Sub-competitive freediver here, so I thought I’d comment a bit on how my sport stresses the lungs and how the body adapts to that stress.
First a comment about the debates over how often you should breathe...almost certainly, those who advise breathing less often are right. People who haven’t trained in apnea and haven’t learned to tolerate high levels of CO2 in the blood always assume the urge to breathe has to do with not getting enough oxygen. But in those sessions where you were “audibly gasping for air,” you were mainly satisfying your urge to expel the CO2 that had built up in your body and, after 1-2 breaths, your oxygen levels were mostly back to a point where you could’ve started breathing normally again. Even after 5 minute breath holds, I try to only take 2-3 recovery breaths before I return to my normal breathing cadence. Breathing less often, since it sounds like breathing slows you down to some extent, should just be a matter of dealing with the discomfort of a higher build-up of CO2. If you were to specifically train for CO2 tolerance, that wouldn’t be that big of a deal. I’m actually somewhat surprised that apnea training hasn’t become an important part of training to be a competitive swimmer.
Secondly, there have been a few studies that have looked at the physiological changes that happen to extreme breath hold athletes, so those may be of interest to swimmers because they may experience some of the same changes. One study showed increased basal metabolic rate and ability for the blood to hold oxygen. It seems like the training makes the body want to store more oxygen and use less of it to convert stored energy reserves. It wouldn’t surprise me if swimmers saw some degree of those changes as well.
Lastly, one important difference between freediving and swimming is the effect on the heart. Freedivers are specifically focused on not putting stress on the heart. We try to relax and lower our heart rate to use oxygen as slowly as possible. Even in dynamic disciplines, the focus is on slow, relaxed strokes, even if that results in more time spent underwater. A freediver swimming 200m on a single breath (whether horizontally or vertically) will likely have fewer heartbeats during that swim than that 50m swimmer you described. But what’s interesting about that is that freedivers still experience some of the beneficial changes to the heart that swimmers and runners do. For instance, when I first took up the sport, my resting heart rate dropped to about the level mentioned in the article (below 60 bpm) and my blood pressure dropped to the point where my doctor was somewhat worried (90/56 at one point). I think there’s something to what you mentioned about putting pressure on the lungs. The heart and lungs are really one interconnected system and you can affect one by affecting the other.
First a comment about the debates over how often you should breathe...almost certainly, those who advise breathing less often are right. People who haven’t trained in apnea and haven’t learned to tolerate high levels of CO2 in the blood always assume the urge to breathe has to do with not getting enough oxygen. But in those sessions where you were “audibly gasping for air,” you were mainly satisfying your urge to expel the CO2 that had built up in your body and, after 1-2 breaths, your oxygen levels were mostly back to a point where you could’ve started breathing normally again. Even after 5 minute breath holds, I try to only take 2-3 recovery breaths before I return to my normal breathing cadence. Breathing less often, since it sounds like breathing slows you down to some extent, should just be a matter of dealing with the discomfort of a higher build-up of CO2. If you were to specifically train for CO2 tolerance, that wouldn’t be that big of a deal. I’m actually somewhat surprised that apnea training hasn’t become an important part of training to be a competitive swimmer.
Secondly, there have been a few studies that have looked at the physiological changes that happen to extreme breath hold athletes, so those may be of interest to swimmers because they may experience some of the same changes. One study showed increased basal metabolic rate and ability for the blood to hold oxygen. It seems like the training makes the body want to store more oxygen and use less of it to convert stored energy reserves. It wouldn’t surprise me if swimmers saw some degree of those changes as well.
Lastly, one important difference between freediving and swimming is the effect on the heart. Freedivers are specifically focused on not putting stress on the heart. We try to relax and lower our heart rate to use oxygen as slowly as possible. Even in dynamic disciplines, the focus is on slow, relaxed strokes, even if that results in more time spent underwater. A freediver swimming 200m on a single breath (whether horizontally or vertically) will likely have fewer heartbeats during that swim than that 50m swimmer you described. But what’s interesting about that is that freedivers still experience some of the beneficial changes to the heart that swimmers and runners do. For instance, when I first took up the sport, my resting heart rate dropped to about the level mentioned in the article (below 60 bpm) and my blood pressure dropped to the point where my doctor was somewhat worried (90/56 at one point). I think there’s something to what you mentioned about putting pressure on the lungs. The heart and lungs are really one interconnected system and you can affect one by affecting the other.