A simple definition cardiovascular exercise is anything that elevates your heart and breathing rate for an extended period of time.  Basically, cardio makes you sweat and is great for burning off body fat.  Just remember that nutrition and weight training are just as important for long term success.

A general recommendation for healthy living is to do cardio at least 3 times per week for 30 minutes each session.  To burn fat, you will have to do more.

This does not necessarily mean that you must go to a gym and use a treadmill or exercise bike though.  Healthy activities such as rollerblading, cycling, hiking, swimming, jogging or even a brisk walk are all cardiovascular. 

Here are some of the benefits of doing regular cardio:

1.  Burning Calories.  Any exercise that burns extra calories will help you lose fat.
2.  Increase your Metabolism.  The faster your metabolism, the more calories you will continue to burn even when you are not exercising.
3.  Improve your Mood.  Exercise is a recommended treatment for depression.  It simply makes you feel better by doing something physical.
4.  Sleep better.  Who doesn’t want to sleep better?  Some people find it difficult to sleep right after exercising, so you may need to exercise a few hours before you go to bed.
5.  Disease Prevention.  Exercise reduces the risk for several diseases including heart disease, adult-onset diabetes, high blood pressure or hypertension, breast cancer, osteoporosis and colon cancer.

There is a limit of how hard you should push yourself.  This is known as your maximum heart rate.  This is a safety guideline and should not be regularly broken by anybody.  Professional athletes may reach their maximum heart rate during competition, but they do not train anywhere near this level on a regular basis. 

A very simple estimate of your maximum heart rate is 220 – your age.  For example a 30 year old person’s maximum heart rate would be 220-30 = 190 beats per minute.  You do not need to work anywhere near you maximum heart rate to burn fat.

How hard should you be training for maximum cardiovascular benefit? 

You should train between 60-90% of your maximum heart rate to get the most benefit out of doing cardio.  A 30 year old’s maximum heart rate is 190.  The low end heart rate would be 114 beats per minute. (190×60%=114)  The high end would be 171 beats per minute.  (190×90%=171)

You will notice that when you first start out, your heart rate will be very fast while exercising.  The more fit you become, the slower your heart rate will be at the same intensity.  Your resting heart rate will also drop as your heart becomes stronger.  The average resting heart rate for an adult is between 60-70 beats per minute.  A top marathoner’s resting heart rate would be in the 40-50 range.

How to check your heart rate.

The simplest way is to is to use a watch or timer and feel your pulse on your wrist or your neck.  You will get the most accurate result by counting beats for a full minute.  You could also count for 15 seconds and multiply your result by four.  The problem with this way of checking your pulse, is that you need to stop exercising to measure it.

A common tool, especially used by runners to check their heart rate, is a heart rate monitor.  These are available at most running stores and some sporting goods stores.  A strap is fastened around your chest to sense your heart beat.  You then wear a special watch that is linked wirelessly to the strap around your chest.  To see your pulse at any time, you simply need to look at your watch.

The final way to check your heart rate is to use exercise equipment that has a heart rate monitor built into it.  The most common place to see a heart rate monitor is where you would normally hold on to the machine.  These usually look like a strip of metal incorporated into the handle.  For example, while riding an exercise bike, if you hold onto the handlebars, the handlebars will have the sensor in them and they will measure your pulse through your palms.

How hard should you be training for maximum fat loss?

When I was in University, training to become a Phys. Ed teacher, the common recommendation for burning fat was “Long Slow Distance”.  People were encouraged to do very long cardio sessions with easy intensity.  A recommended workout might be a 90 minute ride on an exercise bike at an easy level of resistance to burn fat.

We now know that the amount of overall calories burned during exercise is most important factor in fat loss rather than the amount of time spent exercising.

You need to find a balance between the intensity of your exercise and the amount of time that you can keep exercising.  It is true that you will burn a lot of calories very quickly if you are exercising at 90% of your maximum heart rate, but you may only be able to exercise for 5 minutes.  If you keep your heart rate at 70% of your maximum heart rate for 30 minutes, you will burn more calories and more fat.

How often and how long should you do cardio?

Depending on the intensity that you exercise, and your specific goals, you should spend 20-60 minutes per session.  After 60 minutes of exercise, you will quickly start to lose the benefits of it as you tire.

For maximum fat loss, I would recommend at least 4-6 days per week.  If you have the time and the dedication, some people will even do two cardio sessions in one day.  Bodybuilders will use this technique when they are dieting before a show.  It is important though to make sure that you have at least one rest day per week.

When I am doing cardio for the purpose of fat loss, I set myself a goal of the total amount of calories that I will burn by the end of the workout.  I usually set a goal of at least 600 calories.  Depending on what I choose to do for cardio, this takes me between 30 minutes and an hour.  Personally, I try to do the exercises that will get me out of the gym the fastest.