Originally Posted by sclim
It's interesting how much Mandy sinks on too much exhalation, even given her normal female body fat distribution. Imagine how much worse the problem becomes for us super skinny guys.
Yup - and us not so skinny guys too ;-) A good test each swimmer can do is the buoyancy test. In the pool, fill your lungs, deep breath - then hold knees to chest, face in water and bob on the surface for a moment until body stabilizes. Then begin exhaling quickly and continuously to see/feel when your body begins to drop to the bottom of the pool. This will give you a sense of how much air is needed in your lungs to maintain buoyancy.
I've seen swimmers exhale almost all air in their lungs and remain at the surface (lucky!), while on the other extreme, some will head to the bottom after just a few seconds of exhaling (sinkers!). The majority seem to be within 60%-40% lung capacity before falling to the bottom of the pool.
Its a fun and interesting test - give it a try.