Average peak VGRFs for all subjects for all OU conditions were found to be quite similar regardless of the wooden platform height. Further analysis of the GRF, motion capture, and video data collected for this study may be necessary to understand the reason(s) for this unexpected similarity. Average peak VGRFs for all subjects for all OD conditions were higher than expected given the previous study of Ollie kinetics (Frederick et. al., 2006). In that study average peak VGRFs for professional skateboarders Ollieing down from a 45.7CM platform were found to be 4.519 ± .582BW. The authors noted that these forces were higher than expected given relatively lower VGRFs from other jump landing studies. They concluded that this was caused by the subjects intentionally "spiking" their landings in order to stabilize themselves on top of the skateboard. In our study average peak VGRFs for subjects Ollieing down from a similar height were found to be .92BW greater. Perhaps amateur skateboarders need to spike their landings even harder to stabilize themselves. It is also possible that this difference in force was due to a difference in the height the subjects Ollied off the 45.7CM platform before landing down on the force plate. Average peak N/T tail-smack forces were unexpectedly similar in magnitude among all OU conditions and trials for all subjects. Interestingly this peak N/T GRF corresponded with a peak vertical tail-smack force. The magnitude of this force is not reported in this abstract.
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