Many trainers today talk about performing intervals. This may be in reference to strength training or cardio workouts. The strict definition of interval training is athletic training which alternates between two different activities, such as walking and jogging, or between two different rates of speed. Most fitness experts refer to the using different rates of speed within one cardio workout to supercharge your system and burn more calories.
Cardiovascular activities are those that are sustained for a long enough period of time to evoke the aerobic energy system (5 or more minutes), but aren’t performed at an intensity level greater than 85% of max. heart rate capacity. You have probably seen that chart on your gym wall which says to stay within 60-85% of your max heart rate.
Now, many trainers are saying it is better to use a strategy of high intensity which means to go beyond these levels in an effort to burn more calories. So, here’s the big question along with a surprising answer…
Does the body burn more fat at higher or lower intensities?
The body does burn a higher percentage of calories from fat stores doing less intense (60-65 % MHR) work. However, it burns a greater amount of calories at highly intense (80-85% MHR) work. So, do you want to burn more fat or more calories?
Here is an interesting study performed on a 130lb. woman:
Low Intensity High Intensity
(60-65% MHR) (80-85% MHR)
Total Calories Burned
Per Minute 4.86 6.86
Fat Calories Burned
Per Minute 2.43 2.7
Total Calories Burned
Per 30 min. 146 206
Fat Calories Burned
Per 30 min. 73 82
Percentage of Calories
From Fat 50% 39.85%
I have always favored higher intensity cardio training because it makes sense to me to burn more calories overall in order to reach my goal quicker. However, high intensity training is more taxing to the body and she be used sparingly as opposed to an every day approach.
