If you are looking to burn body fat, stop doing steady state aerobic exercise. Thirty minutes of light jogging with your heart rate consistently between 140-150 bpm is a great form of general fitness, but not an effective way of burning body fat. However, completing thirty minutes of interval training where your heart fluctuates between 100 bpm and 170 bpm will significantly increase your metabolism and in turn, burn more body fat.
Let me tell you the science of what is going on in your body during each of these forms of exercise. During aerobic or steady state exercise, your heart rate slowly increases to a certain rate (typically between 100-150 bpm). It will remain there for as long as you are exercising. Once you stop moving, your heart rate will return to its resting level within 30 minutes to an hour, depending on your fitness level. Your metabolism will also return to its resting rate since it is aware that you are no longer exercising.
When completing interval exercises, especially ones that have you working anaerobically, your heart rate will vary over time. There will be times where you are completely out of breath and other moments when you feel rested. During this type of workout, your body does not know when you are done with exercise. Every time you let the heart rate fall and the body rest, you return to the high intensity exercise. Your metabolism is under constant fluctuation. From a survival standpoint, your body wants to keep your metabolism as low as possible in order to hold onto as many calories as possible. By keeping the intensity variable, your body has to keep your metabolism higher than it would prefer because it never knows when you are going to break back into burpees.
To sum all of that up, interval training is more effective because your metabolism has to stay slightly higher than its previous resting rate since it does not know when you are going back into sprints.
Excess Post Oxygen Consumption (EPOC) is how much oxygen your body consumes after exercise. The more oxygen you consume, the more calories you burn. Simple as that. Because your metabolism and heart rate take a longer time to return to a resting rate after interval exercise, you consume more oxygen than you would when completing aerobic or steady state exercise. And we aren't talking a slight increase in EPOC. The figure is closer to 4-5 times more oxygen is consumed post interval exercise than steady state.
If losing body fat is your goal, you need to be doing short intense bouts of exercise followed by longer periods of rest. Cardiovascular workouts should total 30-60 minutes. To be honest, I'd rather have a client complete a 30 minute grueling interval workout than a 60 minute workout with moderate intensity. It's simply more effective at burning body fat.
In my Body Fat Burn program, I provide interval workouts that will help you achieve this body fat loss.
Thank you for reading and I hope I've taught you something about the effectiveness of interval training! If you learned something in particular, I'd love to hear about!