Sometimes referred to as “the kicker muscle” or “soccer muscle”, the rectus femoris is the most commonly injured muscle of the anterior thigh among athletes, especially soccer players. While the two-joint rectus femoris makes up just about a tenth of the quadriceps muscle cross-section, its role and function is significant and more versatile than the three knee extensor companions, the one-joint vastii muscles.
While advocates of ”functional training” may dismiss the open chain seated knee extension, bodybuilders and physiotherapists never abondened this exercise. Simply, because it is the only exercise that maximizes use of rectus femoris, and the entire quadriceps. It has remained as a user-friendly, very safe, standard piece in the fitness gym. There are several pecularities about rectus femoris “at work” worth mentioning.
Fact #1: Put a man or woman and crutches for five wks; while all three vastii muscles show about 10% atrophy, the size of rectus femoris remains unaltered! Obviously, just movement about the hip (”swinging” the limb while walking with crutches), is sufficient to ensure this muscle stays in shape.
Fact #2: Have these persons simultaneously train (4 sets of 7 reps every third day) for five wks on the YoYoTM #214 Knee Extension. The rectus femoris by far, shows the most impressive hypertrophic response among the four quadriceps muscles! Rectus femoris size increases by 15%! Evidently, this muscle is very prone to grow, when subjected to high eccentric loading!
Fact #3: Using the same ”4 sets of 7 reps every third day” regime with an established commercial weight stack machine, the rectus femoris hypertrophy is significantly less compared with YoYoTM #214 Knee Extension.
Fact #4: No Squat or Leg Press exercise in the world will bring in rectus femoris at its full potential.