Cerebral oxygenation and skeletal muscle responses to time trial, maximal oxygen uptake and time to exhaustion exercise

Abstract This study investigated cerebral and neuromuscular responses to three exercise models: time trial (TT), maximal oxygen uptake () and time to exhaustion (TTE). Fourteen participants completed the tests in the following order: , TT and TTE. To compare responses across different intensities, TT and trials were matched for total work (kJ), and the average TT power output was used to set intensity for TTE. Throughout exercise, near‐infrared spectroscopy from the prefrontal cortex and electromyography from the vastus lateralis and rectus femoris were recorded. Ratings of perceived exertion and the feeling scale were collected post‐exercise. Total work was similar across trials. Tissue oxygenation index (TOI) was significantly lower during TT ( P = 0.0308) and TTE ( P = 0.0400) than . Deoxyhaemoglobin increased more during TTE ( P < 0.0001), and oxyhaemoglobin was higher during TTE from 60% to 100% of test completion ( P = 0.0040–0.0001). Participants rated as more pleasant (6.7 ± 2.9) than TT (5.9 ± 3.0, P = 0.0412) and TTE (4.9 ± 2.3; P = 0.0124). Despite equivalent work, each exercise model elicited distinct neurophysiological profiles and distinct temporal patterns of prefrontal oxygenation and muscle activation. TT and TTE showed earlier reductions in TOI than , but end‐exercise brain oxygenation was similarly reduced across paradigms, while was perceived as more pleasant. These findings suggest that exercise modality alters the trajectory, rather than the endpoint, of prefrontal oxygenation/perfusion responses.