The Biomechanics and Energetics of Skateboarding

I investigated the ground reaction forces (GRF), stride kinematics and metabolic cost of skateboarding on an instrumented treadmill. Superficially, skateboarding appears to be a hybrid of walking, running, and cross-country skiing. I hypothesized that the push-foot in skateboarding would exhibit a vertical GRF peak similar in shape to running but with a lower magnitude. Further I hypothesized that the push-foot would exhibit greater propulsive GRF than braking GRF. Regarding stride kinematics, I hypothesized that skateboarders would increase their stride length (sL) at faster speeds. Finally, I hypothesized that skateboarding would have a smaller metabolic cost compared to walking and running at comparable speeds. Subjects (9 males/2 females) skateboarded on a force-instrumented treadmill at 1.00, 1.25, 1.50, 2.00, 2.50, 3.00, 3.50, and 4.00 m*sec-1, walked at 1.25m*sec-1, and ran at 3.0m*sec-1. Upon GRF analysis, I discovered two distinctly different groups of skateboarders: subjects who demonstrated a braking force (“brakers”) and subjects that did not (“non-brakers”). The peak vertical and horizontal GRF for brakers resembled running with half of the magnitude. Both groups showed decreased SF at faster speeds, but brakers used slower SF than non-brakers. Walking and skateboarding 1.25m*sec-1 had the same metabolic cost at but at 3.0m*sec-1, skateboarding required approximately half the metabolic cost of running. Skateboarding is a unique mode of locomotion, with two distinctly different forms, that allows a person to move at a running velocity with the GRF and metabolic cost of walking