Identifying Fatigue-Related Gait Patterns Using Multiple Inertial Measurement Units and Statistical Parametric Mapping: A Continuous Analysis of an Outdoor Full Marathon in Male Recreational Runners

Male recreational runners exhibit a marked decline in performance only after 35 km. The progressive increase in rearfoot lateral acceleration and external rotation velocity during the propulsion phase, may be associated with a compensatory distal strategy to maintain balance stability. The gradual reduction in anterior tilt velocity of the shank during the loading response likely reflects a stiffness-enhancing mechanism in the lower limb to preserve locomotor efficiency under fatigue. The increased anterior acceleration of the pelvis at the 40 km mark suggests a proximal shift in propulsion mechanics due to fatigue. These findings underscore the necessity of long-distance protocols, continuous kinematic monitoring, and full stance-phase analysis to study running fatigue.