If you HIIT, listen up. Exercise science has found the sweet spot when it comes to determining your work-to-rest intervals—2:1. In other words, if you're sprinting for 4 minutes you should rest for 2 before your next sprint. This work-rest ratio allows enough time for recovery, according to the research published in the April issue of the Journal of Strength and Conditioning.
How did researchers figure this out? Sixteen extremely fit people ran as hard as they could for six 4-minute intervals on a treadmill and then rested for an assigned 1, 2, or 4 minutes between each sprint. “We concluded the 2:1 was the right dose because when the recovery was reduced to only 1 minute, the levels of intensity were blunted,” says study author Matt Laurent, PhD, CSCS, assistant professor of exercise science at Bowling Green University. “In addition, when we gave them 4 minutes of recovery, their levels of intensity were not any higher than with 2 minutes. Therefore, we concluded that 2 minutes was enough time to recovery optimally while minimizing the overall time of the session as well.”
So there you have it: resting for half your effort time produces results.