How Do I Know How Hard I Should be Exercising?

 The general exercise guidelines and most heart rate charts you will see will tell you to exercise between 60 and 80 or 85 percent of your maximum heart rate; this is also referred to as your intensity level. However, this is a very broad range. The easiest way to estimate your maximum heart rate is to subtract your age from 220; this is your estimated maximum heart rate. For example, if you’re 35 years old, your maximum heart rate would be 185. Keep in mind that this is a general guideline. If you are very fit or very unfit, this formula may not apply to you. Exercising with a heart rate monitor is a great way to monitor your intensity.

Another way of monitoring your intensity is called Rate of Perceived Exertion or RPE. This simply refers to how hard you feel you are exercising. Using a scale of 1 to 10 where 1 is very easy (i.e., you’re sleeping) and 10 is maximal effort (i.e. you’re puking), you can monitor your intensity. This is useful if you can’t easily check your pulse or are not wearing a heart rate monitor. It is also good for people who might be taking medications that affect the heart rate.

Here are some more specifics based on your fitness level that may be more appropriate. However, you should always check with your physician before starting an exercise program and to determine what is most appropriate for you.

• Unhealthy Beginner – this means you have never really exercised or it’s been a very long time since you have exercised and you have some underlying health conditions. This can also apply to people who are rehabilitating after an injury or recent major illness and have been cleared by a physician.
  • 55 – 65% of your maximum heart rate
  • RPE of 5 to 6.5
• Healthy Beginner – this means you are generally healthy with no medical problems or conditions and are beginning an exercise program.
  • 60 – 75% of your maximum heart rate
  • RPE of 6 to 7.5
• Regular Exerciser – this means you exercise on a regular weekly schedule to maintain fitness benefits and have no medical problems.
  • 70 – 85% of your maximum heart rate
  • RPE of 7 to 8.5
• Athletes – this means that you are an athlete whose goal is to improve performance and are likely training for an upcoming competitive event.
  • 85 – 90% of your maximum heart rate
    *Note: this level of intensity is what is considered to be anaerobic. Training at this level increases the risk of injury, so no medical problems should be present.
  • RPE of 8.5 to 9.5

 Should I be Concerned About Exercising in the “Fat Burning Zone”?

 The concept of “fat burning” versus “carbohydrate burning” exercises is a common misconception when it comes to weight loss. Many people make the faulty assumption that in order to lose fat, they should exercise at a lower intensity so that they are primarily burning fat calories. Regular exercise is beneficial for weight loss because it creates a prolonged calorie deficit; the fuel burned to create this deficit is insignificant. There is no current research to suggest that specifically burning fat as fuel will lead to greater fat loss when compared to an equal calorie deficit created by “carbohydrate burning” exercises.

When you exercise at a higher intensity, you will likely burn more calories. But it is not the calories burned during exercise that is of great importance; it is what happens after exercising that has a great impact. The more carbohydrates you burn during exercise, the more fat you burn after exercise; when there is not much carbohydrate to burn, the process of fat oxidation is naturally accelerated. This means that while a greater percentage of fat may be burned with low-intensity exercise, the total grams of fat burned is actually greater with high-intensity exercise.

A simpler explanation is that low-intensity exercise uses a higher percentage of fat for fuel than high-intensity exercise, but these fat calories are burned at a relatively slow rate (e.g. 4 to 5 calories per minute). High-intensity exercise burns a smaller percentage of fat, but this percentage is being burned at a higher rate (e.g. 10 to 13 calories per minute). Therefore, the total amount of fat burned is greater during high-intensity exercise. People have confused the proportion of fat used for fuel with the rate of fuel utilization – which is an important concept.

The bottom line is that if your goal for your exercise program is to lose weight, then the exercise you choose needs to create a calorie deficit. There are 3500 calories in a pound, so you need to have a deficit of 3500 calories in order to lose a pound, regardless of whether those calories are from fat or carbohydrate. Keep in mind that for safety purposes, overweight individuals who are new to exercise should stick with low-to moderate-intensity exercise because high-intensity exercise for this population is associated with increased risk of injury and higher dropout rates.