By Stephen E. Alway, Ph.D., FACSM
The evolution of modern weight-training equipment and gyms has created a paradox. On one hand, it’s allowed us to move quickly and easily from one exercise to another; the machines have eliminated the tedious task of breaking the bar down after the exercise. However, excessive use of the machines, especially for the lower body, robs the gym rat of a structural mass base from which to refine for competitive purposes. Muscular thighs with definition emanating from every fiber aren’t built on leg extensions alone. Rather, some form of barbell squats is the best strategy to obtain sculpted thighs.
Squats add to the mass and depth of the anterior thigh muscles. In addition, the gluteal muscles, smaller hip muscles, lower and middle back, hamstrings and even the calves are all activated to some extent during this exercise. Does this mean that to have great thighs you must possess a sadistic gene that pushes you through the pain barrier toward exhaustion on every set? Probably not, but gut-busting work is necessary to maximally enlarge the thighs and there’s no better exercise than barbell squats.
Structure and Function
Even though the squat involves many muscles, the intent of this article is to focus on the muscles of the anterior thigh, which together are called the quadriceps femoris muscle group. The quadriceps femoris (“quads”) is a group of four muscles covering the anterior and lateral parts of the femur bone of the thigh. The three vasti muscles take their origin from the respective part of the femur; the vastus lateralis muscle from the lateral part of the femur; the vastus medialis from the medial part of the femur; and the vastus intermedius from the central, anterior part of the femur.
As a result, the vastus lateralis muscle is positioned on the lateral (outer) part of the thigh and the vastus medialis covers the medial (inner) part of the thigh. The vastus intermedius is located intermediate and deep to the vastus lateralis and the vastus medialis muscles. The tendon from the vastus lateralis combines with the tendons from the other two vasti muscles and the tendon of the rectus femoris to form the quadriceps tendon. The quadriceps tendon attaches to the patella (kneecap) and continues inferiorly (toward the foot) from the patella, where it’s called the patellar ligament. The patellar ligament inserts into the tibial tuberosity, a bumpy portion on the tibia bone of the lower leg.
The rectus femoris (rectus=straight) is the fourth muscle in the quadriceps group. Unlike the vasti muscles, it begins on the hipbones at the iliac crest and above the socket where the head of the femur sits (acetabulum) in the hip. Its fibers run straight down from the hip to the knee. The tendon of the rectus femoris joins the tendons from the three vasti muscles to attach to the patella. Together, the three vasti and the rectus femoris muscles form the only real manner we have for extending the leg at the knee. The rectus femoris is much weaker when the hip is flexed (e.g., seated position, such as during leg extensions).