The Effect of Inclination on Spatiotemporal Gait Parameters in Special Forces Operators Under Tactical Load

Area of Science:

• Biomechanics
• Human Movement Science
• Military Physiology

Background:

• Special Forces Operators (SFO) frequently operate in terrain inaccessible to vehicles.
• External load carriage and variable inclines can impair walking efficiency and combat readiness.

Purpose of the Study:

• To analyze the effects of ground inclination on gait spatiotemporal structure in SFO.
• To evaluate gait under varying loads (0 kg and 27 kg) across different inclines (0-15%).

Main Methods:

• Fifty Polish SFO participated in treadmill-based gait analysis (h/p/cosmos Gaitway).
• Inclination levels: 0%, 5%, 10%, 15% with and without a 27 kg load.
• Statistical analysis included Friedman test, Durbin-Conover, and linear mixed models; gait symmetry was assessed using the Robinson Symmetry Index (SI).

Main Results:

• Increasing inclination significantly altered gait spatiotemporal parameters, most notably at 10-15% grades with a 27 kg load.
• Observed changes included shortened step length and gait cycle time, with a slight increase in cadence at 15% inclination and max load.
• Step width remained consistent, and the Robinson Symmetry Index indicated stable gait symmetry.

Conclusions:

• Ground inclination and military load substantially influence SFO locomotion.
• Stable gait symmetry and step width suggest effective operator adaptation mechanisms.
• Significant spatiotemporal gait modifications at higher inclines/loads may elevate overuse injury risk.