Hamstring Strain Causes and Prevention
Hamstring strains usually occur either through sprinting such as in team sports or track & field, or over from over stretching the muscles for example in gymnastics or martial arts.
Sprinting related hamstring injuries often feel worse but recover more quickly, whereas stretch related hamstring strains can take longer to heel as the injury is more likely to the tendon where blood flow is lower.
The hamstring muscle group consists of three separate muscles; the semitendinosus, semimembranosus and biceps femoris. They originate from the lower part of the pelvis and insert into the back of the shin bone. When contracting they mainly bend the knee and extend (straighten) the hip joint. They also weakly rotate the hip and knee joints.
The biceps femoris muscle has two parts. One part originates from the ischial tuberosity at the bottom of the pelvis and the other part originates along the femur or thigh bone. The muscle inserts onto the outside of the tibia (big shin bone) and top of the fibula (thinner, outside shin bone).
The semitendinosus muscle is the one on the inside and also originates from the ischial tuberosity but inserts on the inside surface of the tibia. The Semimemranosus is the middle hamstring muscle and originates and inserts similar to the semitendinosus.
Acute or sudden hamstring strains usually happen in two ways, either sprinting related or stretch related for example in martial arts, gymnastics or dancing.
Sprinting related strains most commonly occur lower down the thigh in the long head of the biceps femoris muscle (at the point where the muscle joins the tendon). During sprinting the hamstring muscles work extremely hard to decelerate the shin bone just before the foot strikes the ground and it is at this point that the hamstring is most likely to tear.
Stretch related injuries usually occur higher at the back of the thigh in the tendon of the semimembranosus muscle.
It is important to rule out other causes of hamstring pain such as a contusion resulting from a direct blow or impact and referred pain which may be the result of problems in the hip or lower back. Problems with the lower back and pelvis may increase the likelihood of suffering a hamstrings strain and should always be considered, particularly for recurrent hamstring injuries.
Hamstring strains are common injuries but there are things you can do to prevent them. Here are our top tips for preventing hamstring strains!
Preventing a pulled hamstring
Whilst some common factors known to contribute towards hamstring strains are unavoidable for example age and previous injuries. Others can be addressed to reduce your risk of pulling a hamstring!
Warm up - one of the most important methods of preventing a pulled hamstrings is to warm-up correctly- this has been scientifically proven to reduce the risk of hamstring strains. This should consist of some light aerobic exercise followed by stretching and sports specific drills with gradually increasing intensity.
Flexibility - Research has shown that the greater the flexibility of the hamstrings the less prone they are to injury. Hamstring tightness is measured by flexing the hip as far as possible (laying flat on the back, raise the straight leg up).
A normal range of motion for this movement is a minimum of 80 degrees at the hip (just short of a right angle). Movement less than this indicates tight hamstring muscles.
Hamstring strength - similarly studies have shown that lack of hamstring strength is strongly linked to hamstring injury. Eccentric strength is particularly important as it is eccentric contractions which most often cause hamstring strains. Eccentric contractions are those that occur whilst the muscle lengthens, to control or slow down a movement. In the case of hamstring strains, eccentric contractions work to decelerate the forward movement of the lower leg when sprinting.
Eccentric exercises are only performed once concentric contractions (where the muscle shortens - most hamstring exercise when bending the knee or extending the hip) are strong and pain-free. The most common example is the Nordic curl.
Tiredness and fitness - when a player is fatigued he or she loses coordination between certain muscle groups. The biceps Femoris muscle is known to become damaged due its two portions being innervated by two separate nerves. In states of tiredness, lack of synchronization between these two nerves can lead to a mismatch in firing resulting in a pulled hamstring.
This can be prevented by avoiding playing when physically tired. This can be difficult to do when towards the end of a match or competition. However, this is where fitness comes in. A player needs to be fit enough for the activity or sport they are playing. If you find you are overly tired towards the end of a competition this suggests you need to work on increasing your endurance and possibly looking at hydration and nutrition.
Compression shorts and hamstring supports - compression shorts are useful products for reducing the risk of a hamstring injury. These are designed to increase the warmth, blood flow and support for the muscles. Warm, flexible muscles are less prone to injury.
Some compression shorts are made from fine lycra type material. They are more comfortable to wear for longer periods of time and allow better movement. Some products are made from neoprene which retains the heat much better but is less comfortable to wear for longer periods of time.