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A few years ago, researchers at the National Institute of Health and Nutrition in Japan put rats through a series of swim tests with surprising results. They had one group of rodents paddle in a small pool for six hours, this long workout broken into two sessions of three hours each. A second group of rats were made to stroke furiously through short, intense bouts of swimming, while carrying ballast to increase their workload. After 20 seconds, the weighted rats were scooped out of the water and allowed to rest for 10 seconds, before being placed back in the pool for another 20 seconds of exertion. The scientists had the rats repeat these brief, strenuous swims 14 times, for a total of about four-and-a-half minutes of swimming. Afterward, the researchers tested each rat’s muscle fibers and found that, as expected, the rats that had gone for the six-hour swim showed preliminary molecular changes that would increase endurance. But the second rodent group, which exercised for less than five minutes also showed the same molecular changes.This research dovetails with an article on Clarence Bass's site titled High Intensity Aerobics Amazingly Effective...
Izumi Tabata and his colleagues at the National Institute of Fitness and Sports in Tokyo, Japan, compared the effects of moderate-intensity endurance and high-intensity intermittent training on V02max and anaerobic capacity. (Medicine and Science in Sports and Exercise (1996) 28, 1327-1330). Interestingly, the high-intensity protocol had been used by major members of the Japanese Speed Skating team for several years; it's a real-world training plan. As you will see, however, the protocol is unique among aerobic training programs for its intensity and brevity.
Here are the details (stay with me on this): In the moderate-intensity group, seven active young male physical education majors exercised on stationary bicycles 5 days per week for 6 weeks at 70% of V02max, 60 minutes each session. V02max was measured before and after the training and every week during the 6 week period. As each subject's V02max improved, exercise intensity was increased to keep them pedaling at 70% of their actual V02max. Maximal accumulated oxygen deficit was also measured, before, at 4 weeks and after the training.
A second group followed a high-intensity interval program. Seven students, also young and physically active, exercised five days per week using a training program similar to the Japanese speed skaters. After a 10-minute warm-up, the subjects did seven to eight sets of 20 seconds at 170% of V02max, with a 10 second rest between each bout. Pedaling speed was 90-rpm and sets were terminated when rpms dropped below 85. When subjects could complete more than 9 sets, exercise intensity was increased by 11 watts. The training protocol was altered one day per week. On that day, the students exercised for 30 minutes at 70% of V02max before doing 4 sets of 20 second intervals at 170% of V02max. This latter session was not continued to exhaustion. Again, V02max and anaerobic capacity was determined before, during and after the training.
In some respects the results were no surprise, but in others they may be ground breaking. The moderate-intensity endurance training program produced a significant increase in V02max (about 10%), but had no effect on anaerobic capacity. The high-intensity intermittent protocol improved V02max by about 14%; anaerobic capacity increased by a whopping 28%.
Dr. Tabata and his colleagues believe this is the first study to demonstrate an increase in both aerobic and anaerobic power. What's more, in an e-mail response to Dick Winett, Dr. Tabata said, "The fact is that the rate of increase in V02max [14% for the high-intensity protocol--in only 6 weeks] is one of the highest ever reported in exercise science." (Note, the students participating in this study were members of varsity table tennis, baseball, basketball, soccer, and swimming teams and already had relatively high aerobic capacities.)
The results, of course, confirm the well-known fact that the results of training are specific. The intensity in the first protocol (70% of V02max) did not stress anaerobic components (lactate production and oxygen debt) and, therefore, it was predictable that anaerobic capacity would be unchanged. On the other hand, the subjects in the high-intensity group exercised to exhaustion, and peak blood lactate levels indicated that anaerobic metabolism was being taxed to the max. So, it was probably also no big surprise that anaerobic capacity increased quite significantly.
What probably was a surprise, however, is that a 4 minute training program of very-hard 20 second repeats, in the words of the researchers, "may be optimal with respect to improving both the aerobic and the anaerobic energy release systems." That's something to write home about!
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