Adolescent Endurance Runners Exhibit Suboptimal Energy Availability and Intakes of Key Nutrients

Backgroud: Despite the evidence of an elevated prevalence of low bone mass in adolescent endurance runners, reports on dietary intake in this population is limited. Objectives: This study aimed to evaluate energy availability (EA) and dietary intake among 72 (n = 60 female, n = 12 male) high school cross-country runners. Methods: The sample consisted of a combined dataset of two cohorts. In both cohorts, the Block Food Frequency Questionnaire (FFQ; 2005 & 2014 versions) assessed dietary intake. Fat free mass was assessed using dual-energy x-ray absorptiometry or bioelectrical impedance analysis. Results: Mean EA was less than recommended (45 kcal/kgFFM/day) among male (35.8 +/- 14.4 kcal/kg FFM/day) and female endurance runners (29.6 +/- 17.4 kcal/kgFFM/day), with 30.0% of males and 60.0% of females meeting criteria for low EA (<30 kcal/kgFFM/day). Calorie intake for male (2,614.2 +/- 861.8 kcal/day) and female (1,879.5 +/- 723.6 kcal/day) endurance runners fell below the estimated energy requirement for "active" boys (>3,100 kcal/day) and girls (>2,300 kcal/day). Female endurance runners' relative carbohydrate intake (4.9 +/- 2.1 g/kg/day) also fell below recommended levels (6-10 g/kg/day). Male and female endurance runners exhibited below-recommended intakes of calcium, vitamin D, potassium, fruit, vegetables, grains, and dairy. Compared to male endurance runners, female endurance runners demonstrated lower relative intakes of energy (kcal/kg/day), protein (g/kg/day), fat (g/kg/day), fiber, vegetables, total protein, and oils. Conclusion: This study provides evidence of the nutritional risk of adolescent endurance runners and underscores the importance of nutritional support efforts in this population.