Background/Objectives: The Q-Collar™, a device that mildly compresses the jugular veins to increase cranial fluid volume, has been investigated for potential protection against brain changes associated with concussive and subconcussive impacts during athletic events involving physical contact. However, physiological responses using this device as well as the physical and cognitive performance outcomes remain unclear. Therefore, the purpose of the study was to investigate hemodynamic, metabolic, prefrontal cortex oxygenation (PFC-O₂Hb), choice reaction time (CRT) via the Stroop test, and time-to-completion outcomes with and without Q-Collar™ use. Methods: Eleven male participants qualified for inclusion into the repeated-measures randomized crossover study following an incremental cycling cardiopulmonary exercise test. Upon qualification, participants visited the lab twice to complete a 5 km cycling time trial with and without Q-Collar™ use. Each visit was separated by at least 72 h. Results: No statistically significant differences in hemodynamic, blood lactate (BLa⁻), PFC-O₂Hb, or time-to-completion outcomes were found comparing Q-Collar™ use to a Control condition. However, improved CRT was found during, immediately following, and 10 min post the time trial relative to a resting CRT baseline. Conclusions: No statistically significant acute differences were detected between Q-Collar™ and Control for measured outcomes during a 5 km cycling time trial in this exploratory study. Smaller effects cannot be excluded, and because jugular compression was not verified during exercise, these findings reflect the effect of wearing a manufacturer-fitted Q-Collar™ rather than verified jugular compression. CRT was shorter during and after exercise relative to rest in both conditions, although repeated-testing effects cannot be excluded.