CrossFit Science: Tabata This!

 Time to Read: ~10 Minutes

From the Archives: This is an original (pre-2021) SFF blog post that has been reposted with updated information.

Take Home Points:

Introduction

The desire to spend as little time as possible exercising (or training) while still reaping significant health or fitness benefits is one reason why high intensity training (HIT) has become extremely popular over the past 20 years. Another reason for its popularity is due to the high visibility placed on this training modality by CrossFit. Instead of limiting this type of training to common modalities (bike, rower, etc.), CrossFit has applied it to a wide range of exercise movements (e.g., pull-ups, box jumps, power cleans, etc.). Since it's very hard, and at some point impossible, to work at high intensities for long periods of time, high intensity interval training (HIIT) is a much more manageable form of HIT training. Perhaps the most common HIIT modality (again, largely due to CrossFit's endorsement) is the Tabata interval. Classically, this interval is performed as 20 seconds of intense/maximal work followed by 10 seconds of rest. You then repeat this interval for any number of rounds, with 8 rounds being most common. 

Origins of the TABATA Interval

The Tabata interval is extremely popular, but where did this interval come from and why does CrossFit incorporate it as a core training modality? Are there scientific studies out there supporting the effectiveness of Tabata-based training? It turns out there are. The Tabata interval is named after its creator, Izumi Tabata, who is now a professor at Ritsumeikan University. Although Dr. Tabata has published many papers to date, there are three key studies that form the basis of the Tabata interval and I will discuss those below.
 

The Original TABATA Studies

The Tabata workouts found in CrossFit are a bit different than what were actually executed by participants in Tabata's studies, so let's take a look at the original three studies in more detail.

Tabata et al., 1990 – This is the seminal work where Tabata, as lead author, lays the foundation for his work in training intensity and muscle power. 6 male physical education students were enrolled in the study and required to exercise 5 days a week for 7 weeks. The training was interval training with a cycle ergometer (an ergometer is an instrument that measures mechanical work accomplished, in this case by pedaling a bicycle) such that power output for each subject was 90% of their VO2max (maximum oxygen uptake). Subjects were asked to maintain pedaling at this intensity level. When their intensity dropped, they were given exactly 5 minutes of rest, after which exercising resumed. This cycle was repeated until the subject reached the prescribed quantity of training time for that week. The nature of this endurance training was one of low resistance, moderate speed, muscle training. The results indicated that the increase in isokinetic (at a given speed) muscle power after training was greater if the starting isokinetic muscle power was lower. In other words, subjects with high initial muscle power were less capable of increasing muscle power by means of this aerobic training. The implications of this study were that if one wants to maximize their power output (get more work done in a shorter amount of time), longer, aerobic bouts may not be the most effective approach for muscle training. If so, then what is most effective?

Tabata et al., 1996 – In this next study Tabata again enlists subjects and monitors their power output on cycle ergometers. However, now he compared 6 weeks of moderate endurance training (exertion at only 70% VO2max) to a high-intensity, intermittent training group which performed 7-8 sets of 20 seconds of exercise at a whopping 170% of VO2max followed by 10 seconds of rest. The results showed that the high-intensity group increased their VO2max by 7 ml/kg/min, indicating an increase in aerobic capacity. In addition, maximal accumulated oxygen deficit fell by 28%, which said another way, means a 28% increase in anaerobic capacity for these high-intensity subjects. Anaerobic capacity is a measure of how your body uses energy without oxygen and is thus an accumulation of energy obtainable from existing ATP (adenosine triphosphate) molecules as well as the lactic acid and phospho-creatine pathways. So, what about the moderate intensity subjects? They actually had no gain in anaerobic capacity and, although they did have gains in aerobic capacity, the gains were small, comparable to or less than those of the high-intensity subjects (I can’t say for sure if the gains were the same or less because the actual data values were not presented – only a graph of the data). Thus, in this simple, yet groundbreaking study, Izumi Tabata demonstrated that high intensity interval training gives both an aerobic and anaerobic benefit.

