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

at a rate of 1 Hz (BG-331RGTGT, Mighty GPS, Toronto, ON) and was connecteddirectly to the laptop through a USB port.The second sensor located in the boat was a custom fabricated axial transducer that wasconnected in series with the tow rope and used to measure rope load at a rate of 20 Hz.The transducer was constructed with four strain gauges (N11-Fa-10-120-11, ShinowaCorporation, Tokyo, Japan) mounted in a full Wheatstone bridge on the surface of analuminum tube. The load transducer was powered and amplified by a custom built straingauge amplifier (DiCaprio and Thomason 1989). The amplifier was powered by a powersupply (E3630A, Agilent Technologies Canada Inc, Mississauga, Canada) that ran off a300W power inverter (Zantrex, Elkhart, IA) connected to a 12 V deep cycle marinebattery (Nautilus No. 10-279904, Canadian Tire Corporation, Toronto, Canada). Theoutput from the amplifier was converted to a digital signal using an A-D converter (USB-6211, National Instruments Corporation, Austin, TX) that was connected to the laptopthrough a USB port. The voltages readings from the load cell were converted to Newtonsusing a calibration curve that was created before each test day. The curve was derivedusing a data file that was created from a series of static load measurements from varyingcalibration weights.Data files created for each ski run were used to calculate (Micrsoft Excel, MicrosoftCanada Co, Mississuage, Canada) two performance parameters of interest, rope load andskier velocity. A resultant peak performance parameter was found for each subject’s:deep water starts, left turns and right turns. The resultants were then used to calculate an59