For a new study, some people foam rolled their lower bodies three times a week for six weeks while others did not. By the end, those who foam rolled were able to reach 1.9 centimeters farther in a sit-and-reach test, a sign of improved hamstring flexibility.
Foam rolling changes the elastic properties in your muscle tissues, making them more limber, says lead study author John Porcari, Ph.D., professor of exercise and sports science at the University of Wisconsin-La Crosse.
Your hamstrings respond really well to the treatment because they're flat and relatively insensitive to stimulation, which means you can roll them more deeply. Building flexibility in these muscles is important for efficient strides and lifts (think: squats, deadlifts, and more).
The bottom line:
To get the benefits, you’ll need to loosen the hamstrings and the surrounding muscles, Porcari says. He suggests foam rolling your low back, glutes, quads, hamstrings, calves, and IT bands for 20 seconds each before any type of workout. Complete 3 rounds and do it at least 3 times per week.