FHSU is in the MIAA conference. The MIAA conference doesn't have wrestling because there are only 4 schools that have wrestling in the conference. The RMAC said that because of this, FHSU can continue to wrestle in the RMAC, even though all their other sports are in the MIAA. The MIAA duals started last year and was decided upon by the schools in the MIAA that had wrestling (Truman, UNO, CMSU, and FHSU). Truman, UNO, and CMSU will all wrestle regionals in Warrensburg, MO while FHSU will be at the RMAC/Championships regional in Alamosa, CO.
San Francisco State and Grand Canyon University are also members of the RMAC in wrestling ONLY. SFSU is in the California Collegiate Athletic Association and Grand Canyon is in the Pacific West Conference. This is not uncommon and can happen with any sport who's school's conference doesn't have enough members that have that sport.
