While Lehmann (1962) found 50 to 60 kg to be the most efficient load to carry, smaller ones are more convenient and are'safer' for the body (as discussed below ) but require more journeys and carrying one's own body weight to and fro increases the total consumption of energy, of course, the carried weight might be broken into smaller portions which can be attached to the back, the shoulders, the chest or even be put on the head. Carrying a medium load (of about 30 kg) distributed on the back and chest is the least energy consuming, as Table 6.4 shows