Long COVID Can Destroy Your Ability to Exercise. Now We Know Why.
A study explains why long COVID patients experience difficulty exercising due to muscle damage and disrupted energy metabolism.
The Link Between Long COVID and Exercise Difficulty
For many people with long COVID, one of the major symptoms is difficulty with exercising. When these patients push themselves too hard, it can lead to a devastating cycle of fatigue that worsens their condition. This difficulty with exercise, known as post-exertional malaise (PEM), is also a defining symptom of myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS).
In a new study published in Nature Communications, researchers explain the underlying reasons for this exhaustion in long COVID patients. After exercising, these patients experience widespread muscle damage, changes in muscle composition, and disrupted energy metabolism. The study provides concrete evidence of the damage caused by post-exertional malaise, such as inflammation, scarring, and clots in the muscles. The researchers also found differences in how the mitochondria function—the body's energy factories—following exercise.
The Response to Post-Exertional Malaise: Pacing
To better understand the effects of post-exertional malaise, the study recruited 25 young long COVID patients who experienced significant reductions in their work and social life due to the condition. These patients had to exhibit post-exertional malaise to participate in the study. They underwent a cardiopulmonary exercise test, which triggered a bout of post-exertional malaise.
The results of the test showed differences in the body's ability to generate energy compared to healthy patients. Patients with long COVID had lower levels of oxidative phosphorylation—a process that produces ATP, the body's energy molecule. They also experienced decreased mitochondrial activity after exercise. This impaired mitochondrial function and disrupted metabolism create a vicious cycle for patients, worsening their symptoms with each exertion.
Changes in Energy Systems and Muscle Composition
Long COVID patients with post-exertional malaise have unique changes in how their bodies use energy. Exercise pushes their bodies into anaerobic metabolism sooner, meaning they reach exhaustion with less exercise. This change is not seen in patients with other conditions that make exercise difficult. Additionally, the study found changes in the muscle composition of long COVID patients. They had a higher proportion of fast-twitch muscle fibers, which fatigue more quickly.
The study also revealed evidence of muscle damage in long COVID patients. Normally, muscles undergo a repair process after exercise that leads to increased strength. However, in patients with post-exertional malaise, this repair process doesn't occur properly, resulting in accumulated damage. The researchers observed muscle scarring, inflammation, and blood clots in the muscles of long COVID patients, indicating impaired exercise recovery.
