Stephen E. Alway, PhD, FACSM
Proper thigh training is really tough work. Most guys who have a bit of a sadistic streak love to work the thighs. These are the ones who actually look forward to pounding their thighs rep after rep and set after set, until the buckets must be retrieved so they can unload their last meal. Now, I like hard work as much as the next guy, but puking isn’t my idea of a great workout. Instead, if you’re a bit more on the sane side, you can still develop great thighs with balanced, hard, strong and thick muscle bellies without having to enter psychotherapy to get you through your next workout.
There’s no doubt that for sheer muscle mass, there are few exercises more effective than barbell squats. But, as good as squats are, to obtain the best underpinnings possible, you need to have thighs with muscle bellies that seem to have been chiseled from a granite surface. One of the best ways to do this is to continuously activate your thighs throughout the complete set (constant tension). Single-leg hack squats induce constant tension by activating all of the muscle fibers continually throughout the set, but at the same time, it deprives the muscle of any opportunity for rest until the set is over. This makes the exercise a hard ride, but one with a great reward that after about three months, will unveil outstanding thighs. Hack squats can add a new dimension of chiseled hardness and muscle growth, especially in the mid-regions of the thighs.
The anterior thigh consists of four major muscles collectively known as the quadriceps femoris (“quadriceps” or “quads”). These cover the anterior and lateral parts of the femur bone of the thigh. The quadriceps group is made up of three vastus and the rectus femoris muscles. “Vastus” is a Latin name meaning large or great. The three large vastus muscles are named to indicate their position on the thigh. The vastus lateralis muscle lies on the lateral (outer) part of the thigh over the lateral part of the femur bone. The vastus medialis covers the medial (inner) part of the thigh. The vastus intermedius is located intermediately on the femur bone, between the vastus lateralis and the vastus medialis, and covers the central and deeper parts of the thigh. The fourth muscle is the rectus femoris. The top part of this muscle attaches to the hip and it courses down the central portion of the thigh. All four muscles come together above the knee to attach to the patellar tendon. This attaches to the patella (kneecap) and the patellar ligament attaches the patella to the top part of the tibia bone just below the knee.
Together, the quadriceps extend (straighten) the leg at the knee joint by pulling on the patella and through it, to the patellar ligament that’s attached to the lower leg (tibia bone). The rectus femoris also flexes the thigh at the hip joint by pulling the knee and thigh toward the chest. The rectus femoris muscle is a weak knee extensor when the hip is flexed because it’s mechanically unable to make a major contribution to force production when the hip is flexed (e.g., sitting). On the other hand, hack squats do a much better job because the hip is quite straight during much of the lift and during this time, the rectus femoris can be strongly activated.