Marilyn Fierro began her martial arts training in September of 1972. She was introduced to Isshin-Ryu in March of 1973 through one of Sensei Nick Adler’s students, and in September of 1974, began training under Sensei Adler at the Bayshore Dojo.
It was a time of little acceptance for women in the martial arts, however, when she discovered Isshin-Ryu karate, she actively sought admission to a traditional school beginning her journey into Isshin-Ryu karate for earnest. Through perseverance and dedication she went on to earn her Black Belt at a time when women in martial arts was a rarity.
In 1980, she took over the Smithtown Karate Academy which she had opened with Sensei Adler in 1978, and in 1989, moved it to a larger location. She pioneered a Woman's "Attack Prevention" program on Long Island and created a video tape with the BOCES school district in order to present it to more students through the Physical Education Programs. It is now in eleven Long Island High Schools
Sensei Fierro has written numerous articles for various Martial Arts publications as well as local newspapers. Her first story published in 1982 called "The Limitless Spirit of the Martial Arts" was published in Taekwondo Times. She has appeared on numerous television shows highlighting her Womens program as well as the value of a children's martial arts program. News 12 Long Island ran a 15 minute special broadcast filmed in Sensei Fierro’s dojo highlighting her Womens program.
On March 24, 1985, she received the "Bushido Award" from the Greater Long Island Karate Championships, and was the recipient of the "Samurai Spirit Award" at the Northeastern Karate Open on September 23, 1990.
As a competitor she has placed consistently in combined Men and Women's divisions for weapons and Over 35 kata throughout the United States. In 1991, she traveled with Sensei Adler to Okinawa where she trained and performed in a Master's demonstration, and again in 1994 for the Pre-World tournament. In 1992, Sensei Fierro took a team of athletes from Suffolk county, Long Island, to the Junior World Maccabbi games in Baltimore. She organized the regional Maccabbi Karate event on Long island in 1995 which included teams from California, Mexico & Israel, in addition to the area athletes.
On July 12, 1996, Sensei Fierro was promoted to the rank of Nana Dan by both Master Adler and Master Angi Uezu on Okinawa making her the first woman Isshin-Ryu Master recognized on Okinawa.
In April of 1997, Sensei Fierro was inducted into the N.Y. Jewish Sports Hall of Fame as the second woman and the first Karate-Ka. Inducted with her were sports notables, Bill Mazur, Harry Danning, Red Sarachek, Barny Ross and Barry Landers. She was also inducted into Don Nagle's Hall of Fame as Master Instructor, Contributor to the Martial Arts and Woman of the Year in September of 1997.
In September 1997, Sensei Fierro created her own Television show called "Taking Charge" which airs twice a month on public access. The show which is martial arts based is geared toward helping others achieve their own potential and covers a variety of informative subjects.