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

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.

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.

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.

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.