussions the following day.Physical activity in children with JIA results in a slight transient systemic inflammation but seems to be followed by counter-regulation at 24 h post-exercise with a decrease in proinflammatory markers.

Bone-adiposity cross-talk: implications for pediatric obesity. A narrative review of literature.

The rising prevalence of overweight and obesity among pediatric populations has become a major global concern. The objective of this review is to demonstrate potential interactions between the products released by fat tissue and the hormonal production of bone tissue in obese children and adolescents. Advancing the understanding of the complex interactions between adipocyte and osteocyte activities may contribute to the mechanistic understanding of the body's responses to weight loss during adolescence. This knowledge could also reveal any side effects encountered with these interventions. Currently, the concept of bone-adiposity crosstalk has not been fully elucidated, and the mechanisms remain controversial. Understanding the local interactions between the released products by fat tissue and hormones produced in bone tissue requires further investigations.

Comparison of total body and abdominal adiposity indexes to dual x-ray absorptiometry scan in obese adolescents.

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.

Physical activity for weight loss in children: is there any compensatory mechanism?

Although physical activity is primarily considered for its effects on energy expenditure for prevention and treatment of both overweight and obesity, its role in the regulation and control of energy balance seems more complex. Not only does physical activity affect energy expenditure, it also leads to modifications in energy intake and appetite that have been identified in children and that should be considered for weight loss. It also appears that it may not systematically favor increased energy expenditure due to individual differences in compensatory responses. This brief paper summarizes the pediatric evidence regarding those potential compensatory responses to physical activity and suggests that these compensatory responses of increasing physical activity levels may depend on children's adiposity status.

Pathways of sleep disturbances in juvenile idiopathic arthritis and recommendations for clinical management approaches: A critical review.

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease affecting young people. It has a profound impact on their physical, mental and social lives, leading to long-term disability. With the growing awareness of the importance of sleep in all areas of functioning in young people, an emerging literature has drawn attention to the role of sleep in the pathogenesis of JIA. Sleep disturbances in children and adolescents with JIA arise from a wide range of symptoms and pathways, leading to a vicious cycle that exacerbates subclinical inflammation, symptoms and disease progression. Putative factors contributing to sleep disturbances include chronic inflammation, JIA-associated sleep disorders, JIA symptoms (e.g. pain), psychological comorbidities and potential circadian disruption, which may be exacerbated by the transition to adolescence. Here, we review these pathways and advocate key strategies and alternatives for sleep management in young people with JIA in clinical settings. We identify gaps in knowledge and suggest future directions to improve our understanding of JIA sleep disorders, including clinical trials investigating potential strategies to improve sleep health in this young population.