AUTHOR=Kojima Chihiro , Morishima Takuma , Ito Reita , Yasunaga Sosuke , Shimogaki Takumi , Hashimoto Takeshi , Isaka Tadao , Iemitsu Motoyuki 

TITLE=Blood and salivary lactate responses to active rest following circuit exercise

JOURNAL=Frontiers in Physiology

VOLUME=Volume 16 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2025.1534668

DOI=10.3389/fphys.2025.1534668

ISSN=1664-042X

ABSTRACT=The present study investigated blood and salivary lactate concentrations with or without active recovery following intensive exercise. Seven men and four women were randomly assigned to two trials consisting of a control (CON) trial and an active recovery (AR) trial separated by at least 1 week. In both trials, participants performed total 30 min of circuit exercise for lower extremities. Afterwards, in the AR trial, participants completed 15 min of light cycling exercise; in the CON trial, participants remained seated during postexercise. Blood and salivary concentrations were measured before and immediately after the circuit exercise, immediately after each trial, and the next morning, using a portable device. Blood lactate concentrations increased significantly immediately after circuit exercise in both trials (AR: 11.9 ± 2.9 mmol/L, CON: 13.4 ± 3.0 mmol/L, P < 0.05), and a significant difference was observed between trials, immediately after each trial (AR: 4.2 ± 1.4 mmol/L, CON: 6.9 ± 2.8 mmol/L, P < 0.05). In addition, both trials showed salivary lactate concentrations increased significantly following circuit exercise (AR trial: 4.4 ± 3.0 mmol/L, CON trial: 5.4 ± 3.9 mmol/L, P < 0.05), and there was a significant difference between trials after the intervention (AR trial: 0.8 ± 0.4 mmol/L, CON trial: 3.1 ± 2.0 mmol/L, P = 0.007). In addition, there was a significant correlation between blood and salivary lactate concentrations during the postexercise period (r = 0.856, P < 0.001). Thus, salivary lactate concentrations may reflect relative changes in blood lactate concentrations during the postexercise period with active recovery following intensive exercise.