I came across this article while searching for workout tips, with the main claim being:
This training method is so simple, yet so incredibly difficult, that athletes tend to try it once, acknowledge its greatness, and then vow to never speak its name again. What is it? It's simple: take one exercise and perform it in the following manner:
1) For twenty seconds, do as many repetitions as possible.
2) Rest for ten seconds
3) Repeat seven more times!
That's it! You're done in four minutes! Oh, and that thing you're trying to brush off your face? That would be the floor.
When I looked for the original claims, I found this paper by Tabata et al, with the abstract claiming:
...this study showed that moderate-intensity aerobic training that improves the maximal aerobic power does not change anaerobic capacity and that adequate high-intensity intermittent training may improve both anaerobic and aerobic energy supplying systems significantly, probably through imposing intensive stimuli on both systems.
However, the number of subjects for the study were 7. A later study published in 1997 by the same group showed the 20s/10s protocol was effective, but now with N=9:
IE1 consisted of one set of 6-7 bouts of 20-s exercise at an intensity of approximately 170% of the subject's maximal oxygen uptake (˙VO2max) with a 10-s rest between each bout. ... this study showed that intermittent exercise defined by the IE1 protocol may tax both the anaerobic and aerobic energy releasing systems almost maximally.
Is this a generally effective exercising technique? Have there been studies where N is at least greater than 10 showing it?