Movement, the strongest way

For a long time, exercise was considered something cancer patients had to earn: first get healthy, then get back to it. That has now reversed. Today, every major recommendation states that exercise is essential. while Treatment and its aftermath are beneficial – not only for mood, but measurably for fatigue, energy, sleep, anxiety, and quality of life. The 2019 international consensus of sports medicine experts describes the evidence for this as "strong." That's a word these bodies rarely use.

What the new study really shows

Until 2025, observations had shown that people who exercised more after a cancer diagnosis lived longer. However, no one could say whether exercise was the reason or simply that healthier people tend to be more active. Then a study dissected this: 889 people with colon cancer who had completed their treatment were randomly divided into two groups. One group received informational materials. The other was supported for three years by an exercise coach – initially every two weeks, later less frequently – with the goal of permanently increasing their walking, cycling, and swimming habits. No equipment, no supplements, just guidance.

After five years, around 80 out of 100 patients in the exercise group were relapse-free, compared to 74 in the other group. After eight years, around 90 out of 100 patients in the exercise group were alive, compared to 83 in the other group. This is the first evidence of its kind, and it initially applies to colorectal cancer and to people whose treatment had been completed. Whether the same holds true for other types of cancer is currently being investigated. But the trend is clear, and it aligns with all previous observations.

Why are we explaining this in such detail?

Because that's what we're looking for on this entire page: something natural, something the body does itself, something that costs nothing, that no one sells – and yet stands up to scrutiny in studies. Movement is the proof that it exists. We measure everything else in this area against it.

People with fatigue are usually advised to rest. This advice is well-intentioned but wrong. With ordinary tiredness, rest replenishes energy reserves. With fatigue, this doesn't happen – the energy reserves aren't depleted, they're disrupted. Lying down leads to muscle loss, reduced fitness, and a loss of circadian rhythm, all of which exacerbate exhaustion the next day. This creates a downward spiral that many sufferers don't recognize as such for months because each step seems reasonable.

What the body needs

The opposite approach: small, regular movements, especially on days when you don't feel like it. Not to exhaust yourself, but to signal to your body that it's needed. In studies, it's almost always endurance exercise that makes the difference: walking, cycling, swimming, at an intensity where you can still talk. Strength training is added because muscles are where fatigue tends to accumulate.

What is often overlooked in this context: Fatigue also has causes that can be treated. Anemia, thyroid issues, pain, sleep disorders, depression, certain medications. The treatment team should look at these things before blaming everything on exercise. Both factors combined are the approach the guideline suggests.

Our position on this

We believe that fatigue is the point where family members can help the most—and also make the most mistakes. "Rest" is the phrase almost everyone says. "Come on, let's walk to the corner" is the phrase that helps. Anyone supporting someone with fatigue should know this.

The problem with target values is that they are discouraging when you're far from them. For someone who can only manage 20 meters after surgery, "150 minutes per week" isn't helpful, it's an insult. That's why the most important sentence on this page is this: The effect begins with the first step, not with the target value. The studies show that those who benefit the most are precisely those who start with very little.

What carries at the beginning

• Everyday life matters. Taking the stairs instead of the elevator, walking to the bakery, talking on the phone while standing, setting the table yourself. This isn't just a cliché about replacing exercise – in the large colon study, walking was the most frequent form of movement.
• Fixed time, small goal. Go outside at the same time every day, even if it's just for five minutes. Regularity is more important than duration. Those who intend to go "sometime today" usually don't.
• For two people. It's easier with someone else, and that's not a weakness, but rather the reason why group training performs better than individual training in studies. If you don't have anyone to train with, you can find information about available groups in Chapter 6.
• Plan for bad days. There will be days when nothing works. They are not a setback, they are part of the process. Start again the next day, not from scratch, but from where you left off.
• Outdoors, if possible. Light, air, and path together. Why this is more than the sum of its parts is explained on the page about... Key topic: Sunlight.

If the bed is the place

There's something you can do there too. Circle your feet, pull your legs in and straighten them, press against the mattress, sit up and lie down again. Many wards have physiotherapists who can guide you through these exercises, and a stationary bike that can be brought to you. It's worth asking. The muscles you lose in two weeks of lying down take months to regain – that's why movement starts so early on the ward.

