Changes in the Saliva Metabolome Occur Very Rapidly in Response to Acute Physical Stress

Saliva metabolomics can detect change over time in the metabolic response to physical stress including sustained military training. Whether saliva metabolomics can provide insight into the effects of acute stress, such as a brief hand-to-hand combat match, on metabolic function is not known. This study characterizes changes in saliva metabolome at rest, prior to, and immediately following a brief, but high stress hand-to-hand combat event, among West Point Cadets. Cadets (N=60, 21 ± 1 years, 77 ± 14 kg, 16 females) provided saliva samples at the beginning of a hand-to-hand combat course under rested conditions (baseline), and after 3 months of training immediately before (pre-fight) and after (post-fight) the final, 3-minute match of the course. Salivary samples were analyzed with global metabolomics profiling. MetaboAnalyst 6.0 was used to detect changes in metabolites between timepoints. Of the 406 analyzable metabolites detected, none significantly differed between baseline and pre-fight. At post-fight, 81 metabolites increased and 2 decreased ≥ 2-fold compared to pre-fight. Changes in metabolites were primarily related to carbohydrate (19%), lipid (27%), and amino acid (34%) metabolism, specifically glutamate and histidine metabolism, suggesting a rapid increase in energy availability. Saliva metabolomics successfully identified significant changes in metabolism in response to a brief hand-to-hand combat match, demonstrating rapid increases in energy availability in response to an acute physical stress event.