Brick Carter wrote: > > A Discovery Channel documentary featuring the sperm whale explained that its > deep diving ablility for long periods was due to the tremendous muscle mass > acting as an oxygen store. > > Since humans share the "mammalian diving reflex", should this mean > bodybuilders make better freedivers than marathon runners? > No, I don't think so. Or rather, they might be better divers but not exactly for that reason. Or they might be worse divers. What makes whales able to dive isn't just the mass of their muscles, but special characteristics of the muscle tissue. Indeed, it's your muscles that are using oxygen, so just having more muscles would mean using more oxygen, which would seem to be a break-even at best. Harold McGee in "On Food and Cooking" says that whale muscle is almost black with intense concentrations of myoglobin (the form in which oxygen is stored inside cells, like the hemoglobin in blood). Whales have large muscles that are in nearly constant motion, and are the slowest of slow-twitch muscle. Which means they have many mitochondria and burn fats using oxygen. But beyond that they have adapted to the special requirements of diving by storing extra huge amounts of oxygen right in the muscle. (If they took giant lungfuls of air down there instead they would have all that buoyancy to overcome). I would think that being strong and muscular would make you a better diver, but the whale thing is a bit different.