Several muscles cross the front of the hip and create hip flexion, pulling the thigh and trunk toward each other, but probably the most important is the iliopsoas. It is actually composed of two muscles, the iliacus and the psoas, which lie deep in the back of the abdomen. If you looked at the front of a body with the internal organs removed, you would see the psoas lying alongside the spine, attached to the sides of the lumbar vertebrae. The iliacus originates on the inner bowl of the pelvis. Both muscles cross the floor of the pelvis, emerge at the outer edges of the pubic bones, and finally insert on the inner upper femur (thighbone). Because the muscles are buried so deep, we can't see or touch them, so it's easy to understand why there is much confusion about their location and action.
I HATE that the resistance training community can be so tribal. I have been preaching to bodybuilders for years about the benefits of powerlifting, or Olympic lifting or kettlebells or even Crossfit style conditioning and many have been receptive. Learn from each other and achieve levels of fitness you simply could not have otherwise. Don’t brush off bodybuilding wisdom…it could be the missing factor in your program.