I grew up swimming all my life so thats what I do for cardio, I hate just about any other types like running though. Its full body cardio, and if you have been doing it for years I feel like its easier to build up a nice back when you hit the weights. Also some guys on my team were deceptively strong since a lot of those guys look like twinks lol. Some of the sprinters I've seen at the higher tier meets had some tree trunk legs and jumped off the block like they were fucking superman.
Also, some of the other teams (specifically a mostly all black team in Atlanta) looked suspiciously jacked, probably had some help with genetic potential by getting some magic protein shakes. These kids were 13 years old and looked like grown men. Some of them had thick beards too, it was just bizarre.