Written by Zita Sham, Principal Physiotherapist at Phoenix Rehab, AHPC A1302159H.Clinically reviewed by Louise Yow, Principal Physiotherapist & Director, AHPC A1300363H.Last reviewed 3 November 2026.
Two weeks after the knee replacement, one calf is sore and tight on the walk to the kitchen. You did your exercises yesterday. Is it the exercises, or should somebody look at this today?
Most calf pain is a strain, a cramp or a tendon. A few causes are not, and those come first on this page. It covers the signs that mean a doctor today, calf pain after surgery on the leg, how to tell the common causes apart, why a calf keeps going at the same spot, and what to do when it is not improving.
What causes calf pain?
Calf pain usually comes from a muscle strain, a cramp, soreness after unfamiliar exercise, the Achilles tendon or a nerve from the lower back. Less often it comes from a blood clot, narrowed leg arteries or pressure building inside the muscle. A clot is the one to rule out first, especially after surgery.1
Key takeaways
- Calf pain is usually a strain, a cramp, delayed soreness, the Achilles tendon or a nerve from the back.
- A swollen, painful calf on one side is treated as a possible blood clot until a doctor has ruled it out.
- Recent surgery, a cast, bed rest and long journeys are all listed risks for a clot.
- Up to 60% of adults report leg cramps at night, usually in the back of the calf.
- Older age and a previous calf strain are the most strongly supported risk factors for a calf strain.
- A physiotherapist compares the two calves under load, including single-leg heel raises counted on each side.
First, the signs that mean a doctor, not this page
- Call 995 if you are suddenly short of breath, have chest pain or cough up blood, especially with a sore or swollen calf. A clot can travel to the lungs.1
- Go to the emergency department now if one calf is swollen, painful, warm, or red or darker than the other with no injury to explain it, especially after surgery, a cast or bed rest, a journey of more than four hours, or during or just after pregnancy.1 The same goes if the foot turns cold, pale or numb, if the calf is very tight and hard with severe pain that keeps climbing after an injury or a hard workout, or if severe muscle pain comes with dark, cola-colored urine.
- See a doctor the same day if the calf is newly sore or tight in the weeks after surgery on that leg, even without swelling. Phone your surgeon’s clinic. The same goes if you felt a snap at the back of the ankle and cannot rise onto your toes, if the foot has started to drag, or if the calf comes with a fever.
- See a doctor soon if the calf aches at the same walking distance and settles within minutes of stopping. That pattern can mean narrowed leg arteries, and it matters more if you smoke or have diabetes. The same goes for a tight, bursting ache at the same point in every run, gone soon after you stop.
None of these? Then the rest of this page is for you.
Calf pain after surgery on the leg
Surgery is one of the listed risks for a blood clot, and so is limited movement afterward.1 After a knee replacement, an ACL reconstruction, an ankle fracture fixation, an Achilles repair, or any weeks in a cast or boot, a new sore or tight calf gets a doctor’s check first. That holds even if you are doing your exercises, and even if the calf is not visibly swollen. Waiting for the next review is the wrong call here.
Once a clot has been ruled out, the reasons are usually plainer. Weeks in a boot or on crutches leave the calf smaller and weaker than the other side. The heel raises your therapist added are new load. After ankle surgery, the calf and the Achilles have to learn push-off again. Your surgeon’s protocol sets what the leg may do. See physiotherapy after surgery, the Ankle Fracture Surgery Recovery Program and knee replacement recovery.
Had an injection for the calf or the Achilles?
Whether an injection suits you is a question for your doctor, and so is what the leg may do in the days after it. Pain easing afterward does not tell you the muscle or tendon can take load. That is measured separately. More on physiotherapy after an injection.
