Aerobic vs. anaerobic (HIIT) | Cardio 101 | Forum

So I  read recently that recent studies have shown that a few sprints, only a couple of times per week, do just as good a job for heart/lung health and controlling fat percentage as jogging five times per week.  I may not have these statistics exactly, but it was somewhere along those lines.  I do not, however, know the details of this study or group of studies.

But here is the dilemma I'm having in my mind.  If one of the goals of cardio exercise is to improve or maintain the efficiency of our aerobic capacity (which has health benefits in itself) and to improve the efficiency of our bodies to burn fat at rest; then why should a person simply just switch to HIIT, even if he or she can obtain just as healthy a heart?

Now I'll ramble what I've organized in my mind and please feel free to show me the err of my thinking.  I'm not intending to show off what I know, but to reveal to others, and be corrected where my logic is off, so I can better understand where these studies are coming from.

To me, these are the main elements of cardiovascular exercise:

1. The amount and size of muscle used during the activity.  For instance, running uses more muscle, and therefore, more blood demand, than rowing or walking, because larger muscle groups are working harder (glutes, hip flexors, upper thighs).  For this reason, in my mind anyway, running or jogging is a better heart exercise than walking or rowing, because it gives your heart a bigger challenge to provide more oxygenated blood per beat than for walking or rowing.  I realize that there are other exercises that could be superior to running in this regard, but I simply use this as an example.

2. The duration of the exercise.  I've heard anywhere from ten minutes to one hour is the best duration for heart health, but the traditional, aerobic theory is 20-60 minutes. For HIIT, it's 10-20 minutes (or somewhere thereabouts).  And the recommended duration depends also on how intense the movement is performed at.  When I do steady state, I stay towards the lower duration, so as to maintain weight and muscle.

3. Intensity.  And this is where I have questions in my mind.  In my mind our bodies use aerobic energy all the time for regular activities, but in order to improve our bodies' efficiency at using aerobic energy, we need to stress that system by getting our heart rates up to at least 65% of maximum heart rate and no more than 85%. Although aerobic energy is being used at a lower heart rate, it's not being sufficiently challenged.  And, although aerobic energy is being utilized above 85% max. heart rate, a lesser percentage of aerobic energy is being utilized as compared to anaerobic energy.  

But if I do HIIT, I'm using mostly anaerobic energy, so if I have a long-term goal to stay aerobically fit (not just cardiovascular fitness), then why should I abandon steady-state, aerobic training?  I naturally stay lean, and I naturally excel at endurance exercises and perform poorly at fast-twitch, strength, and power-type exercises.  But still, if I go a couple of weeks without steady-state exercise, I can tell that I start losing my aerobic fitness, even if I've being lifting and doing HIIT religiously.  I inquire not because I like running.  Unlike Darrin, I don't particularly like jogging even though I'm a natural.  I would prefer to do sprints, because it requires less time, however, I like the feeling of knowing that I can jog eight minute miles without hardly breaking a sweat. Lately, I've been doing HIIT and lifting only.  Yesterday, I went jogging and I can't jog at near the pace I did before without raising my heart rate higher than I did before. I'm definitely not as aerobically fit as I was two months ago.

P.S.  I hate jogging as well… although I am starting to kinda like the stairmaster at work :)

I guess the only thing I don't like about quitting steady state for good is that I seem to quickly lose my aerobic capacity.  By this I mean that after only nixing steady state for one month I can't run near the same pace without going beyond 85% of maximum heart rate.  I have this fear, since I'm forty-six, that'll I'll stop steady state for a few months and then never be able to gain that ability back again.

It does seem, however, that I can jog only once or so per week (after I become aerobically fit), and I can stay aerobically fit.

I'm considering doing one session of HIIT per week and one session of steady state per week.  If I go this route, I'll probably keep the SS session short and easy.

The only issue I have with HIIT is that it seems to cause me to require more recovery time.  It's almost as though I must lose one workout per week for every HIIT session I have per week.  If I don't follow this strategy, my performance goes down during lifting sessions.