Rectus Femoris

The rectus femoris is the central muscle of the quadriceps and the only biarticular muscle among them. Since it originates from the pelvis, when it loses flexibility and becomes stiff, it pulls the pelvis forward.

Conversely, if the rectus femoris is stretched while the gluteus maximus or hamstrings are overly tight, the pelvis tilts backward.

In this way, as a biarticular muscle, the rectus femoris has a significant influence on pelvic tilt.

Rectus Femoris
Rectus Femoris

Rectus Femoris

Anatomy

[Origin]

  • Anterior inferior iliac spine (ASIS)
  • Groove above the acetabulum

[Insertion]

  • Patellar tendon, inserting at the patella and tibial tuberosity

    [Action]

    • Hip Flexion with Iliopsoas
    • Knee Extension
    • Hip Joint Stabilization

    Clinical Relevance

    When it comes to knee condition, the strength ratio between the quadriceps and hamstrings is often considered important.

    Generally, a ratio of “Quadriceps : Hamstrings = 2 : 1” is thought to be ideal, but this can vary greatly depending on a person’s activity level. For individuals with high levels of physical activity, such as athletes, some studies suggest that having less of a strength gap between the two muscles is preferable.

    From an injury prevention standpoint, it has been found that the difference in strength between the left and right sides has a greater impact on injury risk than the strength ratio between the quadriceps and hamstrings.

    ~ Evidence-Based Exercises ~

    According to an EMG study, the exercises that demonstrated significant muscle contractions of Rectus Femoris are;

    • Knee Extension
    • Single Leg Squat
    • Front Lunge

    Knee Extension

    Knee Extension

    Single Leg Squat

    Single Leg Squat

    Front Lunge

    Front Lunge

    < Reference >

    • Keith L. Moore, Anne M. R. Agur, Arthur F. Dalley. Moore Clinically Oriented Anatomy 7th Edition, Lippincott Williams & Wilkins, 2013
    • Coombs R, Garbutt G. Developments in the use of the hamstring/quadriceps ratio for the assessment of muscle balance. J Sports Sci Med. 2002;1(3):56-62.
    • Aagaard P., Simonsen E.B., Trolle M., Bangsboo J., Klausen K. (1995) Isokinetic hamstring/quadriceps ratio: influence from joint angular velocity, gravity correction and mode of contraction. Acta Physiologica Scandinavica154, 421-427
    • Burkett L. (1970) Causative factors of hamstring strains. Medicine and Science in Sports and Exercise2, 39-42
    • Coratella G, Tornatore G, Caccavale F, Longo S, Esposito F, Cè E. The Activation of Gluteal, Thigh, and Lower Back Muscles in Different Squat Variations Performed by Competitive Bodybuilders: Implications for Resistance Training. Int J Environ Res Public Health. 2021;18(2):772.
    • Muyor JM, Martín-Fuentes I, Rodríguez-Ridao D, Antequera-Vique JA. Electromyographic activity in the gluteus medius, gluteus maximus, biceps femoris, vastus lateralis, vastus medialis and rectus femoris during the Monopodal Squat, Forward Lunge and Lateral Step-Up exercises. PLoS One. 2020;15(4):e0230841.