A 4-second workout may be all you need
bicycle with a heavy flywheel and no resistance that has been used at the physiology lab to test the leg and lung power of professional athletes. In those tests, athletes generated a tsunami of power and achieved all-out exertion within about two seconds of pedaling.
The scientists reasoned that if athletes needed two seconds of pedaling to reach maximum exertion, the rest of us probably would require, say, twice as much. So, they asked their volunteers to clamber on the bikes and sprint as hard as possible for four seconds, then stop pedaling, rest for 45 seconds and sprint again, repeating that sequence five times.
The volunteers completed these brief interval sessions once every hour for eight hours, for a total of 160 seconds of actual exercise that day. Otherwise they sat, then returned the next day to down the unctuous breakfast shake.
Their metabolic responses differed this time, though, the researchers found. The volunteers arrived at the lab with lower blood levels of triglycerides to start with and burned more fat during the next six hours, so their triglycerides remained about 30% lower throughout the six hours of monitoring than on the morning after nonstop sitting.
The results suggest that frequent, intense and extremely abbreviated exercise “can undo” some effects of being sedentary, said Ed Coyle, a professor of kinesiology and health education at the University of Texas, who conducted the study with his graduate student Anthony Wolfe and others. (Coyle has equity in the company that manufactures the bicycles at his lab but said his stake did not influence the design of the study or reporting of results.)
This was a small, shortterm study, and its results are limited. They do not tell us if the desirable metabolic outcomes after sprinting linger past the next day or whether four-second intervals represent the right dose of exercise or merely the teensiest. The study also relied on an uncommon type of bicycle. Standard stationary bicycles or spin-class versions would likely require us to sprint for more than four seconds to reach an all-out exertion level, Coyle said. So would racing up and down stairs or jogging in place.
But the underlying theory of the study remains achievable, he adds. When you find yourself sitting for most of the day, try to rise frequently and move, preferably intensely, as often as possible and for as many seconds as you can manage.