PubMed · 15802045
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2005. Piscator.. https://pubmed.ncbi.nlm.nih.gov/15802045/
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A skeletal design which favours running and walking, including the greatest ratio of leg length to body weight of any mammal; the ability to sweat and so to exercise vigorously in the heat; and greater endurance than all land mammals other than the Alaskan Husky, indicates that humans evolved as endurance animals. The development of tools to accurately measure time and distance in the nineteenth century inspired some humans to define the limits of this special capacity. Beginning with Six-Day Professional Pedestrian Races in London and New York in the 1880s, followed a decade later by Six-Day Professional Cycling Races - the immediate precursor of the first six-day Tour de France Cycliste race in 1903, which itself inspired the 1928 and 1929 4,960 km "Bunion Derbies" between Los Angeles and New York across the breadth of the United States of America - established those unique sporting events that continue to challenge the modern limits of human endurance. But an analysis of the total energy expenditure achieved by athletes competing in those events establishes that none approaches those reached by another group - the explorers of the heroic age of polar exploration in the early twentieth century. Thus the greatest recorded human endurance performances occurred during the Antarctic sledding expeditions led by Robert Scott in 1911/12 and Ernest Shackleton in 1914/16. By man-hauling sleds for 10 hours daily for approximately 159 and 160 consecutive days respectively, members of those expeditions would have expended close to a total of 1,000,000 kcal. By comparison completing a Six-Day Pedestrian event (55,000 kcal) or the Tour de France (168,000 kcal), or cycling (180,000 kcal) or running (340,000 kcal) across America, requires a considerably smaller total energy expenditure. Thus the limits of human endurance were set at the start of the twentieth century and have not recently been approached. Given good health and an adequate food supply to prevent starvation and scurvy, these limits are set by the mind, not by the body. For it is the mind that determines who chooses to start and who best stays the distance.
In Ireland, several studies have monitored the air pollution due to traffic in both urban and rural environments. However, few studies have attempted to quantify the relative exposure to traffic derived HC pollutants between different modes of commuter transport. In this study, the difference in pollution exposure between bus and cycling commuters on a route in Dublin was compared by sampling for five vehicle related hydrocarbons: benzene, 1,3-butadiene, acetylene, ethane and ethylene. Samples were collected during both morning and afternoon rush hour periods using a fixed speed pump to gain representative concentrations across the whole journey. Journey times were also measured, as were typical breathing rates in order to calculate the overall dose of pollutant inhaled on the journey. Results clearly picked up significantly higher pollutant concentrations in the bus compared to cycling and also revealed elevated concentrations on the congested side of the road compared to the side moving against the traffic. However, when respiration rates and travel times were taken into account to reveal the mass of pollutants inhaled over the course of a journey, the pattern was reversed, showing slightly enhanced levels of hydrocarbons for the cyclist compared to the bus passenger. In addition, the concentrations of these compounds (excluding ethane), were ascertained at playing pitches in the vicinity of a heavily trafficked suburban motorway and in Dublin city centre. Although the concentrations were relatively low at all sites, when breathing rates were taken into consideration, the average inhaled weights of pollutants were, on occasion, higher than those average values observed for both bus and bicycle commuters.