One of my main yoga instructions is to “Stay out of your hip flexors!” which often elicits the question, “What are the hip flexors?” A flexor muscle is one that assists in drawing two body parts closer together. If you are standing and lift your knee towards your chest you are engaging the hip flexors to accomplish the task.
Trouble with the hip flexors is the average yoga student’s nightmare. If you are someone with hip flexor trouble you know exactly what I mean. When someone with hip flexor issues starts to build the strength of the abdominal muscles one particular muscle freaks out and basically seizes up in an attempt to do all of the work.
An important question to narrow the field of study is, “what are the hip flexors that matter?” The psoas major is the body’s most important hip flexor (without going into the argument of whether the psoas actually flexes or not). In standing it lifts the knee to towards the chest or pulls the knee forward to begin the action of walking. Laying down the psoas helps to lift the trunk towards a sitting position. Anyone who reads this blog knows that I think the psoas is the body’s most important muscle. But when it comes to abdominal or core work it isn’t usually the psoas that starts freaking out.
There are a number of other hip flexors as well as the psoas. The ilacus is a muscle that aids the psoas with hip flexion. The sartorius, the longest muscle in the body is also a hip flexor.And the adductor muscles of the inner thigh do their tiny bit to aid in flexion of the hip as well as the tensor fascia latae.
But to return to the question of “what is the hip flexor that matters?” we return to the “one particular muscle” of the second paragraph. The rectus femoris is one of the four quadriceps muscles but the only one that attaches onto the pelvis. I think it is the tendon of the rectus femoris muscle that is the problem when we say that the hip flexors try to take over when we work on building core tone.
The feeling of this hip flexor seizing is like having a steel cable pulled taut in the space between the leg and the pelvis. It hardens, or engages, and won’t let go. There is no easy answer for someone with this issue. Resolving the issue requires bringing greater tone to muscles that can’t find tone because the hip flexor takes over and won’t let them work. What a conundrum.
You have to learn to love the conundrum of the body and have patience as you work to figure how out to get the brain to let the abdominal muscles work instead of the quadriceps.