Exercise during radiotherapy: is it safe and does it help?

Usually yes, if you build up gently and your team agrees. Cancer Research UK says that "if you have cancer, you should check with your doctor before starting any exercise" [2]. It also says "people with cancer should try to be active and get back to their normal activities as soon as possible" [2].

Research on exercise during radiotherapy on its own is limited. A 2023 Cochrane review looked for trials in people having radiotherapy with no other cancer treatment and found only three studies with 130 people, all with breast or prostate cancer [4]. Two of those studies recorded adverse events linked to exercise "and reported no events" [4]. The reviewers still describe their confidence as low, because the studies were few and small [4].

If you are also having chemotherapy, the advice in our guide to exercise during chemotherapy applies as well, including the cautions about blood counts and lines.

It may. The international exercise guidelines for people with cancer (the ACSM roundtable, 2019) found that exercise "can significantly reduce cancer-related fatigue both during and after treatment" [7].

Two trials tested exercise during a course of radiotherapy directly:

• Prostate cancer. In one trial, 121 men starting radiotherapy were given usual care, resistance (strength) exercise or aerobic exercise for 24 weeks; "In the short term, both resistance and aerobic exercise mitigated fatigue" [5].
• Breast cancer. In another trial, 160 women having radiotherapy after surgery did either 12 weeks of progressive strength training twice a week or a relaxation class [6]. The authors concluded the strength programme "was a safe, feasible and efficacious strategy to improve cancer-related fatigue" [6].

An honest limit: nearly all of this research is in breast and prostate cancer [4][5][6]. The ACSM roundtable also says the effect of exercise on how well people tolerate radiotherapy is still unknown [7]. For a fuller guide to tiredness from any cancer treatment, see cancer-related fatigue.

Radiotherapy tiredness usually builds up over the course rather than starting on day one [1]. Cancer Research UK explains that "your body is using energy to repair damage to healthy cells from the radiation" [1].

Daily travel to hospital adds to it: Cancer Research UK lists travelling "quite a way for your radiotherapy appointments" as a cause of tiredness [1]. It also notes that "you might not feel tired at the beginning of your course but might do towards the end", and that you "might feel tired during your radiotherapy treatment and for a few weeks afterwards" [1]. Plan lighter activity for the later weeks.

There is no set rule, so choose the time when you have most energy. Cancer Research UK suggests you "pick the time of day when you are feeling least tired" and stresses balancing exercise "with resting" [1].

Ways to fit activity around daily appointments:

• Start with "short chunks (10 to 15 minutes) of gentle activity", such as a walk, and "gradually build up", as Cancer Research UK suggests [2].
• Have short naps if you need them and drink plenty of water, as Cancer Research UK advises [1].
• Scale back on days when side effects are worse; the amount you do "depends on how much you're used to exercising" [1].

The ACSM roundtable's fatigue programmes were mostly moderate aerobic exercise for 30 minutes, three times a week, for 12 weeks, with strength work twice a week as an option [7]. Many people having radiotherapy will need to start well below that.

Ask your radiotherapy team first, because UK advice differs and chlorine can irritate the treated skin. Macmillan advises: "You should avoid swimming, as the chemicals in the water can irritate your skin" [3]. Cancer Research UK says: "If your skin is not blistered or peeling, you may go swimming" [8].

If your team agrees to swimming, Cancer Research UK advises you to "shower immediately afterwards to wash off the chlorine and then apply moisturiser", and "You must stop swimming if it irritates your skin" [8]. Do not swim with broken skin: "you shouldn't swim until it is healed" [8]. Macmillan adds that "After treatment ends and any skin reaction has gone, it is fine to swim again" [3].

If you have a central line or PICC line, Macmillan says "you should avoid swimming" because of the risk of infection [3]. For PICC lines, Cancer Research UK also notes "There may be an infection risk from using a public pool" [12]. Either way, ask your team before you swim.

