Is the Hamstring to Quadriceps Strength Ratio Really Important?

Posted on 12 Dec 2011 23:25

By Ground Up Strength

Many strength trainees, bodybuilders, and exercisers are told that there should be a certain ratio between the strength of their hamstring and quadriceps muscles. Called the H/Q ratio and reported to be anywhere from .50 to .75 with a normative value of .60, the strength ratio of this important agonist/antagonist pairing is considered essential to the stability of the knee joint and to prevent ACL and other injuries. It is also sometimes thought to be predictive of those at risk for hamstring strain.

Some strength and conditioning experts actually test the maximal strength of the quadriceps and hamstring muscles of their clients, using leg extensions and leg curls, respectively, believing that they should observe a certain ratio in maximum weight of each movement and that this relationship will tell them whether their clients are at risk for a knee injury. To calculate the hamstring-quadriceps strength ratio, the maximal knee extensor moment and the maximal knee flexor moment is tested at identical velocities (isokinetic), and the flexion result is divided by the extension result.

It is quite true that the functional relationships between an agonist muscle, like the quadriceps, and its antagonist muscle, the hamstrings are very important, but the idea that testing the strength of each muscle for an ideal ratio is an accurate screen for injury potential is rather crude and simplistic.

In reality there is not one ratio for concentric hamstring and quadriceps torque ratios but a range of ratios depending on joint angle and speed of movement. These have been well studied, producing averages anywhere from 0.5 to 0.75. The mechanical advantage of a muscle tends to change with the joint angle which changes the angle of pull of the muscle. As the mechanical advantage of one muscle increases the mechanical advantage of the other muscle may decrease. Also, the speed of the movement changes the angle at which peak torque occurs. Therefore, although important considerations for screening, these agonist/antagonist muscle relationships certainly are not static entities.

Another problem is that conventional testing, as described above, involves testing the maximal strength of the quadriceps and hamstrings using the same concentric action. This may make no sense because these muscles do not function in terms of concentric-concentric actions but concentric-eccentric actions.

Another observation is that quadriceps weakness is a feature of ACL deficiency. When people with anterior knee pain are tested, weakened quadriceps with normal hamstring strength is often found. In other words, weak quadriceps are typical in those with ACL dysfunction but this does not mean that weak quadriceps are a cause of ACL problems.

See DEVELOPMENTS IN THE USE OF THE HAMSTRING/QUADRICEPS RATIO FOR THE ASSESSMENT OF MUSCLE BALANCE for an indepth review of this subject, including conventional viewpoints and new developments concerning joint angle and muscle action.


Coombs, Rosalind, and Gerard Garbutt. "DEVELOPMENTS IN THE USE OF THE HAMSTRING/ QUADRICEPS RATIO FOR THE ASSESSMENT OF MUSCLE BALANCE." Journal of Sports Science and Medicine 1 (2002): 56-62. <>

Dvir, Zeevi. Isokinetics: Muscle Testing, Interpretation, and Clinical Applications. Edinburgh: Churchill Livingstone, 2004. Print.

Brown, Lee E. Isokinetics in Human Performance. Champaign, IL: Human Kinetics, 2000. Print.

Bennell, K., H. Wajswelner, P. Lew, A. Schall-Riaucour, S. Leslie, D. Plant, and J. Cirone. "Isokinetic Strength Testing Does Not Predict Hamstring Injury in Australian Rules Footballers." British Journal of Sports Medicine 32.4 (1998): 309-14.

This page created 12 Dec 2011 23:25
Last updated 17 Jul 2016 21:35

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