Intervals
Benefits of interval workouts
Burns more calories than regular cardio. Doing steady state cardio requires what are called slow-twitch muscle fibers. Intervals requires more fast-twitch muscle fibers. Fast-twitch muscle fibers require more energy – aka burn more calories when being used.
Continues to burn calories, even after you’re done working out. This is due to what’s called the Excess Post-exercise Oxygen Consumption (EPOC) effect. To illustrate, think about your car. After you turn it off the engine is not instantly cool, it stays warm for a while. A similar effect happens with your body after exercise, your metabolism stays elevated for some time after. EPOC is not influenced by the duration of your workout, rather, by the intensity.
Scientifically proven to stimulate anti-aging hormones. Intervals stimulate the production of human growth hormone.
An increase in endurance. Intervals is one of the fastest ways to build your endurance. The gold standard for measuring endurance is through a VO2 Max test. Those who do intervals consistently have superior scores to those doing conventional cardio.
The science behind high intensity interval training
High intensity interval training (H.I.I.T.), also known as “burst training”, is one of the most important exercises you will learn and do in our ten minute fitness program. It is highly effective, and a huge time saver. Watch this video to understand why.
There are even more health benefits of doing your intervals workout on a mini trampoline
More scientific benefits of intervals
Most people do moderate-intensity cardio to improve their aerobic capacity and to burn fat. One study, involving 36 healthy, untrained men, compared steady-state running for 150 minutes a week to interval running for 40 minutes weekly. At the end of 3 months, the group that worked out interval style enjoyed greater improvements in aerobic capacity compared to the other two groups. They experienced an average 14% increase in V02 max (a measure of aerobic capacity) versus 7% in the steady-state group. In addition, the interval training group experienced comparable reductions in blood glucose in response to training. This study suggests that exercise intensity is more important than training volume for improving aerobic capacity and for cardiovascular health.
A study published in the International Journal of Obesity showed INTERVALS training three times weekly for 15 weeks led to greater reductions in belly fat and total body fat compared to steady-state exercise. High intensity exercise also improved insulin sensitivity more. In another study, overweight young men who performed intervals training for 20 minutes three days a week experienced a 17% decrease in belly fat. Pretty impressive for an hour of interval training weekly. Improvements in cardiovascular health and aerobic capacity, fat loss and improved insulin sensitivity – those are some of the things you can expect when you do a high-intensity interval workout.
Plus, intervals training is more time efficient. You can get fitness benefits in half the time compared to steady-state training. That’s all good but why is high-intensity exercise so effective? Hormonal Response to interval training Hormones are the driving force behind changes in body composition. Interval training, due to its intensity, causes a significant increase in catecholamines, hormones activated during periods of stress. These hormones are important because they also mobilize fat stores to be used as fuel. In addition, high intensity interval training maximizes release of the fat-burning hormone growth hormone.
One study found higher levels of growth hormone in the bloodstream after high-intensity compared to moderate intensity. In fact, research shows there’s a minimal exercise intensity needed to elicit significant release of growth hormone. In one study, ten minutes of high-intensity exercise consistently increased growth hormone levels in healthy men. Release of these hormones maximizes the benefits of interval training. Once you’ve finished your workout, these hormones boost fat burning for hours after you’ve recovered.
One of the benefits of interval training is the after burn it creates, the ability to burn more fat during the post-exercise period. In contrast, when you finish a moderate-intensity workout, the afterburn effect is minimal. When you do long periods of moderate-intensity exercise, an hour or more, your cortisol level rises. High intensity exercise also boosts cortisol due to the stress of training, but the rise is short term. Exercise of longer duration causes a more sustained increase in cortisol. Studies have found endurance athletes that run for long periods of time have more prolonged increases in cortisol. You don’t want that. Cortisol breaks down muscle tissue and increases appetite and cravings for high-carb foods. People who have sustained elevations in cortisol also put on more belly fat.
Improvements in Aerobic and Anaerobic Capacity is one of the benefits of interval training is it improves aerobic fitness without causing a sustained rise in your cortisol level and it does it in the shortest time possible. Intervals also improves anaerobic capacity, the point at which your body has to turn to anaerobic metabolism to generate energy. When you exercise at a high intensity, your body is forced to use anaerobic energy pathways to make ATP, your body’s energy currency, because your aerobic system can’t keep up with the demand. As a result, lactic acid builds up in your bloodstream because you can’t remove it quickly enough. That’s why interval exercise is so fatiguing and why a rest interval follows each high intensity interval. The rest intervals help remove some of the lactic acid and restore your body’s pH to normal. When you do regular high-intensity workouts, your body becomes more efficient at removing lactic acid and you can exercise at a high intensity longer without having to stop. Most experts believe your anaerobic threshold, the intensity with which you can exercise without building up lactic acid, is a better indicator of fitness than aerobic capacity. It’s even a better predictor of how well you’ll perform during aerobic exercise than V02 max. Steady-state exercise improves aerobic capacity but not anaerobic capacity. INTERVALS training is designed to improve both.
References:
Med Sci Sports Exerc. 2010;42(10):1951-1958.
J Obes. 2011; 2011: 868305.
Poloquin Group. “Is Aerobic or Anaerobic Training Best for Getting Rid of Belly Fat?” Int J Obes (Lond). 2008 Apr;32(4):684-91. doi: 10.1038/sj.ijo.0803781. Epub 2008 Jan 15.
Psychoneuroendocrinology. “Elevated Hair Cortisol Concentrations in Endurance Athletes” (2011) Am J Physiol Endocrinol Metab. 2014 Oct 1;307(7):E539-52. doi: 0.1152/ajpendo.00276.2014. Epub 2014 Aug 5.
J Clin Endocrinol Metab. 1992 Jul;75(1):157-62.
