Energetics of Load Carriage by Bamboo Carrying Poles

Abstract Unlike western conventions of rigid body attachments (e.g. backpack), carriers in Asia prefer to use bamboo poles, an ancient, ingenious, elastically-suspended equipment, especially when carrying heavy loads. As an elastically-suspended equipment, bamboo pole might have some potential benefits including reducing peak shoulder forces as well as saving metabolic transport cost, but certain skills should be needed for loading. Experienced carriers routinely carry loads exceeding their own body mass (Mb) for a long distance, while novices might hurt themselves. However, no skillful bamboo pole carriers’ performance or loading with heavy load has not been reported as far as we know. We set out to determine the loads capability and distances carried by skillful carriers, measure their metabolic cost for carrying the loads, and observe whether their natural walking speed changed as a function of load. In this paper, we compared the skillful carriers’ energy expenditure on carrying loads in both normal bamboo pole on shoulder and typical backpacks with hip support. Both carrying postures were normal, just as what subjects used in their daily life. The O2 consumption and CO2 production were measured in 13 subjects while standing or walking with loads. All subjects were asked to carry loads ranging from 0 kg to their load capacity in two loading type, while walking on a 1-meter wide nearly circular level track at their preferred speed. These speeds were record by cameras placed beside the track. Experimental results show that bamboo pole perform better under heavy load: 1. Loading by bamboo pole helped carriers to load 16% body weight heavier than by backpack on average. 2. With the load increasing, the walking speed loading by backpack would decrease from 1.3m/s (0kg) to 1.1m/s (load capacity), however loading by bamboo pole would slightly increase. 3. The rate of energy consumptions both increase with load increasing. Bamboo pole require more metabolic consumption than backpack with same load. 4. Since natural walking speed by bamboo pole faster than by backpack, the cost of transport by bamboo pole would be more economic than by backpack while the load is 50kg or more.