Cummings joined the Los Angeles Athletic Club (LAAC) in 1934 and received her first financial support in 1935, helping her attend that year's Far Western Championships. She captured the American national 200-meter breaststroke championship in 1936, which led to her participation in that year's Olympic trials and her selection as a member of the United States delegation to the 1936 Summer Olympics in Berlin. She was required, however, to raise her own funds for travel to the Games and spent much of her time leading up to the tournament collecting money rather than training. In the women's 200-meter breaststroke, she placed fourth in her heat in the opening round and was eliminated. Despite this, she remained as national champion in the event through 1939, although she left the LAAC in 1937. She placed second at the 1939 National Championships and retired from active competition shortly after, deciding that the 1940 Summer Olympics were unlikely to occur. In 1941, she earned a degree in physical sciences and math from the University of Southern California.