In springboard diving the effect of the fulcrum setting on height generated by the backward press has not been determined. The purpose of this study was to model the springboard and diver as an oscillating spring system as well as to determine a prediction equation in order to predict the fulcrum setting at which the diver generates the most amount of height. 11 male and 9 female collegiate divers participated in the study. Video data were sampled at 60 Hz with a shutter speed of 1/250 sec. Data were digitized using a Motion Analysis VP-110 processor interfaced to a Sun minicomputer. Reflective markers were placed on the diver and on the springboard. Divers were filmed oscillating in laboratory and pool sessions. Divers were also filmed oscillating at fulcrum settings of 1, 3, 5, 7, 9 on the springboard and their preferred fulcrum setting as well as on the ground.
The results from the study indicated that it was possible to model the springboard and diver as an oscillating spring system with the weight and spring located at the tip of the board. It was also possible to predict the fulcrum setting at which divers generated the most height by performing a bootstrap stepwise regression analysis including the variables obtained in the study. The results indicated that preferred fulcrum setting, diver mass and oscillation rate on the ground were good predictors of fulcrum setting explaining 82% of the variance in the equation. The final prediction equation for optimal fulcrum setting is: $$\rm Y = 10.458 + 1.242(B1) - 4.501(B2) + -.026(B3)$$where(UNFORMATTED TABLE OR EQUATION FOLLOWS)$$\vbox{\halign{#\hfil&&\enspace#\hfil\cr &\rm Y&= \rm predicted\ fulcrum setting\cr\cr&\rm B1&= \rm preferred fulcrum setting\cr\cr&\rm B2&= \rm post pool Hz (frequency of oscillation on the ground)\cr\cr&\rm B3&= \rm weight of the diver (in pounds)\cr}}$$(TABLE/EQUATION ENDS)
The correlation between actual and predicted values for each individual was r = 0.90 and the mean difference between predicted and actual values was $-$0.005. The equation seems to be good at predicting fulcrum setting for this particular group of subjects; however, the equation still needs to be tested on other groups of divers. The equation may also differ for different springboards with different stiffnesses.
