During the early 1960s Terpstra was a well-known freestyle swimmer in the Netherlands, specializing in the 100 meters distance. She participated in the 1960 Summer Olympics in Rome where she came sixth in the 100m Freestyle, and fourth in the 4x100 Medley Relay. Following the Olympics she joined the HZ&PC swim team in The Hague. While a member of this team she was again chosen to be an Olympic athlete for the Netherlands and won two medals at the 1964 Summer Olympics in Tokyo: the bronze medal in the 4x100 metres Freestyle Relay and the silver in the 4x100 metres Medley Relay, Toos Beumer en Winnie van Weerdenburg ). At her only individual start, on the 100m Freestyle, she finished in fourth position in the final. In addition to her Olympic exploits, Terpstra won the 1962 European championships and was champion of the Netherlands several times.
Interim years
After her swimming career Terpstra became a teacher, teaching Dutch to Chinese immigrants. Following that she became a sports journalist.
Politics
In 1977 Terpstra was elected to the parliament for the People's Party for Freedom and Democracy, just barely making it into parliament on a seat appointed to the VVD in the fractional division. She remained in parliament through 2003 though, with a four-year break during which she served as state secretary for Health, Welfare and Sport in the Kok-I cabinet. Upon leaving parliament in 2003, she was the senior member of the House, having been re-elected with a large number of preference votes each term.
Sports official
On 21 October 2003 Terpstra was elected chairperson of the NOC*NSF, beating out Ruud Vreeman in the election. As chair in 2005 she was the first to present the new Fanny Blankers-Koen Trophy, which was named for legendary Dutch athlete Fanny Blankers-Koen. Terpstra presented the award to Anton Geesink, Sjoukje Dijkstra, Nico Rienks and Ard Schenk in the new skating rink in Turin, a few months before the start of the 2006 Winter Olympics. She was supposed to award an FBK Trophy to Johan Cruijff as well, but he couldn't make it due to obligations at the pool drawing for the 2006 FIFA World Cup in Leipzig. During her tenure with NOC*NSF she was always well known for being present at every major sporting event in which Dutch athletes competed and for being exuberantly enthusiastic at every success. Terpstra retired from NOC*NSF in May 2010.
Film and television
Terpstra made her movie debut in 2004 in the movie version of the children's bookPluk van de Petteflet by Annie M.G. Schmidt. She played the role of mayor. Since early 2011 Terpstra hosts her own Travel-TV programme Erica op Reis for Dutch broadcaster Omroep MAX.
Personal life
Terpstra has a Theosophist background. She is very drawn to Buddhism. Rather than considering herself a Buddhist though, she refers to herself as a "life-long student of Buddhism".