Investigating oral biofluid markers as a tool for the chemometric discrimination of different physical exercise intensities utilizing ATR-FTIR spectroscopy

Abstract

Physical and mental capacity of a person to perform sport activities is affected by exercise intensity, especially noted in athletes who push themselves to the limits of endurance. The present study investigated variations of oral biofluid samples (saliva) during different physical exercise intensities utilizing Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy coupled with multivariate analysis. Samples were collected from 32 high-level athletes at i) rest and after different exercise intensities: ii) walking (4–5 km/h), iii) jogging (9–10 km/h) and iv) running (14–15 km/h). PLS-DA model with ten components succeed to classify spectral profile of saliva in the four (i-iv) different groups with an accuracy of 74.3%. The observed discrimination appears to be attributed to the presence of infrared vibrations related to thiocyanate, phospholipids, lactate, phosphate, and glucose. Second derivative ATR-FTIR spectroscopy was utilized to evaluate biomarkers adaptations during the different exercise conditions, and thiocyanate vibration of ATR-FTIR spectra was investigated as a novel index associated with physical exercise intensity. According to our research, monitoring a biochemical change using ATR-FTIR focusing on thiocyanate could serve as a promising supplementary indicator for non-invasively monitoring athletes' training.