I'm sure this topic has been run over with a steam roller many a time, but I have been reading a bunch of articles and must ask again. Which would be more beneficial to me?

I'm looking to stay as lean as possible, while keeping my current muscle mass. I dont know if my body will be able to handle the intense stress put on it by performing HIIT. I currently jog on a treadmill, 5 times a week, 3 days a little over 6 miles and the other 2 between 7 and 8.

I dont know if this would be considered a form of HIIT but every few minutes, usually about 5, I either up the incline by a % or 2, or I increase the speed by a half mph or so, trying to increase my heart rate and prevent my body from gettin used to the consistent speed that I jog at. I stay at the upped incline or increased speed for about 45 seconds, and then go back to normal. I end up doing this about 10-12 times throughout a 60-75 minute period, which is how long my run usually lasts.

If you feel that this is a sufficient routine to fulfill my goals, then great, if not, then give me some suggestions please.

Thank You