Acute effects of combat boots and minimalist shoes on Achilles tendon loading during running under different load carriage magnitudes in soldiers.

This study investigated the acute effects of combat boots and minimalist shoes on Achilles tendon (AT) loading during running under different load carriage magnitudes in soldiers. Eighteen rearfoot-strike soldiers performed running tests under three load conditions (0, 10, and 20 kg) while wearing either minimalist shoes or combat boots. The coordinates of the body landmarks and ground reaction force data were simultaneously collected using the infrared high-speed motion capture system and force plates. The musculoskeletal model was established to calculate AT biomechanical parameters. Results showed that AT force impulse and stance duration increased with higher load magnitudes. Load carriage increased AT force during the midstance phase but decreased it during the early stance phase. Compared with combat boots, running in minimalist shoes decreased AT force during the terminal stance phase and shortened stance duration but increased AT force during the early stance phase. However, no main effect of footwear on AT force impulse was found. Additionally, no interaction effect between footwear and load carriage magnitude was observed for any biomechanical parameter. These findings suggest that minimalist shoes provide limited acute benefits in reducing cumulative AT loading and therefore are not recommended for soldiers during load carriage.