Calf Strain (Tennis Leg): Why It Happens & How to Come Back

You push off hard for a wide ball on the padel court, and it feels like someone kicked you in the back of the leg. You spin around — no one's there. That sharp, sudden pain in the calf, sometimes with an audible "pop", is one of the most recognisable injuries in sport. It has a nickname: tennis leg.

Calf strains are common, they're painful, and — this is the part people underestimate — they are one of the most re-injured muscle injuries in sport. In elite footballers, the recurrence rate after a calf strain is among the highest of any muscle group (Green et al., AJSM, 2020). The good news: with the right plan, they heal well and stay healed.

What Actually Tears

Your calf is really two muscles: the gastrocnemius (the big superficial one that crosses both the knee and ankle) and the soleus (deeper, crosses only the ankle). "Tennis leg" is a tear of the medial head of the gastrocnemius — the inner part of the calf — usually near where the muscle blends into its connective tissue.

It happens in a very specific position: the knee straightens while the ankle is forced upward (dorsiflexion). That lengthens an already-contracting muscle — a lunge for a drop shot, a sprint start, a check-step in Muay Thai. The gastrocnemius, crossing two joints, is uniquely exposed to this, which is exactly why it's the calf muscle that usually goes (Green & Pizzari, BJSM, 2017).

How Bad Is It? Grading the Strain

• Grade 1 (mild): a few fibres overstretched. Tight, sore, but you can walk and often keep playing. Typically settles in 1–3 weeks.
• Grade 2 (moderate): a partial tear. Sharp pain at the moment of injury, difficulty pushing off, sometimes bruising down the calf over the next days. Usually 4–8 weeks.
• Grade 3 (severe): a large or complete tear. Significant pain, swelling, and difficulty weight-bearing. Can take 3 months or more, and occasionally needs specialist review.

One important safety point: not every calf that hurts is a strain. A deep vein thrombosis (DVT) — a blood clot — can mimic calf pain but comes on without a clear injury, with swelling, warmth, and redness. If there was no obvious moment of injury, get it checked before assuming it's a muscle.

Do You Need a Scan?

Usually, no. A skilled physiotherapist can grade the injury and identify which muscle is involved through a hands-on assessment. Ultrasound or MRI is reserved for severe cases, when the diagnosis is unclear, or when timelines matter for a competing athlete — imaging that shows the connective tissue is involved can help predict a longer return (Prakash et al., BJSM, 2018).

What Actually Works

Forget weeks of rest. Modern calf rehab is about progressive loading — giving the muscle a reason to rebuild, in a controlled, graded way.

• First 2–3 days: protect and calm it down. Relative rest, avoid the movements that hurt, and gentle pain-free ankle movement to keep things mobile. Skip aggressive stretching — pulling on healing tissue is counterproductive.
• Early loading: as pain allows, start gentle calf work — double-leg calf raises, isometric holds — well within your comfort. Loading is the stimulus that rebuilds capacity.
• Progressive strengthening: build toward single-leg calf raises through full range, then heavier and slower loading. The calf takes several times your body weight when you run — rehab has to reach those loads.
• Return to running & sport: reintroduce jogging, then change of direction, then explosive push-off and sprinting. Each stage is earned by tolerating the last one without a flare.

Calf Strains in Cyprus: What I See in the Clinic

Certain patterns come through my door in Nicosia again and again:

• The padel boom. Padel has exploded across Cyprus, and it's the perfect storm for tennis leg — explosive lunges, quick net-to-baseline changes, and a lot of players over 35 who play hard on weekends without much preparation.
• Runners and the summer heat. Our running clubs train through brutal heat. Fatigue and dehydration change how the calf fires late in a run — that's often when soleus strains show up.
• Triathletes and Ironman. The run leg off the bike loads the calf in a fatigued state, and high training volume leaves little room for the muscle to recover between sessions.
• Combat sports. Muay Thai and kickboxing athletes live on the balls of their feet, bouncing and checking kicks — repetitive, explosive calf load that both strains the muscle and, over time, sets up the tendon (see our combat sports injury prevention guide).

Stopping It Coming Back

• Build real calf strength. Most people never train the calf hard enough. Heavy, full-range calf raises — both straight-knee (gastrocnemius) and bent-knee (soleus) — are your best insurance.
• Respect the loading gap. Don't jump from "pain-free" back to full sport. Bridge it with graded running and change-of-direction work.
• Manage your training spikes. Sudden jumps in volume or intensity — a padel tournament, a race build-up — are classic triggers. Ramp up gradually.
• Don't ignore the warning tightness. A calf that keeps feeling "tight" mid-game is often a strain waiting to happen. That's the time to get assessed, not after it tears.

The Bottom Line

A calf strain is not a serious injury — but it is a sneaky one, because it feels healed long before it actually is. The muscle stops hurting, you go back to sport, and it tears again in the same spot. The way to break that cycle is to rehab capacity, not just pain: load the muscle progressively until it can handle everything your sport throws at it.

Come back once — the right way — instead of coming back three times.

Antonis Petri, BSc, OMPT

Lead Clinician & Founder at Right Track Physiotherapy. Clinical Instructor in the Department of Life and Health Sciences at Frederick University. A former amateur footballer with over a decade on the pitch, he specializes in sports rehabilitation and return-to-performance programs for athletes in Cyprus.