Reduce rubbing and keep the treated area out of the sun. Macmillan advises: "If you have a skin reaction due to radiotherapy, wear loose fitting clothing when exercising" [3].

• Friction. Skin reactions are more likely where "skin rubs against skin, such as under the breast" [8]. Choose loose clothing; Breast Cancer Now suggests "a soft cotton bra or vest" [9].
• Washing after exercise. Cancer Research UK advises you to "wash your skin gently with soap and water and gently pat dry" and not to rub the area [8].
• Sun. Protect the treated area outdoors and "continue to protect the treated area from the sun for at least one year after you have finished treatment", using SPF 50 [8].
• Timing. Skin reactions develop "gradually throughout your course" and "usually settle down 2 to 4 weeks after your treatment ends" [8]. Tell your radiographer about any soreness [8].

Yes. Side effects depend on the area treated.

Pelvic or tummy radiotherapy (for example bowel, bladder, prostate, womb or cervical cancer). Cancer Research UK says "It is normal to have diarrhoea during or after radiotherapy to your abdomen or pelvis", and that it can leave you weak and tired, "so it is important to rest if you need to" [10]. Drink plenty, as "you can easily get dehydrated" [10]. Plan walking routes with toilets nearby if you have urgency, and tell your team about any bleeding or painful passing of urine [10]. Some people "only leak urine when you laugh, sneeze or exercise" [10]; our prostate cancer and bowel cancer guides cover pelvic floor work.

Breast or chest radiotherapy. Breast Cancer Now says "Continuing to do arm and shoulder exercises during radiotherapy and for several months afterwards may help minimise or prevent any stiffness or discomfort" [9]. Part of the lung behind the area can become inflamed, which "may cause a dry cough or shortness of breath"; speak to your treatment team if you notice it [9]. Shoulder and arm exercises after surgery are covered in our guide to shoulder exercises after breast surgery.

Head and neck radiotherapy. Leeds Teaching Hospitals NHS Trust says "Side-effects tend to build up from about the second week of treatment" and "generally last a number of weeks or months after the treatment has finished" [11]. It advises "Try to continue with some of your normal routines and activities if possible" and says "Gentle exercise can help reduce the symptoms of fatigue" [11]. If your jaw is in the treated area and stiffness is a risk, "you will be given jaw opening exercises to do", and "Doing the exercises regularly will help with this problem" [11]. "Continue to complete any swallowing exercises advised by your SLT throughout your treatment" (SLT means speech and language therapist) [11].

Stop and get advice if you get sudden new symptoms. Macmillan lists: "feeling dizzy", "chest pain", "a racing heart", "breathing problems", "feeling sick", "unusual back or bone pain", "unusual muscle pain" and "a headache that does not go away", and says "Speak to a doctor straight away if you notice any of these, or any other symptoms" [3].

During radiotherapy, also contact your care team if you:

• notice a new dry cough or shortness of breath after chest or breast radiotherapy [9]
• have any bleeding, or pain when passing urine, after pelvic radiotherapy [10]
• have sore, itchy or broken skin in the treated area [8]

Expect side effects to keep going for a while after the last session, then build up slowly. Skin usually settles within 2 to 4 weeks [8], and Breast Cancer Now says tiredness "may last for weeks or months after your treatment has finished" [9].

Increase activity in small steps as your energy returns, keep up any arm, shoulder, jaw or swallowing exercises you have been given [9][11], and keep protecting the treated skin from the sun for at least a year [8]. Our guide to exercise after cancer treatment covers the longer-term targets and late effects.

A clinical exercise physiologist (CEP) is a university-trained professional who designs exercise for people with long-term conditions, including cancer. They can plan exercise around daily radiotherapy, fatigue and area-specific side effects, and work alongside the physiotherapists, speech and language therapists and dietitians your hospital team may refer you to. Request a match with a verified clinical exercise physiologist through The Health Nav.