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Updated: Feb 3, 2026

Ex vivo Mechanical Loading of Tendon
Published on: May 28, 2007
Effect of different loading conditions on running mechanics at different velocities
Germán Carretero-Navarro1, Gonzalo Márquez1, Doménico Cherubini1
1a Departamento de Ciencias de la Actividad Física y del Deporte, Facultad de Ciencias de la Actividad Física y del Deporte - UCAM , Universidad Católica San Antonio de Murcia , Murcia , España.
Abstract:
Weighted vests are widely used to improve running economy and performance. However, it is not well-studied how running mechanics are adapted to counteract the higher peak vertical ground reaction forces (Fpeak) while running with such a device. Therefore, the present study aimed to investigate the effects of different loading conditions on running mechanics at different velocities. Thirteen subjects participated in two separate sessions one week apart. In the first session, maximal aerobic speed (MAS) was determined through a maximal incremental running test while in the second session, they were instructed to run during one minute under different loading (0%, +10% and +20% of body mass [BM]) and velocity (60%, 80% and 100% of MAS) conditions in a random order. Spatiotemporal data were recorded and then running mechanics modelled using the spring-mass model. The main results indicated that vertical and leg stiffness (Kvert and Kleg, respectively) were increased (P < .001) as velocity increased but remained unaltered (P > .05) when load was changed. At the same time, alterations of the running kinematics were observed such as longer contact times, reduced flight times, stride frequencies and step lengths, as well as an increase of the centre of mass dynamics. Based on these results it is assumed that runners maintain a certain stiffness level for each velocity despite different loading conditions. As a consequence, Fpeak increases and this probably causes spatiotemporal adjustments in the movement kinematics.
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