A 1947 graduate of Sargent College, Brennan played both volleyball and basketball her freshman year in 1944. Then, in 1945, she suffered a spinal fracture, which prevented her from participating in sports until her return to the volleyball and basketball courts in 1946-47.
It was during her post-graduate days, though, that she achieved her greatest athletic successes, and, ironically, it was neither in volleyball nor basketball.
She excelled in field hockey and was on the Boston Field Hockey Association Second Team.
Her best sport, though was lacrosse, as she was a goalie on the United States teams that toured Great Britain and Ireland in 1957 and traveled to Australia in 1969.
Prior to her international travels, she was on the Boston second team from 1949-52 and the first team from 1953-64 and again in 1967. Her playing for the national team began in 1953 when she was named to the U.S. Team, and she remained there until 1956. She was again named to the U.S. Team from 1958-61 and during 1963-64. She was on the U.S. reserve team in 1962 and 1967 and an honorable mention selection in 1957.
In 1957, she was on the U.S. team that toured Great Britain and Ireland. During that tour, the team compiled an undefeated record, including a 7-7 tie with England. It marked the first time that a British team had not won a game outright in the history of the women's game. It was also reported at the time that the U.S. team had the best record of any touring team in any sport, either men's or women's.
Twelve years later, in 1969, Roberta was on the U.S. team that toured Australia.
