Calf Injury

Anatomy of a calf injury

The calf comprises three different muscles that function together to create powerful ankle movements required for high-performing athletes. The three muscles are the medial gastrocnemius, the lateral gastrocnemius, and the soleus. Both gastrocnemius muscles attach from the backside of the femur (thigh) bone, and the soleus muscle attaches from the backside of the shin bones. All three blend through a fascial connection (connective tissue) to form the Achilles tendon, which connects to the calcaneus bone (heel bone).1,2 These three muscles function to help create push-off during running, jumping, and cutting. There is a great deal of elasticity to this muscle group, which allows it to function similarly to a spring when running and jumping, where the muscles recoil to create energy.¹

Any calf muscle can be injured; however, the most common is the medial gastrocnemius.^1,2 A phenomenon seen with calf injuries is in addition to the muscle injury, the fascial connection between the three muscles can also be injured, and pockets of swelling can form between the muscles that contribute to pain and impact performance.^1,2. MRI studies in high-level athletes show that fluid collection between the medial gastrocnemius and soleus is one of the most common findings, and the severity of fascial involvement may predict time lost.³

Like all muscle injuries, there is a grading scale for severity. Several different scales have been created, and the following is one way to grade calf injuries:³

• Grade I (mild): Minimal or no loss of strength and range of motion, <10% of muscle fibers injured.
• Grade II (moderate): Weakness and loss of range of motion, swelling within the muscles, 10-50% of muscle fibers injured.
• Grade III (severe): Significant weakness and loss of range of motion, 50-100% of muscle fibers injured.

Cause of a calf Injury

Lower body muscle injuries are prevalent in football and can sideline players for several weeks and impact their performance when they return. In the NFL, calf muscle injuries are the fourth most common lower body muscle injury, following injuries to the hamstrings, groin, and quad muscles.^4,5 Studies on the NFL show an average of 57 calf injuries occur per season across all position groups, with defensive players accounting for 67%.⁵ Despite only 33% of calf injuries occurring in offensive players, this is still a very impactful injury for fantasy-relevant players.  

The calf is commonly injured when initiating a sprint, jumping, or changing direction. These powerful movements cause the ankle to rapidly change from a plantarflexed position (like pressing the gas pedal) to a dorsiflexed position (the ankle is flexed, so toes go towards the shin) while the knee is fully extended, causing tremendous forces through the calf muscles while they are in a fully stretched position.^1-5 This makes sense why these injuries are more common in defensive players, as they are reacting to the offense and changing directions. However, these injuries still frequently occur in fantasy-relevant players.

Factors that may increase the risk of an athlete suffering a calf muscle injury include age, a previous calf injury, or any previous lower-body injury.^6,7 Older age reduces the elasticity of muscle tissue, making it less able to withstand significant forces and stretch as much. Previous calf muscle injuries contribute as sometimes players never fully regain the strength they had before the injury. A history of other prior lower body injuries can alter the ankle flexibility or coordination of muscles with an athletic activity that can increase stress on the calf muscles.⁷

Recent studies emphasize that decreased plantarflexor strength and impaired eccentric control of the calf complex are modifiable risk factors that should be screened during preseason assessments.⁹ Athletes who have asymmetry in calf muscle endurance (measured by single-leg heel raises) also demonstrate a higher injury risk.

Like all muscle injuries, injury recurrence is a concern. Limited data exists for NFL players and calf injury recurrence rates; however, studies on professional soccer and Australian football show 14–16% recurrence.⁷. More recent tracking from European soccer suggests recurrence rates could be as high as 18–20% if athletes return before meeting strength and load tolerance benchmarks.¹⁰. Overall, fantasy football players can understand that calf injury recurrence is somewhere around 15-20% in elite athletes.

Calf injury return-to-sport outlook

Studies looking at the time it takes to return to play from a calf injury for NFL players average around 17.4 days, equal to missing two games.⁵ This is a similar timeline to sports such as soccer and Australian football, which is important to mention because there is much more data on those sports.⁶ ⁷

In elite soccer, the median return for Grade I–II injuries is 8–21 days, but Grade III injuries can result in over 35–60 days lost.⁸ Players with intermuscular fluid and fascial tears involving both the gastrocnemius and soleus show longer recovery times, regardless of muscle tear grade.⁸. Furthermore, reinjury risk is highest in the first 4 weeks post-return, especially if athletes demonstrate less than 90% limb symmetry in plantarflexion strength or incomplete tolerance to sprint drills.¹⁰

Calf injury rehab process

Rehab is initially focused on protecting the injured muscle and may briefly consist of immobilizing the ankle in a boot, though this is typically limited to no more than 3–5 days.³ ⁴ During this initial phase, emphasis is on reducing pain, reducing swelling, and preventing loss of range of motion.³ ⁴ This is accomplished through rest, ice, compression, and elevation.³ ⁴ Often, lymphatic massage will also be utilized to help flush out swelling, and electrical stimulation can be used as needed for pain relief.

