Turning up the heat on skeletal muscle adaptations and neuromuscular function: key considerations for passive heating prescription and best practices.

Despite compelling evidence supporting the benefits of passive heat therapy in promoting skeletal muscle adaptation and enhancing neuromuscular function, the topic remains debated. Some recent studies report no significant effects on muscle protein synthesis, muscle mass, recovery, strength, or power. This raises critical questions: is passive heat therapy not actually effective? Or do these discrepancies reflect inconsistencies in study protocols and an overgeneralisation of the term passive heating? Despite its growing recognition as a health treatment, exercise mimetic, and tool for sport performance and recovery, the interpretation of outcomes is often simplistic or misinformed. In this opinion article, we discuss the disparities in the literature and highlight the risks of oversimplification, such as the binary view that passive heat therapy either "works" or "does not work." We also propose incorporating the FITT (Frequency, Intensity, Time, and Type) principles from exercise science into thermal therapy research to enhance methodological consistency and clarity. By adopting a more structured and rigorous approach, the field can better realise the potential of passive heat therapy as a scientifically grounded intervention for both health and sport performance applications.