The impact of hyperoxia and hypoxic interval training on the plasma metabolome in skiing athletes

Metabolomics is a promising tool for investigating molecular changes induced by physical exercise, as metabolic adaptations to external stimuli can occur in a short period of time. Moreover, these studies enable to monitor both the physiological response and the recovery after an injury or a competition, thus providing the possibility to develop a personalised training. This study aimed to evaluate the influence of hypoxic interval training with and without hyperoxic recovery on the blood metabolome in eleven male trained alpine skiing athletes. Each athlete performed two different test trials, involving hypoxic exercise sessions at a simulated altitude of 3500 m interspersed by 15 min of passive recovery. During one trial, 100% oxygen was administered during recovery. In the second trial, recovery was conducted simulating 3500 m oxygen level. Blood was collected before, immediately after, and seven days after the trials. Untargeted high-resolution mass spectrometry approaches were used to perform both the metabolome and the lipidome analyses of plasma extracts. Systematic alterations of relative blood metabolite and lipid concentrations in trained athletes were observed in response to a single session of high intensity eccentric/concentric exercise performed during simulated altitude. Specifically, short-term metabolome differences involved the fatty acid b-oxidation and the tricarboxylic acid cycle, while the long-term variations were associated with malate-aspartate shuttling, urea cycle alterations, lysine degradation, and branched chain amino acids degradation as a consequence of varying oxygen availability. Similarly, lipidome analysis showed specific changes according to the type of oxygen exposure and short term versus long term recovery. Overall, we observed systematic alterations of plasma metabolite and lipid concentrations in response to high intensity exercise performed at different simulated altitudes.