Muscle strains are the nemesis of running athletes such as footballers, soccer players and track and field athletes. Despite advancements in sports medicine, muscle strains continue to occur and frequently reoccur during the same season which can have a profound effect on the fitness and form of the injured player.

Common muscle groups involved include the hamstrings, calves and quadriceps.

But why do they re-occur?

Here are some of factors that may influence the muscle susceptibility to re-injury:

Inadequate rehab following initial injury.

It makes sense that if you try to return to sport before you are ready, then you are a strong chance to re-injure. Rehab is designed to restore your pre-injury function and even improve it. Stretching and passive modalities such as massage and Dry needling can help reduce pain and stiffness temporarily, but it does nothing to address the structural performance of the muscle, therefore it won’t reduce the risk of re-injury.

Some of the key criteria that rehab addresses include:
  • Restoring Strength – particularly eccentric muscle strength
  • Restoring Power – which is the ability of the muscle to contract quickly (pretty important if your running). This is often neglected but is very important, as it has been shown that power deficits persist even after strength has been fully restored.
  • Restoring running capacity – injured muscles have a greater propensity to fatigue with repeated running efforts compared to previously uninjured muscles.

Poor Eccentric Strength:

Eccentric strength training, which is the ability of a muscle to contact while it is lengthening, is an important component to injury rehab and prevention for 2 reasons.

  1. Most muscle injuries involve a high eccentric force. Eg: the hamstrings slowing the leg down in the terminal swing phase of running. Therefore, being able to tolerate high eccentric loads is a good thing.
  2. Eccentric exercise increases muscle fascicle length. Long muscle fascicles are associated with a reduced risk on injury

Central Tendon Injury:

The advent of MRI has allowed for more insight regarding muscle injury and severity. In particular, whether or not the muscle strain involves the central tendon within the muscle.

Most muscles, including the biceps femoris in the hamstrings, rectus femoris in the quadriceps and soleus in the calves have a ‘central tendon’ that runs along the length of the muscle (figure 1.)

When the injury involves the just the muscle fibres, the recovery tends to be a lot faster (usually 3-6 weeks). If the injury involves the central tendon, it becomes a different clinical entity. It’s essentially a ‘tendon-injury disguised as a muscle-injury” and takes a lot longer to heal (up to 12 weeks).

Muscle Healing Time-frames:

Just because you can be back playing sport within a couple of months following a muscle injury, it does mean that the muscle is fully healed. A study by Bayer et al. (2018) looked at MRI’s of injured muscles at 3 and 6 months post-injury. They found that the muscle was still far from fully healed 6 months after injury, even though most players were back playing at 2 months. They also found that 3 months after injury, the affected muscle had a reduced in size by about 10%, and this had not changed 6 months after injury.

It goes to show that just because you have returned to sport, it doesn’t mean that the rehab is done. it really does take months for the muscle to return to normal.


Unfortunately, there is a link between getting older and risk of muscle injury. I’m over 30 years old myself so I’m not going to harp on it! The key message is, if you are getting on in your sporting career and you’ve had a history of muscle injuries, it would be in you best interests to improve things like your eccentric muscle strength to reduce your risk of an early retirement.


Thanks for reading, if you have any questions or would like any further information please get in contact with us.


Todd Bird

Peak Sports Physiotherapy Wangaratta and Benalla




Bayer et al. (2018). Role of tissue perfusion, muscle strength recovery, and pain in rehabilitation after acute muscle strain injury: A randomized controlled trial comparing early and delayed rehabilitation. Scandinavian Journal of Medical and Science in Sport, 28. 2579-2591

Prakash et al (2018). Connective tissue injury of calf muscle tears and return to play: MRI correlation. British Journal of Sports Medicine, 52, 929-933

Comin et al. (2013). Return to competitive play after hamstring injuries involving disruption of the central tendon. The American Journal of Sports Medicine. 41(1), 111-115.

Lord et al. (2019). Greater loss of horizontal force after a repeated-sprint test in footballers with a previous hamstring injury. Journal of Science and Medicine in Sport. 22, 16-21

Green, B., Pizzari, T. (2018). Calf muscle strains in sport: a systematic review of risk factors for injury. British Journal of Sports Medicine, 51, 1189-1194.