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Understanding & Preventing Hamstring Injuries in Football
Hamstring injuries have become renowned as the most common injury in football. They account for 37% of all football injuries, making them the most common injury for footballers. Research has reported an average of five hamstring strains per club per season.
Despite this, surprisingly few players actively work on reducing the risk of suffering from a hamstring injury, and those players unfortunate enough to pick one up (in the past) are highly likely to experience a reoccurrence of that injury.
So, how do you go about lowering the risk? We’ll get to that but first let’s look at the anatomy of the hamstrings and their function in the body.
The hamstrings and their function
The hamstrings are made up of three large muscles (biceps femoris, semimembranosus and semitendinosus) which run along the back of your thighs. They extend from your pelvis to the top of the lower leg and each play an important role in movements such as walking, running and jumping.
The 2 main functions of the hamstrings:
Knee flexion: This basically means bending your knees, but your hamstrings also help to rotate your lower leg. Two of your hamstrings attach to the inside of your knee and help to rotate your lower leg inwards. The third hamstring (attached to the outer border of your knee) rotates the lower leg outwards. Your hamstrings also act like brakes on a car to slow the speed at which you move your leg forward whilst kicking or running.
So, you can see if you want any chance of being athletic on the pitch, having your hamstrings functioning properly is key!
Hip extension: This is the backward movement of your thigh. Although the glute muscles are the main muscles that perform this movement, your hamstrings assist. Hip extension occurs when you move from sitting to standing, as well as with actions such as squatting and jumping. The hip extension action performed explosively also helps propel your body forward as you run.
In relation to football, both knee flexion and hip extension occur when you bring your leg back to begin striking the ball. The hamstrings continue working as you contact the ball, aiding in the deceleration of your leg during the final part of the strike (to prevent you from over stretching and causing an injury).
The higher % of fast twitch muscle fibres in the hamstrings compared with other leg muscles means that they are capable of producing very high amounts of force, helping you to perform quick, explosive movements, such as sprinting and aiding in your agility on the pitch.
Causes of hamstring injuries
There are 2 main causes of hamstring injuries in football: eccentric muscle contraction and over-stretching of the muscle (outside of its normal limit).
In terms of striking the ball, most hamstring injuries happen in the later phase of the strike when the hamstring muscles generate tension while lengthening (eccentric contraction) to decelerate knee extension.
Relating to over-stretching, when you’re flexed at the hip (when trying to stretch upwards to control a pass for example), your hamstrings are forced to lengthen and the tension between them increases. So, if you suddenly overstretch and the tension becomes too great, then that’s when you’re at risk of suffering a hamstring injury in this situation. You’ll see this tension in action if you put your thigh in flexion over 90 degrees and then try to straighten at the knee at the same time (unless you already have very good hamstring flexibility).
Sprinting and high-speed running are also one of the most common times to pick up a hamstring injury. During the foot-strike phase of your stride, the hamstring is in transition from eccentric to concentric (lengthening to shortening or vice versa depending on whether you are moving towards or away from the ground). The biceps femoris is the muscle where the most significant stretching usually occurs during this phase of sprinting, making it more prone to injury than the other two muscles of the hamstrings.
Risk factors for hamstring injuries
The main risk factors for hamstring injuries are a lack strength, poor flexibility and having a history of previous hamstring injury.
Lack of flexibility in hamstrings: A strong link has been found between pre-season hamstring tightness and the development of a hamstring injury later in the season. Players with hamstring flexibility of less than 90° have been shown to be at significantly higher risk.
Previous hamstring injuries: Footballers who have had a previous hamstring injury are more than twice as likely to obtain a subsequent hamstring injury. The exact reason for a previous injury increasing future risk isn’t known but it is thought that it may be due to scar tissue formation or other structural changes.
It’s also likely to be as a result of returning to play before restoring full functionality in the hamstrings. A lot of the time this is because of pressure from coaches and also believing that not feeling any hamstring pain in day to day life means that you are ready to return to match play.
Hamstring injury stats
Studies have found an injury recurrence rate of around 22% within the first 2 months of returning to match play and 25% of players obtaining a recurrent injury in the following season.
Hamstring injuries are mostly sustained towards the end of matches and training when there is a higher level of fatigue. Studies have shown that the incidence of hamstring injuries in recent years has increased. This is probably as a result of the game becoming more physically demanding and play getting faster and more intensive than ever before.
Studies show that approximately 57% of all hamstring injuries occur during running. The vast majority of hamstring injuries come about without contact, player to player contact is only responsible for around 7% of hamstring injuries, and there have been slight differences found between the dominant and the non-dominant kicking leg (53% v 45%), most likely due to strength imbalances.
Consequences of hamstring injuries and returning to play
Three grades are used to describe the severity of a hamstring injury. Grade 1 is a mild strain injury with a minor loss of strength (out of action for around 17 days) and Grade 2 is a moderate strain injury with a significant loss of strength that results in marked functional limitations (around 22 days out of action). Grade 3 is a severe strain or complete rupture and is associated with severe functional disability (approximately 75 days out).
The majority (97%) of all hamstring injuries are classified as grade 1 or 2. A complete tear of the hamstring muscle is rarer, only occurring in about 1% of cases.
Often because the symptoms of a grade 1 or 2 injury are not very noticeable during normal daily activities, (as I mentioned above) players often return to play too quickly, and as a result increase the risk of further damage and re-injury.
This can lead to continual unsuccessful efforts to return to match play…and the big issue here is that the injury can then become chronic, meaning even longer rehabilitation times and in extreme cases the end of your football career.
Needless to say, make sure you get it sorted properly first time – it can be very frustrating but if you don’t, it’s likely that it will continually come back to haunt you over at least the next couple of seasons. Recurring hamstring injuries can even lead to lumbar spine abnormalities, meniscal problems in the knee, and adhesion of the lateral popliteal nerve (nerve in the lower part of the leg).
I understand that’s a lot to take in! But hopefully it’s now pretty clear that you should be doing something to avoid getting a hamstring injury in the first place, so here’s a few things you can do…
Preventing hamstring injuries
Strength training is extremely important, particularly eccentric strength training. Stronger muscles can absorb more energy before failure than weaker muscles, meaning increased resilience to injury.
Nordics are especially effective at increasing eccentric hamstring strength. Research has shown that performing Nordics regularly (at least 2x per week) reduces hamstring injury incidence rates by 65% to 70% and is particularly effective in preventing recurrent injuries.
So, to sum up here’s the bare minimum that you should be doing:
- Nordics 2x per week
- Thoroughly warming up before every training session and match
- Working on your flexibility post exercise
- Consistently developing and maintaining your levels of strength
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