Exercise and the Late Effects Nobody Warned You About

Here is something you were almost certainly not told when treatment ended.

The thing that will do more for your fatigue, your fear of recurrence, your mood, your sleep, your nerve damage, your risk of the cancer coming back, and your long-term survival than almost anything else available to you — is free, requires no prescription, no referral, and no equipment, and you can start it today.

It is not a supplement. It is not a diet. It is not a mindfulness programme.

It is exercise. And the reason you probably weren't told is that the system that should have told you either didn't know, or knew and didn't manage to say it in terms that meant anything, or said it and then watched you nod and didn't follow through on what saying it actually required.

This is not a chapter about getting fit. It is not going to tell you to think positively or make the most of your recovery. It is going to tell you what the evidence has actually established — some of which is genuinely extraordinary and changes the picture — and then it is going to tell you what to do about it today, specifically, in your situation, with the body you currently have and the energy you currently don't.

It will also cover some things that happen to the body after cancer treatment that nobody warns you about. The feet that feel strange. The arm that swells. The teeth that started crumbling. The hearing that shifted. Because you deserve to know what these are, why they happen, and what actually helps — rather than spending months wondering whether you are imagining something that has a name and a management route and a person you can call.

The thing that makes cancer-related fatigue worse — and why you've probably been doing it

When you are exhausted after cancer treatment — and the exhaustion is unlike anything ordinary tiredness — the instinct is to rest. Of course it is. You are tired. Resting when you are tired is what humans do. And the advice you may have been given by well-meaning people, including sometimes clinical ones, is some version of take it easy, listen to your body, don't overdo it.

The evidence says that advice is wrong. Not partially wrong. Wrong.

More than 180 studies covering more than 22,000 cancer patients have now established clearly that exercise — not rest — is the primary evidence-based treatment for cancer-related fatigue. The specific exhaustion that comes with and after cancer treatment is not relieved by rest. Rest makes it worse. It deepens the deconditioning, worsens the fatigue cycle, and removes the one thing that most reliably shifts it.

The first randomised controlled trial on this was published in 1989. Researchers at Ohio State University took breast cancer patients on chemotherapy and put half of them through ten weeks of aerobic training. Improved function, reduced nausea, better body composition. In 1989. That finding has been replicated and expanded for thirty-six years. Exercise is more effective for cancer-related fatigue than any pharmacological intervention that has been tested against it.

This is the thing a friend would have grabbed you by the arm about. This is the light bulb. The treatment that feels counterintuitive — getting moving when everything in you is saying lie down — is the one that actually works. Rest is the trap. Movement is the way through.

And then there's the recurrence question

If that wasn't enough, here is the part that stopped researchers in their tracks.

In June 2025, results were published from a trial called CHALLENGE — nearly nine hundred people who had finished treatment for colon cancer, followed for up to fifteen years. Half received education about diet and exercise. The other half received the same education plus a supervised exercise programme for three years. The result: the exercise group had a 28 per cent reduction in the risk of recurrence, new primary cancer, or death.

Twenty-eight per cent. In a randomised controlled trial. Not an observational study where active people happen to do better. A trial where people were randomly assigned to exercise or not, and the ones who exercised were significantly less likely to have their cancer come back.

This is one study in colon cancer. But it sits in a much larger landscape. A meta-analysis published in 2025 pulled together data from 151 cohorts covering nearly one and a half million cancer patients and found that people who were physically active after diagnosis had a 31 per cent lower risk of dying from breast cancer, 29 per cent lower from colorectal cancer, 27 per cent lower from prostate cancer, and 24 per cent lower from lung cancer. An earlier analysis of more than fifteen thousand patients found that higher physical activity after cancer diagnosis was associated with a 45 per cent reduction in the risk of recurrence.

These are not small effects. They are comparable to the benefits of some chemotherapy agents. And exercise is free, has no toxicity, and the research has been building for decades.

