Effect of physical exercise on taste perception and saliva composition: An exploratory study

Physical exercise has known physiological effects. Although it is empirically assumed that these effects extend to changes in salivation and even in appetite, the influence of exercise on oral biochemistry - and its potential interplay with taste perception - remains poorly understood. This exploratory study investigated the impact of physical exercise on salivary composition and intensity perceived for sweet and bitter tastes, considering high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT), in both active and sedentary individuals. Unstimulated saliva samples and taste intensity rating were assessed in 36 participants (18 men, 18 women), 18 sedentary and 18 active, before and after each of the two training sessions (MICT and HIIT). Saliva analysis included secretion rate, total protein concentration, and proteomic profiles using electrophoresis techniques (SDS-PAGE and 2-DE, in this last case for 9 male active individuals), while sweet and bitter taste intensities were evaluated using sucrose and quinine taste strips. Results revealed that MICT significantly increased sweet taste intensity rating in active individuals, while HIIT had this effect in sedentary individuals. No changes were observed for bitter taste intensity. Salivary secretion rate decreased, and protein concentration increased after exercise. However, the effects of exercise in salivary protein profile depended on whether participants were active or sedentary and on the type of exercise. Only in active individuals, levels of albumin and zinc-α2-glycoprotein + carbonic anhydrase VI decreased following acute exercise; notably, the latter was negatively associated with changes in both bitter and sweet taste intensities. Moreover, in these individuals, amylase increased, but only after HIIT. Results from this exploratory study indicate that the effect of physical activity on saliva composition and taste perception may vary according to exercise intensity and lifestyle (active or sedentary). Therefore, nutritional management strategies involving physical activity need to take these aspects into account.