In the video bellow, New York Times’ Phys Ed columnist Gretchen Reynolds talks with Martin Gibala, chair of the kinesiology department at McMaster University, who has good news for time-strapped people who don’t want to be health strapped: 20 minutes a day three times a week will do it, if that 20 minutes is spent doing high intensity interval training, or HIIT.  You know, one minute ON, one minute OFF..