I planned on doing 15-20 minutes of HIIT cardio after my chest/tri's session. I started with a warmup, then i started my 1 minute sprint, 1 minute jog, etc. After 7 minutes i had to quit, i couldn't feel my legs, my ankles were tight as hell, and my heart rate was at 180! The thing that really concerned me was my heart rate, i weigh 215 and im 22 years old, so this puts it pretty close to my max...should i start off with some other type of cardio and work my way up to HIIT?
Yes, definitely don't jump onto the hardest cardio routine you can find as your first foray into it in several years...
I dont know about everyone else, but when I do my HIT I find it rare that my HR goes below 170, most of the time its sitting around 185. And i'm 23 and 240lbs. What I think really matters is how well your able to recover after doing it. What you might work for you is increase the rest time between sprints if your doing interval training, or do interval training. But I've found I dont really need to worry bout the HR untill I start to see black spots, at that point its time to ease off a little bit.