Acute Changes In The Saliva Metabolome After A Hand-to-hand Combat Event In West Point Cadets

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 hand-to-hand combat match (i.e., combatives) on metabolic adaptations is not known. PURPOSE: This study characterizes changes in saliva metabolome at rest, and prior to and immediately following a brief but high stress combatives event among West Point Cadets. METHODS: Cadets (N = 60, 20.8 ± 1.1 years, 77 ± 14 kg, 16 females) provided saliva samples at the beginning of a combatives course under rested conditions (BASE), and after 3 months of training immediately before (PRE) and after (POST) the final, 3-minute hand-to-hand combat match. Salivary samples were analyzed with global metabolomics profiling and cortisol levels. MetaboAnalyst 6.0 was used to detect changes in metabolites between timepoints. Anxiety was assessed with the Profile of Mood States at BASE and PRE and with the Competitive State Anxiety Inventory-2 (CSAI) at PRE. RESULTS: Of the 406 metabolites analyzed, no metabolites significantly differed between BASE and PRE. In POST, 81 (20%) of the identified metabolites increased and 2 (0.5%) decreased ≥2-fold compared to PRE. Changes in metabolites were primarily related to carbohydrate (19%), lipid (27%), and amino acid (34%) metabolism, specifically glutamate (22%) and histidine (16%) metabolism, suggesting a rapid increase in energy allocation. Changes in the metabolome were not associated with match outcomes (win vs. loss). Cortisol levels (P = 0.01) and tension (P < 0.001) increased significantly from BASE to PRE, while average CSAI score was elevated, indicating increased anxiety prior to the final match. CONCLUSION: Saliva metabolomics identified significant changes in metabolites in response to a brief hand-to-hand combat match but did not reflect the psychological stress indicated by mood questionnaires and cortisol levels. As such, saliva metabolomics may not be sensitive to psychological stress but is a useful non-invasive tool to detect acute physiological changes in response to physical stress. Funded: MRMC. Views expressed are not official US Army, DoD, or government policy. Supported by: MRMC