So first, let me explain what interval training is all about. It's harder than regular cardio, but also easier. And an interval training workout is always shorter than a long, slow, boring cardio workout.
Here's how the interval training workout breaks down.
Start with a 5-minute warm-up. You can use lots of other traditional aerobic movements, such as biking, running outside, etc.
Get prepared with a warmup, and then move on to your first set. For your interval, work hard for one minute. After 60 seconds, you will decrease the intensity to a very easy pace for 60-120 seconds.
That is one interval, and should be repeated 3-6 times and then followed by a cooldown.
An interval can be any length, from 5 seconds to 5 minutes, but for fat loss, I generally stick to 30-60 seconds of work followed by 60-120 seconds of rest.
One of the most common questions I get about interval training is, "What is the best equipment to use for interval training?"
Without considering anything else, for maximum results, treadmill sprinting is best. Sprinting is a total body exercise - it's not just your legs that are working hard. Your abs, your arms, and your back on working hard to push you forward.
So sprinting results in a lot of "turbulence" applied to the muscles of the body. Not only does that burn a lot of calories in the workout, but it boosts your metabolism and burns calories and fat for a long time after exercise.
However, the treadmill has several logistical problems (i.e. difficulty changing speeds, possibility of falling off) and sprinting has a greater risk of injury (due to the high velocity nature of the movement).
Therefore, I prefer stationary cycling against a heavy resistance (allowing for 80-100 RPM to be achieved during the work interval). This provides the optimal combination of intensity and safety.
With the bike, you still apply a lot of turbulence to the big leg muscles, ensuring lots of fat and calorie burning. All this with a lot less risk of falling (please tell me you won't fall off a stationary bike!) and an easier time changing speeds.
All other machines and methods are generally accepted, however if you find you are NOT getting results, than your interval training method should be evaluated and perhaps you should experiment with another option.
To be honest, I'm not a huge fan of the elliptical machine. I'd rather someone use the bike or the treadmill. However, if you have knee problems, this machine is great for allowing you to work hard without any extra pounding on your joints.
Rowing machines are good if you are an experienced rower. I don't like crosstrainers that much. Stick with the basics.
You can also swim, but this only seems to work if you are actually a good swimmer.
With interval training, you will get more results in less time than with slow, boring cardio. There are lots of ways to do intense cardio.