Circuit training 0:55'49.6 Average heart rate 130 bpm.
This routine validates HIIT, incorporating 2 protocols, Boutcher & Tabata, 4 different exercises, at high intensity, with a peak pulse of 186, the theoretical max for someone aged 34, & a VO2 max of 54 -- which would be high performance for a man 30 years my junior. This proves that HIIT up-regulates cardio pulmonary capacity. And it was compact. I burned more than 700 calories in less than an hour.