Your hamstrings are the large muscles in the back of your legs that run from your glutes to your knees. And they are the source of two common fitness complaints: tightness, or lack of flexibility; and hypermobility, or the inability to hold tension. Both are symptoms of poor hamstring mobility, the balance between flexibility and stability.
Prolonged sitting is a major lifestyle factor that causes tightness, says Minnesota-based physical therapist Erin Babineau, DPT. Running, skiing, and other activities that call for repeatedly contracting the hamstrings can contribute to the problem as well.
Weak glutes, which put pressure on the hamstrings to power lower-body movement, can also lead to tightness, adds Los Angeles–based trainer and sports physical therapist Brian Schwabe, DPT, CSCS.
At the other end of the spectrum is hypermobility. People with naturally flexible joints and muscles don’t typically have trouble achieving full range of motion, but they often lack control in that full range, Babineau explains. If hypermobility isn’t supported by adequate strength to stabilize joints, it can potentially lead to pain and injury.
Schwabe notes that hypermobile people will sometimes complain of hamstring tightness, but their issue isn’t a lack of flexibility; it’s a lack of strength. “They’re tightening up because their body is searching for stability,” Schwabe says. Once you start strengthening your hamstrings, the tightness will likely disappear.
Both hypermobility and hamstring tightness can be addressed with exercises that strengthen your hamstrings and glutes in an extended-leg position. Babineau recommends performing the following routine two to four times per week, depending on your regular exercise routine.