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Annoying calf strains? Why this can happen and what to do about it

Updated: Jan 22, 2022

This article written by Steph Davies at Sports Physio Hwb Lampeter aims to explain what puts you at risk of recurring calf muscle strains or 'muscle pulls', and how to go about getting it sorted for good.

A familiar story?

One day you're running along in the hills, fresh air filling your lungs and cantering along at a happy pace, and then seemingly out of absolutely nowhere your calf suddenly tightens up or pulls. Sound familiar? It's happened to me too in the past!

Even worse, this might be the second, third or even fourth time this has happened to you, after it felt better from resting it (and resting it drove you crazy!) - only for it to return again when you started running again.

Why? Here's what we know from the research. And it's incredibly common, so it's something we've dealt with many, many times before.

What causes a calf muscle injury?

Most calf strains, and indeed other muscle pulls and tears, are most commonly caused by a mismatch between what your muscle is conditioned to tolerate, and what you are asking it to do. This might not be related to that specific run, but might be cumulative e.g. having fewer rest days than normal, transitioning to hillier terrain, more minimalist shoes, or working at too high an intensity pace on too many of your weekly runs.

The two biggest calf muscles are the gastrocnemius (we'll call it gastroc for short) and the soleus. Typically, the gastroc is more associated with power and higher intensity activity, while the soleus is more of a 'steady state' endurance muscle. Research shows that together, gastroc and soleus generate the largest force during the stance phase of running (this is the part of the running gait where your foot is in contact with the floor, either landing, stabilising or pushing off). The ground reaction force through the calf complex can be between 6-12 x your bodyweight! That's loads! So if your muscle wasn't strong enough, or didn't have the endurance it needed to run the hills or distance that you wanted to do, then it' no surprise that it would have been more likely to fail at some point and result in a muscle injury / strain / tear / pull. ('Strain', 'tear' and 'pull' are different words, but in this situation they all mean the same thing so I'll be using them interchangeably).

What happens during a strain?

Muscles are made up of bundles of muscle fibres, and during a strain some of these fibres have torn. Severity can vary from just a few fibres (a grade 1 strain), a moderate tear (grade 2), an extensive tear (grade 3) to the whole muscle being completely torn all the way through (grade 4). Calf muscle injuries are also more common in sports involving high speed running, accelerating / decelerating quickly, or under high volume and highly fatiguing conditions.

Why does it keep happening?

Recurrent calf strains usually occur because:

  1. You haven't rested it for long enough before trying to run again (e.g. got impatient!)

  2. You haven't addressed the underlying strength, power or endurance deficits that caused it to be overloaded in the first place (most common)

  3. You haven't modified your training programme appropriately to recondition after injury (also common)

  4. There may also be other, underlying biomechanical factors that might be contributing to the risk of the calf muscle being injured again - things such as hamstring weakness, core stability, flexibility, dynamic balance.

All or any combination of the above. If you're not sure about how to go about addressing these issues, we would be very happy to help you structure an individualised treatment and rehab plan to get you sorted once and for all.

What other risk factors are there?

Two risk factors for calf muscle strain that are backed up by high quality research are:

  1. Age - it's a sad fact of life that as you get older, the quality of the muscle fibres can deteriorate making them more at risk of injury. A bit like how your skin gets more wrinkly. It also takes a little longer to recover compared to sustaining the same injury in your younger years. This doesn't mean that you can't get better, it's just slightly harder work.

  2. Previous calf muscle strain - there's usually an area of weakness in the muscle where it has previously repaired with scar tissue that is more susceptible to future injury. Hence why it is so important to address the strength, training and biomechanical issues before returning to running.

Lower quality research suggests that previous other lower limb injuries (like ankle sprains, hamstring tears etc) or poor flexibility put you at a higher risk of calf strain too.

The good news is, that there is no good evidence that either your physical stature, or running in colder or wetter conditions have any bearing on your risk of calf muscle injury. So you can have long legs or short legs, and go running the sunshine or the rain without it affecting your risk of calf muscle injury.

In summary

So there we have it. Recurrent calf strains are incredibly common, especially in runners over 30. They are not a good reason to put away your running shoes for good, but instead need a comprehensive and individualised plan to get you back up to full strength. Age isn't helpful, but isn't a deal breaker. And there are lots of things we can help you identify and address to get you back on the road and running again.


Please get in touch and we will be happy to help answer any queries or to arrange a physiotherapy appointment at our Lampeter clinic.


Pollock N, James SLJ, Lee JC, et al British athletics muscle injury classification: a new grading system. British Journal of Sports Medicine 2014; 48: 1347-1351.

Green B, Pizzari T. Calf muscle strain injuries in sport: a systematic review of risk factors for injury

British Journal of Sports Medicine 2017;51:1189-1194.

Nielsen RO, Buist I, Sørensen H, Lind M, Rasmussen S. Training errors and running related injuries: a systematic review. International Journal of Sports Physical Therapy 2012; 7(1): 58-75.

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