The kinetic and kinematic effects of increasing load carriage upon the lower limb

Increased knee flexion occurs post heel contact whilst carrying a heavy load. To establish the influence of increasing load carriage the gait of 10 military subjects was assessed under four conditions (unloaded barefoot, and in issue boots: unloaded, 20 and 40 kg loads). Loads up to 64% of an individual’s body mass had little effect on sagital plane gait motion. Ground reaction force data and peak force time parameters were derived. Force data were expressed as percentage of body weight and also of total weight. In these trained subjects ground reaction forces rose in proportion to the load carried. Peak forces changed with loads as low as 20 kg and the forces necessary for balance increased significantly when load was carried. Lower limb loading and unloading rates did not rise in relation to load. It is suggested this may be a protective response to mitigate a potential for injury.