There is no question that moderate aerobic exercise has a role to play in fat loss. But as you progress into your program, cardio workouts can become a bit stale and time-consuming. Heck, I know some regular exercisers who probably wouldn’t do cardio if they couldn’t watch "American Idol" while on the treadmill. Now that’s fine, but if you want ongoing change you need to keep finding new ways to challenge your body. A great way to do that is to use Interval Training in your fitness routine.

Interval training involves alternating periods of high intensity work with periods of lower intensity "active recovery" (e.g. alternating running with walking). This has several advantages. First, the short duration "burst" during the high intensity phase stimulates muscle in a way which moderate, steady-pace cardio does not. And, if you remember, last month we learned that the key to being able to burn more calories and fat around the clock, 24 hours a day, is to increase muscle. Now if you’re thinking, "yeah, but didn’t he also say that high intensity cardio burns muscle tissue?" then you’re correct. The key is short duration, explosive spurts. Think of the physique of an elite sprinter vs. that of the marathon runner, and you’ll start to get the picture.

Aside from being muscle-producing, interval training also burns more total calories. In fact, there is evidence to suggest that this effect continues up to 24 hours after an intense interval training workout. This is most likely because your body expends more calories in recovering and repairing than it would for a less intense workout. Thus, it is possible for you to get a very effective cardio session in a lot less time. Great for those of us with hectic schedules!

Training with intervals is dynamic and challenging, which makes it a great deal more interesting than regular cardio. You can alternate a minute of skipping rope with pedaling a stationary bike, weighted step-ups with walking on the treadmill, even jogging up and down the stairs of your house or building, alternated with periods of walking circles around your dining-room table! There are so many possible variations.

Alright, so know that you know why it works, you’re probably wondering, "how can I start incorporating interval training into my workouts?" Well, I usually like to start clients off by doing intervals on a stationary or recumbent bike, because it’s simpler and there is less chance of injury. At first, each interval should be a bit longer, and the "active recovery" phase should be longer than the "sprint," say 3 minutes compared to 2 minutes of high intensity. Try to use a perceived 80% effort for those two minutes, by the end of which your legs should be burning and you should have the feeling that you couldn’t keep going for very long. Do this by increasing the resistance and the speed of pedaling. Then, to get the most out your intervals, it’s important that you slow right down to a comfortable 30% output for the recovery phase. Repeat this process 3-6 times initially, but don’t forget to warm-up 5-10 minutes first, and cool down for about 5 minutes afterwards. The overall duration of your session should be between 15 and 35 minutes.

As you become more advanced, try to challenge yourself with shorter, more intense intervals, and equal periods of recovery. Try 4-10 intervals of 45 seconds at 90% effort, alternated with 45 seconds at 30%, and vary the type of cardio as well. As with anything type exercise, you will get maximum results if you start gradually and push yourself more and more as your strength and stamina improves.

Also, the best time for you to interval train is probably immediately after your resistance training workout, but because it is relatively brief, you may find it quite suitable to perform this workout as your AM cardio, as long as you properly warm up first.

So here it is in a nutshell. To make best use of interval training:

1. Warm up for 5-10 minutes

2. Alternate periods of 80% to 90% effort with periods of 30% effort, depending on your level

3. Cool down for 5 minutes after

4. Start with longer periods and progress to shorter ones

5. As your strength and endurance improves, challenge yourself with different combinations, and more intense "bursts," while simultaneously reducing rest periods

In recent years, a lot has been said for the effectiveness of interval training, and some even tout it as the fat loss solution. But that is misleading, and while I do believe interval training has it’s place in your fitness program, it’s just one piece of the puzzle. A puzzle which, I hope, is beginning to make more sense to you with each successive issue of this newsletter! Together with cardiovascular exercise, the right nutrition and resistance training are the three synergistic elements that will allow to achieve all your fat loss and fitness goals. Good luck!