We all have heard that doing low intensity cardio (like walking) for more than 45 minutes is ideal to burn fat....but what options do we have if we do not have 45 minutes or more to do our cardio?
Well the answer to this is High intensity cardio. High intensity cardio means that you are going to work your heart at bout 75% to 85% of your maximum heart rate. On the other hand low intensity cardio works your heart at about 55% to 65%.
With high intensity cardio, you burn more calories quicker. To illustrate this, let's say that you walk (low intensity cardio) for 20 minutes and burned 100 calories, about 50 of this calories will be coming from fat stored in your body. (50 calories is about 5 grams of fat).
Now if you were doing high intensity training for 10 minutes, you could burn up to 160 to 180 calories. 40% of these calories will be coming from fat stored in your body. This means that you will burn 64 to 70 calories from fat in only ten minutes or better yet you will be burning 6 to 7 grams of fat.
As you can see you will be burning more fat in less time. Low-intensity exercise only burns calories while you are actually exercising. That means the moment you stop exercising, your caloric expenditure goes back down to nearly baseline levels. Within minutes, you're not burning many more calories than if you hadn't done anything at all.
High-intensity exercise, on the other hand, continues to boost your metabolism long after you're done (often up to 24 hours after, depending on the length and intensity of the training session). This means you're continuing to burn many more calories all day long!
Also it is worth mentioning that high intensity cardio stimulate more your muscle, helping in some cases to develop more.......and we know that the more muscle and better tone, the more calories that we burn while we are not exercising.
Here are some examples of high intensity training.
On a Bike,
ride your bike for 2 min at a easy pace, then increase the intensity, either by increasing the resistance or the speed and ride the bike this way for 1 min. then go back to the easy pace for 1 min, and then after 1 min go back to the higher intensity pace. Try this for ten minutes and you will see the difference, besides it is a fun activity since you will be challenging yourself.
If you have 20 min for your exercise, try different time intervals, for example start with 4 min easy pace, then 2 min at a higher intensity and 30 sec at at even higher intensity then go back to the easy pace. The combination are endless and the only limit is your imagination, the key is to get your heart to 75-85% of your maximum heart rate.