Exercise is good for health, but it can be harmful for some long Covid sufferers, new research shows.
Those experiencing debilitating crashes after strenuous activity — a condition known as post-exertional malaise — risk severe tissue damage from hardcore exercise, scientists in the Netherlands found.
Researchers at VU University Amsterdam subjected 25 long Covid patients and 21 unaffected healthy “controls” to about 8-12 minutes of high-intensity cycling. Participants volunteered blood and muscle biopsy samples before and after the exercise test to identify biological changes that might explain patients’ persistent, debilitating symptoms.
Those with long Covid had a markedly lower exercise capacity than controls — associated with a higher proportion of fatigue-prone white muscle fibers and fewer so-called slow-twitch red muscle fibers — according to the study, published this month in the journal Nature Communications.
The exercise test triggered post-exertional malaise in all of the patients and lasted for three weeks in some of them, said Rob Wust, an assistant professor in muscle physiology who co-led the study. All of the participants with long Covid, including former bodybuilders, taekwondo players, and professional athletes, have had to stop full-time work since developing the coronavirus-induced condition.
An analysis of post-exercise tissue collected from participants’ upper leg muscle found patients were more likely than controls to display signs of severe tissue damage, including dying muscle fibers, inflammation, and metabolic disturbances. Patients also had an increased accumulation in their muscle of amyloid-containing deposits, which other studies have observed in the blood vessels of long Covid sufferers.
The findings don’t establish a cause of long Covid, Wust said. Still, it shows a biological reason for their symptoms and that they aren’t psychological or simply due to deconditioning or lack of physical exercise, he added.
Further research is underway to understand the damaging process, including in patients with myalgic encephalomyelitis/chronic fatigue syndrome, and how it can be treated and prevented.
In the meantime, long Covid patient support groups recommend a “stop, rest, pace” approach to avoid severe crashes triggered by certain levels of physical, mental or emotional activity.
