Hamstrings

The hamstrings are a group of three muscles located at the back of the thigh—biceps femoris, semitendinosus, and semimembranosus. These muscles play a crucial role in bending the knee, extending the hip, and stabilizing the pelvis, making them essential for explosive movements like sprinting, jumping, and sudden directional changes.

For athletes, strong and flexible hamstrings are vital not only for performance but also for injury prevention, as hamstring strains are among the most common sports-related injuries. Maintaining proper strength balance with the quadriceps is key to staying fast, agile, and resilient.

Hamstring
Hamstring

Hamstring

Anatomy

Biceps Femoris

Origin:

  • Long head: Ischial tuberosity (pelvis)
  • Short head: Linea aspera (posterior femur)

Insertion:

  • Head of the fibula

Actions:

  • Knee flexion
  • Hip extension (long head only)
  • Lateral (external) rotation of the leg when knee is flexed

Semitendinosus

Origin:

  • Ischial tuberosity

Insertion:

  • Medial surface of the proximal tibia (part of pes anserinus)

Actions:

  • Knee flexion
  • Hip extension
  • Medial (internal) rotation of the leg when knee is flexed

Semimembranosus

Origin:

  • Ischial tuberosity

Insertion:

Posterior part of the medial tibial condyle

Actions:

 

  • Knee flexion
  • Hip extension
  • Medial (internal) rotation of the leg when knee is flexed

    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 Hamstrings are;

      • Nordic
      • Leg Curls
      • Bridges

    Nordics

    Nordics

    Leg Curls

    Leg Curls

    Bridges

    Bridges

    < 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.
    • Guruhan, Sonay, Nihan Kafa, Zeynep B. Ecemis, and Nevin A. Guzel. “Muscle Activation Differences During Eccentric Hamstring Exercises.” Sports Health: A Multidisciplinary Approach 13, no. 2 (March 2021): 181–86. https://doi.org/10.1177/1941738120938649.
    • Llurda-Almuzara, Luis, Noé Labata-Lezaun, Carlos López-de-Celis, Ramón Aiguadé-Aiguadé, Sergi Romaní-Sánchez, Jacobo Rodríguez-Sanz, César Fernández-de-las-Peñas, and Albert Pérez-Bellmunt. “Biceps Femoris Activation during Hamstring Strength Exercises: A Systematic Review.” International Journal of Environmental Research and Public Health 18, no. 16 (August 18, 2021): 8733. https://doi.org/10.3390/ijerph18168733.
    • Hegyi, András, Dániel Csala, Annamária Péter, Taija Finni, and Neil J Cronin. “High‐density Electromyography Activity in Various Hamstring Exercises.” Scandinavian Journal of Medicine & Science in Sports 29, no. 1 (January 2019): 34–43. https://doi.org/10.1111/sms.13303.