Erm, well, hamstrings. I am not so much a fan of the eating kind of ham. However, the more I looked into glute stuff, the more I realized that when it comes to hip extension, the gluteus maximus usually works in tandem with the hamstrings. So while I’m not quite done talking about the gluteus maximus yet, I am putting that on hold to talk about these a bit:
[And the semimembranosus, the final main muscle in the hamstring group. This pic makes it a little difficult to tell, but the semimembranosus appears smaller here because it is deeper than the other two muscles, not because it's actually smaller.]
So. The hamstrings are a group of muscles that really do — at least as well as muscles can — look like strings. The relevant ones all have their origin on the ischial tuberosities (the sitting bones, part of the pelvis) and and up attaching to different portions of the shin bones. And they all work both to extend the hips as well as to flex the knees.
Tight hamstrings can happen for a number of reasons — spending a lot of time sitting with bent knees (such as at desk or other chairs), repetitive motions like running, even because they’re trying to protect the lower back from strain. Similarly, strong hamstrings are good for knee and hip health, particularly when it comes to balancing the (often bulkier) quadriceps. Because of that, I’ll spend the next few hip series posts looking at yoga postures that do both — though maybe not both at once.