This awesome infographic was spotted on Greatist, coupled with some really epic information:

On why interval training works:

HIIT taxes and maximizes both aerobic and anaerobic fitness, while cardio addresses aerobic only. Aerobic respiration requires oxygen to generate energy in the form of ATP, while anaerobic respiration does not. HIIT affects muscle tissue at the cellular level, actually changing mitochondrial activity in the muscles themselves. Studies indicate as little as 27 minutes of HIIT three times per week produces the same anaerobic and aerobic improvement as 60 minutes of steady state cardio five times per week.

Check out more at Greatist!

Looking for an app to help manage your interval training? Check out my post on timing intervals with RunKeeper.

Are you a pro at interval training? Share your experiences!