An Elgin native and Larkin High School graduate, Armentrout went on to star on the football team at Southwest Missouri State University and was drafted by the Kansas City Chiefs as a free safety in 1985. Mike was awarded an NCAA post-graduate scholarship in 1985. He was an Associated Press All-American Honorable Mention selection in 1983 as a junior after leading all NCAA Division I-AA players in interceptions with 10 in 11 games. He was CoSIDA Academic All-American second team in 1984, was All-Mid Continent Conference and All-Mid Continent All-Academic in 1982, 1983, and 1984. Mike was also Sporting News All-American Honorable Mention in 1984. He had 18 career interceptions at SMSU and started in 37 of a possible 42 games in his career. He was a two-time letter winner in football and track at Larkin. He was Upstate Eight All-Conference first team twice in football, was Chicago Tribune and Chicago Sun-Times All-State as a senior (1980) and played key roles on two straight UEC champions for Larkin. He was Courier-News All-Area first team as a senior on offense and as a junior on defense. In track, he set the Larkin record in the long jump as a senior.