After treatment

Exercise after cancer treatment

Not to get fit. Not to lose weight. Here is the mechanism-by-mechanism case for why movement matters more after treatment than it did before it.

Everyone finishing treatment gets told to exercise. Almost nobody gets told why, in terms specific enough to act on, and the advice usually arrives in the same breath as “eat well and try to reduce stress” — which is how it ends up filed alongside every other vague instruction you have been given.

So here is the specific version: seven mechanisms, each one measurable, each one relevant to a body that has been through treatment.

Inflammation

Regular exercise directly lowers hs-CRP and IL-6, the two most important inflammatory markers for cancer survivors. Chronic inflammation is a key driver of recurrence risk, and both markers are available in the free testing tier through most health systems.

This one matters because it is visible. You can have hs-CRP measured before you start and again ninety days later, and see what your own behaviour did to your own number.

Immune function

Exercise increases NK — natural killer — cell count and activity. NK cells are your body’s primary surveillance system against both cancer cells and viral reactivation, including Epstein-Barr virus.

Lymphatic drainage

Without movement, lymph stagnates. Each skip opens and closes lymphatic one-way valves through vertical bounce.

This is not cardio for fitness. It is mechanical pumping of a system that has no other engine after node removal.

It is also why the exercises were chosen for their mechanics rather than their calorie burn. Skipping creates vertical loading and unloading. The burpee creates thoracic pressure changes that flush the thoracic duct. The squat is weight-bearing and drives the large muscle groups that squeeze the vessels running alongside them.

Autophagy

Exercise activates autophagy, your body’s cellular cleanup system. Combined with a fasting window, this creates a daily repair period in which damaged proteins, dysfunctional mitochondria and cellular debris are recycled.

Oestrogen reduction

Exercise reduces adipose tissue, which reduces aromatisation — the conversion of androgens to oestrogen inside fat cells. For people with ER-positive breast cancer, that lowers a known driver of recurrence.

Worth saying plainly: this is a reason to move, not a reason to feel bad about your body. Most people finish treatment heavier than they started, and the drugs are a large part of why.

Bone density

Weight-bearing exercise such as squats and burpees directly counters the bone density loss caused by aromatase inhibitors and chemotherapy. The landing phase of every skip loads bone.

Bone is the one area where the measurement works differently from everything else. Density cannot meaningfully change in ninety days, so a DEXA scan is a baseline you take once and repeat much later — not a Day 90 marker.

Mental health and fatigue

Exercise reduces cortisol output, increases endorphin production, improves sleep quality, and reduces fatigue — which is the single most common complaint of cancer survivors after treatment ends, and the one most often dismissed.

Gut health

Exercise increases gut motility and microbial diversity, both of which are significantly disrupted by chemotherapy and by the antibiotics commonly used alongside it.

Why only three exercises

Skip, burpee, squat. Sixty skips, eight burpees, thirty connector skips, fifteen squats, then rest and repeat — three rounds at Foundation, building to five at Peak. Around eleven minutes to start, rising to roughly eighteen.

The number is deliberately small. A protocol you will still be doing on Day 90 beats a better protocol you abandon in week two, and anyone who has tried to restart exercise after treatment knows which of those two failures is more likely.

If you leak when you skip

This is the reason women quit skipping, and almost nobody says it out loud.

Skipping is one of the most provocative activities there is for stress incontinence. If you have had children you may already know that. What you may not have been told is that treatment stacks a second risk factor on top: chemotherapy-induced menopause and aromatase inhibitors both drop oestrogen sharply, and low oestrogen thins urogenital tissue and weakens the support around the bladder. Women who were completely fine before treatment can find they are not now.

It is common, it is not your fault, and it is treatable.

The single most useful step is not an exercise written down somewhere — it is a pelvic floor physiotherapist watching what your muscles actually do. Pelvic floor muscle training has good evidence behind it, but a large proportion of women cannot perform a correct contraction from written instructions alone, and for anyone whose pelvic floor is already overactive, more squeezing makes things worse. Ask your GP; in Australia this can sometimes sit within a chronic disease management plan.

Practically, in the meantime: empty your bladder before you start, do not cut your fluids to compensate — concentrated urine irritates the bladder and works against your hydration target — and build impact gradually rather than starting at sixty skips.

Leaking is a reason to change how you move. It is never a reason to stop moving.

Seated bouncing on an exercise ball, a mini trampoline, or calf raises with a bounce all create the vertical movement that opens and closes your lymphatic valves, at a fraction of the impact. Step the intensity up as your pelvic floor allows.

Start where you are, not where you were

The mistake worth avoiding is treating your pre-treatment self as the baseline. A body that has been through chemotherapy, surgery and radiation has different limits, and finding them the hard way in a class you cannot keep up with is a good way to stop altogether.

Low intensity, scaled to where you actually are, with rest days you are supposed to take. Then bloods at Day 0, 30, 60 and 90, so the effort leaves a trace instead of disappearing.