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Wheatstone bridge on a piece of aluminum tubing. The signal from the gauges wasamplified by a custom fabricated strain gauge amplifier (DiCaprio and Thomason 1989),before it was converted to a digital signal using an A/D card (USB-6211, NationalInstruments Corporation, Austin, TX). The amplifier was powered by a power supply(E3630A, Agilent Technologies Canada Inc, Mississauga, Canada) that ran off a 300Wpower inverter (Zantrex, Elkhart, IA) connected to a 12 V deep cycle marine battery(Nautilus No. 10-279904, Canadian Tire Corporation, Toronto, Canada).The outputsignal from the A/D card was sent to the computer directly via USB port. The amplifierallowed for DC offset, excitation voltage and balance adjustments to the system. Theexcitation voltage was set to 5 V, which allowed for the maximum sensitivity of thesystem without overheating the gauges, causing temperature artifacts.The voltage readings from the load cell were converted to Newtons with a calibrationequation. A unique equation was derived for each of the test days using a calibrationprocedure that included static load measurements using known weights. A data file wasproduced while a series of weights were hung from the load cell, allowing for theproduction of a Force vs Voltage plot which could be fit with a linear model (AppendixA).The four instruments previously described had individual output data streams that neededto be linked in time. This allowed for a cross reference type of analysis that couldindicate the skier speed, ski orientation and rope load at a specific point in time during anexperimental ski run. The best way to achieve a time link in this scenario was to create a34
single data collection program that would parse all the incoming data streams and writethem to a data file, where each row of the file represented a single time frame. The dataoutput from the four sensors were received as digital signals and they were converted toan analogue output via the data collection program. The program was created usingLabview (Labview 8.2, National Instruments Corporation, Austin TX) and ran at 20Hz.The program allowed for individual communication baud rate settings that needed to bematched with the baud rate of the particular instrument. The two GPS units wereprogrammed using product software before being connected to the data collectionprogram. Therefore, when they had power they were constantly sending data to thecomputer but the data was not being received and parsed until the data collection programwas initiated. The IMU required commands to be sent to the unit for proper operation andtherefore the data collection program required an interface that was capable of this.This study was reviewed and received ethics approval for its human participation andwritten survey components by the <strong>University</strong> of Guelph Ethics Committee. A sample ofthe survey can be found in Appendix B. There were six human participants that wererecruited based on their skiing ability. They were required to ski two passes of a slalomcourse on four different slalom skis throughout the test day. This made our subject poolto be advanced slalom skiers. In an ideal situation the number of repetitions of eachactivity would have been calculated using statistical power analysis, where statisticalpower would represent our ability to detect an effect, if it does exist. A target powervalue would have been chosen and the number of observations required to achieve thatvalue could be calculated [Park, 2008a]. Given our resources a prospective calculation35
Page 1 and 2: BIOMECHANICAL PERFORMANCE FACTORS O
Page 3 and 4: AcknowledgmentsI would like to star
Page 5: 6.1 Conclusion and Future Considera
Page 8 and 9: 83.42º·s and 48.92 º. There was
Page 10 and 11: List of TablesChapter 4Table 1: Sum
Page 12 and 13: 1.1 The Basics of Water SkiingWater
Page 15 and 16: deep water start a good performance
Page 17 and 18: skills in order to be able to ident
Page 19 and 20: completed their test runs throughou
Page 21 and 22: 1.5 Thesis outlineChapter 2 will pr
Page 23 and 24: Chapter 2: Literature Review13
Page 25 and 26: of material can be used as a force
Page 27 and 28: & Pesty, n.d.; Zang et al., 2004].
Page 29 and 30: instrumentation system used did not
Page 31 and 32: allowed them to plot a velocity ver
Page 33 and 34: Chapter 3: Methods and Instrumentat
Page 35 and 36: AbstractThere are many challenges w
Page 37 and 38: is most likely the main reason why
Page 39 and 40: applicable to dynamic sports [Brodi
Page 41 and 42: The product chosen that best met th
Page 43: ON) that did not require any modifi
Page 47 and 48: Figure 3 - Diagram of slalom course
Page 49 and 50: for patterns in the data that sugge
Page 51 and 52: 200SU EC ST BTA150Angle (degrees)10
Page 53 and 54: 10050Angle (Degrees)0-50-100-150Pit
Page 55 and 56: RF communication systems are easily
Page 57 and 58: The roll profile can be used to det
Page 59 and 60: Chapter 4: Water Skiing Biomechanic
Page 61 and 62: AbstractSix advanced slalom skiers
Page 63 and 64: Recreational and competitive slalom
Page 65 and 66: Table 1: Summary of human participa
Page 67 and 68: Figure 2: Diagram of slalom course
Page 69 and 70: at a rate of 1 Hz (BG-331RGTGT, Mig
Page 71 and 72: adjusted p-value. (SAS Institue Inc
Page 73 and 74: Table 3: Summary of completed turns
Page 75 and 76: Rope load peaks during the cutting
Page 77 and 78: Peak skier velocity for each turn i
Page 79 and 80: 4 DiscussionThere are several varia
Page 81 and 82: trend was seen by Runciman (2011) w
Page 83 and 84: (p=0.2437 and p=0.246). It was expe
Page 85 and 86: velocity and low peak rope load. In
Page 87 and 88: improve the accuracy that a coach e
Page 89 and 90: Chapter 5: Biomechanical Analysis o
Page 91 and 92: AbstractWater skiing has received l
Page 93 and 94: ski manufacturers ability to compar
Page 95 and 96:
given about how the effects of the
Page 97 and 98:
tip. The IMU housing was wrapped in
Page 99 and 100:
(roll, acceleration and deceleratio
Page 101 and 102:
decrease. This portion of the turn
Page 103 and 104:
Roll, Ski Acceleration and SkierVel
Page 105 and 106:
Integral of Roll, Peak Roll (degree
Page 107 and 108:
Integral of Roll, Peak Roll (degree
Page 109 and 110:
Integral of Deceleration (m/s 2 *s)
Page 111 and 112:
Figure 12 shows each ski’s overal
Page 113 and 114:
Integral of Acceleration, Peak Acce
Page 115 and 116:
Integral of Acceleration, Peak Acce
Page 117 and 118:
peak velocity is also occurring at
Page 119 and 120:
was not a significant difference be
Page 121 and 122:
The lack of statistical significanc
Page 123 and 124:
Chapter 6 - Conclusion and Future C
Page 125 and 126:
The data, in combination with a sta
Page 127 and 128:
Bachmann, E.R. (2000). Inertial and
Page 129 and 130:
Appendices119
Page 131 and 132:
Load Transducer Output (V)0.80.70.6
Page 133 and 134:
Skiing Background Information6. How
Page 135 and 136:
Section 2 - Follow up surveyPlease
Page 137:
Appendix C - Ski Survey ResultsThe
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