Comparison of Internal Load in Young Swimmers and Basketball Players During a Single Training Session: Rating of Perceived Exertion Versus Changes in Salivary Biomarkers

Background: This study aimed to compare perceived exertion and changes in selected salivary biomarkers in young swimmers and basketball players. Methods: A total of 50 athletes participated in the study, including 23 swimmers (mean age: 13.8 ± 1.2 years; height: 172.4 ± 10.7 cm; body mass: 62.1 ± 11.4 kg) and 27 basketball players (mean age: 13.5 ± 0.6 years; height: 176.1 ± 11.0 cm; body mass: 61.2 ± 11.4 kg). All participants completed a single training session conducted at the same time of day. Saliva samples were collected from all athletes before and after the training session, and post-exercise changes were expressed as percentage differences. Participants also reported a rating of perceived exertion (RPE) using a 1–10 scale. Results: No significant between-group differences were observed in post-exercise changes in salivary flow rate, saliva pH, total protein concentration, α-amylase activity, or cortisol concentration. RPE did not differ significantly between groups, but moderate associations were found between salivary flow rate in both groups (r = 0.32, r = 0.34). Conclusions: Although perceived exertion was comparable, biochemical responses differed depending on the specific training environment. In turn, salivary flow rate appears to influence subjective perceptions of exercise intensity independently of exercise environment.