Why aren't you sitting in a supervised exercise programme right now? That is not a rhetorical question. It is the question the evidence demands.

Why you weren't told — the ICB conversation

Mike Kinnaird, who built this app, spoke with representatives of an Integrated Care Board — one of the NHS bodies responsible for commissioning healthcare services in a local area — to discuss an exercise programme they were offering to cancer survivors. He mentioned the long well-established history behind exercise and cancer. He asked if they prescribed exercise for the individual patient inline with the mountain of research out there. They said they didn't know about prescribed exercise, didn't see how that would work for cancer patients — surely they'd resist that. In fact they knew nothing of the decades of research, just that exercise seemed a good idea.

The people commissioning the programme didn't know why it existed or whether or how it worked.

This is not an unfortunate blip. It is the specific and maddening result of a system where random ideas are dreamt up to offer a 'good idea' with content which may or may not be appropriate to a given patient. The organisers in this case were surprised and sceptical to hear that targeted, researched exercise in cancer for individual outcomes has been around for decades. Basically, they stumbled on it.

In truth, the first published observation connecting muscular activity and cancer goes back to 1921, when Sivertsen and Dahlstrom reported that muscular work associated with occupation was impacting cancer mortality. That paper was published in the Journal of Cancer Research. The original observation came from watching farmers who kept working into their seventies and eighties showing markedly lower cancer mortality than those who retired early.

For most of the history of exercise oncology, the conversation went roughly like this: exercise is good for you, you should do more of it, here are the general guidelines. It was advice in the way that eating well is advice — true, well-meaning, and almost entirely useless to a person who is exhausted after chemotherapy and doesn't know where to start or what their body can actually manage.

The shift that has been gathering pace over the last decade is a different idea entirely. Not exercise as general encouragement. Exercise as prescription — specific, individual, dosed, monitored, and adjusted the way a drug is adjusted when the response isn't what was expected.

The language is deliberate. When an oncologist prescribes chemotherapy, they don't say roughly this much of something broadly cytotoxic should help, crossed fingers. They specify the drug, the dose, the schedule, the monitoring protocol, and the criteria for adjustment. The argument that is now being made — and taken seriously in the most significant clinical guidelines — is that exercise deserves exactly the same rigour. The right type of exercise for this person's cancer type, treatment history, and current physical capacity. The right intensity, measured and controlled. The right frequency and duration. And a mechanism for monitoring response and adjusting the prescription when it isn't working or when capacity changes.

Researchers including Dr Kathryn Schmitz, one of the most influential voices in the field, have argued explicitly that exercise should be prescribed like a drug — with the same specificity, the same individualisation, and the same professional accountability. The American College of Sports Medicine's Moving Through Cancer initiative, launched in 2019, set a target that every person with cancer should be assessed for exercise and referred to an appropriate programme as a standard part of their care pathway. Not offered a leaflet. Assessed and referred — the same language used for any other clinical intervention.

The practical consequence of this shift is significant. It means that the question is no longer whether you should exercise after cancer treatment. The evidence settled that some time ago. The question is what the right exercise is for you — given your specific treatment, your specific late effects, your current fitness, your cardiovascular function, your bone density, your neuropathy, your fatigue pattern — and how it should be dosed and progressed. That is a clinical question with a clinical answer, and in a system that is catching up with the evidence, it is one that deserves a clinical response.

The gap between what the evidence supports and what most cancer survivors actually receive remains wide. Most people finish treatment and are told to take it easy, or to take gentle walks, or — if they are lucky — are handed a generic exercise leaflet. Very few are assessed, prescribed for, and monitored the way the evidence now says they should be. Knowing that this is a failure of provision rather than a reflection of what is possible is worth something. It means the conversation you have with your GP or your CNS about exercise after treatment is not a conversation about whether it might help. It is a conversation about what specifically you should be doing, who should be guiding it, and what the plan is. That is a different and better conversation to be having.

