Lower limb kinematics and physiological responses to prolonged load carriage in untrained individuals

Practitioner Summary: It is presumed that lower limb injury is associated with prolonged load carriage, especially in new military recruits. Our results suggest that prolonged carriage of a 22 kg load does not cause any functionally relevant gross biomechanical changes despite an increase in the physiological demands and perceived intensity of the task. The aim of this study was to simultaneously assess the changes in physiology, and kinematic and spatiotemporal features of gait, during prolonged load carriage in individuals without load carriage experience. Eleven males, representative of new military recruits, walked for 120 min at 5.5 km h(- 1), 0% grade, on a motorised treadmill while carrying a 22 kg load. The load ( <= 30% body mass) was distributed over a weighted vest, combat webbing and replica model firearm, to reflect a patrol order load. Oxygen consumption and heart rate increased throughout the trial; however, apart from a minor increase in step length, there were no changes in the kinematic or spatiotemporal parameters, despite an increase in perceived exertion and discomfort. These data suggest that individuals with no experience in load carriage are able to maintain normal gait during 2 h of fixed speed walking, while carrying a patrol order load <= 30% body mass.