The answer is your biceps femoris, also known as the hamstrings.
But wait, you say, aren’t those muscles on the backs of my legs? Why, yes they are. The attachments of these muscles are to the legs, but also to the bottom of your pelvis. When they are tight, they tug down on the pelvis. Some of your big spinal muscles attach to the top of your pelvis, which starts the tug-of-war that makes backaches set in.
The causes of low back pain run the spectrum from disc bulges and ruptures, bone spurs, arthritis, joint strains/sprains, muscle strains/sprains and, of course, the common subluxation. Subluxation happens when one or more of the joints of the spine becomes misaligned and stuck, causing pressure at that joint and in the nervous system, because the spine protects the spinal cord.
Tight hamstrings can put lots of strain on the muscles of the low back, but they can also contribute to low spine/pelvic subluxation by inhibiting a healthy motion of the pelvis and low back. The biggest culprit of tight hamstrings is being sedentary. Sitting at a desk, in the car, on the couch, can all cause the hamstrings to tighten. Really, most of what ails your muscles and bones comes from sitting on your butt. I have a three-step solution for a life free from backaches.
Step 1: Stand up, then touch your toes. Feel the stretch. Do this regularly to loosen up your legs and lower back.
Step 2: Start a regular walking routine. Keep your legs and core engaged in exercise and you will have more energy and less pain.
Step 3: Get adjusted by your chiropractor. Keep your spine and nervous system functioning for optimal health.