You are not behind on something you were never told. The system failed to tell you. That is not a comfort exactly, but it is accurate. And knowing it means you can stop waiting for permission that was never coming and do something about it yourself.

What to actually do — starting today

The guidelines that now exist across multiple major organisations — ACSM, ASCO, Macmillan — converge on the same prescription. One hundred and fifty minutes of moderate aerobic activity per week. Resistance training — working against weight — twice a week.

Moderate aerobic activity means you could hold a conversation but would not want to sing. A brisk walk. A gentle cycle. Swimming. Gardening at a sustained pace. Not performance. Not running. Movement at the level your body can currently manage, built on from there.

That is the target. Where you start is wherever you currently are.

If you can currently manage ten minutes of walking before you need to stop, start there. Walk ten minutes today. Tomorrow, the same. Next week, twelve minutes. The research does not establish a threshold below which movement has no value. It establishes a gradient — more movement, more benefit — and every point on that gradient is better than not moving at all. The people who try to jump straight to 150 minutes are the ones who injure themselves or exhaust themselves and stop. The people who start from where they are and build by ten minutes a week are the ones whose return holds.

The resistance training piece matters more than it sounds. The instinct after cancer treatment is to avoid anything that feels like exertion. But working against light resistance — even bodyweight exercises at home, even light weights, even resistance bands — is associated with improved fatigue, improved bone density, and benefits for lymphoedema that specifically overturn decades of wrong advice. More on that shortly.

If you cannot make yourself start alone — if the gap between knowing you should exercise and actually doing it is wider than willpower can cross — there are specific routes into supervised help.

Ask your GP this week about exercise referral for cancer patients in your area. Those words specifically. Some areas have cancer-specific exercise programmes; most GPs know less about them than they should, so being specific helps. Ask your CNS or oncology team whether the cancer centre has a clinical exercise physiologist you can be referred to.

Prehab4Cancer at prehab4cancer.com is an exercise referral scheme specifically for people with cancer — you can self-refer, which matters if you don't want to wait for a GP. Macmillan's Move More programme operates across Scotland and parts of England with trained cancer exercise specialists — ask Macmillan's Support Line on 0808 808 00 00 what is available in your area. Maggie's Centres run exercise classes specifically for people affected by cancer, free, walk-in. The Maple Tree Cancer Alliance at mapletreecanceralliance.org offers free supervised sessions and their resources and research are freely available to anyone.

If none of those exist locally, start walking. Today, not next week. The research does not require supervision to apply to you.

The feet — and why they feel the way they do

If your feet feel numb, or tingly, or burning, or strangely sensitive to temperature, or as if you are walking on cotton wool, or as if the floor is further away than it used to be — this has a name and it is not imagination.

Peripheral neuropathy is nerve damage caused by certain chemotherapy agents. Platinum-based treatments — cisplatin, oxaliplatin, carboplatin. Taxanes — paclitaxel, docetaxel. Vinca alkaloids. These drugs are highly effective at treating cancer. They can also damage the peripheral nerves — the ones that carry sensation and movement signals to and from your hands and feet. The result is the stocking-and-glove pattern: numbness, tingling, burning, or pain in the extremities, sometimes hypersensitivity where touch or cold or heat feel wrong. It affects between a third and two thirds of people who receive these treatments. For many people it improves in the months after treatment. For some it persists. For a proportion it is permanent.

There is no approved treatment that reverses the nerve damage. Duloxetine — an antidepressant — has the best current evidence for reducing neuropathic pain and is worth asking your GP specifically about if the discomfort is significant. Gabapentin and pregabalin are also used, with variable results. What specifically helps the function — the balance, the mobility, the fall risk — is exercise and physiotherapy. A systematic review published in November 2025 covering 26 randomised controlled trials found that balance training and supervised exercise reduce neuropathic symptoms, improve function, and reduce the risk of falls.

