Biomechanical P ... Slalom Water Skiing R1.pdf - Atrium - University ...

have almost fallen but recovered and continued to ski the course. In all cases the writtenobservations were cross referenced with qualitative data before being excluded from theanalysis.The data files were all processed using Microsoft Excel (Microsoft Canada Co,Mississuage, Canada) and the first step was to perform a series of unit conversions. Theorientation matrix from the IMU was then used to calculate pitch, roll, and heading. Theroll data was used to determine the boundaries of each turn such that a turn started andended when roll was equal to 0º. A left turn occurred when the roll angle was greater than0º and a right turn when it was less than 0º. The data files could then be broken down intoleft and right turns and resultant peak rope load, skier velocity, ski roll, ski accelerationand ski deceleration could be calculated. It was also of interest to calculate the integral ofthe respective parameter profiles to investigate the cumulative result over a period oftime. The acceleration data was filtered using a moving average, where five data pointswere used as the averaging window.After the previously mentioned performance parameters were calculated a generalizedlinear mixed-model was employed for statistical analysis. When testing the performanceof the skis, factors included in the model were ski turn and skier as well as theirinteractions. The assumptions of the ANOVA were assessed by comprehensive residualanalyses. Three common numerical normality tests were performed, a Shapro-Wilk test, aKolmogorov-Smirnov test, a Cramer-von Mises test, and an Anderson-Darling test [Park,2008b]. Residuals were plotted against predicted values and explanatory variables to look38