Unless I missed it, nobody has mentioned muscle mass as an oxygen burner. Ever watch MMA fighting? The announcers constantly talk about the fact that if one of the fighters has large muscles he will get tired much faster because they say "muscles burn oxygen so larger muscles burn more oxygen." I have no idea if this is also true for diving, but thought it was an interesting idea.
I think the issue of muscle size is very relevant, but even more important is efficiency of the fin swimming ( coordination of the kick/ muscle fitness for fin swimming/ how much drag has been eliminated by the gear configuration on the diver/ and the aerobic power of the diver, as well as the anaerobic power of the diver-both energy systems have a place in fin swimming).
Take a large leg muscled cyclist, like a Track Sprinter and kilo specialist, that can also do a sub 1 hour 40 k time trial......get him to become a well coordinated diver, with efficient kick stroke.....and a disdain for low efficiency fins like what most scuba divers use--put free carbon fiber or composite freediving fins on them--they will be more efficient in the water at a medium - slow speed like 1 to 2 mph-- than a small muscled diver with only the fitness of an average diver ( which is very poor aerobically) ....and at fast speeds --like the speed of a Gavin Scooter, or faster, again, there is no contest....the small muscled diver with low aerobic power will not be able to keep up , and will run out of air quicker because they will be running too close to maximal effort, and will be breathing like a freight train--whereas the track cyclist diver could still sustain scooter speeds with heart rate in a low aerobic state ( say 125 bpm when the small muscled guy is at 175 bpm)
Where the tiny muscled cyclist can find a place where they can have the advantage, is at a speed so slow that he exerts at the very bottom of his perceived exertion levels--and his muscles will not pull much oxygen----while the Track sprinter diver would only be able slow heart rate and exertion down to a resting HR...maybe 60 bpm.....but would still be using more oxygen for his muscles, that the tiny muscled diver. Many women that are 5 foot 3 or less, can use very little air up, because they have so much less muscle mass than the Track cyclist type diver--or most male divers.....but this is also at slow speeds, such as what you see macro photographers doing...sometimes covering 100 feet in an hour. Try to get them to swim against a major current, and suddenly they go to high air consumption, while the track guy barely changes from a normal dive.
And then the efficient issue from diver to diver is huge....how well the kick shape works to propel the diver at any chosen speed....and how well they change the kick shape with needed changes in speed for efficiency....and the aerobic efficiency of any muscle, large or small.
And the fins.....most fins you see on a dive boat, are junk for efficiency--Scuba pro jet fins among the worst unless you are talking macro speeds and slow frog kicks. Splits are horribly inefficient, so are best used at very slow swimming speeds where the loss of efficiency is less meaningful.
Composite and carbon fiber freedive fins are as far superior in efficiency to scuba pro jet fins and all other scuba fins.....as far superior as a Lamborghini Galardo is from an old Ford Pinto. For the biggest differences, larger leg muscles can yield enormous speed advantages with freedive fins, that traditional scuba fins could not take advantage of...
Composite or carbon fiber freedive fins can have a major impact on distance traveled and amount of air used to get there, unless you are going so slow that almost no perceived exertion exists....and in this situation, the tiny person can win the game, once again.
---------- Post added August 16th, 2015 at 07:06 AM ----------
I'd also add to the issue here....that there are certainly going to be divers that will find freedive fins too long to use for their levels of coordination, or , too long to be easily used on the boats they dive off of, or too long for travel....there are bona fide reasons for some divers, separate from the failure of the dive industry to actually teach proper kicking and propulsion skills.....
So another choice capable of very high efficiency flutter kicking or dolphin kicking, that also does 100% of the other kicks well--is the Extra Force Fin, and the Excelerating Force Fins that Bob Evans developed. While pricier than the cheap garbage fins most of scuba divers have chosen, when you compare this to the cost of regulators or BC's or the cost in having to cut dives short because your air consumption is poor compared to that of others......highly efficient fins can be a great "value". even if they cost $500 a pair
Unlike freedive fins, the force fins are easy to walk in, and easily transported when you travel.
I have to say this again, because it annoys me so much.
The Dive industry paradigm, is "NOT" to spend time on teaching the complexities of kick shape, how kick shape should change with the speed desired, and not to have instructors "waste time" on getting their students to get really good at the mechanics of propulsion....Instead they get sold on the idea of the BC as the "elevator", that magically transports a diver up or down, and that is ultimately the tool that keeps their divers safe--like a life vest for a non-swimmer....and propulsion skills remain poor for most.
To me, propulsion is the big skill a dive instructor should teach FIRST....which is why a scuba diver ought to become a freediver, first. In a perfect world. I know many people would refuse to become divers, if they had this much development required. FReediving allows an instructor to teach efficient fin swimming...and it allows an instructor to create a student, that absolutely does not need a stinking BC
Too many divers today, would actually be in danger, if their BC failed. That's sad!
