Well, let’s take a closer look at how yoga can physically help us. The hamstrings are a muscle group in the back of the legs that is tight for a lot of us. After a long day sitting at a desk or riding in a car, your hamstrings may be feeling tight. They have been both shortened or “pulled in” (because of your legs bent at a 90° angle) and weak (because of sitting) all day.
Day after day, your muscle fibers become used to this position. Over time, your general flexibility level decreases unless you make an effort to counteract this process. When you hold your muscles in a stretched position for more than 30 seconds, the muscle fibers begin to relax and lengthen. This is good, because tight muscles can pull on joints and cause pain, become injured easier, and give you bad posture. Yoga also strengthens muscles, which helps protect against weakness (a contributor to tightness).