Changes in the muscle cells of people battling Long Covid have been found to cause extreme tiredness after bouts of exercise, new research suggests.
The study, published in the journal Nature Communications, involved 25 people with Long Covid who reported tiredness after exercise and 21 people who had Covid but made a full recovery.
Scientists from Amsterdam UMC and Vrije University Amsterdam tested the recovery of each patient after physical exertion on a static bike for 15 minutes, and compared the results.
Researchers concluded that severe exercise-induced muscle damage and subsequent regeneration was associated with the pathophysiology of post-exertion malaise, resulting from changes to the energy producing mitochondria in muscle cells.
Although most people recover fully from a coronavirus infection, some have reported long-lasting effects that include fatigue and brain fog.
Dr Sukhant Bagdia, a pulmonologist at Burjeel Medical City, said results from the Dutch study were consistent with the experiences of the Long Covid patients he has treated in Abu Dhabi.
“These are interesting findings and something that is consistent with what we have seen in patients who have Long Covid,” Dr Bagdia said.
“Most say they are unable to do exercise with the same effort as before they had the virus.
“It is a common complaint, and it is proven by biopsies and tests. Although this particular study is a small sample, we know this is a real problem.”
While there is insufficient data on the total number of people with persistent symptoms associated with Long Covid, a report by the US Centres for Disease Control and Prevention said the condition contributed to 3,544 deaths from 2020 to June 2022.
Of all deaths linked to Covid-19 in the US, the numbers associated with Long Covid peaked in April 2022 at 3.8 per cent, coinciding with declining numbers of deaths from the virus.
Physical effects of Long Covid are similar to those reported by people with myalgic encephalomyelitis (ME), or chronic fatigue syndrome. They can include fatigue, dizziness, pain, sleep disorders and gastrointestinal issues.
Extreme tiredness
The results reported in the Netherlands offer some insight as to why extreme tiredness has become a common symptom associated with Long Covid.
Samples of blood and muscle tissues were collected from both study groups a week before the exercise test, and the day after.
Results showed no abnormalities in the heart or lungs, but did reveal cellular differences in muscle tissue in the Long covid patients.
“Extreme fatigue is not just something that is felt by the patient, but something that has been proven by physiological testing,” Dr Sukhant said.
“The skeletal muscle function helps with breathing during exercise, and when it is impacted in this way [as a result of a virus] it becomes more difficult for people to recover afterwards.”
