Breaking Sitting with High-intensity Interval Training for Brain Health

Inclusion Criteria: 1. Age 40-75 years 2. BMI \<40 kg/m2 3. Sedentary (≥ 6 h/day sitting by a survey question) 4. Physically inactive adults based on the CSEP-PATH: Physical Activity and Sedentayr Behaviour Questionnaire (PASB-Q) Adult (low or medium physical activity range equivalent to less than 300 min of moderate intensity physical activity per week) 5. Capable of exercising vigorously based on the Physical Activity Readiness Questionnaire (PARQ+) 6. Has a medical clearance for maximal exercise and HIIT from a physician 7. Normotensive or participant's blood pressure is controlled 8. Intelligence quotient (IQ) ≥85 9. Fasting plasma glucose \<126 mg/dL 10. Good or corrected vision and hearing 11. Right-handed 12. No significant abnormalities on the ECG during the maximal exercise test 13. No signs and symptoms that suggest an underlying cardiovascular disease as recorded during the maximal exercise test by a study physician. 14. No indications to prematurely stop the maximal exercise test as outlined by the ACSM's Guidelines for Exercise Testing and Prescription 15. Concussion if more than 12 months before the study screening. 16. History of cancer but in full remission for at least 12 months and no history of chemotherapy, signed off by the physician or an oncologist Exclusion Criteria: 1. Physical disability or musculoskeletal disease prohibitive to vigorous exercise 2. Learning disabilities 3. Cognitive impairment (MoCA \<26) 4. Type 1 or 2 diabetes 5. Neurological condition (e.g., Multiple Sclerosis, Parkinson, Dementia, Mild Cognitive Impairment) 6. Color blindness 7. Brain injury (e.g., traumatic brain injury, stroke, concussion) 8. Migraine headaches 9. Presence of other health conditions that may be exacerbated by exercise 10. History of heart disease 11. High cholesterol not controlled by medication 12. Signs and symptoms indicative of underlying cardiovascular disease 13. A chronic pulmonary disease 14. Emphysema 15. Pulmonary embolus 16. Asthma 17. History of renal disease 18. History of seizures 19. A neuropsychiatric disorder 20. Osteoporosis if it interferes with an individual's ability to exercise 21. Severe back problems 22. Severe arthritis if it interferes with an individual's ability to exercise 23. Thyroid disorder not controlled by medication 24. Polyneuropathy 25. Sleep disorders 26. Acquired immunodeficiency syndrome (AIDS) 27. Hepatitis C 28. History of long Coronavirus Disease 2019 (COVID-19) 29. History of cancer if not in full remission for at least 12 months and if a participant had the history of chemotherapy 30. Current or past smoking \<12 months 31. Corticosteroid intake \< 31 days before screening 32. Opioids taken \< 6 months from screening 33. Anabolic androgens taken \< 31 days before screening 34. A serious illness or hospitalization in the last six months 35. Currently taking medications that can affect the central nervous system (except for anxiolytics) 36. Current participation in an ongoing trial likely to influence exercise ability or cognitive function