By: Dr. Mercola
Source: Mercola.com
Did you know that working out just 20 minutes using interval exercise may provide many of the same benefits of much longer workouts done in conventional “long-duration” style?
A growing body of research shows you may not need to spend as much time exercising as you think — provided that you are willing to truly put in some effort when you do.
Most recently, a Canadian research team recently gathered several groups of volunteers, including sedentary but generally healthy middle-aged men and women, and patients of a similar age who had been diagnosed with cardiovascular disease.
The participants were asked to undertake a program of cycling intervals — repeated short bursts of strenuous activity, divided by rest periods.
According to the New York Times:
“Most of us have heard of intervals, or repeated, short, sharp bursts of strenuous activity, interspersed with rest periods.
Almost all competitive athletes strategically employ a session or two of interval training every week to improve their speed and endurance.
But the Canadian researchers were not asking their volunteers to sprinkle a few interval sessions into exercise routines.
Instead, the researchers wanted the groups to exercise exclusively with intervals.”
After several weeks on the program, both the unfit volunteers and the cardiac patients showed significant improvements in their health and fitness. Most remarkably, the cardiac patients showed “significant improvements” in both heart and blood vessel functioning. And, contrary to what popular belief might dictate, the intense exercises did not cause any heart problems for any of the cardiac patients. The belief is that the brevity of the exercise helps insulate your heart from the intensity.
How Intense is “High Intensity” Training?
The key to make interval training work is intensity. The cycling program developed for the out of shape and ill patients in the featured study was a gentler version of the interval training typically used, when you really go all out to reach your maximum heart rate. In this modified routine, the participants did one minute of strenuous effort, raising their heart rate to about 90 percent of their maximum, followed by one minute of recovery.
These intervals were repeated 10 times for a 20 minute long workout.
Your maximum heart rate can be roughly calculated as 220 minus your age. However, to measure the intensity of your effort, you really need a heart rate monitor. It’s nearly impossible to accurately measure your heart rate manually when it is above 150. And accuracy is important. There’s a big difference between a heart rate of 170 and 174 (or 160 and 164 if you are over 50). Once you reach your maximum heart rate you may feel a bit light headed and, of course, VERY short of breath. But your body catches up quite rapidly and in about 30-60 seconds you will start to feel much better. Most people feel tired but great once they’re done.
For the past couple of years, I’ve heavily promoted high intensity interval training as a key strategy for improving your health, boosting weight loss, promoting human growth hormone (HGH) production, and improving strength and stamina. I’ve been doing it myself since April 2010, after meeting fitness expert Phil Campbell (author of Ready Set Go), so I can also vouch for its effectiveness from personal experience.
Summary of my Interval Training Program
The interval program created by Phil Campbell also takes about 20 minutes, but here you’ll want to push your heart rate up to your anaerobic threshold during the exertion portion. The silver lining is that the actual sprinting totals a mere 4 minutes instead of 10! Here’s a summary of what a typical interval routine might look like (for a full demonstration, see the video below):
- Warm up for three minutes
- Exercise as hard and fast as you can for 30 seconds. You should be gasping for breath and feel like you couldn’t possibly go on another few seconds
- Recover for 90 seconds, still moving, but at slower pace and decreased resistance
- Repeat the high intensity exercise and recovery 7 more times, for a total of 8 repetitions
By the end of your 30 second period you will want to reach these markers:
- It will be relatively hard to breathe and talk because you are in oxygen debt
- You will start to sweat. Typically this occurs in the second or third repetition unless you have a thyroid issue and don’t sweat much normally.
- Your body temperature will rise
- Lactic acid increases and you will feel a muscle “burn”
While you may need to slowly work your way up to this point, ultimately you want to exercise vigorously enough to reach your anaerobic threshold as this is where the “magic” happens that will trigger your growth hormone (HGH) release. HGH, also known as “the fitness hormone,” accounts for many of the health benefits of interval training.
But be mindful of your current fitness level and don’t overdo it when you first start out. Also keep in mind that there’s no “magical” speed here. It’s entirely individual, based on your current level of fitness. Some may reach their anabolic threshold by walking at a quick pace, while others may need to perform a mad-dash to get the same effect.
The Many Health Benefits of High-Intensity Interval Training
Once you engage in these high-int ensity exercises two to three times a week, most people notice the following benefits:
The remarkable effectiveness of interval training makes logical sense when you consider that this type of exertion mimics how our ancestors lived. This is also how animals and young children behave naturally (long-duration exercise really isn’t “natural”). By exercising in short bursts, followed by periods of recovery, you recreate exactly what your body needs for optimum health, and that includes the production of growth hormones, the burning of excess body fat, and improved cardiovascular health and stamina.
More Supporting Evidence
In a 2008 study published in the Journal of Physiology, Canadian researchers compared the effects of steady versus interval cycling. Active but untrained young men and women were divided into two groups:
- The interval training group performed four to six repeats of 30-second all-out effort, with 4