Had a similar "chest is constricted, can't breathe, going to die" panic experience in my first open water oly. Thankfully I was able to push through it but I quickly learned that I had to train for that feeling.
The most important thing was frequently (almost every workout) putting myself in that same situation in the pool. Jacking my HR up by doing deck ups and jogging in place and then diving in and immediately swimming a hard 25 or 50 and repeating was a great drill. Learned how to swim with a high HR and manage that feeling of panic. (Thanks, coach!)
Other things that helped (but not as much):
1. Fully exhaling
2. Getting my wetsuit nice and wet prior to starting
3. Trying to go slow on take out
4. Playing rugby and not minding being hit once in awhile :)
Take with a grain of salt as I am a MOP AOS...but learning to love the swim.
The most important thing was frequently (almost every workout) putting myself in that same situation in the pool. Jacking my HR up by doing deck ups and jogging in place and then diving in and immediately swimming a hard 25 or 50 and repeating was a great drill. Learned how to swim with a high HR and manage that feeling of panic. (Thanks, coach!)
Other things that helped (but not as much):
1. Fully exhaling
2. Getting my wetsuit nice and wet prior to starting
3. Trying to go slow on take out
4. Playing rugby and not minding being hit once in awhile :)
Take with a grain of salt as I am a MOP AOS...but learning to love the swim.