| Abstract: | There are many different ways in which loads may be carried, and the mode of load carriage adopted can be determined by factors such as weight, shape and size of the load, the duration for which it has to be carried, the terrain, climate and the physical characteristics and condition of the individual and the clothing he wears as well as his personal preference. It is generally more expensive in terms of energy cost to carry loads on the head, in the hands or arms, or attached to the legs, than to carry the load closely attached to the trunk as when using a backpack. A combined front-and backpack, or carriage of loads around the waist, tend to incur the lowest energy cost for a given load, as lateral and anteroposterior stability is optimized. However, there may be chest restriction and a limitation to evaporate body cooling, and donning and doffing problems may mitigate against the adoption of this method. Hand or arm carriage usually leads to local muscle fatigue rather quickly. Despite this, for convenience, over short distances or for intermittent load carriage, people will often choose to carry loads in their arms or hands. This paper describes six separate experiments that we have conducted in our laboratory. In general, they show that there is seldom a single ‘best’ way to carry a load, and it is often difficult to clearly and objectively distinguish the physiological effects and the effects on the performance of the individual, of different methods of load carriage. We believe that it is wise to supplement objective physiological measurements with subjective opinion. However, it is important that the subjective data should be gathered as objectively as possible, by using appropriate experimental designs, carefully structured questionnaire techniques and standardized subjective rating methods. We have also found it profitable to conduct field studies to supplement our laboratory experiments. In general heavy loads should not be attached to small muscle groups, and optimum use should be made of the large muscle groups of the body in order to minimize fatigue and local muscular discomfort. There is a ‘knack’ to load carriage, and that ‘knack’ lies in the practical implementation of elementary principles. |