The point about falling is real. Neuropathy affecting the feet disrupts the body's sense of where it is in space. Dark rooms, unfamiliar steps, uneven surfaces — all of these are more hazardous than they were before treatment. Non-slip footwear and good lighting are not optional extras. And if your balance feels different from before, ask your GP for a physiotherapy referral specifically for balance training. That specific phrase — balance training — tells the GP and physio what you need.

For help and peer support on living with chemotherapy-induced peripheral neuropathy, the Peripheral Neuropathy Support Group at peripheralneuropathysupportgroup.co.uk is a UK community of people navigating exactly this.

The arm — and the exercise myth that was wrong

Lymphoedema is swelling caused by a build-up of lymph fluid when lymph nodes have been removed or damaged during cancer treatment. It affects approximately one in six women after breast cancer surgery involving the lymph nodes, and can develop months or years after treatment — not just in the weeks immediately following surgery. It can also affect the leg after treatment involving pelvic lymph nodes.

If you have persistent swelling in your arm or hand — swelling that is still there after a night's rest, that keeps coming back, that one side is consistently larger than the other — see your GP or CNS promptly. Do not wait. Early referral to a lymphoedema specialist produces significantly better outcomes than late referral. The Lymphoedema Support Network at lymphoedema.org can help you find services and understand what management involves.

Now the thing that was wrong for a long time, and that matters if you have or are at risk of lymphoedema.

For decades, women were advised to avoid lifting, avoid exertion, avoid resistance training. The logic was: work the arm harder, disrupt the drainage, worsen the swelling. It seemed reasonable. It was wrong.

Kathryn Schmitz, one of the world's leading exercise oncology researchers, led the work that overturned this advice. Her research established clearly that supervised progressive resistance training does not worsen breast cancer-related lymphoedema — and may improve symptoms and arm function. The blanket restriction that many women were given has not been supported by the evidence for years. Women have been unnecessarily limiting their lives based on guidance the research has moved beyond.

If you have lymphoedema or are at risk, ask your lymphoedema specialist specifically about supervised resistance exercise and what is appropriate for your situation. The answer is not: avoid all exertion. The answer is more nuanced and more hopeful than that.

The heart — what to watch for and when to act

Some cancer treatments can affect the heart, and this is worth knowing precisely rather than generally because the treatments that carry the risk are specific and the symptoms that warrant action are specific.

Anthracycline chemotherapy — doxorubicin, epirubicin, daunorubicin, used in breast cancer, lymphomas, leukaemias, sarcomas — can weaken the heart muscle. The damage can be irreversible and can appear not during treatment but months or years after it. Trastuzumab (Herceptin), used in HER2-positive breast cancer, is associated with cardiac dysfunction in a significant proportion of people who receive it with chemotherapy — usually reversible when the drug is stopped, but requiring monitoring. Radiotherapy to the chest, used in breast cancer and some lymphomas, can damage the coronary arteries and heart in ways that may not become clinically apparent for a decade or more.

The symptoms that should take you to your GP this week — not at your next routine appointment, this week — are: shortness of breath that is new or getting worse on exertion, palpitations or an awareness of your heartbeat, persistent ankle or leg swelling, chest pain or tightness, or a fatigue that feels different in quality from the cancer-related fatigue you already know about. If you have had any of these treatments and you are experiencing any of these symptoms, make the appointment and tell your GP specifically what treatment you received. That context changes what they investigate and how quickly.

If you have received anthracyclines, trastuzumab, or chest radiotherapy and have not had any cardiac monitoring since treatment ended, it is worth raising with your GP proactively. A baseline echocardiogram or clinical cardiac assessment is not automatically offered to everyone who needs it. Asking for it is not an overreaction.

The teeth — and why nobody warned you

If your teeth have deteriorated since treatment — decay in unusual patterns, crumbling at the gumline, sensitivity that wasn't there before — this has a mechanism and it is not bad luck.

