Impact of structured high-intensity interval training and sleep quality on metabolic health in adolescent athletes: A longitudinal study

Project Abstract

This longitudinal study investigates how a structured high-intensity interval training (HIIT) program combined with sleep quality monitoring influences metabolic health markers in adolescent athletes over a 12-month period. The primary aim is to determine whether HIIT improves insulin sensitivity, lipid profiles, resting metabolic rate, and inflammatory markers, and how sleep duration and quality modulate these effects. A cohort of 180 adolescent athletes aged 13–18 years from diverse sports disciplines was recruited and randomized into three groups HIIT with sleep optimization, HIIT without sleep optimization, and control with standard training. The HIIT protocol consisted of thrice-weekly sessions, each 30–35 minutes in duration, incorporating interval bouts at 85–95% of maximal heart rate with progressive overload across phases. Sleep optimization involved behavioral sleep education, personalized sleep scheduling, and wearable-based sleep tracking to target 8–10 hours of sleep per night where feasible. Metabolic health outcomes were assessed at baseline, 6 months, and 12 months, including fasting glucose, insulin, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), oral glucose tolerance, lipid panel (total cholesterol, LDL-C, HDL-C, triglycerides), high-sensitivity C-reactive protein (hs-CRP), adiponectin, leptin, and resting metabolic rate (RMR) via indirect calorimetry. Secondary outcomes included body composition (DXA-derived fat mass and lean mass), aerobic capacity (VO2max), marketable sport performance metrics, and psychosocial well-being measures. Sleep quality was evaluated using polysomnography substudy in a subset (n=60) and validated questionnaires (Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale). Statistical analyses employed mixed-effects models to examine main effects and interactions of HIIT and sleep optimization over time, with adjustments for age, sex, pubertal stage, baseline fitness, and dietary intake. Mediation analyses explored whether changes in sleep parameters mediated metabolic improvements and whether improvements in aerobic capacity or adiposity moderated metabolic outcomes. The study anticipates that the HIIT + sleep optimization group will exhibit superior improvements in insulin sensitivity, lipid subfractions, reductions in inflammatory markers, and greater preservation or increases in lean mass compared with HIIT alone and control. Sleep optimization is expected to enhance adherence to training, reduce nocturnal hypoxia risk during intense training periods, and amplify systemic metabolic benefits through improved circadian alignment and hormonal regulation. Potential challenges include adherence variability, menstrual status considerations in female athletes, and accurate sleep tracking in real-world training contexts. Findings will inform evidence-based guidelines for integrating structured HIIT with targeted sleep interventions in adolescent athletic programs to optimize metabolic health without compromising growth, development, and performance. Recommendations will address program design, monitoring protocols, athlete education, and strategies for scalable implementation across school and club settings.

Project Overview

What This Project Is About

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