Why We Positioned This Study
Population aging is accelerating worldwide, and preserving mobility has become a core public health challenge. Loss of walking ability is closely linked to disability, reduced quality of life, and increasing long-term care needs. Yet, mobility decline is often recognized only after it becomes difficult to reverse.
Locomotive syndrome (LS) offers a practical framework to address this gap. LS focuses on mobility impairment caused by musculoskeletal dysfunction and captures an early stage along the pathway toward frailty and disability. Importantly, LS is measurable, communicable, and potentially modifiable, especially when identified before overt functional loss occurs.
Our research team has consistently approached LS as a life-course phenomenon, rather than a condition limited to older adults. In previous cross-sectional studies, we showed that LS frequently coexists with metabolic syndrome and reduced mobility already in middle-aged populations. These findings suggested that metabolic and musculoskeletal deterioration progress in parallel over decades.
What This Study Adds
The key aim of the present study was to examine whether long-term bodyweight increase since early adulthood, a simple indicator routinely collected in health checkups, predicts future mobility decline assessed by LS severity.
Using a 7-year longitudinal dataset of 10,316 Japanese adults aged ≥40 years, we demonstrated that a ≥10 kg bodyweight increase since age 20 was significantly associated with progression of LS severity, assessed by the GLFS-25, the stand-up test, and the total LS assessment. This association persisted after adjustment for age, sex, BMI, lifestyle factors, and cardiometabolic comorbidities.
These findings indicate that long-term weight history reflects cumulative metabolic and musculoskeletal burden beyond current body size alone. In contrast, some mobility measures appeared more sensitive to current mechanical loading, highlighting that different LS tests capture distinct dimensions of functional decline.
Public Health Implications
From a public health perspective, this study highlights an important opportunity.
Both the exposure (long-term weight gain) and the outcome (LS severity) are already measurable using existing, low-cost tools in routine health checkups. In other words, early warning signals for future mobility decline are already embedded in available data but remain underutilized.
LS risk tests are not merely diagnostic instruments. They function as communication tools, helping individuals recognize early changes in mobility and motivating preventive action. This is particularly relevant in midlife, when interventions are more likely to be effective.
Why This Matters Beyond Japan
Although LS originated in Japan, the challenge it addresses is global. Aging societies worldwide face similar issues related to mobility loss, disability, and healthcare sustainability. The LS framework offers a transferable model for early detection and prevention of mobility decline that can be adapted across healthcare systems and cultural contexts.
An Invitation to Use and Collaborate
We encourage clinicians, researchers, and public health professionals to actively use LS risk tests in clinical practice, health screening programs, and community settings. Moreover, LS provides fertile ground for international collaboration—from epidemiological research to intervention studies and policy evaluation.
Mobility matters. Preserving it requires shared concepts, shared tools, and shared data.
If you are interested in applying LS concepts or collaborating in mobility research, we warmly invite you to join us.