Development and validation of the rest experience scale for adults with chronically fatiguing conditions

Introduction
Rest is a key component of rehabilitation but remains understudied and underspecified in research and practice, partly due to limited conceptual understanding and comprehensive assessment tools. This gap may hinder the integration of rest advice into physical activity and fatigue management protocols. This study aimed to develop and validate the Multidimensional Rest Experience Scale (MRES) for adults with Chronically Fatiguing Conditions (CFC).

Methods
Conducted in three phases, Phase 1 involved MRES development via a modified Delphi method to ensure content validity. Phase 2 included preliminary validation by administering the MRES to a representative sample of adults with CFC to assess construct validity and factor structure. Phase 3 evaluated reliability, examining internal consistency and test-retest reliability. Descriptive and inferential analyses were performed.

Results
The Delphi process reached consensus on 25 items. Exploratory factor analysis refined the scale to 22 items with six factors: resting activity, restorative rest, planning and prioritising rest, physical and psychological barriers to rest, emotional response to rest, and risk of under-resting. Resting Activity showed significant positive correlations with Chronic Pain Coping Inventory (CPCI) Rest subscale (r = 0.572, p < 0.001) and Pacing Engagement (r = 0.332, p < 0.001). Planning and Prioritising Rest correlated with CPCI-Rest (r = 0.532, p < 0.001) and Pacing Engagement (r = 0.681, p < 0.0001). Under-resting risk correlated with Over-Activity risk (r = 0.504, p < 0.001). Discriminant validity for the MRES-22 subscales was established, with Heterotrait-Monotrait (HTMT) ratios ≤ 0.85. Internal consistency was acceptable to good (Cronbach’s α = 0.773–0.829, CR = 0.752–0.830), and test-retest reliability was good to excellent (ICC = 0.816–0.943).

Conclusion
The MRES-22 is a valid and reliable tool for capturing the multidimensional components of rest experience, which are often overlooked in fatigue management protocols. This finding supports the use of the MRES-22 in both clinical and research settings to enhance understanding of rest in relation to key health outcomes and to optimise fatigue interventions in rehabilitation.