It is true that a bigger muscle will use more oxygen when in use, but it’s also true that more muscle mass will contain more blood. So if you have minimal movement, wouldn’t it be beneficial to have larger muscles, thereby providing bigger oxygen reserves?
Hi Bengreen. A very interesting subject, and you've been lucky in that most of the guidance you've received from the Forum so far has been pretty solid. Just to add to what's been submitted thus far. Yes, muscle is more biologically active than almost all other tissue. Thus, and all other factors being equal, more muscle = higher O2 consumption and CO2 build-up. So it follows that there will be, for each athlete, an optimal overall RATIO of muscle tissue to total body mass that will define one aspect of their performance potential. But this is only part of the story and while I don't have the technical knowledge to be ultra specific, here are some considerations you might wish to look into more deeply:
1. One of the more curious and unique aspects of apnea is that there doesn't (yet) seem to be a coherent, linear relationship between innate physiological attributes ('talent') and training/conditioning. Ask around and you'll see: few other sports offer such divergent opinions on how to train. It seems to be very personal from athlete to athlete, but most agree on one thing: in apnea ultimate performance potential is heavily weighed towards the mental - and even emotional - component. Big lungs? Some can go very deep, some can't. No muscles? Branko Petrovic is super lean and hold his breath for 12mins but this has not yet translated to depth. Muscular? Big guys like Patric Musimu, Antero Joki (and even Miguel Lozano) answer that question. One of Umberto Pelizzari's Apnea Academy instructor, Tadej Cernos, is literally built like a comic book superhero and he's diving very deep. Age? At age 54 Natalia Molchanova beat her son Aleksei in dynamic competition recently! No, muscle mass is just one factor and it is probably not even one of the most important ones.
2. What is more interesting is innate muscle TYPE - ie the ratio between 'fast-twitch' muscle, which performs under anaerobic conditions (sprinters, weight lifters), and slow-twitch muscle mass (endurance athletes). Much of the weight training elite apneists do is to stimulate their musculature not only for 'power' - though power is important in depth disciplines - but rather to condition it for anaerobic (glycogen-consuming) performance under extreme anaerobic conditions. Again, it is a trade-off that each athlete must discover for themselves through trial and error.
3. Another interesting consideration seems to be the relative size of the spleen and it's (again relative %) ability to contract under hypoxic stress. There is evidence suggesting that this could be as important as lung volume.
4. Most importantly, Apneaaddict has touched on the key issue: there are many factors to work on long before muscle mass becomes a limiting issue. Breathing techniques and the ability to relax mentally and physically have proven time and time again that they are the foundation of apnea training and performance - the 'base of the pyramid' if you will (along with safety). My own opinion is that training, conditioning and technique form the middle, and only when all these have been satisfied do you get to the top of the pyramid where innate 'talent'/genetics starts to play a more significant and/or decisive role.
To conclude finally: make a decision what your personal apnea goals are and work towards them in the knowledge that a good attitude and discipline can get you to very interesting performance levels - long before muscle (or the lack of it) limits your progress. Last advice: go to Will Trubridge's web site and click the 'writings' link. He has dealt with these aspects very eloquently.
Cheers