An interventional study of Mental-Fatigue Protocol (Stroop Task) and Control Protocol (Nature Video) in Mental Fatigue and Athletic Performance, sponsored by Inonu University. Not yet recruiting at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 30 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-21.
Sponsored by Inonu University · Not applicable, Interventional, and Basic science
This study examines whether short-term mental fatigue and different jump instructions affect how high people can jump. Thirty-two physically active university students will complete two testing sessions in random order: one after a 30-minute mentally tiring computer task and one after a 30-minute relaxing video. In both sessions, participants will perform vertical jumps while receiving one of three types of instructions: no special instruction, focusing on their own body movements, or focusing on pushing the ground away. The study will compare jump height across these conditions to better understand how mental tiredness and coaching cues affect jumping performance, which may help coaches and athletes design better training and competition preparation.
This study uses a sex-stratified, randomized, counterbalanced crossover design with repeated measures to examine the effects of acute mental fatigue and attentional-focus instructions on countermovement jump (CMJ) performance. Thirty-two physically active undergraduate students (16 women, 16 men), aged 18-30 years, will be enrolled from the Faculty of Sport Sciences at İnönü University, Malatya, Türkiye.
Each participant will complete two experimental protocols, separated by at least 72 hours: a control protocol (approximately 30 minutes of passive viewing of a narration-free nature video) and a mental-fatigue protocol (a 30-minute computerized color-word Stroop interference task). Protocol order will be randomized and stratified by sex. In both protocols, participants will perform CMJs under three attentional-focus conditions, presented in a randomized order that is held constant within each participant across sessions: no prescribed focus, internal focus (attention directed to the participant's own body movements), and external focus (attention directed to the effect of movement on the environment). CMJ height will be recorded in centimeters using a validated video-based jump-analysis application (My Jump Lab) on a tablet camera recording at 240 frames per second, with the higher of two valid trials retained as the primary outcome for each protocol-by-focus condition.
Subjective mental fatigue will be assessed immediately before and after each protocol using a 0-10 visual analogue scale to confirm the effectiveness of the fatigue manipulation. Stroop task performance (total trials, accuracy) and adherence to the assigned attentional-focus instructions will be recorded as secondary measures.
The primary analysis will use a 2 (protocol: control, mental fatigue) x 3 (focus: no prescribed, internal, external) x 2 (sex: women, men) mixed-model ANOVA on CMJ height, with protocol and focus as within-participant factors and sex as a between-participant factor. Reporting will follow CONSORT 2025 and the CONSORT extension for randomized crossover trials.
175 studies on the registry are indexed under Mental Fatigue; 54 are open to participants now.
This study's planned enrollment of 32 is below the median of 45 across 143 interventional studies indexed under Mental Fatigue.
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Exclusion Criteria:
Participants complete the control protocol (30-min passive nature-video viewing) in the first session and the mental-fatigue protocol (30-min Stroop task) in the second session, separated by at least 72 hours. In both sessions, participants perform countermovement jumps under three attentional-focus conditions (no prescribed focus, internal focus, external focus) in a randomized, participant-fixed order.
Behavioral: Control Protocol (Nature Video) · Behavioral: No Prescribed Focus Instruction · Behavioral: Internal Focus Instruction · Behavioral: External Focus Instruction
Participants complete the mental-fatigue protocol (30-min Stroop task) in the first session and the control protocol (30-min passive nature-video viewing) in the second session, separated by at least 72 hours. In both sessions, participants perform countermovement jumps under three attentional-focus conditions (no prescribed focus, internal focus, external focus) in a randomized, participant-fixed order.
Behavioral: Mental-Fatigue Protocol (Stroop Task) · Behavioral: No Prescribed Focus Instruction · Behavioral: Internal Focus Instruction · Behavioral: External Focus Instruction
A 30-minute computerized color-word Stroop interference task delivered as one uninterrupted block on a custom program, in which participants identify the font color of color-word stimuli while ignoring word meaning, inducing acute mental fatigue prior to countermovement jump testing.
Also known as: Color-Word Stroop Task
Approximately 30 minutes of passive viewing of a narration-free nature video under standardized lighting, seating, and sound conditions, serving as the non-fatiguing control condition matched in duration to the mental-fatigue protocol.
A verbal cue delivered before each jump attempt with no directional attentional instruction: "When you are ready, jump as high as possible."
A verbal cue delivered before each jump attempt directing attention to the participant's own body movements: "When you are ready, focus on extending your knees and hips as quickly and explosively as possible while jumping as high as possible."
A verbal cue delivered before each jump attempt directing attention to the effect of movement on the environment: "When you are ready, focus on pushing the ground away from you as quickly and explosively as possible while jumping as high as possible."
Countermovement Jump Height
Vertical jump height, measured in centimeters, recorded using a validated video-based jump-analysis application (My Jump Lab) at 240 frames per second. The higher of two valid trials in each protocol-by-attentional-focus condition (control vs. mental fatigue x no prescribed focus, internal focus, external focus) will be retained as the outcome value for that condition.
Time frame: Assessed once per attentional-focus condition (higher of two valid trials) approximately 30 seconds after completion of each 30-minute protocol (control or mental fatigue), across two sessions separated by at least 72 hours.
Subjective Mental Fatigue Rating
Self-reported mental fatigue rated on a 0-10 visual analogue scale, in response to "How mentally fatigued do you feel right now?" (0 = not mentally fatigued at all, 10 = the highest possible level of mental fatigue).
Time frame: Immediately before and immediately after each 30-minute protocol (control and mental fatigue), across two experimental sessions separated by at least 72 hours.
Stroop Task Performance
Total trials completed, number of correct and incorrect responses, and accuracy (%), recorded automatically by the Stroop task software during the mental-fatigue protocol.
Time frame: Continuously recorded throughout the 30-minute mental-fatigue protocol, administered in one of the two experimental sessions per participant (protocol order randomized).
Focus-Instruction Adherence
Self-reported adherence to the assigned attentional-focus instructions, rated on a 0-10 visual analogue scale.
Time frame: Assessed once per attentional-focus condition, immediately after completion of each 30-minute protocol (control or mental fatigue), across two experimental sessions separated by at least 72 hours.
Plan to share: No
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