cardio workoutsWhat is the best kind of workout to do on a treadmill, elliptical trainer, or stationary bike? Trick question! There is no single best indoor cardio workout. The most effective exercise program is one that includes a variety of different types of workouts.

Cardio fitness is not one-dimensional. Each type of workout develops certain dimensions better than others. A balanced program that cycles through the various workout types will build your overall cardio fitness more effectively than a one-sided program.

You’ve probably heard this before. Most exercisers are aware that they should include variety in their program but they continue to do the same steady, moderate-intensity workout over and over anyway. The reason is that it takes a lot of mental energy to come up with a new workout to do every time you step onto the treadmill or elliptical trainer or sit down on a stationary bike seat. Exercise already takes a lot of physical energy. We’d rather not have to think on top of that!

But adding variety to your cardio routine doesn’t have to fry your brain. There are four basic types of workouts you should do. Each one focuses on a different dimension of cardio fitness. All you have to do is cycle through them repeatedly, altering each one a bit as appropriate with each repetition. Let’s take a look at these workouts.

The Fat-Burner
You’ve heard of the fat-burning zone. Research has shown that exercisers of all fitness levels burn fat at the highest possible rate when they keep their heart rate steady at about 65 percent of maximum. When you go faster than that your muscles start to burn more carbohydrate and less fat. When you go slower your muscles don’t burn carbs but they also burn less fat.

You can get an estimate of your maximum heart rate by subtracting your age from 220. So if you’re 35 years old, your maximum heart rate is likely to be around (220 – 35 =) 185 beats per minute. Sixty-five percent of that number is 120 bpm. So to do the Fat-Burner you just have to strap on a heart rate monitor and stride or pedal at 120 bpm (or whatever your personal fat-burning heart rate is) for at least 20 minutes.

Exactly how long you continue is up to you, but note that the longer you continue, the more your muscles will rely on fat for fuel. It’s not hard to do fairly lengthy Fat-Burner workouts because the intensity is relatively low and comfortable.

If you don’t have a heart-rate monitor, a 10-point perceived effort scale (where “1” is very easy and “10” is as hard as you can go) can be used to find your fat-burning zone. An effort rating of “4” corresponds to your maximum rate of fat burning.

The Strength Builder
To emphasize the strength component of your cardio training you need to work against greater-than-normal resistance. To do this on a treadmill you can increase the incline to simulate going uphill. On many elliptical trainers you can increase the incline, the resistance, or both. And on a stationary bike you can increase the resistance or (on some machines) the gear ratio.

It’s best to use an interval format for Strength Builder cardio workouts. This entails doing short bursts at high intensity with easier recovery periods between them. Here’s a sample Strength Builder:

1. Warm up for 5 minutes at effort level 2.
2. Increase the incline or resistance of the machine and maintain an effort level of 7 for 1 minute.
3. Reduce the incline or resistance and maintain an effort level of 3 for 2 minutes.
4. Repeat steps 2 and 3 a total of four to eight times, depending on your fitness level.
5. Cool down for 5 minutes at an effort level of 2.

The Aerobic Maximizer
The most effective way to increase your body’s ability to process oxygen—a key component of cardio fitness—is through workouts featuring a sustained effort at a moderately high intensity. The intensity sweet spot for these workouts is a perceived effort level of 6 on a 1-10 scale. It should feel challenging but still manageable. Here’s a sample Aerobic Maximizer:

1. Warm up for 5 minutes at an effort level of 2.
2. Increase your effort level to 6 and maintain it for 10 minutes.
3. Cool down for 5 minutes at an effort level of 2.

The Speed Booster
Interval workouts featuring very short efforts at very high intensities (or what endurance athletes call “speed workouts”) are great for improving body composition. Not only do you burn calories at a high rate during these workouts but your metabolism remains elevated for a long time afterward so your body continues to burn extra fat at rest. Here’s a Speed Booster to try:

1. Warm up for 5 minutes at an effort level of 2.
2. Increase your effort level to 8 for 30 seconds.
3. Reduce your effort level back to 2 for 90 seconds.
4. Repeat steps 3 and 4 a total of six to 12 times, depending on your fitness level.
5. Cool down for 5 minutes at an effort level of 2.

See for Yourself
Adding variety to your cardio routine is an important way to improve your results. And it doesn’t have to be a mental burden. Give these workouts a try and see for yourself!

Matt FitzgeraldMatt Fitzgerald is the author of Racing Weight: How to Get Lean for Peak Performance and serves as a Training Intelligence Specialist for PEAR Sports.