The aim of an interval (or HIIT) session is to arrive DOA at the end of the session not in the middle of the session.
All the immediate responses to intense exercise looks bad, yet the effects are good. You are ‘harming’ your body to improve it. Never, ever, confuse acute with chronic.
- Mark Baker
- A 2005 study published in the Journal of Applied Physiology found that after just two weeks of interval training, six of the eight college-age men and women doubled their endurance, or the amount of time they could ride a bicycle at moderate intensity before exhaustion. Researchers at McMaster University in Hamilton, Ontario, had the exercisers sprint for 30 seconds, then either stop or pedal gently for four minutes. [Ref]