When people talk about exercise during cancer treatment, most think of walking and cycling. That's correct, and it's a good start. But the body loses one thing above all else when battling cancer: muscle mass. The tumor consumes protein, the treatment consumes protein, bed rest consumes protein – and the body takes it from the muscles when it can't get it anywhere else. This is called sarcopenia, and it's one of the strongest predictors of how someone will fare after an illness. Not the number on the scale. The muscles.

What power means here

Not dumbbells and gyms, at least not at the beginning. Strength means: getting up from a chair without using your hands, climbing stairs, carrying a shopping bag, getting out of the bathtub. Those who can do these things have the strength that counts. Those who lose it lose their independence, and that's what ultimately determines their quality of life. That's why all the recommendations say: In addition to endurance, something for strength. Large muscle groups, few repetitions, gradually increased. Your own body weight is sufficient for a long time.

Why both together?

Endurance trains the heart, lungs, and blood vessels—the transport system. It's what reduces fatigue and improves sleep. Strength training maintains the tissue where the transported substances arrive. One without the other is only half the battle: those who only walk still lose muscle mass. Those who only build strength remain tired. In the colon study, endurance was the focus; in the recommendations for fatigue and quality of life, both are addressed.

And one more thing that contributes to the power: Protein. A muscle that is trained but not nourished will not grow. Those who have little appetite during treatment will find information on the... Page Acid, Sugar, Diets the chapter on that.

• Bone. When bones are affected, they bear less weight. Then, impacts, jumps, and weights on the affected side become the issue, not the movement itself. The team knows which bones are involved and what they can withstand.
• Blood. When blood counts are low—too few red blood cells, too few platelets, too few immune cells—the way you feel changes. With a weak immune system, you should avoid crowded halls and swimming pools; with low platelets, anything that causes bruising; and with anemia, avoid exertion that causes dizziness. Have your blood work done, then go for it.
• Heart. Some treatments put a strain on the heart. In these cases, endurance training is not avoided but supported, often with a preliminary stress test. Anyone experiencing heart palpitations, shortness of breath, or chest pressure during exertion should stop and call.
• Annoy. Numb feet and unsteady hands are common after some treatments. Then the risk of falling becomes a concern. Practice balance, wear sturdy shoes, and cycle on a stationary bike instead of on the road.
• Recently operated on. After surgery, there are periods when certain movements are prohibited – lifting after abdominal surgery, raising the arm overhead after breast surgery. These periods are short, and the team will inform you of them.
• Port, catheter, open wounds. No swimming. Everything else is fine.
• Fever. No training. If you develop a fever while undergoing treatment, call immediately, regardless of anything on this page.

And a sentence for your next conversation

„"I want to exercise more. Is there anything I need to be aware of right now – bones, blood values, heart, wounds?" This question almost always gets a clear answer, and most of the time it's: Yes, go.

Many people affected by cancer only find out about this years later. That's why it's included here in a separate chapter: Exercise during cancer treatment is a service you are entitled to, with guidance from people who are specifically trained for this – not as a favor, but as a right.

The four paths, in order

• At the station. Physiotherapy and exercise programs are part of the treatment in many clinics. Some centers have their own exercise therapists. Ask about them on your first day.
• The follow-up rehabilitation. Immediately following hospital treatment, there is a follow-up rehabilitation program, usually lasting three weeks, with exercise as an integral part. The hospital's social services department applies for it, often during the hospital stay.
• Rehabilitation sports on prescription. Afterwards, or even concurrently: the form is called Form 56, any doctor can fill it out, and the health insurance company approves it. Then you join a group, once a week, with people who have had the same experience. Many remain members of the association after the 50 sessions.
• The cancer counseling center. Free of charge, in every major city, and she knows which groups are available near you, including for yoga, qigong, and hiking. The Cancer Information Service has the addresses.

Our position on this

A group is more than just a place to exercise. Studies show that people persevere longer in groups than when exercising alone, and anyone who has ever been in a cancer support group knows why: there's no need to explain anything. We advise you not to see rehabilitation exercise as an obligation, but for what it is – an hour a week with people who know what it feels like, and a body that can do things again.