You Should Sprint: Because A Prius Won't Lose Weight, But A Maserati Will
We've all been taught that long aerobic workouts are the only way to lose weight, and I know many of you are surprised to hear what I have to say about cardio. How can fifteen minutes of sprinting burn more fat than a five mile run? The more time you run, the more calories you burn, and the more fat you lose. That's how it works, right? Wrong. The human body is a highly adaptive machine. Quite simply, we get used to things. So if you train your body that every week you're going to go on a few three mile runs, your body will start to expect those three mile runs, and store fat (for energy) accordingly. In this cycle, you are inadvertently training your body to become calorie efficient. You are now the Prius of runners, and your body will barely burn any fuel (fat) to get you through those 3 miles. Consequently, over time you'll have to run longer and longer distances to get the same results. With burst training, on the other hand, because you shock your system over and over again, you train your body to become a calorie inefficient machine. Think of a Maserati. How quickly do you think that car would burn through a tank of fuel going 100mph every 90 seconds? The more calorie inefficient you are, the less fat your body will store and the more it will burn.
Sprinting increases your Human Growth Hormone: The body's youth serum
"The main difference between health and disease, vibrant youth or aged frailty, is one's hormonal profile" - Robb Wolf
In addition to burning fat, burst training is highly beneficial for increasing your human growth hormone, which is crucial for developing lean muscle mass, speeding up your metabolism and even fixing DNA damage. Studies show that the body's production of human growth hormone increases by up to 771 percent during a burst training workout, largely due to the fact that such intense exercise stimulates your fast muscle fibers, which are rarely used during most exercise programs (unless your trainer throws you on the battling ropes, of course). And the higher your levels of growth hormone, the younger, stronger and healthier you will be.
That sounds great, but I need to work on my endurance for an upcoming race! 15 minutes can't help me.
A study performed in 2008 found that 2.5 hours of sprint interval training produced similar biochemical muscle changes and similar endurance performance benefits to 10.5 hours of endurance training. In other words, less is truly more. In fact, a similar study found that after only 8 weeks of burst training workouts, subjects could bike twice as long as they could before the study, while maintaining the same pace.
So What Do Bursts Look Like?
When I want to do a burst training workout, which is usually about two days a week, I alternate 30s of all out sprints with 90s of recovery for 10 cycles. And as a simple rule of thumb for intensity: on the burst, you should feel that you absolutely cannot talk, and when you recover, you should feel like you can. So it's a sprint followed by a fast walk, Once you can do 10 bursts, start to increase your burst speed. Whether you're walking or lunging stairs, jumping rope, biking, running or swimming, the same principle of 30s burst/90s recovery will not only get you to your goals faster, but will take up less of your day so you'll have more time to do the important things...like go to the farmer's market or take your dog to the beach.