Energy balance of locomotion with pedal-driven watercraft.
In this study, we examined the mechanics and energetics of locomotion with a paddle-wheel boat and a water bike. Power output (Wtot) was measured directly on the water bike by means of an instrumented chain-ring. The simultaneous assessment of oxygen uptake (VO2) allowed the computation of the "overall" efficiency of locomotion (etao = Wtot/VO2). Mean etao was 0.27 (s = 0.02), which was unaffected by the speed, and was assumed to be the same for the two boats as both are semi-recumbent bicycles. For the paddle-wheel boat, Wtot was then obtained from etao and measures of VO2. The power to overcome (passive) drag was calculated as Wd = D x v (where D is the force measured by means of a load cell when towing the boats at given speeds). Propelling efficiency was calculated as etap = Wd/Wtot, which was lower with the paddle-wheel boat (mean 0.35, s = 0.01) than with the water bike (mean 0.57, s = 0.01). The observed differences in etap and Wd explain why at the highest speed tested (approximately 3 m s(-1), the energy required to cover a unit distance with the water bike is similar to that required to move the paddle-wheel boat at 1.3 m s-1).
Zamparo
Paola
P
Corso di Laurea in Scienze Motorie, Università di Udine, Gemona del Friuli, Udine, Italy. paola.zamparo@univr.it
Carignani
Giuseppe
G
Plaino
Luca
L
Sgalmuzzo
Barbara
B
Capelli
Carlo
C
D000328:Adult; D000886:Anthropometry; D001642:Bicycling / Q000502:physiology*; D001696:Biomechanical Phenomena; D002153:Calorimetry, Indirect; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D017276:Friction; D006801:Humans; D008124:Locomotion / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology; D010865:Pilot Projects; D012767:Ships; D013550:Swimming / Q000502:physiology*