Crenotherapy and exercise in knee osteoarthritis: a narrative review of their integrative approach

Knee osteoarthritis is a leading cause of global disability, characterized by joint pain, functional decline, and progressive structural degeneration. Current management emphasizes non-pharmacological strategies, among which crenotherapy and structured physical exercise each have evidence of reducing pain and improving function. This review synthesizes available mechanistic and clinical data for both approaches and proposes a mechanistic rationale for their combined use. Crenotherapy has been associated with short-term pain relief and modulation of inflammatory and neuroendocrine pathways, possibly mediated by local thermal, neurogenic, and humoral mechanisms. By reducing pain, it might also acutely attenuate pain-related quadriceps inhibition, although this has not been directly tested. Structured exercise improves neuromuscular control, joint stability, and cardiovascular conditioning, and elicits favourable systemic anti-inflammatory signalling when performed consistently. We hypothesized that preconditioning with crenotherapy may transiently lower the pain barrier to activity, potentially improving movement quality, enabling a higher-tolerated training dose (in terms of intensity or volume), and promoting exercise adherence. In turn, exercise-induced adaptations could prolong and amplify the benefits initiated by thermal therapy. Whether the combined effects are additive or synergistic remains to be established. Although physiological and single-modality clinical data are consistent with and support this conceptual model, direct empirical evidence from controlled trials of integrated crenotherapy and exercise programs remains limited. This critical knowledge gap highlights the need for rigorous randomized trials to define optimal timing, dose, modality, and patient selection, and to evaluate pain, functional, biomarker, and structural outcomes with adequate follow-up. Establishing evidence-based parameters for combined therapy could advance multimodal rehabilitation strategies and improve long-term outcomes in knee osteoarthritis.