Energy Expenditure, Dietary Energy Intake, and Nutritional Supplements in Adolescent Volleyball Athletes versus Nonathletic Controls

General and sport-specific nutrition knowledge and behaviors of adolescent athletes

INTRODUCTION

Most youth do not meet national nutrition recommendations and overconsume high-calorie, low nutrient-dense foods. Adequate nutritional intake is crucial for growth and development. Nutrition practices play a key role in sports performance and recovery. Nutritional knowledge can affect eating patterns. However, there is limited research on general and sport-specific nutrition knowledge and behaviors of adolescent athletes.

PURPOSE

To examine general and sport-specific nutrition knowledge and behaviors of adolescent athletes.

METHODS

Adolescent athletes were assessed on nutrition knowledge and general and sport-specific nutrition behaviors, including food group consumption, hydration practices, and sport supplement use. Gender differences in general and sport-specific nutrition behaviors were compared using a Mann-Whitney U test. Odds ratios and logistic regression, controlling for age, ethnicity, and years in sport participation were used to determine differences in correct responses between genders. Significance was set at the p < 0.05 level.

RESULTS

One hundred and ninety-four athletes (n = 63 male, n = 132 female, mean age = 14.9 ± 1.63 years) were assessed. Differences in nutrition behaviors were found in fruit, dairy, and sugary beverage consumption between genders. Male athletes were more likely to monitor hydration and use sports supplements. Both males and females scored less than 50% on both general and sport-specific knowledge questions.

CONCLUSION

Adolescent athletes report lower than recommended food group consumption and lack knowledge of general and sport-specific nutrition information. Improvements in these areas can play a significant role in the health and performance of adolescent athletes.

Energy availability and macronutrient intake over a 7-day training period in adolescent rugby players

BACKGROUND

Understanding the dietary intake of elite adolescent athletes and its adequacy with sport nutrition recommendation is a key issue for health and player development, as well as performance and recovery. Energy availability needs to be considered to ensure optimal health and performance in young athletes. The present study aimed to quantify energy availability, energy expenditure and macronutrient intake in young male rugby union players competing at national level.

METHODS

Twelve male adolescent players (15.6±0.6 years) completed a 7-days prospective observational study (5 days of training and 2 days of full recovery). Total energy expenditure was estimated using indirect calorimetry and heart rate measurement. Energy intake was assessed using weighed food by a dietitian in cafeteria (training days) and image-based dietary (recovery days). Energy availability was calculated using (energy intake-exercise energy expenditure)/fat-free mass.

RESULTS

Mean energy availability was 38.5±7.5, 40.2±5.4 and 47.8±5.1 kcal/kgFFM/d on heavy training, moderate training and recovery days, respectively. Players consumed a low carbohydrate (~5.0 g/kg/d), high protein (~2.0 g/kg/d) and high fat (~1.8 g/kg/d) diet on training and recovery days in relation to current international nutritional recommendations for young athletes.

CONCLUSIONS

Athletes showed sub-optimal energy availability on training days, high energy availability on recovery days and did not comply with carbohydrate intake recommendations on training nor recovery days. These results highlight the short-term inadequacy of energy availability as a result of low carbohydrate intake, warning about the possible adverse short-term metabolic effects on health and performance of young athletes.

Differences in nutritional intake and physique according to dietary behaviors in middle school male athletes

Although various dietary behavioral issues affecting healthy development of adolescents have been studied, research on dietary behaviors of adolescent athletes is still limited. This study investigated the relationship between dietary behaviors and body size, energy intake, and nutrient intake in 66 first-year male middle school athletes (12.6-13.8 years old). Dietary behaviors were assessed using the nutritional quotient for adolescents (NQ-A), and energy and nutrient intakes were derived from 3-day food records including 2 weekdays and 1 weekend day. Dietary data were analyzed using CAN-pro 6.0 (Korean Nutrition Society). The results showed that the mean energy intake was 2,301.27±643.57 kcal, which was lower than the estimated energy requirement for this age group. In addition, the intake levels of dietary fiber, vitamin A, vitamin C, calcium, and magnesium were less than 70% of the Korean Dietary Reference Intake. In particular, calcium (r=0.31, P=0.021) and dietary fiber (r=0.28, P=0.038) showed a weak but positive correlation with the NQ-A score. Calcium (F=3.201, P=0.049) and dietary fiber (F=3.376, P=0.042) intake levels were significantly higher in athletes with higher NQ-A grades than in middle or low-grade athletes. However, no significant correlation was observed between NQ-A and physique. In conclusion, when evaluating the dietary behavior of middle school male athletes using NQ-A, athletes with better dietary behaviors were found to consume relatively more calcium and dietary fiber. However, it is important to note that a high NQ-A grade does not necessarily indicate sufficient nutrient intake.

Enhancing Performance in Young Athletes: A Systematic Review of Acute Supplementation Effects

BACKGROUND/OBJECTIVES

The increasing popularity of acute supplementation among young athletes is concerning, given the limited scientific evidence to guide recommendations specific to this group. Therefore, the aim of this systematic review was to synthesize the available scientific evidence on the acute effects of supplementation in young athletes to understand the impact on physical and cognitive performance.

METHODS

Following pre-registration on INPLASY (INPLASY202310017) and according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, systematic searches of three electronic databases (Web of Science, PubMed, and Scopus) were conducted by independent researchers from inception until July 2024. Only original studies in English that examined the acute effects of supplementation on young athletes' physical and/or cognitive performance, specifically when taken on the same day as exercise (before or during), were included. The risk of bias was individually assessed for each study using the revised Cochrane risk of bias tool for randomized trials (RoB 2.0).

