
Freestyle means swimmers can use any stroke, but almost everyone uses the front crawl because it is fastest. Freestyle races range from short sprints to very long distances.
In a 50-meter Olympic pool, 1500 meters equals 30 laps. That's a long race that needs stamina and steady breathing.
They build endurance with long swims, practice speed with interval sets, work on technique in the pool, and do strength and conditioning out of the water.
Official highlights and full races are on sites like Olympics.com and World Aquatics, and many race videos are available on public video platforms.