What is the physiological mechanism behind why people who are overweight or less "in-shape" get out of breath more easily than those who are in good shape?

Is it purely power to weight ratio? What are the factors involved?

  • I would suggest seeing your doc as we can't diagnose you as there are a myriad of reasons. But things that came to my mind were iron deficiency because I've been having shortness of breath as of late, but then I read on to see that you are physically active & have energy. Maybe exercise induced asthma?? But really... no one on here will be able to tell you so ask your GP. There's so many possible reasons. Good luck. May 13, 2017 at 17:57
  • All mammals get out of breath as far as I am aware, the question is not about my personal health, but rather, what factors exist - probably something to do with oxygen right? May 13, 2017 at 17:59
  • Right. I gave a very cursory glance. Sorry about that! (I'm having issues concentrating as of late). Yeah, what I've discovered recently is how/why iron levels impact shortness of breath & just general malaise & concentration. It deals with the amount of hemoglobin (oxygen levels in your blood) being sent to organs. Again, I'm not an expert at all. But yeah... I didn't realize all the vast symptoms a deficiency in one thing can cause. So I can't even imagine all the other factors involved. May 13, 2017 at 18:05
  • Thats kind of the stuff I was looking for in an answer (I know that haemoglobin transports oxygen but I don't get why 2 people with the same amount of blood, breathing in the same amount of oxygen, use up that oxygen at different speeds.) May 13, 2017 at 18:06
  • Also, another odd thing that I was told years ago by my orthopedic surgeon who operated on my spine was... that even though I have fully developed lungs... that I didn't use my lungs to their full capacity because of my high degree of spinal curvature -- lordosis & scoliosis combo. (I haven't researched this to confirm this, which is why I'm not including it in an official answer, but to just throw it out there as another random potential factor). But I'm interested in this. So thanks. May 13, 2017 at 18:18

1 Answer 1


Part of why some people get out of breath faster is due to an inefficiency in the lungs and in the muscles. Muscles use oxygen when they move, the more they move the more oxygen they use. However, muscles are able to adapt and become more efficient in someone who is consistently active. Also, the lungs are powered by intercostal muscles, which are a bunch of small muscles, and the diaphragm. Someone who is fit usually takes deep breaths to account for the increase in Oxygen needed for physical activity, and do this consistently with their exercise routine. Their diaphragm and other lung muscles get stronger with the regular deep breaths taken, making their lungs work more efficiently as well.http://www.active.com/articles/breathing-101-increase-your-efficiency-for-better-oxygen-uptake

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