The NY Times describes what it calls a 7 minute workout that uses only your body weight, chair, wall and the floor.
Interval training, though, requires intervals; the extremely intense activity must be intermingled with brief periods of recovery. In the program outlined by Mr. Jordan and his colleagues, this recovery is provided in part by a 10-second rest between exercises. But even more, he says, it’s accomplished by alternating an exercise that emphasizes the large muscles in the upper body with those in the lower body. During the intermezzo, the unexercised muscles have a moment to, metaphorically, catch their breath, which makes the order of the exercises important.
The exercises should be performed in rapid succession, allowing 30 seconds for each, while, throughout, the intensity hovers at about an 8 on a discomfort scale of 1 to 10, Mr. Jordan says. Those seven minutes should be, in a word, unpleasant. The upside is, after seven minutes, you’re done.