High shear forces: the role of intensive training
It is known that physical activity brings numerous health benefits, from strengthening the cardiovascular system to improving general well-being.
A study conducted in Singapore and published in 2017, however, shows that intensive training could have another, previously unknown effect: the high shear forces generated in the bloodstream could destroy circulating tumour cells (CTCs), which are significantly involved in the spread of cancer.
How shear forces destroy tumour cells
In the study, Regmi S. and his colleagues used a special microfluidic system in order to replicate the conditions in the human bloodstream under intensive loads. High shear forces were generated in the process, which resulted in a 90% destruction of the tumour cells within four hours of exposure to the forces. These shear forces are comparable to the intensive loads that occur in the body during hard training.
The described effects could be observed mainly with very high shear forces, which can arise from intensive loads such as high-intensity interval training (HIIT). With less intensive shear forces, these effects were considerably smaller. This indicates that such effects can above all be achieved through high-intensity training, during which blood flow is increased in order to supply the working musculature with blood, oxygen and other important substances.
Interestingly, healthy blood cells such as leukocytes (white blood cells) remained largely unharmed, which indicates that the cancer cells react more sensitively to shear forces.
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Limitations of the study: no confirmation in humans yet
It is important to stress that these results have so far only been tested in laboratory environments and not on the human body. Although the effects are promising, it is unclear whether they occur in exactly the same way in humans. Further research is needed in order to better understand the precise mechanisms and the potential of this form of therapy in the human body.
Tips for practical implementation
If you train intensively, you can generate these shear forces in the blood through targeted training sessions such as HIIT. Here are a few example protocols that you can try out:
- 30-120 seconds "all out", followed by 1-4 minutes of walking or light jogging for 3-10 rounds
- Tabata training: 20 seconds of maximum load, followed by 10 seconds of rest. Repeat this for 4 minutes.
- Hill sprints: 20 seconds of uphill sprints, followed by 1 minute of walking. Repeat this 8-10 times.
- Norwegian 4x4 protocol: Repeat four times 4 minutes of high-intensity performance (85–95% of your maximum heart rate) with a 2-minute break in between
Before the protocols described above you should of course warm up for at least 3–5 minutes and, after training, likewise cool down for at least 3–5 minutes.
These intensive types of training should, especially in the case of an existing illness, be carried out after consulting a doctor. In the absence of health impairments, however, such training sessions can be integrated into the training plan as a preventive measure in order to benefit from the potential advantages.
Conclusion: movement as prevention
Sport can achieve far more than just improve your physical fitness. It is possible that intensive training also helps, through the increased blood flow and the resulting shear forces, to prevent the future formation of cancer cells. Even if further studies are needed, this is an exciting approach that once again shows how varied the health benefits of movement and of intensive training sessions can be.
