Freestyle - The New Hypoxic

I have to say, I'm not a fan of hypoxic training for masters swimmer, but I am a fan of learning efficiency to the point of not needing air.

Why do it:
This drill, or sequence, can teach you how to monitor your efficiency in the water, as well as teach you a moree effective breathing technique for your regular swimming.

How to do it:
1)  Before starting this excercise, we like to show the swimmers just how easy it is to hold their breath for about :30 seconds.  Typically much longer than it takes them to swim 25 yards.
2)  We'll then start with a length of easy swimming, breathing every 3rd or 5th stroke.
3)  Next, the swimmer will completely relax, and swim a length focusing on a stable head position, and good rotation.  They breathe when they need to, but if done correctly, and if the focus is on the stroke, the swimmer may be at the other end before they realize they haven't taken a breath.
4)  Now, have the swimmer slowly submerge in the water, allowing air to escape from their nose for as long as possible.  Make sure any new swimmers are holding the wall for safety.
5)  Next, have the swimmer push off the wall, exhaling through the nose as they just did in the previous step with a constant stream of air, breathing as necessary.
6)  Finally, have the swimmer exhale slowly through the nose for many strokes, until they need a breath.  Some may make it all the way to the other end.

How to do it really well (the fine points):
Think about how you breathe while sitting at your desk at work, or just watching TV.  A constant, gentle exhale through the nose is very typical.  This method of exhaling constantly, also means more C02 is out of the lungs prior to turning the head for air, so good oxygen can fill the lungs more effectively.

This "new" hypoxic has nothing to do with how far you can go without breathing, but serves more as a check system for how efficient you're swimming so you simply don't need air as frequently.