When we go windsurfing, one of the most exhilarating manoeuvres we can pull is the carve gybe - a manoeuvre that even the most remote person on the planet can see is beautiful, skilled, poised and somehow effortless and magical to achieve. Timing is everything, strength is not needed for a perfect carve gybe
Until around four decades ago hiking was viewed as a low returns skill to be treated with some cynicism as it was too physical to be a valued part of the art of sail racing. Yes, people hiked, but not with anything like the intensity that they do today. Hiking technique has become increasingly important across the classes, and certainly in the Olympic/WS development fleets Laser (so reliant on physical skills!), 470 and 420 are always seeking new levels to get the maximum leverage possible.
Muscles were never really considered too vital in sailing until around 2000. There were of course people who believed that Lasers and Windsurfers needed to be fit, but generally this was not carried over to other classes. Now we see fit sailors winning, and less fit sailors rarely doing so. There is a systematic approach that can be taken to physical training, and this begins with the core.