Frank Glieber, a television announcer for CBS Sports who had been the original radio commentator for the football Dallas Cowboys, died yesterday after apparently suffering a heart attack while jogging at a Dallas health club. He was 51 years old.

After collapsing on the track, he was taken to Medical City Hospital, where he died during treatment.

Mr. Glieber resided in Dallas, where he also served as sports director of the radio station KRLD and conducted several weekly sports television programs.

He covered the National Football League draft on Tuesday for his radio station, and had been scheduled to cover the basketball game between the Los Angeles Lakers and the Portland Trail Blazers for CBS on Sunday. His last network assignment was the Los Angles-Portland game last Saturday.

During his 22 years with the network, he covered virtually every sport carried by it. In a field that can produce sharp rivalries, he was regarded as a generous professional who shared his expertise with a succession of novice broadcasters. Among those he trained, according to the network, were Joe Greene, the former Pittsburgh Steeler lineman; Dick Vermeil, the former coach of the Philadelphia Eagles, and John Madden, the former coach of the Oakland Raiders.

Mr. Glieber, who was born in Milwaukee, was graduated from Northwestern University in 1956 and moved to Dallas. He provided play-by-play radio accounts for the Dallas Eagles baseball team of the Texas League before becoming the first color commentator for the Cowboys when they joined the N.F.L. in 1960.

He joined CBS in 1963 and continued with the network when he moved to Cleveland in 1966 to become the radio voice of the football Browns. He returned to Dallas two years later.

He is survived by his wife, Kathy, and five children.

Frank John Glieber