While
hamstring strains are a common sports injury, the correct diagnosis, treatment
and rehabilitation of the injury is essential if the athlete is to compete at
the same level as before.
What is a
hamstring strain?
Hamstring injuries are a common
injury in sports, especially if participating in activities that require
sprinting, such as track, basketball and football. Usually referred to simply as the hamstring,
it is the group of three muscles and bordering tendons at the back of the thigh
and knee: the semitendionsus, semimembranosus, and biceps femoris. Its function is to bend the knee and move the
thigh backwards from the hip. Injury
occurs when this group is forcibly stretched beyond its limits and the muscle
tissue tears.
Different
types of hamstring strain
There are three degrees of strains,
depending upon the severity of the injury:
Grade 1
First-degree hamstring strains
are simply a few damaged muscle fibres, within the muscle group. There may be some swelling or discomfort, but
usually this will not effect the ability to walk normally.
Grade 2
Second-degree strains involve
damage to a number of extensive muscle fibres, usually requiring the attention
of a dedicated sports-medicine physician. There may be pain, noticeable
swelling, or a limp. It would be
difficult to fully straighten the knee and trying to flex the knee again
resistance causes pain.
Grade 3
Third-degree strains involve a
complete rupture of muscle fibres. There
would certainly be severe pain and very immediate and noticeable swelling. It would be difficult to bear weight without
the help of crutches. Luckily, this is
rare but is often serious enough to require surgery.
What
causes a hamstring strain?
The hamstrings work in a very
specific way during sprinting. Whilst in
mid stride, the hamstring lengthens, usually while under load from the body
weight and shifting forces of the motion impact. It works to pull back the tibia, or the shin,
after it kicks forward when the leg is stretched out to full stride. In addition, the hamstring is responsible
for eccentric deceleration and sudden changing of directions, both of which
incur a lot of stress.
A strain can occur in these circumstances when the weight and forces carried in the body and muscles, is changed in orientation or by sudden changes in direction. This is when the muscle is challenged whilst already under a full load, or is working beyond its capacity and overstriding occurs. The damage often occurs when the muscle is fully stretched out, just before it contracts to bend the knee.