The intensity of your workout, or how hard you exercise, is probably the most important variable in determining the outcome of your workout routine. If you think about it, it makes since. Exercise is supposed to stress your heart, muscles and lungs to make them better. Without a sufficient amount of stress, there is no stimulus for improvement.

To get a stronger heart, it has to beat harder and faster to force healthy adaptation. Bigger muscles — you either need to lift heavier weight or perform more reps (repetitions). Pushing yourself past your limits forces change. But how hard should you exercise?

A historic study done by Borg in 1982, has helped us to determine how hard we should exercise. Through this study, Borg developed a scale of 6-20 that is based on your own honest opinion of how hard you are exercising. A self-rating of 6 is the lowest rating, meaning you are dong no activity. A rating of 20 means you are performing the hardest level of activity possible. Optimally, exercising between a self-rating of 13-17 is optimal for cardiovascular benefit and strength gain.

Another interesting component of the Borg scale is that you can take your self-rating and multiply it by 10 to get quite an accurate estimate of your heart rate! Test it out yourself during your next workout and see for yourself!

If you can’t remember that the range for the Borg scale is between 6-20, a new Borg scale has been developed that ranges between 0-10, with 10 being the highest level of activity. With this new scale, exercising between a self rating of 6-8 is best.

Why is this so accurate? Borg states:

In my opinion, perceived exertion is the single best indicator of degree of physical strain. The overall perceived exertion rating integrates various information, including the many signals elicited from the peripheral working muscles and joints, from the central cardiovascular and respiratory functions, and from the central nervous system.

In addition, using the Borg method of determining intensity is also practical. While modern technology has developed equipment to help you determine your heart rate and intensity, a self-rating of exertion is the most practical and can be generalized to all levels of fitness.

The most important aspect is that you are honest with yourself. If you can exercise for 20-30 minutes between a self-rating of 13-17 (new scale, 6-8) you are exercising at the best intensity to lose weight and improve cardiovascular fitness.

So on your next workout, make sure that you are pushing yourself outside of your comfort zone to improve your fitness.

Here is a great chart for your reference:

borg exertion scale1