Underwaters as you get older - How many, and can you improve on them?

My experience with SDK (streamline dolphin kicking) was one of ceaseless frustration. Swam as a kid 9-18 y.o. Swam recreationally most of my adult life, at varying levels of frequency and intensity. At 45 I stared to train seriously again and compete in pool competitions. One of the big changes in that 27 year gap was development of the SDK. I could see that for people who are good at it, it is a tremendous weapon. Over a period of many years I made a concerted effort to develop my SDK  skill. I tried doing repeat 25s SDK at the end of every practice. I tried adding N SDKs off every wall. I tried with fins. I did an absolutely insane amount of leg lift and core exercises. Yes, my SDKs got better, but the best I was able to do was about 3-4 seconds slower, per 100, doing SDKs than simply doing a powerful flutter kick and getting to the surface quickly. Yes, there is an oxygen penalty so that the longer you are underwater the deeper into oxygen debt you go, and I certainly do not have an impressive lung capacity, but I don't think that was the limitation. I eventually reached the conclusion that I lack the shoulder flexibility to get into a sufficiently good streamline position to make the SDK effective. My arms are not in-line with my torso but always at an angle so that I am plowing water. Yes, I worked extensively on stretching, but the difference between the shoulder mobility I was able to gain and what I would need to gain to develop a good streamline is very great. It was a pretty depressing realization that came over a period of many years. I would watch videos and see myself get destroyed on the walls by swimmers that I would outswim between the flags. LCM is definitely a step in the right direction.
Haven't been in a pool since Feb. 2020. I miss swimming, but the realization that I'll never have a good SDK is kinda depressing because today, swimmers spend a huge fraction of their races underwater.

My experience with SDK (streamline dolphin kicking) was one of ceaseless frustration. Swam as a kid 9-18 y.o. Swam recreationally most of my adult life, at varying levels of frequency and intensity. At 45 I stared to train seriously again and compete in pool competitions. One of the big changes in that 27 year gap was development of the SDK. I could see that for people who are good at it, it is a tremendous weapon. Over a period of many years I made a concerted effort to develop my SDK  skill. I tried doing repeat 25s SDK at the end of every practice. I tried adding N SDKs off every wall. I tried with fins. I did an absolutely insane amount of leg lift and core exercises. Yes, my SDKs got better, but the best I was able to do was about 3-4 seconds slower, per 100, doing SDKs than simply doing a powerful flutter kick and getting to the surface quickly. Yes, there is an oxygen penalty so that the longer you are underwater the deeper into oxygen debt you go, and I certainly do not have an impressive lung capacity, but I don't think that was the limitation. I eventually reached the conclusion that I lack the shoulder flexibility to get into a sufficiently good streamline position to make the SDK effective. My arms are not in-line with my torso but always at an angle so that I am plowing water. Yes, I worked extensively on stretching, but the difference between the shoulder mobility I was able to gain and what I would need to gain to develop a good streamline is very great. It was a pretty depressing realization that came over a period of many years. I would watch videos and see myself get destroyed on the walls by swimmers that I would outswim between the flags. LCM is definitely a step in the right direction.
Haven't been in a pool since Feb. 2020. I miss swimming, but the realization that I'll never have a good SDK is kinda depressing because today, swimmers spend a huge fraction of their races underwater.