Cardio - Interval Training basics

This year, for cardio, I plan on doing Taku's intervals. Taku's intervals are based on the findings of Dr. Tabata. Dr. Tabata describes an ideal interval rate as being 10 sets of 20 seconds all out, and 10 seconds of rest between sets. Taku altered the program to build up slowly to the 10 sets of 20/10. My current program ramps up even slower than Taku's. For the past month and a half I've been doing 4x90/90, 3 times a week. That is, 4 sets of 90 seconds running, with 90 seconds of rest(walking) between sets. This week I just started doing 5x60/50s 3 times a week. I plan on continue the 5x60/50s for December, then, starting in January, moving on. I originally planned on continuing to ramp up slowly, here are the steps involved:

4x90/90
5x60/50
6x45/30
7x30/20
8x20/10
10x20/10

Currently, though, I'm thinking I'll spend a max of 2 weeks on any one step (after this month of 5x60/50s) so that we (my SPSU team will be doing the same workouts) can get to the 10x20/10s faster.

A quick explanation of why High Intensity Interval Training works: Your muscles have 2 (basic) types of muscle fibers. Slow-twitch and fast-twitch muscles. Slow-twitch are the marathon fibers, and fast-twitch are the sprint fibers. Your body activates the slow-twitch muscles first, because they are more energy efficient. If the slow-twitch muscle fibers are insufficient to get the force your need, your body will start activating fast-twitch muscle fibers. So, if you're doing your standard 15-30 minutes of running at a steady pace, you're probably never going to activate your fast-twitch muscles (in fact, you'll train your body to use more slow-twitch muscles, making it harder for you to develop power in a game when you need it). You may still be taxing your aerobic system, but a large percentage of your muscles are being unused. If you do a high intensity exercise, you're going have to recruit both muscle fiber types to get the force you need. This is going to put a higher tax on your aerobic system, and work all of your muscle fibers (and you should see a much lower conversion of fast to slow-twitch fibers, more on that later). Anecdotally, this seems much more like a game of Ultimate than running a steady pace for even just 10 minutes.

One thing I like about the intervals is that you can do them in many different ways. Just straight running is the obvious choice, and it's what we primarily do at practices now, but you can also do them on a bike, elliptical, jump rope or even stairmaster (I did my 5x60/50s on the stairmaster this week and it's brutal). As the intervals get smaller, I envision doing suicides/shuttles/cutting drills etc.

You've got to remember that you should be working as hard as you possibly can over the period of the interval. That doesn't mean I'm sprinting for 90 seconds, it just means I'm running as fast as I can possibly maintain for 90 seconds. You should be exhausted at the end of the workout. Dr. Tabata's subjects were professional cyclists and apparentally they laid on the floor gasping for air after the workouts. I haven't gotten that far yet, but I've got a goal!

Because I want to be exhausted afterwards, I do my intervals after everything else I have planned. If I'm lifting at the gym, I do my intervals afterwards, if I have practice, we do our intervals at the end of practice. It doesn't matter how fast you do them, simply that you're working as hard as possible. If you've been doing legs at the gym, then do the intervals, you'll probably reach exhaustion at a lower level than normal, but you should be getting the same benefit (and I read somewhere, though I can't find it now, that it's even better to do after a workout).

Tabata intervals may have a drawback however. There seems to be some evidence that you can lose some fast-twitch muscle fiber by doing short rest intervals. It's all rather confusing, check out this post on Lean and Hungry Fitness for more details if you're interested. To combat this, I've decided to replace one set of intervals every other week with a speed workout. For instance, if it's a speed week, I'll do a set of intervals on Monday, on Tuesday I'll do 5 40 yard sprints with 4 minutes rest between sprints, then on Thursday I'll do another set of intervals.

So, this week I did 5x60/50s on Monday on the stairmaster, after I did a legs workout.
On Wednesday, I did another legs workout followed by a 5x60/50s on the stairmaster again. It's definitely rough. I'm hitting level 15 for the first two, then having to drop down to 13 so I don't fall off and get sucked into the machine. I don't feel like I'm getting quite as good an aerobic workout as if I was running, but my legs are definitely getting killed. My calves almost cramped up Wednesday. Tonight I plan on running the 5x60/50s after practice with the team, I'll comment here and let you all know how it goes.