Post-cancer fatigue: what it is, and how exercise can help you treat and overcome it

Top triathlete and oncology specialist Lucy Gossage explains how exercise can help with post-cancer fatigue

What is post-cancer fatigue?

Cancer-related fatigue (CRF) is very common. It can be caused by the cancer itself or the side effects of treatment, and is described by up to 90% of people with cancer at some point.

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CRF generally gets better after treatment finishes but it can take several months, or even years, as everybody is different. You can’t rush your recovery and it’s important that you listen to your body while you’re recovering.

The good news is that being active is one of the best treatments for CRF. However, you probably won’t just be able to jump in with the same training you used to do – and not just because of the ongoing Covid-19 pandemic – and will probably have to build up slowly.

How to start training with post-cancer fatigue

I’d suggest setting yourself small, simple goals to start off with. They might be as simple as going for a walk, doing a few lengths in the pool (when they’re open and it’s safe to do so) or pedalling on an exercise bike for 10 minutes (as gyms are out for the foreseeable, can you set up your race bike at home on a turbo?).

Don’t worry about pace, distance, power or anything else. Just focus on gradually increasing your activity levels as you find what level of exercise makes you feel less tired rather than more tired.

There will be a tipping point that’s unique to you and nobody can find that other than you. Over time, you’ll find you can do more but you may need to be patient as your body gets used to not being on treatment.

Anecdotally, lots of people say their heart rate zones are very different after cancer treatment, so, if you’ve previously trained with a heart rate monitor, you may find you need to adjust your training zones.

After some cancer treatments, like breast cancer treatments, some people are also on hormone treatment for several years, which can also alter how you feel and how your body responds to exercise. Patients often tell me that it takes time for them to find their ‘new normal’ and it’s likely that your ‘new normal’ will evolve over time as your fatigue lessens.

Don’t be scared to exercise – it will definitely make you feel better. But do be kind to yourself and don’t do too much too soon.

For when group activities/events start running again, and if you’re not in self-isolation, you could check out ‘5K Your Way, Move Against Cancer’ (, a community-based initiative linked to Parkrun. If there’s a group local to you, it may be a good place to meet like-minded people living with, or recovering from, cancer so you can share experiences.

Good luck. That triathlon finish line will be so incredibly special!

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Top image credit: Getty Images