Because Joan (Langdon) McLagan reached the peak of her swimming career during World War II, she was forced to limit herself to competing at national and Pacific Northwest championships, as all major international meets were temporarily suspended during the war years. Joan was coached by fellow BC Sports Hall of Famer Percy Norman.

By age thirteen, Joan had set her first Canadian record and was a member of the 1936 Canadian Olympic team that competed in Berlin.

At the 1938 British Empire Games she won a bronze medal in the 220-yard breaststroke and helped the Canadian medley relay team to a fourth place finish.

Between 1936 and her retirement from active competition in 1944, Joan won numerous national swim titles and set many records including: 150-yard medley relay; 50, 100, 150, 220, and 440-yard breaststroke; 300-yard medley relay; and the 150-yard individual medley.

In 1940, Joan set a world record for the 50-yard breaststroke. She won the Velma Springstead Trophy as Canada’s outstanding female athlete in 1942 and 1943.