With the speed of technology and the crazy, intense pace of our lives, our bodies can't help but live in a chronic state of stress. (mindbodygreen.com)
You would work at a very intense pace, usually for a span of three to four minutes, then spend thirty to sixty seconds resting before repeating the circuit. (topexpertchoices.com)
The rest period can be complete rest or a less intense pace. (onnit.com)