The intensity of cardiovascular training is one of the most important parameters for obtaining the maximum profit of your sessions. Different intensity settings allow focusing on burning fat or improving the endurance. This post details the different goals that can be achieved by adequately setting your intensity and provides pointers for being able to set this intensity easily.
The intensity of cardiovascular training is typically measured with respect to the target heart rate. Traditionally, several training zones have been distinguished. Anything above 85% is considered anaerobic training. Low intensity zone (50-60%) is intended for warming-up or burning calories without stressing the body, though burning a significant amount of calories requires a lot of time. This zone is also a good choice for people just getting started with cardiovascular training or returning from an injury.
The 60-70% heart rate zone is commonly referred as the fat-burning zone, because here the higher percentage of burned calories comes from fat: over 65% according to performed studies. For this reason, this zone is a great option for burning fat with minimal muscle breakdown. Notice that this does not mean that this is the necessary zone for burning fat. In fact, you can burn fat in other zones, as described later.
Aerobic zone (70-85%) is mainly intended for improving endurance, but can be also used for burning fat. In fact, though only the 45% of burned calories will come from fat, this zone can burn a higher amount of fat calories than the fat-burning zone, due to the increased intensity. However, this must be approached with caution, since muscle protein wasted in this zone is also higher. For this reason, it is important to maintain also your effort on weight training to avoid losing muscle. An added benefit of cardiovascular training, especially noticeable when training in the aerobic zone, is that it maintains your metabolism elevated for some hours after ending training, which improves your capability for burning fat during these hours.
Calculating your target heart rate (THR) requires knowing first your maximum heart rate (MHR). The MHR can be theoretically defined as the most times that your heart can safely beat in the span of one minute. There are several methods for calculating your MHR. In the simplest one, the MHR results from subtracting 220 minus your age. This method works quite well, but if you want a more accurate value of the MHR, you can use the Tanaka method, where the MHR results from the following formula: 208 - 0.7 x age. Once you have the MHR, you can obtain the target heart rate by multiplying the MHR by the percentage in which you want to stay (e.g. MHR x 0.65).
It has been speculated that the above methods for determining the MHR are not very accurate, since they only depend on the age. Of course, individuals with the same age can have different sized hearts, stroke volume, blood pressure, resting heart rates, etc. which will contribute to different MHR among them. According to this, some improvements of the formula for calculating the THR have been proposed. One of them is known as the adjusted heart rate or Karvonnen formula. This method takes also into account the resting heart rate by removing it from the MHR before applying the percentage.
Let’s see an example comparing all the discussed methods. Suppose a 25 years old person, who has a resting heart rate of 60, and wants to stay at the 80% of his maximum. His target heart rate using the traditional method will be (220 – 25) x 0.8 = 156. Using the Tanaka method, it will be (208 – 0.7 x 25) x 0.8 = 152.4. Using the Karvonnen formula, it will be (((220 – 25) – 60) x 0.8) + 60 = 168.
You can find further information about the importance of intensity in cardiovascular training in the article “Priming the Cardio System” by Matt Danielsson, and the article “Heart Matters: Are You Training Your Heart?” by Jeremy Likness.
The intensity of cardiovascular training is typically measured with respect to the target heart rate. Traditionally, several training zones have been distinguished. Anything above 85% is considered anaerobic training. Low intensity zone (50-60%) is intended for warming-up or burning calories without stressing the body, though burning a significant amount of calories requires a lot of time. This zone is also a good choice for people just getting started with cardiovascular training or returning from an injury.
The 60-70% heart rate zone is commonly referred as the fat-burning zone, because here the higher percentage of burned calories comes from fat: over 65% according to performed studies. For this reason, this zone is a great option for burning fat with minimal muscle breakdown. Notice that this does not mean that this is the necessary zone for burning fat. In fact, you can burn fat in other zones, as described later.
Aerobic zone (70-85%) is mainly intended for improving endurance, but can be also used for burning fat. In fact, though only the 45% of burned calories will come from fat, this zone can burn a higher amount of fat calories than the fat-burning zone, due to the increased intensity. However, this must be approached with caution, since muscle protein wasted in this zone is also higher. For this reason, it is important to maintain also your effort on weight training to avoid losing muscle. An added benefit of cardiovascular training, especially noticeable when training in the aerobic zone, is that it maintains your metabolism elevated for some hours after ending training, which improves your capability for burning fat during these hours.
Calculating your target heart rate (THR) requires knowing first your maximum heart rate (MHR). The MHR can be theoretically defined as the most times that your heart can safely beat in the span of one minute. There are several methods for calculating your MHR. In the simplest one, the MHR results from subtracting 220 minus your age. This method works quite well, but if you want a more accurate value of the MHR, you can use the Tanaka method, where the MHR results from the following formula: 208 - 0.7 x age. Once you have the MHR, you can obtain the target heart rate by multiplying the MHR by the percentage in which you want to stay (e.g. MHR x 0.65).
It has been speculated that the above methods for determining the MHR are not very accurate, since they only depend on the age. Of course, individuals with the same age can have different sized hearts, stroke volume, blood pressure, resting heart rates, etc. which will contribute to different MHR among them. According to this, some improvements of the formula for calculating the THR have been proposed. One of them is known as the adjusted heart rate or Karvonnen formula. This method takes also into account the resting heart rate by removing it from the MHR before applying the percentage.
Let’s see an example comparing all the discussed methods. Suppose a 25 years old person, who has a resting heart rate of 60, and wants to stay at the 80% of his maximum. His target heart rate using the traditional method will be (220 – 25) x 0.8 = 156. Using the Tanaka method, it will be (208 – 0.7 x 25) x 0.8 = 152.4. Using the Karvonnen formula, it will be (((220 – 25) – 60) x 0.8) + 60 = 168.
You can find further information about the importance of intensity in cardiovascular training in the article “Priming the Cardio System” by Matt Danielsson, and the article “Heart Matters: Are You Training Your Heart?” by Jeremy Likness.
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