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Chronic lymphocytic leukaemia (CLL) is the most common adult blood cancer in the western world, and it predominantly affects older adults. Most people are diagnosed after the age of 70, but increasing numbers of younger people, some under 60, are also being affected.

CLL starts when a type of immune cell called a B cell – normally responsible for producing antibodies – becomes cancerous. This not only stops it from working properly, but also weakens the rest of the immune system.

For many people, CLL begins as a slow-moving, low-grade disease that doesn’t need immediate treatment. These patients are placed on “active monitoring,” where they’re regularly checked for signs of progression. Others, especially those with more aggressive forms of the disease, will need immediate and targeted treatment to destroy the cancer cells.

But regardless of the stage, CLL involves a prolonged and often unpredictable course. It’s associated with a higher risk of infections, secondary cancers and a heavy symptom burden that can affect quality of life for years.

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People on active monitoring often find themselves in a kind of medical limbo: well enough not to need treatment, but not well enough to feel secure. Fatigue, anxiety, social isolation and fear of infection are common. For those receiving treatment, side effects including nausea, bleeding, diarrhoea and extreme tiredness can make everyday life even more challenging.

Because CLL weakens the body’s ability to fight infection, many people begin avoiding places where germs might spread: busy shops, family gatherings, even the gym. But while this instinct is understandable, it can come at a cost. Over time, isolation and inactivity can chip away at physical fitness, reduce resilience and make it harder to recover from illness or cope with stress.

The role of exercise

Exercise is good for everyone but for people living with CLL, it can be life-changing. Our research shows that physical activity is strongly linked to fewer symptoms and a better quality of life. Fatigue, the most common and often most debilitating symptom, was significantly lower in people who stayed active. Many also reported reduced pain and a greater sense of physical wellbeing.

Cancer-related fatigue isn’t just feeling a bit tired. It’s a deep, persistent exhaustion that doesn’t improve with sleep or rest. The exact biological reasons behind it aren’t fully understood, but one thing is clear: regular movement helps. People who are more active tend to feel better – and live better.

The good news is that even gentle activity can make a difference. Low-intensity activities are safe for almost everyone and come with meaningful health benefits. Walking, yoga, swimming – anything that gets you moving – can help ease symptoms. In fact, research shows that just 12 weeks of regular exercise can reduce fatigue and improve day-to-day wellbeing.

People with additional health concerns, such as heart disease, diabetes or bone conditions, should take extra care. It’s always a good idea to speak to a doctor or physiotherapist before starting a new routine. The PAR-Q+ (physical activity readiness questionnaire) is a helpful tool to assess whether it’s safe to begin exercising.

Once cleared, the goal is to work up to the recommended activity levels: 150–300 minutes of moderate activity a week (like brisk walking or cycling) or 75–150 minutes of vigorous activity (like jogging or swimming), along with two sessions of muscle-strengthening activities per week. Start slowly and build gradually.

Because people with CLL are immunocompromised, it’s important to reduce infection risks while staying active. That might mean exercising outdoors, avoiding crowds, wearing a mask, or choosing quieter times at the gym. But, as long as precautions are taken, the benefits of movement far outweigh the risks.

Benefits of keeping active

In one of our pilot studies, people with CLL who had not yet started treatment showed smaller increases in tumour cell counts after 12 weeks of exercise. Their immune systems also appeared more robust, with stronger responses to abnormal cells. This research is still in its early stages, but it’s encouraging to see that exercise doesn’t appear to accelerate disease progression – and might even help to slow it.

The biggest improvements were seen in people who started off with the worst symptoms or poorest physical condition. In other words, those with the most to gain, gained the most. Older adults, in particular, seemed to benefit from even modest activity.

People receiving treatment were generally less active and reported lower quality of life than those who weren’t but their symptom levels were similar. That suggests physical activity might offer especially meaningful benefits for people going through treatment.

Exercise is already a well-established part of care for people with solid tumours such as breast or bowel cancer.

What’s different about CLL is that many people don’t receive treatment for years – yet still experience symptoms and lower quality of life. Our study shows that physical activity matters just as much for this group. Whether someone is on active monitoring or undergoing treatment, staying active can help ease symptoms, boost energy and improve daily life.

It’s a powerful reminder that even small steps can make a big difference and that living well with CLL isn’t just about waiting for treatment. It’s about reclaiming strength, mobility and agency, one movement at a time.

David Bartlett receives funding from the American Society of Hematology