170% VO2max is the standard Tabata protocl: http://robertsontrainingsystems.com/...e-tabata-myth/

http://www.ncbi.nlm.nih.gov/pubmed/8897392

I didn't understand it at first either- How can one be over 100% breathless? Hence, why real Tabata is so hard...even though of such short duration (And also why it yeilds amazing results!)