The name comes from "Vale tudo" (tudo = all, vale = valid). Vale tudo are martial art events where any fighting style is allowed with very few rules. The precursor of MMA.
Valetudo is the roman name for the greek goddess Hygieia, which is the goddess of health, cleanliness and hygiene.
We get "valetudinarian" from this word, one who worries (excessively) about one's health.