Key takeaways
In the Cooper Center study, men with high midlife fitness had fewer lung and colorectal cancers
Fitter men who did develop cancer were less likely to die from it later
Links are observational and vary by cancer type, so fitness is one factor among many
Cardiorespiratory fitness is best known as a marker of heart health. But large cohort studies have also linked it to cancer — both to how often cancer develops and to how people fare after a diagnosis. Here is what the research shows, and how to read it calmly.
The Cooper Center Longitudinal Study
The best-known study comes from the Cooper Clinic in Dallas. Lakoski and colleagues (2015) followed more than 13,000 men who had a maximal treadmill test in midlife, then linked their records to Medicare claims after age 65.
They found that:
- Men in the highest fitness group had a substantially lower risk of developing lung and colorectal cancer than men in the lowest group.
- There was no lower risk of prostate cancer — if anything, fitter men were diagnosed slightly more often.
- Among men who did develop lung, colorectal or prostate cancer, higher midlife fitness was linked to a lower risk of death from cancer and from cardiovascular disease afterwards.
The prostate result is a useful reminder: health-conscious men are likely screened more often, so more early, slow-growing tumours are found. Fitness studies are shaped by who gets tested.
Fitness and cancer death
Schmid and Leitzmann (2015) pooled cohort studies on fitness and cancer mortality. People with high fitness had a clearly lower risk of dying from cancer than people with low fitness, and the risk fell gradually as fitness rose. The finding held in both men and women, though women were far less studied.
What about physical activity?
Fitness is partly genetic and partly built by training. Studies of physical activity point in the same direction. In a pooled analysis of 1.44 million adults, Moore and colleagues (2016) found that higher leisure-time activity was associated with a lower risk of 13 of the 26 cancer types studied, including colon, breast, endometrial and kidney cancer, and oesophageal adenocarcinoma. Some of the association was explained by body weight, but much was not.
| Cancer type | Link with fitness or activity |
|---|---|
| Colorectal | Consistently lower risk |
| Lung | Lower risk (smoking makes it hard to separate) |
| Breast, endometrial | Lower risk with more activity |
| Prostate | No lower risk; screening may distort results |
| Skin (melanoma) | Higher in some activity studies, likely sun exposure |
Why might fitness matter?
Plausible explanations include lower levels of insulin and inflammation, less visceral fat, healthier sex-hormone levels, faster gut transit and better immune function. A fitter body also tolerates surgery, chemotherapy and radiotherapy better, which may explain part of the survival advantage. None of these is fully proven.
What these studies do not prove
- They are observational. Fit people smoke less, eat differently and have other advantages. Researchers adjust for what they can measure, not for everything.
- Most fitness data are from white men. The Cooper cohort was mostly well-educated men, so results may not apply equally to everyone.
- Fitness was measured once, often decades before diagnosis.
- Risk is relative. A lower relative risk does not mean fit people cannot get cancer. Screening and avoiding tobacco remain essential.
Exercise after a diagnosis
An international roundtable led by Campbell and colleagues (2019) concluded that exercise during and after cancer treatment can improve fatigue, anxiety, depression, physical function and quality of life. It is now part of mainstream cancer care. If you are being treated for cancer, ask your care team before starting a new programme.
What to do
- Know your number. Estimate your VO2max with the VO2max calculator and compare it with the VO2max chart.
- Aim to leave the bottom group. As with longevity, the biggest change in risk comes from going from unfit to moderately fit.
- Build a base, then add intensity. Start with easy aerobic training, then add intervals such as the Norwegian 4×4.
- Keep it going into older age. Fitness declines with age, but training slows it — see VO2max and ageing.
Frequently asked questions
Does high VO2max prevent cancer?
No single factor prevents cancer. Higher fitness is linked to a lower risk of some cancers, such as colon and lung cancer, but the studies are observational and cannot prove cause.
Which cancers are linked to fitness?
The strongest and most consistent links are with colorectal and lung cancer. Prostate cancer is not lower in fit men, possibly because they are screened more often.
Is exercise safe during or after cancer treatment?
For most people, yes, and guidelines encourage it. Ask your oncology team for advice tailored to your treatment.
Sources
- Lakoski SG, et al. Midlife cardiorespiratory fitness, incident cancers, and survival after cancer in men: the Cooper Center Longitudinal Study. JAMA Oncol, 2015.
- Schmid D, Leitzmann MF. Cardiorespiratory fitness as predictor of cancer mortality: a systematic review and meta-analysis. Ann Oncol, 2015.
- Moore SC, et al. Association of leisure-time physical activity with risk of 26 types of cancer in 1.44 million adults. JAMA Intern Med, 2016.
- Campbell KL, et al. Exercise guidelines for cancer survivors: consensus statement from international multidisciplinary roundtable. Med Sci Sports Exerc, 2019.