Longstanding aging metrics have focused on how long people live and how long they live free of chronic disease, but both overlook a core component of daily well-being: the ability to move through the world with ease and confidence. Professor Li Li from Georgia Southern University, USA, formally proposes a groundbreaking conception "Movement Span" as a new and independent dimension of aging, reshaping how we define, measure, and address age-related functional decline.
The article was made available online on June 02, 2026, and published in Volume 15 of the Journal of Sport and Health Science . The opinion paper is the first formal proposal to position movement span as a standalone construct alongside life span and health span, with clear conceptual boundaries, measurable indicators, and actionable clinical and public health implications. It extends the discourse beyond longevity and disease status to everyday movement quality and adaptive capacity, drawing on geroscience, motor control research, and clinical geriatrics evidence.
Movement span is defined as the duration of life during which an individual can move with confidence, responsiveness, and adaptive control. It goes beyond basic walking ability to encompass real-time adjustment to unexpected changes, fluid transitions between movement patterns, and reliable performance under variable daily conditions—capacities central to autonomy, identity, and unselfconscious social participation.
The paper outlines a nested, partially overlapping relationship between the three constructs: Life span forms the outermost boundary of all aging trajectories; health span sits within life span, representing years free of disabling disease; movement span is nested within both, and typically begins declining earlier than diagnosable health conditions.
A key clinical observation is that movement span narrows before health span collapses.
It typically begins to decline before overt organic pathology emerges, manifesting as subtle changes such as slower reaction time, reduced balance recovery ability, and a preference for predictable movement environments—making it an important early indicator of subsequent health risks. The author further notes that the significance of movement span extends far beyond predicting fall risk or mortality. And this construct also helps explain the paradox of avoidance: As movement capacity gradually diminishes, individuals tend to self-restrict their behaviors and activity scope, which in turn accelerates the deterioration of physical function.
For movement span to be recognized as a meaningful clinical and public health construct, it must be reliably measurable. Gait speed, assessed over a standardized distance at both usual and maximal pace, has the strongest evidence base as a functional indicator of aging health. Beyond gait speed, a comprehensive movement span assessment should encompass balance under varying sensory conditions, reaction time to unexpected stimuli, and the capacity to coordinate movement transitions such as starting, stopping, turning, and changing direction. Professor Li also recommends the Timed Up and Go (TUG) test, a compound task combining sitting-to-standing, 3-m walking, turning, and sitting back down. This task mirrors the transitional demands of everyday movement and is especially sensitive to the adaptive motor control.
Professor Li says the movement span framework fills a longstanding gap in aging research and clinical practice. "For decades we've progressed from asking 'how long do people live?' to 'how long do they live well?'—but 'well' has mostly meant 'without diagnosed disease,'" Prof. Li says. "What we're missing is the everyday experience: Can someone navigate a crowded room confidently? Recover from a stumble without thinking? Step off a curb automatically, without deliberate caution? That quality of movement shapes autonomy and identity every single day, and it starts fading long before any disease is diagnosed. By establishing movement span as a formal construct, we give clinicians and public health practitioners an earlier warning system. We can intervene before falls occur, before health span is compromised, while behavioral change still has the greatest impact. This isn't just about avoiding disability—it's about helping people stay fully present and active in their own lives."
The movement span framework offers actionable insights for research, clinical practice, public policy, and person-centered care: It advances mobility measurement, reframes clinical care around movement capacity, promotes activity-supportive policies, and fosters lifelong purposeful movement. It redefines successful aging as maintaining meaningful mobility long-term, not just longer, healthier survival.
