I have read in a number of places (magazines and some online) that when training for things like a 10K run, half marathon or cycling event doing HIIT training can help but you should not do too much of it as it takes a lot out of you. For example 10-15% of your training should be HIIT while the rest should not get your heart constantly above 70/75% of max.
My question is what is the 10-15% of:
1) Number of times worked out in a week? 2) Time worked out that week? 3) Distance achieved that week?
For times that would suggest I only do HIIT training once ever other week, which doesn't seem like a lot
Time or distance seem more like it but not sure which is more appropriate.