Running biomechanical alterations during a 40-km mountain race.

Background: The purpose of this study was to analyze running biomechanical alterations according to different slopes (flat, uphill and downhill) and distance, during a 40-km mountain trail running race.

Methods: Throughout the race, eight runners were equipped with Runscribe inertial units placed on each running shoe. Measurements included spatiotemporal parameters (contact time, step frequency, stride length, running speed), kinetic (impact peak and braking force) and kinematic data (foot pronation velocity and foot pronation excursion).