Saliva is the mouth's protection system. It neutralises acid, washes away bacteria, and remineralises enamel continuously. Certain chemotherapy agents and radiotherapy to the head and neck reduce saliva production — dry mouth, known as xerostomia, is a recognised and common side effect. When saliva is reduced, decay can progress rapidly and in ways that look different from ordinary dental decay. The gumline is particularly vulnerable.

Tell your dentist specifically about your cancer treatment and when it finished. A dentist who understands the mechanism — not just that you had cancer, but that your saliva production may have been affected — will monitor differently, may prescribe high-concentration fluoride, and will advise on saliva substitutes that genuinely help. Macmillan has specific guidance on oral health after treatment at macmillan.org.uk — it is more detailed and more useful than most people are told in a follow-up appointment.

The hearing — and when to act on it

If your hearing has changed since treatment — conversations are harder to follow, certain frequencies sound different, there is a ringing or tone that wasn't there before — this too has a mechanism.

Cisplatin, a platinum-based chemotherapy used in testicular cancer, bladder cancer, lung cancer, head and neck cancers, and others, is ototoxic. It damages the sensory cells of the inner ear. The damage is usually permanent and typically affects higher frequencies first, which is why speech comprehension in noisy environments is often the first thing that feels different. It can be mild enough to go unnoticed for months or significant enough to affect daily life substantially.

See your GP and ask specifically for an audiology referral. Tell them you received cisplatin. The referral is straightforward, the assessment is straightforward, and appropriate support — which can include hearing aids — makes a significant practical difference to daily functioning. Action on Hearing Loss at actiononhearingloss.org.uk and the British Tinnitus Association at tinnitus.org.uk are both current UK resources for support and information.

What to do today

The question underneath this chapter

Why didn't anyone tell me?

Because the gap between what the research has established and what reaches the consultation room is — in exercise oncology in particular — one of the largest disconnects in modern cancer care. The evidence has been there for nearly four decades. The guidelines from every major organisation now say the same thing. The survival data is extraordinary. And most people coming out of cancer treatment are still being told to rest and take it easy and listen to their body.

The ICB that didn't know about its own exercise programme is not an outlier. It is a representative sample of a system where the knowledge is there and the dissemination has failed. The research outran the infrastructure. The infrastructure outran the communication. And you are the person at the end of that chain who deserved better information than you got.

You have it now. That is what this chapter is for.

If you are experiencing new or worsening shortness of breath, palpitations, chest tightness, or ankle swelling — particularly if you received anthracyclines, trastuzumab, or chest radiotherapy — contact your GP this week rather than waiting for a routine appointment. Cardiac effects from these treatments can develop long after treatment ends. They deserve prompt assessment.

• Prehab4Cancer (self-referral exercise scheme for cancer patients) — prehab4cancer.com
• Macmillan Move More (cancer-specific exercise — call to find your local programme): 0808 808 00 00
• Macmillan Support Line (free, 8am–8pm seven days, can identify local exercise support): 0808 808 00 00
• Maggie's Centres (free exercise classes for people affected by cancer, walk-in) — maggies.org
• Maple Tree Cancer Alliance (free supervised exercise for cancer survivors, research and protocols freely available) — mapletreecanceralliance.org
• Macmillan on physical activity and cancer — macmillan.org.uk/cancer-information-and-support/treatment/preparing-for-treatment/physical-activity-and-cancer
• Lymphoedema Support Network — lymphoedema.org
• Peripheral Neuropathy Support Group — peripheralneuropathysupportgroup.co.uk
• Action on Hearing Loss — actiononhearingloss.org.uk
• British Tinnitus Association — tinnitus.org.uk
• Macmillan on mouth care and dry mouth after treatment — macmillan.org.uk
• Cancer Research UK on exercise and cancer — cancerresearchuk.org/about-cancer/treatment/complementary-alternative-therapies/individual-therapies/exercise