This study aims to compare the immediate effects of two common types of exercise-moderate-intensity continuous exercise and high-intensity interval training (HIIT)-on attention, alertness, and physiological responses in physically active young adults.

Attention and mental alertness are essential for learning, academic performance, and daily functioning. Previous research suggests that a single session of exercise can temporarily improve cognitive performance, but it is not clear whether moderate exercise or high-intensity interval exercise is more effective in producing these immediate benefits.

In this study, participants will complete two supervised treadmill exercise sessions on separate days: one session of moderate-intensity continuous exercise and one session of high-intensity interval training. The order of the two exercise sessions will be randomized, and there will be a rest period of 48 to 72 hours between sessions.

Before and immediately after each exercise session, participants will complete computerized cognitive tests that measure sustained attention and reaction time. Heart rate, oxygen saturation, perceived exertion, mood, and alertness will also be measured to evaluate physiological and psychological responses to exercise.

By comparing the effects of these two exercise approaches within the same individuals, this study aims to identify which type of exercise leads to better immediate cognitive performance and favorable physiological responses. The findings may help guide exercise recommendations for improving attention, alertness, and overall mental performance in young adults.

This study is a randomized within-subject crossover clinical trial designed to compare the acute effects of moderate-intensity continuous exercise (MICE) and high-intensity interval training (HIIT) on cognitive performance and psychophysiological responses in physically active young adults.

Each participant will complete two supervised treadmill exercise sessions-one MICE session and one HIIT session-on separate days, with a 48-72-hour washout period. The order of the two exercise conditions will be randomized using a computer-generated sequence. This crossover design allows each participant to serve as their own control, reducing inter-individual variability and increasing statistical power.

Cognitive performance will be assessed immediately before and after each exercise session using validated computerized tests of sustained attention and vigilance, including the Sustained Attention to Response Task (SART) and the Psychomotor Vigilance Task (PVT). Primary cognitive outcomes will include reaction time, accuracy, response inhibition, and attentional lapses.

Psychophysiological responses will be monitored throughout the exercise sessions and immediately post-exercise. These include heart rate, oxygen saturation, rating of perceived exertion, mood, and alertness. Exercise intensity will be prescribed based on percentages of age-predicted maximum heart rate and continuously monitored to ensure protocol adherence and participant safety.

Data will be analyzed using within-subject statistical comparisons to evaluate differences between exercise conditions. The findings are expected to provide evidence on how acute exercise intensity influences immediate cognitive and physiological responses, informing exercise recommendations for optimizing attention and alertness in young adults.

Inclusion Criteria:

• Aged between 18 and 30 years.
• Physically active individuals, as assessed by the International Physical Activity Questionnaire (IPAQ).
• In good general health.
• Cleared for physical activity participation based on the Physical Activity Readiness Questionnaire (PAR-Q).
• Enrolled as university students.
• Able and willing to provide written informed consent.

Exclusion Criteria:

• History of cardiovascular, neurological, or musculoskeletal disorders that may affect exercise safety or cognitive performance.
• Presence of uncontrolled hypertension, recent concussion, or any medical condition contraindicating exercise.
• Use of medications that may influence cognition, mood, or cardiovascular responses.
• Pregnancy.
• Failure to pass PAR-Q screening without medical clearance.
• Heavy smoking or history of substance abuse.
• Visual or hearing impairments that could interfere with computerized cognitive task performance.

Individual participant data (IPD) will not be shared publicly. All collected data will be analyzed and reported in aggregate form only to ensure participant confidentiality and data protection.

Due to the nature of the exercise interventions, participant and care provider blinding is not feasible. However, cognitive outcome assessors are blinded to the intervention order to minimize assessment bias. Data analysis will be performed using coded datasets to ensure objectivity.