New MMQ Questionnaire Detects Mobility Decline in Middle Age Before It Becomes Serious

Mobility begins declining in midlife long before most people seek clinical attention. Up to 60% of middle-aged adults report mobility-related difficulties, and fall risk nearly triples between ages 40–44 and 60–64. Despite this, clinicians and researchers have lacked a validated self-report tool designed specifically for the 45–64 age group. Most existing questionnaires were built for older adults and suffer from pronounced ceiling effects when applied to middle-aged populations, rendering them insensitive to early, subtle decline.

To fill this gap, the research team developed the Mobility in Middle-Age Questionnaire (MMQ) through a rigorous 7-step Delphi process conducted from April to September 2024. Ten multidisciplinary experts — including physical therapists, gerontologists, epidemiologists, a psychologist, and a physiologist from the US and Israel — iteratively evaluated, revised, and reached consensus on items across three rounds. The process began with a 24-item draft spanning five domains and two structural factors: Factor 1 (Current Mobility Ability), assessing strength, aerobic capacity, flexibility, stability, and outdoor function; and Factor 2 (1-Year Mobility Change), capturing perceived functional trajectory. After expert consensus and a pilot with 50 middle-aged adults, the final instrument comprised 16 items rated on five-point Likert scales, achieving a Scale-Level Content Validity Index of 0.92.

Psychometric validation was conducted in two independent cross-sectional online survey samples: 610 adults in the US and 594 in Israel. The MMQ demonstrated excellent internal consistency (Cronbach's α = 0.94 English; 0.92 Hebrew) and strong test-retest reliability (ICC = 0.89–0.90). Exploratory factor analysis explained 66% of total variance, and confirmatory factor analysis confirmed good structural fit (CFI = 0.99, TLI = 0.99, SRMR = 0.05). All pre-specified construct validity hypotheses were confirmed through correlations with the PF-10 physical functioning scale from the SF-36.

The MMQ's most clinically compelling advantage was its markedly lower ceiling effect compared to the PF-10 — just 3.9% vs. 34.5% in the US sample, and 0.17% vs. 25.25% in Israel (p < 0.001, large effect sizes). This means the MMQ can differentiate among individuals who score at the top of older tools, making it sensitive to gradations of function that matter in midlife. A preliminary risk threshold of a score of 50 (20th percentile) was proposed as a 'Potential Mobility Risk Zone' to identify individuals who may benefit from early preventive intervention.

The study's cross-cultural, bilingual design strengthens generalizability, and adherence to COSMIN guidelines ensures methodological rigor. However, the authors acknowledge that longitudinal validation is still needed to confirm the MMQ's predictive value for future disability and its responsiveness to intervention-related change. The current samples were also recruited via online panels, which may not fully represent all socioeconomic or health-status groups.