Is it a strain, a cramp, the Achilles or something else?
| What you notice | What it usually points to | Who checks it |
|---|---|---|
| One calf swollen, warm and painful | A blood clot, until a doctor has ruled it out | Emergency department |
| A sudden sharp pain or a feeling of being kicked, pushing off or running; sore to press at one spot | A calf muscle strain | A physiotherapist |
| A hard spasm lasting minutes, often at night, sore afterward | A cramp | Usually nobody. A doctor soon if frequent or new |
| An ache in both calves a day or two after new or hard exercise | Delayed muscle soreness | Usually nobody |
| Pain low down near the heel, stiff for the first steps of the morning | Achilles tendinopathy | A physiotherapist |
| A snap at the back of the ankle, and you cannot rise onto your toes | An Achilles rupture | A doctor, the same day |
| Pain that runs from the back or buttock, sometimes with tingling | A nerve from the lower back | A physiotherapist or doctor |
| A tight, bursting ache at the same point in every run, gone soon after you stop | Chronic exertional compartment syndrome4 | A doctor soon, who arranges the tests |
| An ache at the same walking distance, gone within minutes of stopping | Narrowed leg arteries | A doctor soon |
The full detail is in pulled calf muscle, Achilles tendinitis and sciatica. If the pain sits behind the knee, start with back of knee pain or Baker’s cyst, because a burst cyst can look like a clot.
Why does my calf hurt at night?
Usually a cramp. Up to 60% of adults report leg cramps at night, most often in the back of the calf. A cramp lasts about nine minutes on average, and the soreness can stay for hours afterward. Stretching and massage are the usual first things to try, although the evidence for them is limited.2 A swollen calf is not a cramp. Follow the signs at the top of this page.
How long does calf pain last?
It depends on the cause. A cramp eases in minutes. Delayed soreness usually fades in two to three days. A mild strain often settles over one to three weeks, and a larger tear can take six weeks or more before running. The time a calf strain takes is judged by what the calf can do, not by the date.
What can you do for calf pain from walking too much?
If both calves ache after more walking than usual, with no swelling and none of the signs above, cut the distance for a few days and keep moving within comfort. A gentle calf stretch against a wall for 30 seconds, with the knee straight and then bent, and some heat afterward, are reasonable to try. If it came on suddenly at one spot, skip the stretching for the first few days and take shorter steps. One calf swelling means stop, and go to the emergency department now.
Why the calf keeps going at the same spot
The thinking goes: it stopped hurting, so it has healed. Stretch it and go again.
It went at the 8 km mark six weeks ago. You took two weeks off, did a few easy runs, and then it grabbed at the same spot on the first hard set. Now you run the first kilometer listening to your own leg. The calf sleeve lives in your gym bag. The race you signed up for is in March, and you have stopped telling people you are doing it.
In the research, older age and a previous calf strain have the strongest evidence as predictors of the next one.3 Stretching does not test what a calf can do. Can that side do as many single-leg heel raises as the other? Has anyone counted, with the knee straight and again with it bent? The bent-knee count matters because the deeper soleus muscle does more of the work in that position, and it does much of the work in distance running. If not, the calf went back on how it felt.
What a physiotherapist does with it
Finding the real problem is half the battle. Treating it is the other half.
At the Assessment & Treatment, a physiotherapist asks when it hurts, in your words, then checks the things that need a doctor before anything else. If anything suggests a clot, a rupture or poor blood flow, we stop and send you to a doctor with a letter. Scans and blood tests are theirs. After that come the tests a label does not give you: where the calf is sore to press and stretch, single-leg heel raises counted on each side with the knee straight and bent, ankle movement, the Achilles, the lower back and nerve tests, and how you walk or run.
Most of the 45 minutes is treatment: hands-on work, work on ankle movement, and loading the calf in steps it can take, measured up at each review. You leave knowing which stage you are in, what is limiting the calf, and a written plan.
Every appointment is one to one with your physiotherapist for the full 45 minutes, at five clinics: Orchard, Tampines, Serangoon, Tanjong Pagar and Jurong East. Bring your surgeon’s protocol if you have had an operation, and any ultrasound report.
Questions about calf pain
When should I worry about calf pain?
Go to the emergency department now if one calf is swollen, warm, red or darker and painful, especially after surgery, a cast, bed rest or a long journey. The same goes for a cold or numb foot, or severe pain that keeps climbing. Call 995 for sudden breathlessness, chest pain or coughing up blood. See a doctor the same day for a snap at the ankle.
What causes calf muscle pain without swelling?
Usually a mild strain, a cramp, delayed soreness after exercise, the Achilles tendon or a nerve from the lower back. A calf with no swelling still needs a doctor the same day after recent surgery, because a clot does not always swell much. Pain at the same walking distance can come from narrowed arteries.
