I’m a personal trainer who spends a lot of time helping clients stretch out tight hamstrings (the muscles on the back of thighs). It’s a common problem for runners and hikers—but it’s an issue for people who spend a lot of time sitting, too.
Having tight hamstrings can cause all kinds of problems. If they’re really tight, these muscles can pull the back of the pelvis down, leading to a posterior pelvic tilt. This imbalance puts stress on your lower back and causes strain throughout lower-body joints and muscles, too.