News items Can exercise do more harm than good? Mini-heart research is uncovering new answers

29 September 2026

‘Exercise is medicine’ is a commonly quoted phrase. But, as is so often the case with medications, more is not always better. What counts as too much exercise, and how can it affect the heart? Does running a marathon or competing in an Ironman triathlon boost your health, or might it do the opposite? The development of the Micro-Athlete mini-heart (a heart-on-a-chip that mimics the human heart) is giving researchers valuable new insights into cardiovascular disease.

A marathon in the laboratory

With cultured human heart tissue and electrical stimulation, researchers can simulate endurance exercise in the laboratory. "We can simulate exercise conditions by making the heart tissue beat at a frequency of 150 beats per minute," says Thijs Eijsvogels of the Radboud university medical center. The results are promising. The stimulated heart tissue shows the same change in the contraction force squeezing strength and release of biomarkers as in people who exercise intensively. This makes the model a reliable starting point for follow-up research into the effects of strenuous exercise on the heart.
Research with patient-specific heart tissue
The cultured heart tissue is made from human stem cells and can even be developed from cells from individual patients. "By studying how this cultured heart tissue behaves, we can find out what causes heart disease," says  Robert Passier of the University of Twente. According to the researchers, the model is an important step towards more human-oriented research models, which can reduce dependence on animal testing.

On the way to personalised sports advice

In time, the Micro-Athlete model may help explain why extreme exercise is harmful to some people, while others don't experience any problems because of it. It also offers opportunities for more personalised training and treatment advice for patients, recreational athletes and top athletes.

About HealthTech Nexus

This research is part of HealthTech Nexus, the strategic collaboration between Radboudumc and the TechMed Centre of the University of Twente.

Read the more about the research, the technology behind the Micro-Athlete model, and the researchers working on it here.

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