After the first few days, as pain and swelling subside, rehab progresses to gentle stretching and isometric muscle contractions (where the muscle activates but the ankle does not move). Isometric exercises help maintain muscle activity and prevent further strength loss.⁴

During this phase, rehab will also address factors that may have contributed to the injury, such as ankle stiffness, imbalances in hip and core strength, or altered running mechanics.⁴ Cardiovascular training should be maintained using methods that offload the lower body (such as an arm bike or swimming) to preserve conditioning.

When the range of motion is normal, there is no pain with isometrics or gentle stretching, and they can stand on the injured leg without pain, athletes can progress to:

• Balance exercises
• Dynamic stretching
• Light concentric calf strengthening (muscle contracts and joint moves), starting with low resistance
• Low-impact cardio like cycling or elliptical

More advanced protocols incorporate blood flow restriction (BFR) training in the mid-rehab phase to preserve muscle mass and speed up strength gains in cases of mild to moderate injury.¹¹

Once there is no pain with walking, standing, or moderate resistance calf work, rehab progresses to:

• Eccentric calf strengthening (muscle contracts while lengthening under load)
• Anti-gravity treadmill jogging
• Return to full lower-body strength training
• Progressive plyometrics, sprinting, cutting, and sport-specific drills

Return-to-play benchmarks now often include:

• Completion of field-based return-to-run protocols under load and fatigue.¹²
• ≥90% single-leg heel raise symmetry
• ≥90% strength symmetry in seated and standing calf raise tests
• Pain-free performance of sprint mechanics

Rehab Phases4	Treatments4	Criteria to Enter Phase4
Early Phase	Rest, ice, compression, elevation. Brief immobilization in boot and crutches (3-5 days). Gentle stretching. Lymphatic massage for swelling. Electrical stimulation. Glute and core strength. Hip mobility. Calf isometrics if tolerable. Cardiovascular training (arm bike)	N/A first phase
Intermediate Phase	Gentle stretching. Gentle calf concentrics. Soft tissue work, dry needling. Glute and core strength. Hip mobility. Balance exercises. Cardiovascular training (bike>elliptical>anti-gravity treadmill>treadmill)	Full range of motion. No pain with early phase exercises.
Sports Specific	Calf eccentrics. Full weight lifting. Running (anti-gravity treadmill initially, progress to treadmill or land). Agility, plyometrics, jumping, position-specific drills	No pain with standing, or walking. No pain with any intermediate phase exercises.

References

1. Bright J, Fields K, Draper R. Ultrasound Diagnosis of Calf Injuries. SPH. 2017;9(4):352-355.
2. Harwin J, Richardson M. “Tennis Leg”: gastrocnemius injury is far more common cause than plantaris rupture. Radiol. Case Rep. 2017;12:120-123.
3. Hsu D, Chang K. Gastrocnemius Strain. StatPearls. 2021. Treasure Island (FL): StatPearls Publishing: 2022.
4. Palermi S, Massa B, Vecchiato M, et al. Indirect Structural Muscle Injuries of Lower Limb: Rehabilitation and Therapeutic Exercise. J. Funct. Morphol. Kinesiol. 2021;6(75).
5. Werner B, Blkin N, Kennelly S, et al. Acute Gastrocnemius-Soleus Complex Injuries in National Football League Athletes. Orthop. J. Sports. Med. 2017;5(1).
6. Green B, Pizzari T. Calf muscle strain injuries in sport: a systematic review of risk factors for injury. Br. J. Sports. Med. 2017;51:1189-1194.
7. Green B, Lin M, McClelland J, et al. Return to Play and Recurrence After Calf Muscle Strain Injuries in Elite Australian Football Players. Am. J. Sports. Med. 2020;48(13):3306-3315.
8. Guermazi A, Roemer F, Alizai H, et al. MRI-Based Classification of Calf Injuries in Elite Soccer Players: Prognostic Implications. Br J Sports Med. 2021;55(14):792–798.
9. Eirale C, Farooq A, Smiley F, et al. Calf Injuries in Professional Football: Strength Imbalance and Risk. Scand J Med Sci Sports. 2022;32(1):95–102.
10. Tol J, Hamilton B, Arundale A, et al. Risk Factors for Calf Injury Recurrence in Elite Football: A Multicenter Cohort Study. Am J Sports Med. 2023;51(1):95–104.
11. Hughes L, Patterson S, Rosenblatt B, et al. Blood Flow Restriction Training in Sports Rehabilitation. Front Physiol. 2020;11:1561.
12. Hickey J, Shield A, Williams M, et al. Return to Running Progression After Lower Limb Muscle Injury: A Decision-Making Framework. Sports Health. 2024;16(2):132–140.