1. Introduction
fatigue
Current address: Department of Physiotherapy, LUNEX University—International University of Health, Exercise and Sports S.A., 4671 Differdange, Luxembourg.Current address: LUNEX ASBL Luxembourg Health and Sport Sciences Research Institute, 4671 Differdange, Luxembourg.Inspiratory muscle training (IMT) is known to promote physiological benefits and improve physical performance in endurance sports activities. However, the metabolic adaptations promoted by different IMT prescribing strategies remain unclear. In this work, a longitudinal, randomized, double-blind, sham-controlled, parallel trial was performed to investigate the effects of 11 weeks (3 days·weekSports performance in endurance athletes can be limited by various factors, primarily due to the impairment of the functioning of the respiratory system. The primary role of the respiratory system involves regulating alveolar ventilation while maintaining the oxygen (OIn this sense, studies have explored the potential benefits of inspiratory muscle training (IMT) on physiological parameters and athletes’ endurance performance. IMT is a low-cost, easy-to-apply, safe, and nonpharmacological intervention that focuses on enhancing the strength or endurance of the muscles involved in breathing, such as the diaphragm and accessory muscles of inspiration [Previous studies suggest that mechanisms underlying fatigue of respiratory muscles affect exercise performance via a phenomenon known as respiratory metaboreflex [Toward this goal, metabolomics has emerged as an analytical tool for the systematic study of metabolites (i.e., amino acids, organic acids, carbohydrates, nucleotides, and lipids) in a biological sample, typically utilizing either proton nuclear magnetic resonance spectroscopy (To date, only a few studies have investigated the induced metabolic adaptations instigated by IMT based on metabolomic approaches [In this way, the training-induced metabolic adaptation in athletes is expected to be sport- or activity-specific. For instance, endurance training tends to increase the activity of oxidative enzymes and mitochondrial content in muscle [Therefore, the aim of this study was to investigate the effects of IMT, at different exercise intensities, on systemic metabolic adaptations, highlighting the main regulated metabolic pathways in apparently healthy recreational male cyclists, employing a comprehensive metabolomic approach based on 