RESULTS

A total of 16 studies were included in the review. A range of ages, participants, sports, and methodological approaches were involved in the studies included in the current review. The studies mainly used carbohydrates, beetroot juice, and sodium citrate, with carbohydrates being the most used acute supplementation. Carbohydrate supplementation enhanced endurance capacity and increased blood glucose, but mixed results were found for anaerobic performance. Mixed results were found for beetroot juice, with one study finding increases in power production. One study used sodium citrate supplementation, with improvements in technical performance observed.

CONCLUSIONS

Since this review identified only three substances meeting our eligibility criteria, further research is needed to confirm the acute effects of supplements in young athletes and to better understand their benefits and limitations. Carbohydrate supplementation shows strong evidence for enhancing endurance performance, particularly during prolonged activities, while sodium citrate appears to support the preservation of skill performance. In contrast, the effects of beetroot juice are less consistent. Additional research is required to confirm the acute effects of supplements like beetroot juice in young athletes.

Junior athletes' nutritional demands: a narrative review of consumption and prevalence of eating disorders

Information regarding the dietary requirements and consumption of young athletes is limited. Hence, the aim of this narrative review is to provide a comprehensive combination of research and review papers on the nutritional status of young athletes aged 5-18 years old, as well as quantitative, qualitative, wholesome foods, food choices, and eating disordered data concerning the dietary requirements for growing young athletes. This study involved systematic searches of electronic databases, including Google Scholar, PubMed, Science Direct, Scopus, and Web of Science. The specific criteria for identifying research papers published in English from July 1980 until May 2024 were included. Only 48 studies out of 1,262 were included in this narrative review. The findings of this study suggest that, compared with adults, junior athletes need a unique approach to meet their dietary needs. Growth, development, and general athletic performance depend on macronutrients, as they are vital nutrients for young active athletes. However, research on enhancing junior athletes' performance is still in progress, and studies on hydration status, and eating disorders are limited.

Association between Low Energy Availability (LEA) and Impaired Sleep Quality in Young Rugby Players

Low energy availability (LEA) has been associated with several physiological consequences, but its impact on sleep has not been sufficiently investigated, especially in the context of young athletes. This study examined the potential association between energy availability (EA) status and objective sleep quality in 42 male rugby players (mean age: 16.2 ± 0.8 years) during a 7-day follow-up with fixed sleep schedules in the midst of an intensive training phase. Participants' energy intake was weighed and recorded. Exercise expenditure was estimated using accelerometry. Portable polysomnography devices captured sleep on the last night of the follow-up. Mean EA was 29.3 ± 9.14 kcal·kg FFM-1·day-1, with 47.6% of athletes presenting LEA, 35.7% Reduced Energy Availability (REA), and 16.7% Optimal Energy Availability (OEA). Lower sleep efficiency (SE) and N3 stage proportion, along with higher wake after sleep onset (WASO), were found in participants with LEA compared to those with OEA (p = 0.04, p = 0.03 and p = 0.005, respectively, with large effect sizes). Segmented regression models of the EA-sleep outcomes (SE, sleep onset latency [SOL]), WASO and N3) relationships displayed two separate linear regions and produced a best fit with a breakpoint between 21-33 kcal·kg FFM-1·day-1. Below these thresholds, sleep quality declines considerably. It is imperative for athletic administrators, nutritionists, and coaches to conscientiously consider the potential impact of LEA on young athletes' sleep, especially during periods of heavy training.

Association between Variation in Body Fat Mass Magnitude and Intake of Nutrients, including Carbohydrates, Fat, and B Vitamins, in a Cohort of Highly Trained Female Athletes

The most common sports nutrition strategies were constructed not only for maximizing musculoskeletal adaptations to exercise, but also to minimize health risks in athletes. Given the lack of research highlighting the potential effects of the intake of carbohydrates, fats, and B vitamins on body fat percentage in a population of female athletes, this study aimed to elucidate whether the intake of macronutrients and B vitamins could be associated with the variation in body fat percentage in a cohort of professional female athletes. This cross-sectional study was weighted to represent Lithuanian elite female athletes (n = 89). The dietary assessment of the female athletes was carried out using a 3-day dietary recall method. Their body composition was assessed using the bioelectrical impedance analysis method. For females, the reported average intakes of energy, carbohydrates, protein, and fat were 2475 kcal/day, 5.1 g/kg/day, 1.5 g/kg/day, and 36.7%, respectively. Excess B vitamin intake was revealed, ranging within plus 1-2 standard deviations (SDs) around the mean requirements. As a consequence, excessive body fat percentage was potentially factored as a negative outcome in maintaining optimal body composition in female athletes. Multivariate logistic regression analysis of a sample of female athletes revealed that, despite a slightly positive energy balance (∆ 95 kcal/day), the carbohydrate-deficient diet (adjusted odds ratio (aOR) 0.3, 95% confidence interval (CI) 0.1; 0.7), along with higher intakes of vitamin B1 (aOR 2.9, 95% CI 2.6; 7.8), vitamin B2 (aOR 6.7, 95% CI 1.1; 8.3), and vitamin B3 (aOR 1.8, 95% CI 1.4; 7.8) from food, was associated with a lower percentage of body fat. Therefore, more attention should be given to the intake of B vitamins in professional athletes with a range of body fat mass percentages for the purpose of achieving long-term goals of maintaining body composition and fitness.