Born in Leamington on February 1, 1936, Gagnier is a product of Bernard Newman’s W. D. Lowe High School and the Windsor Gymnastics Club.
Gagnier competed for the Windsor Gymnastics Club from 1951 to ’55. Over the course of his career with the Club, he accumulated 112 total accolades: 72 gold medals, 27 silver medals, and 13 bronze medals at competitions in North American locales like Detroit, Dayton, Chicago, Cleveland, Cincinnati, Indianapolis, Toronto, and Vancouver.
In 1954, Gagnier won two silvers and one bronze medal at the Canadian Championships, where he was named the Canadian All-Around Men’s Champion for his performances in the high bar, parallel bar, and flying rings events.
That same year, Gagnier became the first gymnast to be selected by the Amateur Athletic Union of Canada for the Viscount Alexander Trophy, which recognized the nation’s Most Outstanding Junior Athlete.
In 1955, Gagnier won the all-around silver medal at the Canadian Men’s Open. He took gold in the still rings, free calisthenics, parallel bars, side horse, and rope climbing. Gagnier qualified for the Pan Am Games that year, but declined his invitation in order to concentrate on his studies at the University of Michigan.
Gagnier captained Michigan’s gymnastics teams for two years, winning Big Ten titles in the parallel bars, all-around, and vaulting. In the first two events, Gagnier went on to place second in NCAA competition. In 1955, he was named the school’s Most Outstanding Gymnast.
Following his competitive career, Gagnier became an incredibly successful coach at the NCAA level. Working for Iowa State University, he was named NCAA National Coach of the Year in 1970, ’73, and ’74. He won six NCAA Regional Coach of the Year honours, in 1965, ’66, ’67, ’68, ’70, and ’71. His Iowa State teams won 131 meets, including 10 Big 8 Conference Team Titles and 3 NCAA Team Titles. During Gagnier’s tenure, Iowa State failed to win only 19 meets. All in all, Gagnier coached 13 NCAA individual champions and 65 at the Big 8 Conference level.
Gagnier was named coach of the USA national team at the 1969 World University Games (FISU) in Italy. He served as NCAA Gymnastics Rules Chairman from 1969 to ’75, and he was Secretary of the USA Gymnastics Olympic Committee between 1970 and ’73. He also served as Director of Athletic Development at Iowa State.
In 1982, Gagnier was inducted into the NCAA Gymnastics Hall of Fame. In 1992, he was named an honoured member of the University of Michigan’s Hall of Honour.