Tabata et al., 1997 – In this follow-up study Tabata compared the previous high-intensity 20/10 interval (20 seconds work/10 seconds rest) to a new interval comprised of 30 seconds of work and 120 seconds of rest (30/120). The goal here was to see just how effective the initial 20/10 interval really is. The results demonstrated that the 20/10 subjects achieved an oxygen deficit that was statistically identical to their maximal oxygen deficit (i.e., their anaerobic capacity). Thus, the 20/10 exercise regimen brought subjects to maximum oxygen debt (quite a workout!). In contrast, the 30/120 subjects did not reach an oxygen debt level near their measured maximum (they could have been working harder or resting less). Further, peak oxygen uptake was statistically identical to VO2max for the 20/10 groups but lower than VO2max for the 30/120 group, indicating that the 30/120 group was not working at maximum aerobic capacity either. Taken together this study indicated that the 20/10 interval worked both the anaerobic and aerobic energy releasing systems better than the 30/120 (and possibly even worked those systems to their maximum). Thus, for the best training of energy exchange and oxygen utilization, the 20/10 interval reigned supreme and the Tabata interval was born.

Later TABATA Studies

From this point on Tabata’s work shifted and expanded. Some interesting studies have come out of his lab including two using rats subjected to Tabata swimming intervals. In Terada et al., 2001, the authors showed that high-intensity Tabata training results in maximal levels of glucose uptake into skeletal muscle. This indicated that, contrary to popular belief, maximal glucose uptake was likely not achievable only through low-intensity exercise. In Terada et al., 2004, the authors conducted a similar study in swimming rats and showed that high-intensity Tabata training increased citrate synthase (CS) and 3-beta hydroxacyl CoA dehydrogenase (HAD) activity (both markers of increased fat breakdown) just as much as low-intensity training.

Recent Investigations

Since the early 2000s, Tabata has continued to publish research. He published a paper indicating that both exhaustive and non-exhaustive interval exercise can enhance production of brain derived neurotropic factor (BDNF), a molecule important in brain development and implicated in the prevention of cognitive decline. 

In Tabata's most recent article (Xu et al., 2024), the authors examined college students (n=30) using a mixed-exercise training program. Participants performed 7 rounds of 20 sec work and 10 sec of rest, but each round alternated the work from a bike ergometer to a treadmill. They also set their intensity of work at a level that would exhaust them only by rounds 6 or 7. This data was compared to data from 16 of these same students who only did one or the other (bike or run) for their 7 rounds (n=8 each), again at an intensity to reach exhaustion by round 6 or 7. The authors found that in the bike-run mixed program, the VO2max during the last round of bicycle exercise was much higher than in the program of only bicycle exercise. There is a lot more data in this study (including a mixed program with a lower body and upper body movement pattern), but so as not to make this article too long, I will just summarize by saying this paper indicated that using multiple exercises over several rounds at intensity levels somewhat below maximum, can result in VO2max levels higher than if training a single exercise modality alone. As a practical example, a higher VO2max might be achieved using a workout like this:

4 Rounds
20 Sec: Max Kettlebell Swings
10 Sec: Rest
20 Sec: Max Burpees
10 Sec: Rest

as compared to this:

8 Rounds:
20 Sec: Max Kettlebell Swings
10 Sec: Rest

Again, the above assumes you keep your intensity levels set so that exhaustion only sets in by round 6 or later. So, why do multiple exercises appear more effective for training maximal oxygen consumption in this manner? We aren't entirely sure, but it may be a result of greater excess post-exercise oxygen consumption (EPOC) due to the multiple exercises and greater muscle mass being used.

Final Thoughts

The body of work that Tabata has put forth in both humans and animals for over two decades has made a convincing case for choosing high-intensity Tabata interval training as one of the (if not the) optimal means to become a more powerful endurance athlete or simply a fitter individual. For sure, the success of CrossFit wouldn’t be nearly as great without Izumi Tabata’s work.

 

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