Australasian Science: Australia's authority on science since 1938

The Physics of Hamstring Injuries

Illustration: Elia Pirtle

Illustration: Elia Pirtle

By Bronwyn Dolman

A spring-mass “hamspring” system explains why one particular muscle in the hamstring group is so prone to injury in sprinting sports.

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Hamstring strains are a common sporting injury at all levels of football, from weekend warriors through to the professional ranks. Each Australian rules football club will have six or seven players sidelined with hamstring strains each year, and the 2013 AFL Injury Report states that “hamstring strains are still the number one injury in the game in terms of both incidence and prevalence (missed games)”.

Your hamstrings are three muscles in the back of your leg – the semimembranosus, semitendinosus and biceps femoris. All three muscles attach at the same point in your hip at one end, and to both sides of your knee at the other.

As you move, your quadriceps on the front of your thigh accelerate your leg forwards, and your hamstrings then kick in as the brakes to slow your leg down, plant your foot on the ground, and repeat.

There are two common types of hamstring strains. The first occurs in overstretch activities, where the hamstrings are forcibly pulled, such as in a water skiing accident when the skis are pulled out from under you. The second and more common injury occurs in sports that involve sprinting or sudden changes in direction.

When hamstring strains occur in sprinting activities, doctors will anticipate that the biceps femoris has been injured. They are right approximately 80% of the time. Why is this muscle so predictably injured...

The full text of this article can be purchased from Informit.