Calf muscle strains are one of the most common muscle injuries experienced by recreational runners. The impact of calf strains is substantial, with time out of running lasting anywhere between 10 days to 3-4 months, and that’s often not the end of the issue! Recurrence rates of calf strains in runners are extremely high. The primary reason for this is the high workload of the calf during running and the fact that many runners don’t fully rehabilitate their calf back to the level of strength and endurance needed to propel the body forward during jogging or sprinting (Dorn et al 2012).
This blog will cover the following topics:
An overview of calf muscle injuries
The common signs and symptoms of calf strain
Common management pathways
Have you just had a calf strain? or are you being plagued with recurrent calf strains?
Come on in for an assessment, so our Sports Physio’s can get you back on track as soon as possible.
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CALF MUSCLE ANATOMY
Calf strains in runners and others occur in one of the 2 major muscles of the calf complex - the gastrocnemius or soleus muscles.
Both of these muscles form the ‘superficial’ group of the calf complex in addition to a smaller and lesser known muscle, the plantaris.
There are other deeper muscles that sit beneath the main calf muscles. These include the following muscles:
- Tibialis posterior,
- Flexor digitorum longus,
- Flexor hallicus longus, &
Types of calf muscle injuries
Calf injuries in runners most commonly occur at the musculotendinous junction (the meeting point of muscle to tendon) of the gastrocnemius or soleus. However, there is now a greater appreciation of strains occurring in the tendon itself and/or in the muscle fascia (thin fibrous ‘stocking’ that surrounds the muscle). The type of injury and structures involved all have an influence on recovery times and prognosis.
Sometimes scans like Magnetic Resonance Imaging (MRI) or ultrasound scans are ordered to determine the grade of injury.
Location of calf muscle strains
The ‘calf strain’ can be subclassified depending on the site:
- Myofascial (peripheral)
- Myotendinous junction / muscular
Grading calf muscle injuries
The grades below have been adopted from the British Athletic Injury Muscle Classification System:
- Grade 1 (mild) <10% cross-section or longitudinal length (<5cm) with <1cm fibre disruption
- Grade 2 (moderate): 10-50% cross-section; longitudinal length 5-15 cam with <5cm fibre disruption
- Grade 3 (extensive): >50% cross-section or longitudinal length >15cm with >5cm fibre disruption
- Grade 4: complete rupture
Recovery time for calf strains
As a loose guide, the time frames below can provide a rough guideline as to the expected length of time for healing:
- Myofascial injury: 10 days up to 3 weeks
- Musculotendinous injury: 4-8 weeks
- Tendinous injury: 2-4 months
Symptoms of calf strain
Typical symptoms of calf strain in runners can range from experiencing gradual onset of tightness within a run to a sudden acute onset of muscle pain. A common description of acute calf strain is ‘being kicked in the calf’, where this represents a more significant muscle tear.
Runners are often not aware of an ‘event’, rather experiencing a progressive tightening of the calf throughout a run which may lead to the runner having to finish the run early. This may happen in association with a rapid increase of load in the form of greater volume, speed work, interval training and/or steeper running gradients.
On the other end of the spectrum are acute tears that occur with a distinct and sudden loss of function, limping and pain. This situation is likely to reflect a higher-grade calf strain and is more commonly associated with rapid acceleration or a sharp change of direction when running (more common in field-based sports). This type of mechanism is usually associated with greater strain across the calf muscles and therefore a higher grade of injury.
The Biomechanics of a Calf Strain in Runners
Prevalence and recurrence rates are high when it comes to calf strains in runners. This is in part to do with running mechanics and the high loads in the calf complex.
Research by Dorn and colleagues (2012) suggest that for speeds up to 7m/s, the ankle plantarflexors (soleus and gastrocnemius) contribute most significantly to vertical support forces and increases in stride length.
At speeds greater than 7m/s, the shift in mechanics to increase speed is achieved via increasing stride frequency, requiring the calf complex to generate more force in shorter time periods.
