[BennyB]

Competitive finswimming for 50m is anywhere between 15 and 20 seconds, which is hellishly fast when you see it (and the wave following the athlete).

Usual rolling along pace is about 1 to 2m per second.

Arms up is more streamlined so less effort, arms down causes a bit less hydrodynamic so you work a bit harder and glide for less. I also find that directionally it's a bit harder with hands down (harder to stay in a straight line).

Cheers,
Ben