Quick Take
A social media post claims that high-intensity exercise can destroy cancer cells. However, after fact checking, we found that this is mostly false.
The Claim
According to an Instagram post, “High-intensity exercise like HIIT, heavy weightlifting, and sprints can destroy cancer cells in the bloodstream through high shear stress.”
Fact Check
Does high-intensity exercise create high shear stress in the bloodstream?
Yes, according to a 2017 study. Shear stress is the pressure that blood puts on the walls of your blood vessels and the cells flowing in your blood. When you do high-intensity exercise, like sprinting or lifting heavy weights, your heart beats faster, and your blood moves more quickly through your body. The 2017 study from Nature Scientific Reports says that this fast blood flow can create a shear stress of 60 dynes/cm², which is a measure of that pressure. Other research on exercise agrees that intense workouts can increase shear stress to this level.
We spoke with Hakim Bharmal, Master Trainer and Contest Preparation Coach from Maharashtra, to know whether high-intensity exercise can create shear stress. He says, “High-intensity exercise does increase blood flow and create some level of shear stress in the bloodstream. And, this is great for heart health, circulation, and overall fitness. Regular exercise supports your body in many ways. But still, it’s important to understand that the effects of exercise on things like cancer cells go beyond what fitness alone can address.”
Can high shear stress destroy cancer cells in a lab setting?
Yes, specific to the study conditions. The 2017 study showed that a strong pressure from blood flow, called shear stress, at 60 dynes/cm² killed over 90% of cancer cells in the blood within 4 hours. This happened because the cells were damaged and died, a process called necrosis. The few surviving cells died more slowly over 16–24 hours through apoptosis, a natural breakdown process. High shear stress can kill CTCs (circulating tumour cells) in a lab setting, suggesting that intense exercise, which increases SS, might help reduce metastasis risk.
Similarly, another post claims that bee venom can kill cancer cells within 30 minutes, based on a preliminary lab study. However, this is misleading for now.
Does high-intensity exercise destroy cancer cells in the human bloodstream?
No, it doesn’t. The study was done in a lab using a special device called a microfluidic system, not in people. In the study, they kept the strong blood flow pressure, called shear stress, going for 4 hours straight to destroy a lot of cancer cells. But when you do high-intensity exercise, like sprinting, it usually lasts less than an hour. Once you stop exercising, your blood pressure drops, so it doesn’t stay elevated as long as in the study. Plus, the human body is far more complex than a lab setup—factors like the immune system and fluctuating blood flow can influence the outcome. While a small human study from 2018 (sample size: 23) found that regular exercise reduced circulating tumour cells in colon cancer patients, it did not test whether exercise directly kills cancer cells through shear stress. The Instagram post takes lab results and applies them to real life without solid proof.
Can we rely on high-intensity exercise to destroy cancer cells as a treatment?
No, it is too early to confirm this. Even if shear stress from exercise could destroy some circulating tumour cells, it’s not a reliable method to destroy cancer cells in the bloodstream. Cancer involves primary tumours and ongoing cell production, which CTC destruction wouldn’t address. The 2017 study suggests a potential preventive role for exercise in reducing metastasis, but this is unproven. Medical treatments like chemotherapy or surgery are proven to target cancer cells effectively.
We spoke with Dr Pooja Khullar, Radiation Oncologist at Dharamshila Narayana Super Speciality Hospital, New Delhi, for her opinion on high-intensity exercise as a potential treatment to destroy cancer cells in humans. She says, “High-intensity exercise offers numerous health benefits—improving cardiovascular fitness, boosting mood, and supporting the immune system—but there is no solid evidence to suggest it can directly “destroy” cancer cells as a treatment. Cancer cells are complex; they do not simply await elimination through physical activity.”
Dr Khullar adds, “Treatments such as chemotherapy, radiation, or immunotherapy target cancer at a cellular level in ways exercise cannot replicate. That said, exercise can play a supportive role in cancer care. Studies indicate it may help reduce inflammation and improve overall resilience, potentially lowering cancer risk or aiding recovery post-treatment. For instance, research from the American Cancer Society shows that regular physical activity can reduce the risk of certain cancers (such as breast and colon) by up to 20-25%. However, as a standalone cure, exercise is not effective. Cancer is too complex, and while exercise offers many health benefits, it is not a precise tool for targeting cancer cells. Any claims that exercise alone can treat cancer should be approached with caution, as they often misinterpret the available evidence.”
Likewise, carrots and green leafy vegetables are healthy, but can they prevent lung cancer—even in smokers? Not really.
THIP Media Take
The claim that high-intensity exercise can destroy cancer cells is mostly false. While exercise has numerous health benefits and may play a supportive role in cancer prevention and management, the idea that it directly destroys cancer cells in the bloodstream lacks solid clinical evidence. We need more human studies to understand the real-world impact of exercise-induced shear stress on cancer cells.
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