Common lung dysfunction makes people weaker
Getting stronger mostly seems like something almost anyone can do, and should do — it’s one of the most powerful anti-aging tools we have, and it plays an important role in a lot of injury rehab. But the biology playing field is not level! Some people will struggle to get stronger for reasons that are out of their control. For instance …
Chronic lung trouble — which may not be obvious or diagnosed — makes people about 25% weaker across the board, according to a new Brazilian study by Garcia et al. They just don’t have muscle like people with healthier lungs. Yikes!
And there are probably a lot more people in that boat out there right now, thanks to Covid, according to another recent study. Interstitial lung disease is a large category of disorders that mess with lung function in dozens of ways.
“Interstitial” usually refers just to the spaces between cells (like the mortar between bricks). But with ILD, “the term interstitial is a misnomer because the pathologic processes are not restricted to the interstitium” (Goldman and Cecil’s Internal Medicine, 25th edition, chapter 92, “Interstitial Lung Disease”). It also includes the empty spaces in the lung, the air-filled tubs and sacs, their walls, the tiny blood vessels and lymphatics. All of that is “involved in the pathogenesis and manifestations of ILD.” Lungs are all about being hollow, so that you can fill them with air. In other words, the lung is full of spaces, and ILD is about anything that limits out ability to fill and use those spaces. This is most obviously caused by things like pollutants and genetic diseases, and, of course infections like covid.
Covid definitely aggravates existing ILD, and it can probably also fire up a fresh new case of ILD. So there are likely millions of people out there who have new or aggravated ILD since their last covid infection.
And they are probably all weaker for it.
Garcia et al tested the muscle strength in 112 people with ILD, comparing them to 48 healthy adults, and found that they were about 25% weaker on average. For example, the quadriceps muscles were 58–87% as strong as they were without ILD, average of 72%. Lower body muscles were generally weaker, and the triceps fared the best at 84%.
Only a handful of the ILD-impaired could match the strength of health people in any muscle. The authors concluded:
“Adults with ILD present a generalized reduction in peripheral muscle strength.”
😬
How does that work? I find it morbidly fascinating that muscles might wilt like dry house plants when they are chronically deprived of O2. I also wonder how it might aggravate other health issues, including pain.
But the weakness could also just be a function of a strong exercise headwind. Being hungry for air might just sap your energy and make it 25% harder to exercise on average! Is that a limitation that could in principle be overcome with enough oomph, like a cyclist working 25% harder to maintain speed in a headwind? Or are they doomed to weaker muscles? Or a bit of both?
Covid can hit the lungs so hard they are never quite the same ever again … which will probably weaken you.
I’ve integrated this science into my guide to strengthening … which has gotten a bit rambly and needs some editing, but it is full of intriguing pieces like this, stuff you just won’t find elsewhere.