I'm currently getting ready to ship to BMT and head into the CCT pipeline, I have been doing lots of water con prep so hopefully some of this is of use to you, most all of what I'm saying here is straight from the mouth of the spec ops developer I've been working with or from my buddies in AFSOC who have been helping me with my training:
- After pushing off the wall, and after each keyhole stroke, wait until you are essentially at a dead stop before doing a frog kick/recovering. Lots of people waste forward momentum by getting impatient, which in turn wastes oxygen on unneeded movements. This especially gets harder by stroke 3-4 I find.
- 4 to 5 strokes is a good goal, watch youtube videos of people shooting for world records on underwater swims, you'll see they're usually at 3, and they're incredibly efficient.
- Your kicks look a little frantic, definitely using up precious oxygen, I would work on either 1 or 2 solid dolphin kicks after your keyhole, or learn to do without kicks altogether if you can.
- Do breath hold exercises to get your body used to being hypoxic (there are many exercises listed online to try out)
- Box breathing and one/two breathing will help you regulate your heart rate as best as possible during tests and events (look up Mark Divine on youtube)
- Do multiple underwaters with set rest periods in between (start with say 2min), use the 2 min to one/two breathe, and then go on the 2 min mark, get used to repeating this many times.
- If you are getting ready to take the PAST then this may very well be something to take note of: Get to the point where you are able to do your underwater, touch the crack of the pool, turn around and kick back off the wall before surfacing. Most pools are 25yrds, not 25m... When I took the PAST I was surprised to find out I had to do the underwater, turn around, kick off the wall, and swim a short distance before surfacing. I had to do that for the first time, on test day, after a recruiter got me there late and I literally had to jump right into the pool and "GO!". It wasn't a huge deal, but also it wasn't fun having that extra surprise thrown in right before my PAST.
Hope that is of some help to you,