Amsterdam-based researchers have isolated a physical mechanism behind the fatigue that strikes some people for months after a covid infection. It comes down to the mitochondria in muscle cells, which underperform compared to those in uninfected folks:
“We’re seeing clear changes in the muscles in these patients,” says Michèle van Vugt, Professor of Internal Medicine at Amsterdam UMC.
25 long-COVID patients and 21 healthy control participants participated in the study. They were asked to cycle for fifteen minutes. This cycling test caused a long-term worsening of symptoms in people with long-COVID, called post-exertional malaise (PEM). Extreme fatigue occurs after physical, cognitive, or emotional exertion beyond an unknown, individual threshold. The researchers looked at the blood and muscle tissue 1 week before the cycling test and 1 day after the test.
“We saw various abnormalities in the muscle tissue of the patients. At the cellular level, we saw that the mitochondria of the muscle, also known as the energy factories of the cell, function less well and that they produce less energy,” says Rob Wüst, Assistant Professor at Department of Human Movement Sciences at the VU University. “So, the cause of the fatigue is really biological. The brain needs energy to think. Muscles need energy to move. This discovery means we can now start to research an appropriate treatment for those with long-COVID,” adds van Vugt.