How pain affects mental fatigue, movement, and cycling performance in recreational cyclists.

Mental fatiguing task: For the mentally fatigue intervention, participants complete an electronically administered 30-minute modified Stroop test. The Stroop test requires response inhibition and sustained attention and is recognized and validated as an effective method for inducing mental fatigue. The version of the Stroop test to be used is a publicly available app-based program called “Brainiversity” (Version 2.0 for personal computer). On a tablet the Stroop test requires participants to answer multiple choice questions by selecting the colour of a word when it was different to the name of the word (e.g., selecting “blue” when the word “red” is printed in blue). There were four options to choose from per question. Participants were instructed to respond as accurately and quickly as possible to cues presented on the screen. The number of correct answers after each 60s Stroop test is recorded as the participants score for each of the 30 trials. No time restraints are imposed and upon completion of all trials, the test was reset until the 30-minute threshold had been reached. Adherence to the mental fatiguing intervention will be monitored through direct supervision and task performance metrics recorded by the Stroop test software: Participants complete the task under researcher observation to ensure continuous engagement, correct task execution, and to prevent use of external distractions (e.g., mobile phones or unrelated applications). Task completion will be verified by confirming that participants complete the full 30-minute protocol without interruption. Also, performance data generated by the application (number of correct responses per 60-second trial, for all 30 trials) will be reviewed to confirm ongoing task engagement. Consistently low or absent responses within a trial were used as indicators of non-adherence or disengagement; however, no participants will be excluded on this basis. Participants will also be verbally reminded at standardized intervals to maintain focus and respond as quickly and accurately as possible. Each participant will attend two testing sessions scheduled one week apart. One session will involve completion of the mental fatigue task, and the other will involve the control task. All participants will therefore complete both conditions. The order in which participants complete the mental fatigue and control sessions will be randomly allocated prior to testing using a coin toss. Cardiorespiratory fitness will be assessed after the completion of the mental fatiguing task and the control task in a standardised manner via a symptom-limited graded exercise test (GXT). Participants will complete the GXT on a cycle ergometer (Excalibur Sport; Lode B.V. Groningen, Netherlands) using a ramp protocol. The test will consist of stationary cycling at a cadence of 90 ±2 revolutions per minute, with a starting resistance of 100 W, until volitional exhaustion is reached. Heart rate (Polar Electro Oy, Kempele, Finland) will be monitored throughout the test with peak value recorded at cessation.