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Cancer and exercise – how does it work? We ask the “Cancer Doctor”!
- Sara Carlsson
- 19 hours ago
- 3 min read
A healthy lifestyle with lots of movement generally makes us more resistant to diseases. But how does exercise work when you already have cancer? We find out, together with “The Cancer Doctor”, Robel Malki.
We have read Robel Malki’s book “Den där sjukdomen : om cancer och allt däromkring”, which was published in January 2026. In the section about exercise for people who already have cancer, “The Cancer Doctor” writes, among other things, about the many benefits of exercising when you have cancer. For example, it can slow down the development of cancer and reduce the risk of recurrence.
Robel Malki has answered three questions for us.
1. Why is exercise good for cancer patients?
– The effects of exercise on cancer are many and truly cover many layers. Physical activity after a cancer diagnosis reduces the incidence – and severity – of anxiety, worry, depressive symptoms, pain and fatigue. On top of that, sleep, cognitive function, quality of life and physical ability also improve. So it is not just the body that feels better, but the whole person.
– There are also studies that suggest that exercise can reduce the risk of recurrence and increase survival, especially in prostate and breast cancer. The strongest scientific support is for colon, breast, lung and prostate cancer.
2. Which heart rate zone has the best effect on cancer?
– Moderate intensity is the heart of the recommendations, but the most encouraging news is that intensity actually plays less of a role than whether you exercise at all. Studies have shown that just 3–5 minutes of intense exercise a few times a day can reduce the risk of cancer by over 30 percent. So all exercise counts!
– What constitutes “moderate intensity” is also completely individual. For someone who is exhausted from treatment, it may be a leisurely walk. For a well-trained person, jogging may be required to reach the same level. A simple guideline: You should be able to talk while you move, but still feel like you are exerting yourself a little.
3. Can high-intensity exercise have a negative effect on cancer?
– The short answer is that high-intensity exercise is generally considered safe, but with some important exceptions. During ongoing chemotherapy treatment, in the case of bone metastases, low blood counts or low white blood cell counts, exercise needs to be adjusted. If you have a fever or an ongoing infection, you should rest completely.
– But for the vast majority of people: Go at your own pace. For someone who has just gotten out of bed, a walk around the block is just as scientifically well-motivated as a gym session.
Exercise...
...builds muscle and burns any excess fat that may have been stored during hormone or cortisone treatment.
...affects the tumor environment by increasing blood flow, oxygenation and immune activation – which in turn allows you to recover better and the effect of the treatment is strengthened.
...reduces cancer-related fatigue.
...improves mood and reduces anxiety.
...can slow the development of cancer and reduce the risk of recurrence.
You can read about the above – and much more – in Robel Malki's book. There he also points out that you don't have to train like a bodybuilder, but that regardless of how your cancer looks, exercise is good. At your own pace and in your own way.
