RESUMEN
BACKGROUND: Multiple sclerosis (MS) exercise terminology lacks consistency across disciplines, hindering research synthesis. OBJECTIVE: The 'Moving exercise research in MS forward initiative' (MoXFo) aims to establish agreed definitions for key MS exercise terms. METHODS: The Lexicon development methodology was employed. A three-step process identified key exercise terminology for people with multiple sclerosis (pwMS): (1) consensus and systematic review, (2) Delphi round 1 and consideration of existing definitions and (3) Delphi round 2 for consensus among MoXFo steering group and exercise experts. Final definitions and style harmonisation were agreed upon. RESULTS: The two-stage Delphi process resulted in the selection and scoring of 30 terminology definitions. The agreement was 100% for resistance exercise, balance and physical activity. Most terms had agreement >75%, but 'posture' (60%) and 'exercise' (65%) had a lower agreement. CONCLUSION: This study identified key terms and obtained agreement on definitions for 30 terms. The variability in agreement for some terms supports the need for clearly referencing or defining terminology within publications to enable clear communication across disciplines and to support precise synthesis and accurate interpretation of research.