The other key muscle groups (particularly the hip musculature – iliopsoas, gluteus maximus and hamstrings) have been shown not to reach peak force until higher speeds are reached - above 7m/s. This is in contrast to the calf musculature, experiencing similar strain rates across low and high running speeds.
The point of mentioned this research is to highlight the amount of work the calf does at all speeds. Greater than 50% of running force propulsion is generated below the knee during steady state speeds, with only 5-10% of force production coming from the hip muscles, and the remaining amount produced by knee musculature.
NOTE: Note the peak force that the ‘soleus’ experiences through all four running speeds, in comparison to the hamstrings that don’t reach peak strain until > 8.99m/s (sprinting).
This data helps direct rehab priorities towards the development of top end strength and rate of force development (power) when it comes to returning an individual back to running (Dorn et al. 2012).
Fundamentals of calf strain rehabilitation
1. Early protection and promotion of healing
a. Protect (relative offloading) and prevention of muscle atrophy
b. Compex muscle stimulators and blood flow restriction can be options to stimulate the muscle at low loads during this initial phase to prevent unwanted muscle wasting
c. Cross-training the other limb
d. Maintain strength across unaffected joints and muscles
e. Develop intrinsic foot strength and other ‘plantarflexors’
f. Restoration of any loss of range of motion at the various foot and ankle joints
2. Load introduction
a. Building base line tissue strength and resilience
Developing endurance capacities of the calf musculature in various positions (straight knee and bent knee calf raises, different angles and within movement patterns to develop running specific strength)
b. Progressive overload towards maximum strength capacities
c. Develop rate of force development in preparation for plyometrics
a. Progress through a graduate continuum of plyometrics to recondition the calf and prepare it for the rigours of running
b. Restore reactive strength qualities of the calf complex (repeat bounding)
c. Address any movement patterning issues that may have contributed towards the calf overload in the first place
4. Running load re-introduction
a. Introductory running loads to bridge the gap from plyometrics in the gym to running demands
5. Running performance and economy
a. Optimisation of running form as required (Green et al. 2022)
**Note: a common rehabilitation error is too quick of a progression from a pain-free state to plyometrics/running. As highlighted above, the calf is subjected to huge peak forces during running, so reaching appropriate strength benchmarks during the early to mid stages of rehab is critical to set up for running success.
Most common reasons for recurrent calf injuries in runners
There are 2 main reasons for persistent or recurrent calf strains in runners.
Too much - Too soon
A common rehabilitation error is progressing too quickly from a pain-free state to plyometrics (bounding, jumping, hopping) or high speed/effort running. Time to progress will vary depending on the runner and type and severity of injury, as we mentioned above. Progressing too quickly may prevent adequate progress or sometimes even worsen the injury.
Failing to complete higher-end rehabilitation
The other main reason for ongoing calf injuries and repeat calf strains, if failing to follow-through with full rehabilitation. Many people stop rehab when they can walk or job lightly without pain. However, as we have highlighted, the calf is subjected to huge peak forces during running. Reaching appropriate strength benchmarks during the early to mid-stages of rehabilitation, and power and agility benchmarks for later stage rehabilitation is critical to set up for success in recovery from calf injury and success with return to running.
If you’ve just had a calf strain, or if you are being plagued with recurrent calf strains, come on in for an assessment, so our Sports Physio’s can get you back on track as soon as possible.
Do you you need help recovering from an injury? Improving your performance? Or just getting back to doing the things that you love? Visit us at PhysioTec, and let one of our physios assess you and provide you with a personalised program to help you get on-top of your condition, and feel at your best.
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Green, G, McClelland, JA, Semciw, AI, Schache, AG, McCall, A & Pizzari, T 2022, ‘The Assessment, Management and Prevention of Calf Muscle Strain Injuries: A Qualitative Study of the Practices and Perspectives of 20 Expert Sports Clinicians’, Sports Med – Open, vol. 8, no. 10