Soldier performance and strenuous road marching: Influence of load mass and load distribution

Abstract

Fifteen male soldiers performed six maximal-effort, 20-km road marches. They carried load masses of 34, 48, and 61 kg, using a standard military backpack with frame or an experimental doublepack. March times decreased as mass increased and were faster with the standard pack than with the doublepack. The doublepack resulted in less low back discomfort and a lower incidence of blisters at the highest load, but also resulted in more discomfort in the neck and hips. Neither load mass nor pack type affected soldiers' marksmanship ability, grenade throw accuracy, or cognitive ability. The maximal-effort march itself affected the marksmanship task by increasing the post-march vertical shot group dispersion. The concept of distributing the load mass more evenly around the center of mass of the body has both positive and negative aspects and warrants further investigation.