Question: Hi there,

I'm a 36 year old male trying to get more fit and healthier in general. I've been working steadily on it the last several years, and in many ways I'm making progress. The bad news is I'm still obese (5'11" and a little under 250 lbs...246 or so at the moment), my father died of a heart attack quite young while exercising (53), and my blood pressure is prehypertensive. The good news is I don't smoke, exercise regularly (and even though I'm still obese, look MUCH better since exercising), eat lots of fruit, veggies, nuts, and other antioxidant rich foods in moderation (green tea, chocolate, etc.), have done some work to improve my sleep, and do a bit of breathing exercises most every day. I also take several supplements approved by my doctor that should be beneficial (things like fish oil, garlic, cayenne, grape seed extract, a food-based multivitamin, etc.)

On a perfect week, I do cardio 4 days a week and some light strength training, stretches, and balance exercises 3 days a week. I do take holidays and special event days off, but I'd say I average at least (and probably often more) than 20 exercise days a month.

The past few years, for cardio days, I've done a map-based (inclines vary wildly) cardio incline trainer (treadmill with higher inclines) workout aiming at my target heart rate zone. That means for this year, I took 220-36 to arrive at my Maximum Heart Rate of 184. Then I tried to work at about 85% of that, or ~156. That means quite a lot of walking (almost always with inclines) and a little bit of running, especially on flats or declines. I've worked up from 30 minutes or so to an average of 45 (sometimes a bit more, sometimes a bit less).

Recently, I got a new incline trainer, and it has some very cool video workouts. They incorporate some strength training as well, and essentially you're working out with a personal trainer who tells you when to walk/jog/run all out, etc. It automates the speed, but there's no way I can keep up with these trainers at my size - still, it allows me to adjust my own speed while automatically regulating incline, so I've been doing that.

I'm having a great time, and it feels like a much better workout for me. I use my own speed scale. (For example, some of the trainers consider 5 mph to be a run, something I could never safely keep up with, so I usually aim for 3.6-4 depending on the intensity of the run, and I adjust recovery walk to be slow enough to actually recover). What I do try to do is run when they tell me to run and walk when they tell me to walk, but at speeds I'm comfortable with. Most of these are interval workouts, meaning a few minutes of really hard work, then a few minutes of a slower recovery pace, etc. I've been doing this the last several weeks, and it's actually really helping me lose some weight and feel really good.

Here's the issue. Even though as far as perceived effort, I'm fine (it's hard, but I feel good doing it...no nausea or feeling like I'm gonna collapse or chest pains), I can't keep my heart rate under the 156 (85% of Maximum Heart Rate), especially during the hard work intervals and often for a little bit of recovery. In talking with some experienced runners on a forum, they suspect (since the equation to get MHR is fairly arbitrary) my XXXXXXX is simply higher than I think, but there's really no way to tell. There are definitely periods where I'm well under 156 (say 140's or so), but there are just as many, if not more, where I'm in the 160's, 170's, or even very rarely 180's.

My dilemma is, after doing those slower, non-interval workouts for a few years, they just aren't giving me the results I want, and these seem to be working better. BUT, I don't want to be doing something risky if this substantially increases my risk of a heart attack or stroke.

I had an echocardiogram 3 years ago that was normal, and am scheduled for another shortly because of concerns about my dad's heart attack. Cholesterol tests were okay (basically, I'm low in everything...LDL as well as HDL, but my doctor things overall it's a good result). I haven't had a stress test, because I have white coat hypertension and anxiety, and my doctor felt it might result in a false positive and wasn't something I needed at this time.

So, I guess this is just a long-winded way to ask if what I'm doing with the interval workouts (pushing myself during the intervals) safe?

What's disappointing is that if I don't push like this, I don't think I'll be able to do the interval workouts at all, which would be disappointing. It's no fun, not to mention discouraging, to keep walking when somebody is encouraging you to run for an interval.

Thank you for your help!