I'm not really sure where to post this as most discussions regarding cardio revolve around fat loss. So here goes...

It's simple really. I'm happy where I am progressing muscularly. I'm happy with my gains in strength, I'm content with my progress in size, and I'm satisfied with my bf%.

But I'm concerned with my overall cardiovascular health. I want a strong heart and lungs and better circulation. Better in the sense that I'll have more energy now and live longer later.:tu:

What kind of fitness work will give me gains in this direction? Is this an area best suited for HITT cardio or is there a better way?

I personally don't like HIIT for fat loss, but for improving cardiovascular strength, it's absolutely the way to go.

It's simple really. I'm happy where I am progressing muscularly. I'm happy with my gains in strength, I'm content with my progress in size, and I'm satisfied with my bf%.

But I'm concerned with my overall cardiovascular health. I want a strong heart and lungs and better circulation. Better in the sense that I'll have more energy now and live longer later.:tu:

What kind of fitness work will give me gains in this direction? Is this an area best suited for HITT cardio or is there a better way?

HIIT is excellent for most things. The H'er the I, the better. But that only addresses two of the big cardio things. To really shift your metabolism up you also have to do some long low intensity sessions. This is actually an approximation; you can set up activity specific workouts, and also, there is a slight different between working on your VO2max and working on your lactate threshold which I have glossed over.

I do a lot of this sort of thing, have done for a couple years now, and for the same reason as you. You can see some things I've done in my journal.

Note that I am not saying you have to run or cycle. You can use almost any exercise for this work. I have used moderately heavy exercise, such as long squat sets at 225#, but also high energy exercises (where you move less weight through a very long distance like dumbell lunges with curl and press), as well as medicine ball work and jump rope and rowing machine (classic cardio work).

The one thing that really frees you from one specific sort of exercise is a heart monitor. Then you know how hard is the same intensity from one sort of exercise to another. You can do whatever comes into your head and as long as the heart is cranking at the rate you want, you are doing what you want.

There's a ton of neat stuff you can do for cardio, run, bike, skate, row(an actual boat:)), basketball, tennis, hike, rock climbing, jump rope, plus the stuff others mentioned.