On the 7X SS you can't set up a HIIT 45/15 activity for a 45 sec work and 15 second rest, because the time can be increased in 10 second steps only. A workaround is to start a Cardio activity and set up a 45/15 interval then edit the activity in Connect and change it to HIIT. It should be possible to set the timer for the HIIT activity in 5 second steps instead of only 10.