What can I do to relieve calf pain after walking too much?
If both calves ache and there is no swelling, cut the distance for a few days, keep moving within comfort, and try a gentle calf stretch for 30 seconds with the knee straight and then bent. Sudden pain at one spot is more likely a strain, so skip the stretching for the first few days.
Why does my calf hurt at night?
Usually a cramp. Up to 60% of adults report night cramps, most often in the back of the calf. They last about nine minutes on average and can leave soreness for hours. Pain with one-sided swelling is not a cramp and needs the emergency department now.
How long does calf pain last?
It depends on the cause. A cramp eases in minutes, and delayed soreness usually fades in two to three days. A mild strain often settles over one to three weeks. A larger tear can take six weeks or more before running.
The same calf, the same spot, the second time this year? Get Assessed & Treated, and leave knowing what the two calves actually measure, which stage you are in, and what the next stage asks of it.
Sources: 1. NHS. Deep vein thrombosis (DVT). nhs.uk. 2. Allen RE, Kirby KA. Nocturnal leg cramps. Am Fam Physician. 2012;86(4):350-355. 3. Green B, Pizzari T. Calf muscle strain injuries in sport: a systematic review of risk factors for injury. Br J Sports Med. 2017;51(16):1189-1194. 4. Buerba RA, Fretes NF, Devana SK, Beck JJ. Chronic exertional compartment syndrome: current management strategies. Open Access J Sports Med. 2019;10:71-79.
Where are you with this right now?
1. It is settling on its own
Most strains and flare-ups settle over weeks with sensible load management and a return to normal movement. Improvement is judged over a month, not over a day, and good days and bad days inside that are usual. If you are doing more this month than last, and sleeping better, it is behaving the way it should. You do not need us for this, and we would rather say so.
2. It has stopped improving
You have adapted without noticing. The other side takes the load, you plan movements you used to make without thinking, and you have quietly dropped things you used to do.
What our patients say
Google reviews from our clinics in Singapore.
Pain is the first thing to leave. Movement and strength are the last things trained back, and most people stop before that part is done. That is the gap worth measuring, and it is not measured by how you feel on the day.
The Stalled Recovery Review is three appointments over three weeks with the same therapist, because what the body does under load cannot be read in one visit. The first finds what is limiting it. The next two measure how it responds.
3. You have had surgery, or you have a date
After a knee replacement, an ankle fixation, an Achilles repair or any weeks in a boot, a new sore calf gets a doctor’s check first. Once a clot is ruled out, bring your surgeon’s protocol and we work inside it. See physiotherapy after surgery, or all the recovery programs, hand and physiotherapy.
All of it runs on the same four stages. The Phoenix Recovery Protocol explains what each stage works on and what you have to meet to move up. No referral needed to start.
Next step
Find out which stage you are in
Pain is the first thing to leave. Movement and strength are the last things trained back, and most people stop before that part is done. One Assessment and Treatment is a single 45-minute appointment at $230, nett, no GST. Your therapist finds what is actually limiting you, treats it in the same appointment, and you leave with your current stage and a written plan.
Prefer to phone? Each of our five clinics has its own number on the clinics page. No referral needed to book.
Related reading
Where we are
Clinics across Singapore
ORCHARD
400 Orchard Road #12-12
Orchard Towers, S238875
NS22 Orchard MRT
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WhatsApp 8800 1830TAMPINES
9 Tampines Grande #01-20
Asia Green, S528735
EW2DT32 Tampines MRT
Physiotherapy and hand therapy in Tampines →
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265 Serangoon Central Drive #04-269
S550265 · Lift C only
NE12CC13 Serangoon MRT
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WhatsApp 8892 4121TANJONG PAGAR
10 Anson Road #02-77A
International Plaza, S079903
EW15 Tanjong Pagar MRT
Physiotherapy and hand therapy in Tanjong Pagar →
WhatsApp 8227 7074JURONG EAST
2 Venture Drive #02-02
Vision Exchange, S608526
NS1EW24 Jurong East MRT
Physiotherapy and hand therapy in Jurong East →
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