Wednesday, September 4, 2013

Tabata Workouts: Do They Work & How Energy-Demanding Are They? 14.5 Kcal/Min Sounds Nice, But You Must Earn It!

Tabata training is intense: So if you don't have the guts to do it on your own, find someone to suffer next to you. Trust me that'll keep you going, if you'd have long surrendered if you had trained alone. Some gyms even offer special courses.
Most of you will probably be familiar with the ultra-short + ultra-intense HIIT prescription that's known as the Tabata protocol. Not really? Well, here is the elevator pitch, then:  "Tabata training," was first described by the Japanese scientist Izumi Tabata in 1996. Tabata and his colleagues (Tabata.1996) conducted a study that compared moderate-intensity continuous training at 70% of maximal oxygen consumption (VO2max) for 60 minutes, with HIIT conducted at 170% of VO2max. The HIIT training consisted of eight, 20-second all-out exercise bouts followed by 10 seconds of rest for a total of 4 minutes of exercise. Based on what you have read about the contemporary HIIT research here at the SuppVersity, you will be aware that Tabata's protocol is more intense, but also much shorter than the currently favored HIIT regimen with their ~1-4min (sometime even 8min!) intervals at 80-100% intensity.

Now, the "original" study found that HIIT improved aerobic capacity to a similar degree as moderate intensity continuous training (aka LISS). Nevertheless, it did resulted in an impressive +28% increase in anaerobic capacity.

Tabata 2.0? Is it time for a modification?

Meanwhile Tabata training has evolved to include a variety of modes and exercises. What has always remained an essential characteristic of this type of HIIT training, though are the classic 20-10 patterns (i.e., 20 seconds of all-out effort followed by 10 seconds of rest).

According to Talisa Emberts, John Porcari , Scott Doberstein, Jeff Steffen and Carl Foster, the general physiological effects of this type of training are well documented. What would be lacking, however, is data on the the relative exercise intensity and energy expenditure of Tabata training (Emberts. 2013). Therefore, the purpose of the study at hand, which comes right from the labs of the Department of Exercise and Sport Science at the University of Wisconsin, was to determine the u exercise intensity and energy expenditure of a Tabata workout.

What did the scientists do?

In order to measure the energy expenditure, the researchers recruited 16 trained volunteers (8♂: 35.3 ± 8.1 years, 1.81 ± 0.06 m, 93.7 ± 8.70 kg, 53.2 ± 0.6 ml·kg·min -1; 8♀: 28.4 ± 9.3 years, 1.71 0.09 m, 71.9 ± 12.0 kg, 42.9 ± 11.3 ml·kg·min -1). After the usual initial fitness tests, each subject completed two identical workouts.
Table 1: .Exercises included in the 20-minute Tabata workout; each exercise was repeated twice at a ratio of 20 sec exercise/10 sec rest
  • workouts consisted of four, 4-minute "segments".
  • segments consisted of performing the exercises listed in table 1 twice in succession.  
  • subjects completed as many repetitions of each exercise as possible in 20 seconds followed by 10 seconds of rest.
  • there was 1 minute of rest between each segment.  
As Emberts et al. point out, they "chose to do the four segments of Tabata in succession, since one of the criticisms of Tabata training has been that individuals cannot burn a sufficient number of calories in 4 minutes to favourably impact energy balance" (Emberts. 2013)
Figure 1: Energy expenditure per minute and total energy expenditure in 20 vs. 4 min TABATA studies (Emberts. 2013; Olsen. 2013)
A brief glimpse at the data in figure 1 goes to show you that the relative energy expenditure per minute was as impressive as in previous studies:
"Caloric expenditure averaged 14.5 ± 2.7 kcal·min -1 , which is very similar to the value found by Olsen (2013), who reported a slightly lower value of 13.4 kcal·min -1 . This was probably due to the fact that her study included 13 women and only 3 men. Total energy expenditure ranged from 240 to 360 kcals for the 20-minute workout, which is significantly higher than the estimated 54 kcals expended during the 4 minutes of exercise reported by Olson." (Emberts. 2013)
What was also impressive, though, was the rate of perceived exertion (RPE), which averaged 15.4  ±  1.3 for the two workouts and was that rated as "hard" by these already trained subjects. I mean, ask yourself what an untrained individual would have been telling you after high knee runs, plank punches, jumping jacks, side skaters, rope jumping, in/out boats, line jumps, push-ups, burpees, russian twists, squats, lunges, mt. climbers, push-ups, split squats and box jumps... right probably nothing: The average sedentary inhabitant of the Western Obesity Belt would simply have collapsed after two exercises ;-)

If you are a pro (and I mean "are" and not think of yourself as one) looking for an intense workout that will help you cut body fat and gain muscle at the same time, look no further. The cross-fit protocol Smith et al. used in a study I wrote about earlier this year has what you are looking for - unfortunately it has a similarly insane intensity: "From 16% to 8% Body Fat in 10 Weeks: Crossfit Workout Gets The Leanest Shredded - But Only the Fittest Survive" (learn more).
240-360kcal/s in 20 min - is that worth it? It stands out of question that trained individuals who are willing and able to give their muscles and more importantly their central nervous system the recovery time they will need after these workouts will greatly benefit from the intensity of a Tabata routine like this. This is after all, the "uncomfort zone" in which someone with years of training experience under his / her belt can still enforce adaptation.

Contrary to the trained athlete, for whom the total amount of energy expenditure is secondary to proving new "growth" (the word refers to general growth as in increases not just in muscle power or size, but also overall conditioning) stimuli, the rookie and even many intermediate trainees are however going to be overwhelmed by the physical (some also by the mental) demands of this workout. For him / or her, a combination of strength training and LISS (rookie, or someone trying to cut weight) or strength training and "regular" HIIT (advanced trainee) may be thus in fact be  better choice. Not necessarily because it would burn more calories, but rather in view of the fact that it is not as overtraining prone as a 20min session of Tabata training.

References:
  • Olson M. Tabata  interval  exercise:   Energy  expenditure and post-exercise responses. Medicine & Science in Sports & Exercise 45. 2013; S420.
  • Emberts T, Porcari J, Doberstein S, Steffen J, Foster C. Exercise Intensity and Energy Expenditure of a Tabata Workout. Journal of Sports Science and Medicine. 2013; 12:612-613