For years, I've been plagued by tight hamstrings. No matter how often I stretch the backs of my thighs or how often I attend yoga, these bad boys are always sore the day after a tough workout and unforgiving in my first Standing Forward Fold of class.
Source: POPSUGAR Studios
Founder of the Pilates hybrid workout Burn SF , Lisa Corsello, reassures me that tight hamstrings are one of the most common ailments her clients complain about at her studios. The cause of the issue is often problematic self-diagnosis, since quite often "where we experience tightness or pain isn't necessarily where it originates." Commonly, what we refer to as tightness across the back of the legs has very little to do with the backs of the legs. This pain can be alleviated by stretches that target not only the hamstrings, "but the psoas, hips, lower back, glutes, and calves" as well.
Certified personal trainer and POPSUGAR Fitness host Anna Renderer  also holds a master's degree in clinical exercise physiology. Anna explains that when the hamstrings aren't experiencing a full range of motion, they become shortened — this is especially true if you're sitting most of the time! Without this full range of motion in the hamstrings, there's a "reciprocal effect of tight hip flexors" which affect your calves and hamstrings. When your hip flexors are tight, it causes a pelvic tilt that causes tightness in the lower back, and a tight lower back often results in tight hamstrings.
But it goes beyond the hip flexors. Pilates extraordinaire Brooke Siler — celebrity trainer and author of The Women's Health Big Book of Pilates  — says it's essential to make sure the "Pilates powerhouse muscles (glutes, inner thighs, but mainly abs)" are doing "the lion's share of the load." This way, the hamstrings don't have to support the pelvis on their own. Poor pelvic position from weak abs puts unnecessary strain on the hamstrings, and many women (like me) experience a feeling of "tight" hamstrings that refuse to loosen up.
Brooke says the moral of the story is to "strengthen your Pilates powerhouse (abs, glutes, and inner thighs) and stretch your hip flexors  before going after your poor victimized hamstrings!"