Hamstring stretches and hamstring exercises
As many winter sporting seasons are about to kick off, it is now a good opportunity to discuss one of the most common injuries seen in a sporting population – hamstring injuries. This blog post will discuss hamstring strains, and a common preventative measure undertaken by many physiotherapists.
Why discuss hamstring strains?
Although not as serious as other sporting injures (i.e ACL rupture), hamstring injuries are incredibly common and affect almost every sporting team. Hamstring strains are the most common and prevalent injury in the AFL and comprise roughly 15% of all injuries, with an average of over five new injuries per club each season. Reoccurrence rates are also very high, being 16% in 2014 and 24% in 2013. Reoccurrence rates in elite soccer have also been shown to be as high as 25%. The average injury results in three to four games missed before return to play, with an average of 20 missed matches per season in the AFL in 2014.
As can be seen below, the hamstring is comprised of three distinct muscles; semimembranosis, semitendinosis, and biceps femoris. As a rough guide the biceps femoris sits on the outside of the back of the thigh and the other two sit on the inside of the thigh. The biceps femoris is the most commonly injured hamstring muscle with studies showing that this muscle is the culprit for over 75% of hamstring injuries. The semimembranosis is less commonly injured, and the semitendinosis is rarely injured.
How are hamstring muscles injured?
There are two types of hamstring injuries. Type I injuries involve sprinting, and Type II injuries involve movements that cause excessive stretching or lengthening within the muscle such as bending, lunging or long kicking, and often occur at a slower speed. Type I injuries generally affect the biceps femoris muscle and Type II injuries the semimembranosus. Type I strains generally result in a greater loss of function in the early stages of injury however tend to progress and recover quicker than Type II strains.
Reports of a hamstring injury generally involve a specific incident where pain first came on. If hamstring symptoms gradually came on over time and doesn’t result in a marked loss of function, then it is more likely to be caused by another issue rather than a muscle strain, such as referred pain from the lower back or gluteals, however that is a discussion for another blog post.
When are hamstrings injured?
Hamstring strains occur when greater force than the muscle can withstand is experienced and generally occurs when the muscle is in a lengthened/stretched position. Biomechanical studies show that peak forces going through the hamstring muscle occur during the “late swing phase” of the running gait cycle when the muscle is on stretch or in a lengthened position. During late swing phase, the hamstring works "eccentrically". The other part of the running gait cycle where hamstring injuries often occur is in late stance phase, where the hamstring muscle is also lengthened and working eccentrically.
What does “eccentrically” mean?
When a hamstring muscle contracts while it is being lengthened it is said to be working eccentrically. As described above, when the hamstring is injured while running or sprinting, it is usually in a lengthened position. Other common mechanisms of hamstring injury include bending down to pick up a ball, lunging, or long kicking – all tasks that require eccentric hamstring contraction. It therefore makes sense to strengthen the hamstring muscle while it is lengthening and it is hypothesised that having good eccentric hamstring strength will reduce your risk of injury or re-injury. Recent studies have showed a reduction in the incidence and reoccurrence of hamstring injuries with eccentric strength training.
What does eccentric strength training involve?
Eccentric muscle strengthening involves loading/activating the muscle as it is lengthened. Examples of these types of exercises include deadlifts and arabesques. The opposite of this is a concentric exercise where the muscle is shortened. An example of a concentric exercise is a hamstring curl, which is a commonly seen exercise at the gym.
Why do strength training as hamstring injury rehab?
Strengthening the hamstring following a muscle strain is an essential component of rehabilitation in reducing the chance of re-injury and returning to pre-injury level of function, by returning good structural integrity to the muscle. One of the key criteria to returning to sport following a hamstring injury is to have pre-injury maximal strength without any pain, and this can only be achieved with adequate strengthening. It is not just a matter of waiting 3-4 weeks before returning to sport.
The Nordic hamstring curl exercise
An increasingly popular eccentric hamstring strengthening exercise used by Physiotherapists in hamstring strain rehab and prevention is the Nordic hamstring curl exercise, which can be seen in the image below. Nordic exercises have been shown to not only improve hamstring strength but also prevent reoccurrence of hamstring strains. The benefit of this exercise is that it can be done at home and doesn't require you to go to a gym, and doesn't take much time to perform. All you need is a partner to assist you with the exercise. As can be seen in the image below, you start in a kneeling position with your partner blocking the bottom of your legs. From here you slowly lean forward towards the ground, only putting your hands out to safely prevent your body from hitting the floor.
How many sets and reps of this exercise are prescribed?
The Nordic strengthening program was initially designed for a 5-10 week pre-season training program and has been outlined below. It can however be modified if performed in-season, for example one session per week in-season would be appropriate. Studies have shown a significant reduction in the number of hamstring strains (new or reoccurring) with a 10-week progressive pre-season program followed by a weekly program in-season.
Nordic curl pre-season strengthening program
It is important to note that each individual should be assessed and prescribed on an individual basis due to the varying factors that can influence the prescription of the program, including age, past history of injury, hamstring strength, sport played, position/role in that sport etc. If the exercise is being used in rehabilitation of a hamstring strain then it most definitely needs to be guided by your Physiotherapist. Eccentric muscle strengthening results in delayed onset muscle soreness so it is important that adequate recovery is taken between sessions, i.e. a days rest between exercise.
Important to note…
-You should have a good level of hamstring conditioning before attempting this exercise and should always be guided by your health professional.
-The Nordic exercise program if prescribed by your Physiotherapist is only one component of a comprehensive rehabilitation program.
-The Nordic exercise program is usually a late-stage rehabilitation exercise and occurs following successful completion of previous hamstring conditioning exercises.
Other simple things you can do to prevent hamstring injuries:
-Ensure adequate warm up
-Ensure adequate recovery between sessions
-Listen to your body – a common report following a hamstring injury is that the hamstring or lower back felt tight prior to the incident – don’t ignore a niggle or muscle tightness!