Muscles Involved in Lower Back Pain-Part 2
Last week I discussed two important muscles involved in lower back pain, namely the Erector Spinae group and the Quadratus Lumborum. Click here to read last week’s post, as the information will help you better understand this one. Today’s post will be about related muscles that can lead to lower back pain that are not necessarily considered “lumbar muscles,” namely the Psoas and the Hamstrings.
These two muscle groups are the indirect cause of a lot of lower back pain due to sitting. This will become clearer as we discuss the functions and locations of each of these muscles groups.
The Psoas
The Psoas (pronounced SO-az) is a pair of muscles that flex the hip, meaning they bring the thigh toward the torso. They attach to the sides of the last thoracic vertebra (T12), and first 4 lumbar vertebrae (L1-L4), and run down to the lesser trochanter of the femur (inner edge of the top of the thigh bone). This muscle runs from the back of the body to the front, crossing through the abdominal cavity. It contracts to flex the hip (move the thigh forward), and it stretches when the hip is extended (thigh moving backward).
When we sit for long periods of time, at a desk or driving, the hip stays in a flexed position. In last week’s post I discussed muscles that can be overly stretched with sitting. This week, the problem is over contraction. Many people have trouble standing up after long periods of sitting and here is one reason why: when we stand up, we are lengthening this muscle group that has been overly contracted. If the muscle is tight, it will pull at the attachments, which are the weaker parts of the muscle. The legs are in a fixed position when we stand on them, so as the torso moves away from the thighs, and we feel the pull in in the lower back.
Hamstrings
The Hamstrings are a trio of muscles that run from the base of the pelvis at the sit bones (Ischial tuberosities) down the back of the thighs to attach to the posterior aspect of the tibia (shin bone). They attach to both the medial and lateral aspects of the tibia (on both sides) and fibula (bone to the lateral side of the tibia). As a group, their primary action is knee flexion (bending the knee), with a secondary action of hip extension (moving the thigh backward). The primary action, knee flexion, is what is relevant in this discussion.
Like with the Psoas, when we are sitting for long periods, our knees are bent (flexed), so the hamstrings are in a constant state of contraction. When we stand up and “force” the muscle group to lengthen, it will pull at the attachments. Because the legs are in a fixed place when we are standing, it is the pelvis that moves when we straighten the legs, therefore we feel the pull at the sit bones. When the sit bones are unable to move fully away from the tibia, we compensate by rounding the lower back (lumbar flexion).
As I wrote in the last post, when we are in a constant state of lumbar flexion we strain the muscles of the lower back (Erector Spinae group) and they hurt. Ideally the lower back has a slight lordotic curve toward the front of the body; when we lose that curve, the erector muscles strain. You can find this natural curve when the pelvis is vertical. However if the hamstrings are tight, finding vertical might be challenging when standing.
Simple Yoga Stretches To Relieve Lower Back Pain
Low Lunge: Starting from Table, step your right foot forward toward your hands so that the foot is on the floor directly in front of your right hip and directly below your right knee. Your left knee is directly behind your left hip, your shin pressing into the floor. Your hands can either be on the floor or blocks on either side of your right foot, on your right thigh so you are a little more upright, or above your head, palms facing each other. If the arms are up, move the shoulder blades downward and apart (depression and protraction). This will prevent tension in the neck and shoulders. Activate your left inner thigh to direct your left hip forward, as both hips should face straight ahead (square). Press your left shin and right foot into the floor equally. Hold for 3-5 breaths, then switch to the other side. This pose stretches the Psoas, as the hip of the back leg is in extension.
Half Split: Start in Low Lunge with the right foot forward. Straighten the right leg by pressing the right heel forward and moving the right sit bone backward, away from the heel. Your ankle should be dorsiflexed (toes pointing to the ceiling, heel reaching forward). The leg may or may not straighten fully, depending on how tight your hamstrings are. If the leg is fully straight, try to activate the quadriceps (front of thigh) so that you don’t hyperextend the knee joint. The knee should never bend backward. With hypermobile joints, engaging the quads can prevent that hyperextension of the knee joint. If you find it is difficult to have your hands on the floor, bring them onto yoga blocks or a chair, so that you torso is higher. Hold 3-5 breaths then repeat to the other side. This pose stretches the hamstrings, as the knee of the front leg is in extension.
Click here to watch a short video guiding you through these poses.
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