2 TENDINopathy Severity assessment – Achilles (TENDINS-A): evaluation of reliability and validity in accordance with COSMIN recommendations by Paola Chivers, Peter Malliaras, Robert-Jan de Vos, Ebonie Rio, Dana Hince, Myles Murphy, Sophia Nimphius, Nicola Maffuli, Nonhlanhla Mkumbuzi, Fergus McCleary, Ruth Chimenti, Turner Vosseller