need to remove a portion of a sting

[David Gerber]

I have a value athlete1_birthdate can someone tell me how to parse off
the birthdate

 

[gerberdata]

also what would be the best way to name the field in order to get the
object, value

athlete_1_birthdate?

basically want to do something like this
params.each do |key, val|

#parse the keys
object = athlete
value = birthdate

end