What inspired this study?

In Japan, all working adults are legally required to undergo annual health check-ups. In addition to these statutory screenings, a unique private health check-up program called Ningen Dock has evolved, offering comprehensive examinations that assess not only metabolic risk but also physical function.

These systems have generated a rich database of real-world health data. Recognizing the potential of this resource, we aimed to explore early indicators of age-related decline before clinical symptoms become evident—specifically focusing on locomotive syndrome (LS) and metabolic syndrome (MetS), two critical but often separately evaluated conditions in aging populations.

Understanding locomotive syndrome

While MetS is globally recognized as a major risk factor for cardiovascular disease, LS remains relatively unknown outside Japan. Defined by the Japanese Orthopaedic Association, LS refers to age-related decline in musculoskeletal function, particularly in the lower limbs, which leads to reduced mobility, frailty, and an increased need for long-term care.

To screen for LS, the Locomotive Syndrome Risk Test was developed. It consists of three simple components:

• • A stand-up test to evaluate leg strength
  • A two-step test to assess stride length and balance
  • A 25-item questionnaire (Locomo-25) on physical function and daily living

This test has been implemented in our clinic’s health check-up program since 2016, enabling us to evaluate mobility decline in a large general population.

What we found

Using health check-up data from 35,059 adults, we found:

• • 15% of participants were positive for LS, and 7.5% met the criteria for MetS
  • Those with MetS were nearly 1.8 times more likely to have LS than those without
  • The overlap was most prominent in individuals in their 50s, regardless of sex
  • Participants with both LS and MetS had significantly higher waist circumference, glucose levels, and blood pressure compared to those with neither condition

These findings suggest that mobility decline does not begin suddenly in old age—it often starts silently in midlife, particularly in the presence of metabolic risk factors.

Why this matters

Around the world, countries are facing the challenge of aging populations. Identifying early signs of decline in physical function and metabolic health is critical to extending healthy life expectancy and reducing the burden of disability and long-term care.

This study provides evidence that screening for both MetS and LS in midlife could allow for earlier intervention, and that MetS may serve as an early warning signal for mobility decline. Addressing both conditions together could offer a powerful strategy to delay or prevent frailty.

Implications beyond Japan

The Locomotive Syndrome Risk Test is a low-cost, non-invasive, and scalable tool suitable for large-scale screening. It does not require specialized equipment and can be administered quickly in community or clinical settings.

We believe that this Japan-developed concept and tool could be adapted and implemented globally, especially in aging societies where early detection of physical decline is becoming increasingly important.

What comes next

Our current study was cross-sectional, but we are now preparing longitudinal analyses to better understand:

• • The causal relationship between MetS and LS
  • How persistent LS affects long-term outcomes such as falls, frailty, and care dependency

By tracking individuals over time, we aim to visualize the trajectory of decline and identify optimal timing for preventive intervention. Our ultimate goal is to design a comprehensive and practical health screening model that combines metabolic and musculoskeletal evaluation.

Final thoughts

As aging accelerates globally, countries must prepare strategies to detect and address silent risk factors before they manifest as disability.

Our findings highlight how Japan’s preventive health infrastructure—and particularly the integration of functional testing like the Locomotive Syndrome Risk Test—can contribute to this goal. We hope our work encourages broader attention to early mobility decline and helps inform international health policy and practice.