Couple basics:

• 69 and mostly sedentary tho I was a gym rat several years ago for about 2 years; hadn’t even heard of HIT at the time
• since then I broke a knee cap and lost nearly all the cartilage and a bursa
• tried hill climbing about a month ago — it was about a 45˚ elevation — and really aggravated the knee; I won’t be able to get it remediated until July or September (long boring story; just know I have to live with it for now); I REALLY don’t want to worsen the situation
• don’t know anything about HIT
• mostly want better fitness and to burn a considerable amount of fat

I am presently going to the gym and doing a “weight loss” program on a recumbent bike for 2 programmed cycles. That’s about 9 miles, 300 calories and maybe 70+ minutes including all the warm up and cool down.

• it asks for my age and resting heartbeat — I can answer those questions
• it asks for my target working heartbeat — I just make that up to get a resistance that raises some sweat without being punishing
• the program has a warm up, then cycles between resistances for “work” and “rest”, finishes with a cool down
• I can do the “work” but I never get back to my resting heart rate, even in the cool down — I can’t slow down, my legs just don’t go very slowly (and I’m not going that fast really)
• the computer indicates that I am mostly in a cardio mode and sometimes in a “peak” mode — both above the “fat burning” mode indicated
• I’m doing it 5 days a week

Here are some questions I have:

• is this appropriate for my age and general lack of fitness
• is this a productive way to attempt HIT?
• will i burn fat if I exceed the “fat burning” mode indicated by the computer?
• will I be able to get back to a resting heart rate if I get more fit?
• what could I do to accelerate the time when I get more fit without getting my knee inflamed and painful?

Thanks in advance to anyone who has some good advice.