What it is
Mechanism evidence: human
At a glance
What it is, why people use it, the evidence, and what to know before trying it.
Why people use it
- Improved cardiorespiratory fitness
- Improved selected cardiometabolic risk markers
- Time-efficient aerobic training
Evidence at a glance
A large randomized-trial literature supports HIIT for improving aerobic capacity and several cardiometabolic measures. There is no single best protocol, and greater intensity is not automatically better than a sustainable mixed training plan.
Confidence: strong
Practice safety
Situations where this practice may need modification or professional guidance.
HIIT can cause musculoskeletal injury, marked fatigue or cardiovascular symptoms when intensity exceeds readiness. Build an aerobic base, warm up, progress gradually and stop for chest pain, faintness or unusual breathlessness. People with cardiovascular, metabolic or orthopedic disease should seek individualized clearance and programming.
Forms and variants
This review does not automatically apply to:
- moderate continuous cardio
- resistance training
- all-out sprint interval training when intensity is not specified
Seen in protocols
Public protocols that include High-intensity interval training. Open one to see the full context and source.