I did a challenge like that earlier in the year. Team names were quite varied, some focusing on fitness, some more identifying the people involved. Our team was the "Polyglots" (because we all spoke more than one language), which had nothing to do with fitness!
Some other names, which may inspire you:
Buff babes (a student group)
Deadweight losers
Flab fighters
Hoohaa half dozen (which, like the Fab 5, focused on the number of people on the team)
Ship Shapers
HR Huff 'n Puff Stuff
5 Old ladies and a babe
Lighter writers (from the English department)