Yesterday was the first time I've been in a gym in years. I'm overweight (I'm 6'5" and 310, I weighed 230 in college) and pretty sedentary. So it was an accomplishment just to be doing something active.

I rode the stationary bike for 20 minutes, walked on the treadmill for 10 and then something like 10 more minutes on the bike. I had no idea what my heart rate was, but I would say I was going at a pretty comfortable pace. I was barely sweating and could easily carry on a conversation.

Today, I want back, but wearing a heart rate monitor. I started out with the same work out on the bike and was disappointed to find my heart rate was only around 100. I'm 41, and using the Miller formula in the sticky thread, that would be about 55% of my MHR.

I guess I'm wondering if that's enough intensity to even do any good?

Today, when I saw I was at 100 bpm, I upped the intensity a little and got my heart rate up to like 115-120 for a short time. But I definitely couldn't have kept it up at 120 steadily for 40 minutes. And frankly, if I did, I don't think I could do it every day without being exhausted.

So should I just stick to my slow and steady workout for 30-40 minutes at 100-110 bpm and be happy with that for now? And am I getting any real benefit out of a low intensity workout like that?

Anyone have any thoughts?

Do any good for what?

For all the benefits of cardiovascular exercise I suppose. I guess the bigger question is whether my intensity level is too low?

Using heart rate alone to measure intensity is kinda useless. It all boils down to, as Steve asked, good for what?

If you look at the standard formula, when I run I regularly hit 110% of my maximum heart rate. By any "official" reckoning, that's bad for me and I'm not engaging in productive exercise. But then again, I've been working out for a while now and even at 110% of my max HR for 10 mins, I'm quite comfortable. No, I can't carry on a conversation, but I can keep it up for a while.

HR and exertion is not a fixed number - it's based on your level of exertion and so forth.

It's a starting point. If you're completely untrained, you'll experienced some positive adaptations with regards to your cardiorespiratory system.

You're expending calories which will help get you in a calorie deficit which is required for fat loss.

But again, it's a starting point. As your conditioning improves, you can ramp up the intensity.