Wearable-Derived Locomotor Reorganization and Metabolic–Mechanical Coupling Across Running Slopes
Description
Wearable-derived running power (RPO) is increasingly used to monitor training load in graded running, yet how slope modifies its relationship with metabolic energy expenditure rate (EMET), power-component distribution, and spatiotemporal organization remains incompletely characterized. This study quantified slope-dependent changes in wearable-derived power component (RPOVK%), ground contact time (GCT) and step frequency (SF) and introduced the mechanical–metabolic coupling ratio (MMCR%; RPO/EMET × 100) to characterize the fraction of metabolic energy expressed as observable RPO. Fifteen trained male trail runners completed steady-state treadmill running at −7%, 0%, +7%. EMET was measured using indirect calorimetry, locomotor descriptors were estimated via a shoe-mounted wearable. The EMET – RPO relationship was not influenced by slope (p = .360) or by the slope × RPO interaction (p = .728). Slope markedly redistributed RPOVK%, (−7%: 41.7%, 0%: 29.7%, and +7%: 20.6%; p < .001), alongside significant changes in GCT and SF. MMCR% differed significantly across slopes F(2, 28.0) = 12.6, p < .001 (21.3% at −7%, 22.7% at 0%, and 21.9% at +7%), remained athlete-specific (ICC = .893), and was not independently explained by RPOVK%, GCT, or SF. These findings suggest that slope-dependent locomotor reorganization and MMCR% represent complementary dimensions of individual responses to graded running, with potential applications for terrain-specific load monitoring in trail running