The sartorius originates at the ASIS and proceeds to traverse obliquely and laterally down the thigh to eventually insert at the anterior surface of the tibia, just inferomedial to the tibial tuberosity, as part of the pes anserinus. In addition to flexing the hip and knee, the sartorius aids in the abduction of the hip. It is innervated by the femoral nerve (i.e., the posterior division of L2 and L3).
The first thing you need is a weight training program that signals the muscle building process to begin. Research has shown that a well designed program will generate this “signal” via a combination of progressive tension overload (as in, getting stronger over time), metabolic stress (as in, fatiguing the muscle and getting “the pump”), and muscular damage (as in, actual damage to the muscle tissue itself).
Dynamic stretching (stretching while in motion), is the most efficient way to lengthen and strengthen the hip flexor muscles. An exercise that you can do that will engage the core and all of the lower extremity muscles while focusing on the hip flexors is called the Single Leg Split Squat. Remember that the rectus femoris crosses the hip and knee joint. This exercise involves both the hip and knee joint, making it an appropriate exercise to train the rectus femoris as well as the iliacus.
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.