THE EVOLUTION ACROSS AGES OF EFFICIENCY AND ECONOMY OF (ASSISTED) HUMAN LOCOMOTION AND EXERCISE

Human evolution and ingenuity both collaborated in providing biological/technological tools to move faster, despite of the same actuator, and to better adapt our locomotion to very different environments. While evolution resulted in a versatile musculo-skeletal system featuring optimization and energy-saving mechanisms to produce force and work more effectively, humans also invented passive tools, particularly in the last 4-5 millennia, allowing to moving faster and more economically on land, on/under water and in the air. Among the most featured examples: bone skating on ice, ancient cross-country skiing, bicycling, rowing. But also hand-held masses (Minetti & Ardigo, 2002) enhanced standing long jump and bows/crossbows made us throwing objects at longer distances (a hand-thrown arrow barely reach 25 m, while with a modern bow the distance exceeds 1.3 km). In the past few years we reviewed the historic evolution of passive tools devoted to enhance human locomotion (Minetti, 2004; Ardigo et al., 2005). Sometimes we built replicas of ancient tools (as in cycling - Minetti et al., 2001, cross-country skiing - Formenti et al., 2005 and ice skating - Formenti & Minetti, 2006), in other cases we used modern tools (as fins - Zamparo et al., 2002) in order to study, through biomechanical and metabolic experiments, the progressive adaptation of (the same) muscle to the different machines and environments. The focus of my presentation will be on how limitations of the musculo-skeletal system have been attenuated both inside (gear ratio, tendons) and outside (crank, gears, poles, skis, fins) the body. The relevance into the necessary mechanical work, the economy of transport and the related efficiency of motion/locomotion will be discussed