Steady State Cardio vs. Interval Training Cardio (Part II)

So last time we talked about some of the pros/cons of steady state cardio vs. interval cardio training; you can check it out here. Today, I wanted to talk more specifically about a little relevant history for both as far as who traditionally used which protocol, and the energy systems involved with each. In our final installment, we will make some conclusions as far as which mode of cardiovascular activity would suit you the best.

So, who traditionally employs steady state cardio into their training regimen? Well, obviously endurance runners. As I stated earlier, bodybuilders frequently employed steady state cardio to cut down to competition shape while sparing any muscle they were gaining during resistance training via gluconeogenesis (protein breakdown and utilized as fuel to contribute to the higher intensity activity that running demands when compared to walking).

And, pretty much 3/4 of any gym population still utilizes this training mode. As for interval training, back in the 50s, Roger Bannister is widely credited to first utilize interval training in his successful pursuit to break the 4 minute mile.  Nowadays, interval training is most often utilized by strength coaches with their athletes to get them into “sport specific” condition, as well as savvy weekend warriors who are all for getting in a high intense workout in a short period of time.

So, from an energy systems standpoint, it is important to note that, all other things equal, when an individual is working out at a higher intensity, he or she will be recruiting more from glycogen stores, compared to individuals working out at a lower intensity,where the individual will be recruiting more from fat stores. Keep in mind that these are RELATIVE statements; you’ll still burn fat working out at a higher intensity (mostly due to post-exercise oxygen debt payoff… a phenomenon known as EPOC, excess post-exercise oxygen consumption), just not as much as at a lower cardiovascular intensity, and vice versa for lower intensity cardio. One might be thinking at this point: “well if I’m trying to burn fat, I should exercise at the intensity that will stimulate the body to burn fat, right?” Well, yes and no. It depends on several variables, and you certainly can still burn fat with both interval training and steady state cardio (I’ll go into this in a second) but in my opinion, it really comes down to how LONG you are trying to spend time on your fat burning activity.

Lets take a look at scenario 1, and I’ll use figures that were similar to the last post to explain: Sam is doing his steady state, 3x a week jogging on a treadmill at 5mph for 60 minutes, burning lets say 9 cal/minute. This equals out to about 450 calories per workout, and since this 5mph speed is equal to about 50% of his VO2 max, Sam’s in the ever-so-popular fat burning zone. 450 calories times 3 cardio workouts like this a week, equals out to about 1350 calories of fat per week with a 3 hour time investment. Awesome.

Now lets take a look at scenario 2: Sally is doing interval training, 3x/week, doing intermittent sprinting/walking 15s on: 45s off @ 10mph and 3 mph, respectively, and she’s going for about 30 minutes. Since this is a much higher intensity activity, she is burning upwards near 20/calories per minute (keep in mind these are arbitrary figures, not precise, just trying to make a point), albeit those calories being burned mainly came from glycogen stores, due to the nature of the activity. So we get 600 calories burned, (20cal/min x 20 min), 3x/week, equaling out to 1800 calories burned at weeks end. Also awesome, because we spent 1/2 of the amount of time in the gym.

Now, I know what you’re thinking, “but Mike, aren’t those calories mainly coming from glycogen stores? I want to burn fat!”, hold your hormones, I ain’t done yet.

Let’s talk for a second about this phenomenon called EPOC, or Excess Post-Exercise Oxygen Consumption. As a result of Sally having participated in a higher intensity activity, she has created an Oxygen Debt inside her system, that, when progressed appropriately, will keep her metabolism elevated after her workout is complete. Studies have shown this to be an additional 6-15% of the net caloric cost of the exercise bout.  Thus, even when Sally is not working out, her workouts are still working for her, thus allowing her to continue burning fat.

Now, as stated in Part 1 of this series, I’ve read about bodybuilders walking on an incline at a low speed to further stimulate fat loss, without coming at the expense of burning muscle tissue they worked so hard to build.  The catch is this though; these individuals are spending upwards near 5-10 hours a week on treadmills, stairmills, ellipticals, bikes, etc. to achieve these physiological reactions. Talk about time comittment!  I’m not saying that steady state cardio doesn’t work; I’m merely saying that for most individuals, the work required in order for the fat burning magic to happen ends up taking alot more time then they anticipated.  Therefore, utilizing steady state cardio as your MEANS OF FAT BURNING are sub optimal, and there are better choices to achieve that end.

We’ll finish up with Part III tomorrow!