By far, the most common musculoskeletal complaint in the swimming population is shoulder pain. This should make a lot of sense as the repetitive overhead nature of swimming doesn’t allow much room for error. For example, an elite freestyle swimmer can take anywhere between 20 and 25 strokes every 50 meters. Let’s say you train 7,000 meters per day; that’s between 2,800 and 3,500 strokes every single day. If that same swimmer trains six days per week, that’s as many as 21,000 strokes per week and nearly 1,000,000 in a year. One stroke is not typically going to cause an injury, but this many reps, over time, certainly can.