Just four months a year of structured high-intensity interval training over eight years in

Partially SupportedCredible, validated HIIT interventions can be performed one to several times per week for many months in athletic populations, older adults, and people with cardiometabolic diseases.

Not SupportedThe notion that HIIT is unsustainable or unsafe for some populations is not supported by the literature.

Partially SupportedParticipants with metabolic syndrome who performed the Norwegian 4x4 HIIT protocol 3 times a week for 4 months each year over an 8-year span experienced no increase in medication use.

Partially SupportedFour months per year of structured HIIT over eight years increased aerobic capacity by 14% and power output by 4% in participants with metabolic syndrome, reversing nearly a decade of cardiorespiratory aging.