Exercise in Cancer

The evidence is now strong enough that oncology and exercise bodies recommend both aerobic and resistance exercise during active treatment with curative intent to reduce side effects. Perhaps the most important and counterintuitive message concerns fatigue: cancer-related fatigue, reported by many people during chemotherapy or radiotherapy, is improved by regular adapted activity rather than by rest, so advising a tired patient to stay gently active is usually the right course, while severe or newly worsening fatigue is assessed for causes such as anaemia, infection, treatment toxicity, cardiopulmonary disease or disease progression. Rather than a fixed prescription during active treatment, activity starts from the person's current ability and treatment-related symptoms and builds gradually, with around 150 minutes of moderate aerobic activity a week plus resistance training on two to three days as a longer-term aspiration. There is no single best activity; the one a person enjoys and can sustain is the one that helps, and any reduction in sedentary time is worthwhile for someone who is very unwell.

While activity is safe for most, several situations need specific adjustment rather than avoidance. Where cancer has spread to bone, exercise is guided by specialist risk assessment based on the site of the lesion, pain, fracture risk, treatment and the movement demands of the activity, rather than a blanket rule; often this means controlled, lower-impact activity, though appropriately selected resistance or loading may be possible. Lymphoedema, or the risk of it after breast cancer surgery, is no longer a reason to avoid upper-body exercise: supervised, gradually progressed resistance training is safe and does not worsen lymphoedema, and may help. During treatment that lowers blood counts, no single universal neutrophil, platelet or haemoglobin cut-off decides whether to exercise; activity is modified according to symptoms, bleeding and infection risk and the oncology team's advice, so that vigorous or contact activity and public gyms may be limited when counts are very low. Some treatments, including anthracycline chemotherapy, the targeted drug trastuzumab and radiotherapy near the heart, can affect the heart, so while aerobic activity is generally encouraged, new cardiac symptoms or known cardiac dysfunction warrant clinical or cardio-oncology assessment before activity is progressed. Hormonal treatments for breast and prostate cancer lower oestrogen or testosterone and thin bone, so weight-bearing and resistance activity are particularly valuable. People with a stoma or a central line build up core and upper-body loading gradually, and fatigue is managed by pacing.

A simple way to structure the safety assessment is to check bloods, bones and heart. On bloods, neutropenia during the treatment nadir is a reason to favour home-based exercise over public gyms and swimming pools rather than to stop exercising; thrombocytopenia calls for avoiding contact and high-impact activity because of bleeding risk; and significant anaemia means reducing intensity and working to symptoms. On bones, known bone metastases require avoidance of high-impact activity, heavy spinal loading and forceful twisting, because of fracture and cord compression risk, with a supervised programme where there is doubt. On heart, cardiotoxic treatment such as anthracyclines or trastuzumab means new cardiac symptoms warrant assessment rather than attribution to deconditioning.

Two other modifiers recur. Chemotherapy-induced peripheral neuropathy impairs balance and raises falls risk, so seated or supported options are safer while it persists. And the fatigue paradox is worth stating explicitly to patients: cancer-related fatigue is one of the few symptoms that reliably improves with exercise rather than with rest, and expecting otherwise is the commonest reason people stop.

Two windows deserve particular attention. Prehabilitation, becoming fitter in the weeks before surgery or other treatment, is an emerging field, most studied before major surgery, where preoperative exercise as part of a tailored, often multimodal programme may improve functional recovery and may reduce complications or hospital stay, with the evidence varying by operation and intervention, and the time between diagnosis and surgery often short. After treatment, the advice to be active is the same as during it, increased gradually as the person recovers, and it supports recovery from fatigue, protects bone and heart health, and helps manage weight and mood. Referral to a physiotherapist, cancer exercise specialist or clinical exercise physiologist through local exercise referral schemes provides tailored, supervised support, particularly for people with complex needs or advanced disease, for whom activity still improves fitness, mood and wellbeing.

• •The guiding principle is to avoid inactivity, and to recommend aerobic and resistance exercise before, during and after treatment.
• •Regular adapted activity reduces cancer-related fatigue; assess severe or worsening fatigue for causes such as anaemia, infection or disease progression.
• •Start from current ability and symptoms, building towards about 150 minutes a week plus resistance work on two to three days as a longer-term aim.
• •For bone metastases, use specialist risk assessment of lesion site, pain and fracture risk, not a blanket lower-impact rule.
• •Supervised progressive resistance training is safe in lymphoedema and does not worsen it.
• •Prehabilitation before major surgery may improve recovery and may reduce complications or hospital stay, as part of a tailored programme.