Soldier Performance and Strenuous Road Marching: Influence of Load Mass and Load Distribution

Abstract

Fifteen male soldiers performed six maximal-effort, 20-km road marchers. 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 double-pack. 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 tasks 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.

The effect of load distribution within military load carriage systems on the kinetics of human gait

“…Both of these factors have been shown by other studies to be possible reasons for such increase. The important role that increases in maximum braking force play in the development of blisters is highlighted again in a study by Knapik et al (1997b).…”

“…The main interest with this parameter in respect to LCS design is that increased sheer forces that act on the foot will 'increase the probability of blisters during physical activity' (Knapik et al, 1997a). Foot blisters are the most common load carriage related injury and can also be debilitating (Knapik et al, 1997b;Reynolds et al, 1999). Load carriage has also been shown to increase blister incidence independently to other factors, with Knapik et al (1997a) suggesting that load carriage increases the pressure on the skin and causes more movement between the foot and boot through higher propulsive and braking forces, thus increasing the risk of blister occurrence.…”

Ground reaction forces and plantar pressure distribution during occasional loaded gait

“…The anterior-posterior force helps slow the body down during the initial part of the gait cycle (Birrell and Haslam, 2010). Its increase seems to be related to blister development (Knapik et al, 1997). Birrel and Haslam (2010) suggested that load carriage increases the pressure on the skin and causes more movement between the foot and the shoe through higher propulsive and braking forces, thus increasing the risk of blister.…”

Can load carriage system weight, design and placement affect pain and discomfort? A systematic review

“…Knapik et al assessed the effect of backpack and double pack. They reported that double pack caused less discomfort in low back, lower incidence of blisters, but it resulted in pain in neck and hips and it took longer to complete the march with wearing the double pack [27]. Also, Mackie et al evaluated the influence of four backpacks on perceived exertion and discomfort.…”