Fat-Burning Zone VS. High Intensity Interval Training
Tuesday, January 26, 2010
If you’ve ever stepped on a treadmill to try to lose weight chances are you’ve scrolled through the variety of training programs and seen the fat-burning option. Well there you go! How easy can that be, right? Not so fast. That fat-burning option comes from the belief that if you train at 70% of your maximum heart rate you will be burning more calories from fat than any other source. Carbohydrates are the bodies first choice for energy stores when you are working hard. Your body doesn’t need oxygen to burn carbs (sugars) so when you are out of breath, as when sprinting, your body goes for the easiest source of energy it can tap. Next in the fuel line is fat. Your body needs oxygen in order to burn fat. If you are training above 70% you won’t have enough air to use fat as fuel. The final source of fuel is protein, which is your body’s lean muscle. If you are very lean it is important to monitor the amount of cardio training you do so that your body won’t use muscle as fuel.
Now you know how your body uses its resources as fuel. The alluring Fat-burning zone still sounds like a good choice. Consider the difference in body composition between a marathon runner and a sprinter. Sprinters are incredibly lean as a rule. If you stand at the finish line of marathon you will see participants of all sizes run through. If steady 70% max. pace was the best way to burn fat then why are the sprinters so much leaner? It’s true that while you are in the fat burning zone you burn nearly 50% of your calories in the form of fat, but you burn fewer calories overall.
High Intensity Interval Training is the most effective way to burn calories and drop pounds. When you train in intervals that bring your heart rate up to 85-90% of your maximum heart rate you become anaerobic. Your body is burning calories like mad. Now more of those calories are coming from carbs than fat. The ratio is around 65% carbs and 35% fat rather than 50/50. But if you can burn 500 calories in a 30min session of HIIT vs. 1 hr of “fat-burning” cardio where you’ve only burned 300 you can see the difference. You burn more calories in less time utilizing a HIIT method. As an added bonus HIIT causes an oxygen deficit which allows your body to burn even more calories after you have finished your cardio session. When you are doing intervals at 90% of your max you become out of breath. While you are recovering you are taking in large amounts of oxygen. You are now getting the oxygen you need to burn fat!
There are lots of HIIT routines that are effective for helping you shed pounds. My favorite program is the Tabata Protocol. The protocol was first developed by the coach of Japan’s olympic speed skating team. He developed a series of sprinting intervals that consisted of 8 cycles of 20 second sprints followed by 10 second rests. Dr. Izumi Tabata, Ph.D, a former reasearcher at Japan’s National Institute of Fitness and Sports in Kanoya, and his team studied the effects of the coach’s techniques. In the Tabata study, the researchers found that participants who followed the protocol five days a week for six weeks improved their maximum aerobic capacity (your body’s ability to use oxygen) by 14% and it also improved anaerobic capacity (measures your speed endurance) by 28%. The more oxygen you can use the more calories your body can burn. A seperate study done by a group of scientists in Canada studied the effects of both low-intensity “fat-burning training” and the effects of the Tabata Protocol on overall fat calories burned. The Tabata participants used a 5 minute warm-up, 4 minutes of 20 second on/10 second off intervals followed by a 5 minute cooldown. The participants utilizing the Tabata protocol had a far greater overall calorie burn as well as a greater number of fat calories burned. They concluded that high intensity training raises the metabolic rate and causes you to burn more calories even if after your training session is long over.
Next time you set off to do your cardio forgo the “fat-burning” setting on the treadmill and go for some HIIT sprints instead. It will be the most productive 14 minutes you’ve ever spent!