Some definitions
Steady state training: Any form of aerobic/cardiovascular training where some reasonably steady intensity is maintained for an extended period. So this might be something akin to 20-60 minutes at a steady heart rate of 140-150 (could be higher, could be lower). I'm just going to call this cardio or aerobics, even though I know some people get into longwinded semantic arguments about it. I'm sure everybody knows what I'm talking about.
Interval training: Essentially any form of activity that alternates higher intensity activity (such as 30-60 seconds almost all out) with periods of lower intensity activity. The rest interval can be passive (sit on your butt) or active (keep moving at a low intensity). While weight training can technically be considered interval training, I'm going to restrict this article to interval training done with standard cardio modes (i.e. running, cycling, stair master, etc). A typical interval workout for fat loss might be a short warmup followed by 5 repeats of 60 seconds near maximum intensity alternated with 60-90 seconds of very low intensity activity, followed by a 5' cool down. This is often referred to as high intensity interval training (HIIT) which differentiates it from aerobic interval training discussed immediately below.
Aerobic interval training: For completeness, I want to mention a third, sort of hybrid, form of training that is usually referred to as aerobic interval training. This is a type of training often used by very untrained beginners who are simply unable to perform 20 minutes or more of continuous aerobic activity. So they might perform 5 minutes of low intensity aerobic activity prior to taking a short break, followed by another 5 minutes of low intensity aerobic training, until they accumulated 20-30 minutes of activity. Over their first several weeks of training, they would try to increase the duration of each aerobic interval session while decreasing the rest interval. Additionally, many strength and power athletes do a type of aerobic interval training usually referred to as extensive tempo running: this is a low intensity type of aerobic interval training done in short bouts. So a sprinter might run 10 repeats of 200 meters but at a very low intensity (aerobic intensity) with 100 meters of walking in-between. In this article, I'm not talking about aerobic interval training when I compare and contrast traditional aerobic training and interval training; aerobic interval training is sort of a third category that doesn't apply to this discussion.
Moving on
Ok, so now that we're on the same page definition wise, I want to compare and contrast aerobic and interval training in terms of potential pros and cons. This will allow us, in part 2 (two weeks from now) to look at how to integrate the different types of training into real world workout schemes.
Steady state aerobics
Pros:
1. Depending on the intensity, steady state aerobics tends to burn more calories during the exercise bout than interval training.
2. More appropriate for beginners.
3. Can be done more frequently, daily or more often (if desired) although this depends on the duration, intensity and frequency as well as the setup of the rest of the training program.
4. Some research finds suggests that regular exercise helps people stick to their diet better. In that interval training can't (well, shouldn't) be performed daily, low intensity activity may help people stay on their diets.
Cons:
1. Most indoor aerobics modes tend to be boring, especially for long durations. Exercise can, of course, be done outdoors but this raises a whole separate set of issues (bicycle safety, running outdoors, traffic, etc) that are beyond the scope of this article. This is a big part of why gyms have music and televisions; I have seen one with a cardio movie theater.
2. An excess of endurance training, especially at higher intensities (too close to lactate threshold, a topic for another newsletter) seems to cause muscle loss, decrease strength and power, and cause overtraining. This is major issue for bodybuilders and strength/power athletes but can be avoided by keeping the intensity and duration under control.
3. Too much repetition of the same mode of aerobics can generate overuse injuries, both runners and cyclists are prone to knee problems, swimming causes rotator cuff issues (and the cold water tends to increase hunger), etc. This can be avoided by non-endurance athletes by rotating the type of activity being done.
4. Unless people are tremendously aerobically fit, it can be difficult to burn a huge number of calories unless the duration of each workout is just ridiculous. So, at moderate intensities, the average person might burn 5-10 calories/minute; a 145 lb person burns about 100 calories per mile walking or running. So over an hour aerobic session, you might achieve 300-600 calories burn. While this can certainly add up if done daily, it's still a fairly small expenditure. The people trotting along on the treadmill or spinning on the bike at low intensities, often for only 30 minutes, are burning jack all calories. Which are usually more than compensated when that person figures that they must be burning at least 1000 calories and rationalizes that cheeseburger and milkshake because of it. This is one of those weird ironies: very high caloric expenditures through aerobics are reserved for trained endurance athletes, and they typically don't need it. The people who need to be burning a lot of calories through aerobic activity usually aren't able to, at least not initially.
Before continuing, I should probably bring up one of the more idiotic arguments against steady state aerobics here. The argument goes something along the lines of "Aerobic training is useless because, as you adapt, the same workout that burned a significant amount of calories over 40 minutes takes 60 minutes because you're getting more efficient." This is about as logical as saying that weight training is ineffective because the same weight that was difficult for 12 repetitions is now too light, and you have to do more repetitions with it. Except that, in the case of weight training, the suggestion would be to add weight to the bar. And the same exact thing can be done with aerobic training: as the body adapts (and you become fitter), you can increase your caloric expenditure by increasing the intensity of your workout. So say that you were doing the stair master at level 8 and a heart rate of 140 beats per minute for 40 minutes. Now you've adapted and level 8 is only a heart rate of 130. Well, you could go to an hour, or you could increase the intensity to level 9 and burn more calories during those same 40 minutes.
Interval training
Pros:
1. For a given time investment, interval training leads to a greater fat loss and this occurs despite a smaller calorie burn during activity. This is because interval training generates a much larger EPOC (excess post-exercise oxygen consumption) which are the calories burned post exercise.
2. Interval training may improve the muscle's ability to use fat for fuel more effectively than aerobic training (note: recent studies have also suggested that interval training can generate very rapid improvements in endurance performance in a very short period but this is beyond the scope of this article).
3. Time efficient: Not everybody has the time to devote to an hour (or more) of aerobic training per day. A properly set up interval workout may only take 15-20 minutes.
4. Time seems to pass faster: Compared to regular aerobics, which can be mind numbingly dull (especially if done indoors), the change in intensity with intervals seems to make the workout pass faster.
Cons:
1. The intensity of intervals makes them inappropriate for beginners. One exception is a style of training called aerobic intervals which I mentioned above. But high intensity interval training is simply inappropriate for beginning exercisers, for the same reason that high intensity weight training is inappropriate.
2. Intervals are high intensity training, this has implications for the overall training setup (discussed in more detail in part 2) and integration with the rest of your program (i.e. weight training). Simply put: if you think you can train legs in the weight room 2-3X/week and do intervals an additional 2-3X/week on alternate days, you are incorrect unless you are deliberately trying to overtrain or get injured.
3. Higher risk of injuries: this depends somewhat on the type of activity with high impact activities such as sprinting carrying a higher injury risk (especially for heavier individuals) than intervals done on the bike or stair master.
Limited in how many days they can be performed. Two to three days per week is about the maximum for interval training, most endurance athletes won't do intervals more than twice/week. Have I heard of people trying to interval daily? Yes. Do I think it's a good idea? No.
4. Intervals hurt, especially intervals in the 60-90 second range where muscular acid levels are very high. If you're not willing to push yourself, you won't get much out of interval training. You know the warnings on most aerobics machines, that tell you to stop if you feel signs of exhaustion or fatigue; that's what a properly done interval program should feel like. Sensations of burning in your legs (from high acid levels in the muscle) along with extreme discomfort are not only common but expected. Some people also report nausea initially, this can be made worse if they have eaten too close to training.
In part 2, I'll examine some specific training situations to see which type of activity might be best under a given situation.
