Comparison of Male and Female Responses to Carrying Absolute and Relative Loads While on a Three Hour Military March

Abstract

Recognizing the growing level of female participation in all aspects of military activities, this study undertook to investigate the effect of modifying the load carried according to individual morphologies and to compare male and female responses. Ten male and 10 female subjects were tested in situ on a 12km march under two conditions: (1) carrying an ‘Absolute Load’ of 40kg and (2) carrying a ‘Relative Load’ of 37% body weight. Heart rate responses plus perceptual ratings of exertion and discomfort were recorded at various stages of the march. Female heart rates were significantly elevated under both conditions and did not drop as expected when carrying loads relative to body weight. It is argued that this was at least partly due to the significantly higher percentage body fat of the females, suggesting that when ‘Relative Loads’ are calculated they should be based on lead body mass and not overall mass as tends to be the current method.