What are Tabata Intervals?

Tabata Intervals

written by Brian Jones (MILO DEC 2006, Vol 14 No. 3)

If you are like most people, you don’t have the luxury of unlimited training time.  You have to juggle your workouts with work, school, and family responsibilities just isn’t an option.  Yet this may be exactly what you are doing when you log in your 30 to 60 minutes of moderate-intensity, “fat-burning” cardio on the treadmill three times a week.

Allow me to introduce you to Tabata intervals. Researchers Izumi Tabata and colleagues at the National Institute of Fitness and Sports in Japan found that a high-intensity interval training protocol requiring under 10 minutes per session can be more effective for boosting endurance than the typical half-hour cardio workouts. In addition, other research has demonstrated high-intensity interval training to be superior for cutting body fat. Intervals definitely give you more bang for the buck. Let’s take a closer look at why this is so and how to put the Tabata protocol to work for you.

It’s all about the intensity

The key to Tabata intervals is intensity. For endurance training, the intensity is defined as a percentage of your maximal aerobic capacity, or VO2 max.  An intensity of 100% means that you working at the absolute limits-of your ability to produce energy using oxidative metabolism. Most traditional workouts use an intensity of 50-70% of VO2 max for extended periods. Tabata intervals, on the other hand, involve intensities of greater than 100%. This means that much of the energy produced comes from anaerobic energy sources.

Tabata’s research subjects performed resisted cycling at 70% VO2 max for 20 seconds followed by 10 seconds of rest. The sequence was repeated 7 to 8 times over the course of the workout for a total work out time of around 4 minutes. They did this workout five days a week for six weeks. This interval training group was compared to another group that performed six weeks of aerobic activity for 30 minutes at 70% VO2 max five days per week.

Aerobic capacity increased significantly in both groups. However, the high-intensity interval group also increased their capacity by 28%, while the moderate-intensity group showed no improvement.  Thus, high-intensity workouts lasting only four minutes  were as effective as the half-hour moderate-intensity-workouts for boosting VO2 max and superior for increasing anaerobic endurance. The critical factor appears to be intensity rather than duration.

Interval training and fiber recruitment

The reasons for the effectiveness of the Tabata protocol could be related to fiber recruitment. Low training intensities recruit primarily slow twitch type I motor units.  As the active units fatigue, they are switched off to rest and other type I units take their places.  The fast twitch type II motor units are mostly inactive. Therefore with low-intensity training, only a small portion of the muscles receives  the training stress.  During high-intensity exercise, large amounts of force must be produced rapidly. To meet this demand, slow and fast twitch fibers are all recruited almost maximally.  The result is that more fibers are trained simultaneously and the workouts are much more efficient.

Interval training and fat loss

High-intensity work may also be superior to low- or moderate-intensity training for fat loss.  The reason for this is in the profound effect of high-intensity work on post-exercise metabolism.  Following any workout, your metabolic rate will be elevated.  The degree and length of this post-exercise metabolic boost depends on the exercise intensity rather than its duration . Hard workouts then, even short ones, may end up burning more total calories throughout the day than lighter ones of longer duration. High-intensity work is more stressful and releases greater amounts of epinephrine and norepinephrine. These fight or flight hormones take time to be metabolized. While they remain in circulation, they result in many calorie-burning effects, such as increased heart rate and elevated body temperature.

Tabata interval programming

Although the original Tabata program measured VO2 max and set the work-load based on individual values, this isn’t necessary outside the laboratory setting. The idea is to push yourself as hard as possible during the work intervals, and then back off or stop completely during the rest intervals. If you approach your workouts with this in mind, the intensity will take care of itself. Tabata and his colleagues used resisted cycling in the research study, but many different exercises are possible. When selecting your exercises keep the following guidelines in mind:

1. The greater muscle mass involved, the higher the intensity. Choose exercises that activate the large muscles large muscles legs for the greatest conditioning benefit. Exercises such as curls or bench presses that use only the upper body will not have the same effect.

2.The transition time from work to rest and back must be negligible. Tabata intervals are measured in seconds, so any time wasted getting onto or gathering equipment must be avoided. Stay where you are and keep all equipment at hand during each test.

3. There must be an easy way to tell when the intervals start and stop.  Possible methods include watching a clock that has a second hand, using an interval timer, or having a training partner time you. Whatever the exercises, you must be able to see the clock or hear the timer.

Tabata’s subjects made substantial progress with only 4 minutes per work-out. However, for maximum benefit, you should use this as a starting point for your training. Follow the two week rule for increasing your volume. For every two weeks of consistent training, add some more training time.