HIIT vs LISS. HIIT (high intensity interval training) utilises short intense bursts of training performed at close to 100% of your VO2 max, followed by short active or passive recovery phases. LISS (low intensity steady state cardio) consists of fixed low intensity exercise. LISS causes less of a fluctuation in heart rate and less of a strain on the central nervous system. HIIT leads to higher energy expenditure over the 24 hours post training! Interested? Try it now!