Exercise’s anti-cancer effects are well-documented, but a recent study on breast cancer—the most common cancer in women—offers fresh insight by comparing aerobic and resistance training[^1]. This research strengthens the case for physical activity as a vital tool in cancer prevention and treatment. Exercise combats cancer through three key mechanisms.

1. Myokines: Muscle-Powered Cancer Fighters

Exercise transforms skeletal muscles into an endocrine powerhouse, releasing signaling molecules called myokines (and other “exerkines”). These molecules, often carried in extracellular vesicles through the bloodstream, reach tumors and immune organs to:

• Boost anti-tumor immune responses

• Stress or reprogram cancer cells directly

• Alter the tumor microenvironment

• Promote anti-inflammatory, anti-growth signaling

These effects kick in right after a workout and grow stronger with consistent training. For instance, a 12-week study in men with prostate cancer showed that post-exercise serum, rich in the myokine OSM, suppressed prostate cancer cell growth in lab tests[^2].

2. Physical Stress on Cancer Cells

Exercise increases blood flow, generating hemodynamic shear stress—the frictional force of moving blood. Circulating tumor cells (CTCs), which are fragile compared to normal blood cells, can be destroyed by this force, undergoing apoptosis or necrosis. Lab experiments mimicking exercise-level shear stress have eliminated up to 90% of CTCs from breast, lung, and ovarian cancers[^3].

Exercise also ramps up the activity of natural killer (NK) cells and other cytotoxic immune cells, which target and destroy CTCs. High-intensity, variable exercise creates the most hostile environment for CTCs, suggesting that vigorous workouts may offer unique benefits[^4].

3. Protection Across the Cancer Journey

Exercise benefits every stage of cancer—prevention, treatment, and recovery. Epidemiological data suggest that up to 40% of cancers could be prevented with optimal lifestyle habits, with exercise ranking just behind smoking cessation, maintaining a healthy weight, and limiting alcohol. Regular physical activity cuts the risk of cancers like colon, breast, and endometrial by 20–30%[^5].

For those diagnosed with cancer, prior exercise acts as “prehabilitation,” building fitness, muscle mass, and resilience that improve tolerance for treatments like surgery, chemotherapy, or radiation. A lifetime of activity may delay cancer onset, reduce its severity, or enhance early detection, equipping patients with better reserves for the fight[^6].

During treatment, exercise is a game-changer. It reduces fatigue, improves sleep, and helps patients stick to their full treatment plan—a key factor in long-term survival. Aerobic exercise enhances blood flow and tumor oxygenation, improving chemotherapy delivery and radiation sensitivity, while resistance training preserves muscle mass and may support drug metabolism. Far from the outdated advice to “rest,” exercise enhances treatment efficacy and counters fatigue[^7].

Post-treatment, exercise lowers recurrence risk, strengthens immune surveillance, and mitigates long-term side effects like cardiovascular disease, osteoporosis, and metabolic issues, which cancer therapies can exacerbate[^8].

Final Thoughts

Exercise can’t entirely prevent cancer, nor is it a treatment by itself, but regular physical activity undeniably lowers the odds. Even just one workout releases cancer-fighting myokines and creates a hostile environment for tumor cells, contributing to your body’s defenses[^9].

The next time you hit the gym or go for a run, picture your muscles unleashing a flood of myokines, coursing through your body to battle cancer cells. It’s just one of many reasons to stay active.

[^1]: Newton, R. U., et al. (2023). Exercise mode in breast cancer survivors: A randomized controlled trial comparing resistance and aerobic training. Journal of Clinical Oncology.
[^2]: Rundqvist, H., et al. (2020). Exercise-induced myokines inhibit prostate cancer cell growth in vitro. Cancer Research.
[^3]: Adams, G. R., et al. (2018). Hemodynamic shear stress induces apoptosis in circulating tumor cells. Scientific Reports.
[^4]: Pedersen, L., et al. (2016). Voluntary running suppresses tumor growth through epinephrine- and IL-6-dependent NK cell mobilization. Cell Metabolism.
[^5]: Moore, S. C., et al. (2016). Association of leisure-time physical activity with risk of 26 types of cancer. JAMA Internal Medicine.
[^6]: Cannioto, R. A., et al. (2020). Physical activity before, during, and after cancer treatment. Cancer Epidemiology, Biomarkers & Prevention.
[^7]: Courneya, K. S., et al. (2013). Effects of exercise during adjuvant chemotherapy on breast cancer outcomes. Medicine & Science in Sports & Exercise.[^8]: Campbell, K. L., et al. (2019). Exercise guidelines for cancer survivors. Medicine & Science in Sports & Exercise.
[^8]: Campbell, K. L., et al. (2019). Exercise guidelines for cancer survivors. Medicine & Science in Sports & Exercise.
[^9]: https://link.springer.com/article/