Exploring Salivary Thiocyanate as a Novel Biomarker of Physical Activity Response

Salivary thiocyanate (SCN^-) has long been recognized for its role in mucosal defense and antioxidant function, yet its behavior during physical activity remains unexplored. This study aimed to investigate salivary thiocyanate as a novel salivary biomarker responsive to exercise. A standard Vis-photometric method (thiocyanatoiron-complex formation) was utilized and validated for the rapid quantification of thiocyanate in saliva. The method was applied to two experimental setups: (i) a controlled treadmill protocol involving incremental running intensities (20%, 60%, and 90% VO₂max-mL/kg/min), and (ii) field sampling of athletes from various sports before and after their typical training sessions, managing a total of 162 athletes. This work is the first to quantitatively investigate thiocyanate as an exercise-induced salivary biomarker, validated through both controlled and real-world settings. Additionally, subgroup analysis across sex and smoking status revealed inter-individual variation in salivary SCN^- profiles. Across both setups, during controlled exercise intensity increment and typical training routine, thiocyanate concentrations consistently decreased in response to physical exertion. These results were statistically significant and reflected in both male and female athletes. This is the very first study that determines salivary SCN^- during any kind of physical exercise and opens new pathways for non-invasive sampling and for monitoring physiological stress and immune response in athletic populations.