This post was not about cardiovascular health, but, rather, the reasons why endurance athletes are good at high volume exercise and why power athletes are better at lower volume sprints.
Any exercise regime, however, is better for the heart health than a sedentary lifestyle. I'm a firm believer in being physically active on a daily basis. How you structure that exercise should be based on your personal goals and objectives.
Research has found, that, cardio training, which elevates the heart rate to a high percentage of the max for an extended time frame is the best for cardiovascular health.
There is also some research which suggest that long duration anaerobic training which induces very rapid lactate production, may also improve cardiovascular health. The mechanism, which is hypothesized to be so beneficial, is the metabolism of lactate, post workout. The process of breaking down lactic acid is actually aerobic, similar to the metabolism of endurance training. This type of protocol may actually kill two birds with one stone. The trouble is that it is very taxing on the body if done too frequently.
The latter method falls under the name, High-intensity training.
Well you're the man to know how research on all this is still in its infancy, which is sad and odd, it means we kinda know less about our bodies than we know about the stars.
I always like to think about how our ancestors used to live. People used to recommend running every morning, and now they say that's either pretty much useless or even bad for you (for your knees for instance). I knew that was the case beforehand because running didn't make sense from an evolutionary perspective. People walk. They might even walk for long distances. Very long, sometimes. But they don't run unless it's for short bursts. Energy is like gold in nature and people do everything to preserve it. The body stores fat like it's gonna wait a year till its next meal but builds muscle like children eat broccoli: gruelingly. So it's kinda an odd sight, our fitness culture, of moving about like dancing, running on treadmills, not doing any actual work, none that a single doughnut won't undo. Some kind of manual labor like lifting stuff seems, from this perspective, like the most natural and healthy exercise.
Anyway, this comment is all over the place and I haven't really done the research to be perfectly informed!