Rigorous position
Rigorous position means a position the duties of which are so rigorous that employment opportunities should, as soon as reasonably possible, be limited (through establishment of a maximum entry age and physical qualifications) to young and physically vigorous individuals whose primary duties are -
(a) To perform work directly connected with controlling and extinguishing fires; or
(b) Investigating, apprehending, or detaining individuals suspected or convicted of offenses against the criminal laws of the United States or protecting the personal safety of United States officials.