If you are searching for the best high intensity interval training exercises, chances are that you've been indoctrinated to look for fashionable fitness programs instead of solid results.
This “novel cardio revolution” can be seen in virtually every commercial gym because their endeavor is to keep their clientele rather than giving quality guidance (another pathetic result of our consumerist society).
Contrary to popular belief, high intensity interval training aka HIIT is nothing new, and most professional coaches have been using successfully this technique for at least six decades as a performance enhancer for their athletes – within the context of their specific sport (e.g. cycling, running, swimming, etc).
Interval training allows athletes to perform a certain movement pattern at higher speeds, and also keep constant or increase volume by partitioning their training in more manageable segments.
Logically, working consistently at high intensities would hopefully cause an adaptation of some sort, and the athlete would be able to keep this faster pace for a longer time.
As a side note, it was believed that the better performance was the result of an increased capacity of the body to deal with lactic acid, but such explanation turned out to be simplistic.
Research clearly shows that lactate not only does not cause metabolic acidosis, but even seems to delay muscular fatigue.
Therefore, the old belief that the primary adaptation to interval training is to shift the lactate threshold to the right, allowing higher intensities for longer periods, proves to be wrong.
“Increased lactate production coincides with cellular acidosis and remains a good indirect marker for cell metabolic conditions that induce metabolic acidosis. If muscle did not produce lactate, acidosis and muscle fatigue would occur more quickly and exercise performance would be severely impaired.” (Robergs, et al. 2004)
Nevertheless, using an accurate terminology to describe the anaerobic adaptation is less important than its practical appliance, which, by the way, seems to be rather limited.
The effects of interval training on physiology and performance are fairly rapid (about 3-6 weeks, depending on the training status), but rapid plateau effects are seen as well.
For this reason, only a small amount of high intensity interval training is needed to enhance endurance, and maintain an optimum performance level.
Performance, on the other hand, is determined by the percentage of VO2 max that can be sustained for extended periods. The higher the percentage, the higher the aerobic endurance.
(As a side note, VO2 max, represents the maximum amount of oxygen that can be used by the body within a unit of time.)
Now, VO2 max is determined by two factors: the heart ability to pump blood and transport the oxygen, and muscular capacity to absorb it.
Although there is no clear cut differentiation between aerobic vs anaerobic pathways, high intensity exercise such as interval training induces primarily cardiovascular adaptations, whereas steady state exercise has more a peripheral effect, improving the mitochondrial function.
It's interesting to note that untrained individuals are limited aerobically more so by inadequate blood supply and limitations in the stroke volume, rather than by mitochondrial function.
Probably for this reason, many studies found that interval training improves notably the endurance. However, the results tend to be different when the subjects are experienced athletes that are already doing some form of vigorous exercise.
Besides a potential central cardiovascular adaptation, another reason for using high intensity interval training is to improve the neuromuscular proficiency for a specific movement pattern.
In other words, swimmers, for example, will use intervals to teach their nervous system to swim faster, and hence more efficiently, which also has a positive effect on their endurance.
So my point is that the best interval exercise is specifically related to your sport. A runner will do sprint intervals, a cyclist will alternate faster/slower cycling and so on.
Of course, this is not relevant for Average Joe who just wants to get rid of his belly fat. But even in this case, doing an interval workout has no benefit unless you are already lean, and trying to get very defined.
It should be noted that you can get the same hormonal response if you make a slight adjustment to your regular weight training, which is a more productive way to deal with the stubborn fat.
Most folks enrolled in those stupid Tae-Bo classes don't really care about acquiring self defense skills. So then what's the point?
My advice is that if you want to do martial arts, then really train for martial arts. If you want to learn how to dance, take real dance classes.
Mixing weight loss with a specific skill won't get you anywhere because you will get mediocre results at both of them.
And if your goal is to improve body composition, keep in mind that traditional high intensity interval training can do more harm than good.
Remember, under a calorie deficit you should always train less rather than looking for more exercises.