The Sports.SE site has been around long enough for its scope to be defined. It is clearly stated that in the help center what their scope is.
Sports Stack Exchange is for participants, hobbyists, and fans of all sports and forms of competitive physical activity. We welcome questions of all levels. For a non-inclusive list of example topics, click here.
What I'm interpreting this site to be is the focus on the competitive aspects of sports. Your question is highly general, and while swimming can be competitive, I've seen no evidence in your question that is specific towards competitive swimming. Someone who would be competitively swimming should be able to do a basic front crawl.
For the Fitness site, there is overlap, and your question would be appropriate there. To quote from what's on topic for our site:
Physical Fitness Stack Exchange is for fitness professionals, athletes, trainers and enthusiasts. If you have a question about …
- improving your exercise performance or technique
- choosing a training program
- nutrition as it relates to exercise
- gear and gadgets used during exercise
- achieving physique milestones
- injury prevention
and it is not about...
- the rules of a sport
- a purchase recommendation
- nutrition unrelated to exercise, such as food safety, nutritional needs for children, etc.
- wellness, general health, medical advice and injuries unrelated to exercise
