Changes in temporal and spatial gait coordination during the six‑minute walk test in people with multiple sclerosis

Although gait coordination impairments represent a critical aspect of walking dysfunction in multiple sclerosis (MS), their variation during prolonged walking remains relatively unexplored. This study investigated changes in gait coordination during the six-minute walk test (6MWT) by jointly analyzing temporal and spatial measures of inter-limb and inter-joint coordination. Sixty-five people with MS and 43 matched unaffected individuals performed the 6MWT while kinematic data were acquired using an inertial measurement unit-based motion capture system. Coordination was quantified using the Phase Coordination Index and cyclogram-based geometric features, computed on a minute-by-minute basis. Results showed that people with MS exhibited significantly impaired coordination compared with unaffected individuals across most metrics from the beginning of the test. While both groups demonstrated progressive changes over time, people with MS showed limited additional deterioration during prolonged walking, suggesting a ceiling effect related to baseline neuromotor impairment and reduced adaptive capacity. Inter-joint coordination changes were most evident at the knee-ankle joint. Temporal and spatial measures provided complementary insights, revealing joint- and domain-specific behaviors missed by single-metric approaches. These findings support multimodal coordination analysis to improve gait assessment and guide rehabilitation in MS.