Q: Hi mike, Whats the duration for doing HIIT?

A: I usually recommend doing HIIT in 30-second intervals. So you do 30 seconds of maximum speed sprinting, followed by 30 seconds of walking, followed by 30 seconds of sprinting, followed by 30 seconds of walking, and so on. The total duration of a HIIT session can be anywhere from 3 to 15 minutes, depending on your fitness level -- a newcomer to HIIT type training will typically be exhausted after just 3 minutes but as her strength and endurance builds up she'll be able to slowly keep increasing the length of a singles session up to 15 minutes (which fits in 15 sprinting intervals interspersed with 15 walking intervals). And I would put in 3 HIIT session per week on average.