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13:30   Bio-mechanics; joints Chair: Franz Fuss 13:30 20 mins CENTRE OF PRESSURE BETWEEN HAND AND CRICKET BALL IN SPIN BOWLING: WHICH FINGERS CONTRIBUTE TO THE TORQUE? Franz Fuss Abstract: Spin bowling deliveries are divided into finger-spin and wrist-spin deliveries. In the former delivery, the ball leaves the hand on the radial side of the palm, in the latter on the ulnar side. The fingers including the thumb impart a torque on the ball along the seam in order to speed up the ball to more than 25 revolutions per second. The aim of the research is to discover where the centre of pressure is located with respect to the fingers, i.e. which fingers produce the maximum torque at which stage of the torque phase, and how the centre of pressure moves with respect to the fingers. The smart cricket ball developed by Fuss and co-workers (2012, 2015) was used for recording the angular velocity data during off- (finger-spin with sidespin) and leg-spin (wrist-spin with sidespin). The deliveries were bowled by an ex-first class spin bowler, who is also a professional bowling coach. The centre of pressure (COP) was determined with the method of Fuss (2012). In off-spin deliveries, the COP moves from ulnar to radial, in leg-spin deliveries from radial to ulnar. In leg-spin deliveries, the COP is located close to the seam on the ball’s hemisphere in contact with the palm, in off-spin on the opposite side of the ball. In off-spin deliveries, the initial torque is produced by both thumb and index finger, whereas at the release by the thumb only. In leg-spin deliveries, the initial torque is produced by the index finger, whereas at the release it is shared by thumb and middle finger, with the index finger already detached from the ball. The location of the COP is expected to depend on the bowling technique and expertise. The knowledge of the COP’s location is essential for coaching purposes as well as for classification of spin bowling deliveries. References Fuss F.K., Smith R.M., Subic A., 2012. Procedia Engineering 34, 128–133. Doljin B., Fuss F.K., 2015. Procedia Technology 20:133 – 137. Fuss F.K., 2012. Internal Report. Melbourne: RMIT University. 13:50 20 mins PREDICTION OF ACL AND PCL LOADS DURING ISOKINETIC KNEE EXERCISES AFTER EXPERIMENTAL TESTS AND MUSCULOSKELETAL SIMULATIONS Nicola Petrone, Mattia Nardon, Giuseppe Marcolin Abstract: Aim of the work was the experimental validation of musculoskeletal models of lower limbs during isokinetic knee flexion-extensions at different angular speeds, using OpenSim® code. The adopted approach was: (i) to record the kinematic, kinetic and EMG data on six healthy subjects, (ii) to simulate the isokinetic motions of each subject in the OpenSim code, (iii) to compare the numerical and experimental activation results and (iv) to compare the Knee joint reaction loads and the ACL PCL loads predicted by the code and two analytical models of the knee. The Rev 7000 was used to perform the isokinetic flexion extension exercises at the four speeds of 60,120,180,240 °/s. The Extensor muscles of RF, VM, VL as well as the flexor muscle of BF were recorded with surface EMG in a BTS motion capture system. The opensim Model Lower leg 2392 was driven by the markers trajectories recorded experimentally, as shown in a previous work [1]. The ACL and PCL loads were estimated using the geometrical data proposed by Herzog [2] and also by a simple geometrical model developed. Results of the study showed that (a) there was a large variability of tester’s strength, as well as in the Flexor/Extensor ratio, (b) the Opensim simulations were successful in the prediction of activation levels at the different speeds, (c) the tibia/femur loads predicted by OpenSim were incorrect as the model is unable to resolve the patella forces, (d) ACL/PCL loads can reach high values in high intensity isokinetic exercises. The results allowed to extend the degree of confidence in the use of musculoskeletal models and to combine them with correct analytical or numerical models of the knee ligaments. 1. Nicola Petrone, Daniele Tregnaghi, Mattia Nardon, Giuseppe Marcolin, Musculoskeletal Simulation of Isokinetic Exercises: A Biomechanical and Electromyographical Pilot Study, Procedia Engineering, Volume 112, 2015, Pages 250-255. 2. Herzog W, Read LJ. Lines of action and moment arms of the major force-carrying structures crossing the human knee joint. J. Anat. 1993,183:213-230 14:10 20 mins JOINT TORQUE EVALUATION OF LOWER LIMBS IN BICYCLE PEDALING Hiroki Yamazaki, Akihiro Matsuda Abstract: In this study, a relationship between the ankle angle and normal force in rotation direction of the bicycle crank in cycling pedaling was newly proposed. Also, joint torque of lower limbs in cycling pedaling was calculated using the proposed relationships. To calculate joint torque of lower limbs, free body diagram of lower limbs are formulated in the motion of the 2-dimensional plane. Also we assumed that movement of greater trochanters in cycling pedaling were too small to consider and bicycle shoes were fixed to binding pedal. This free body diagram of lower limbs in 2-dimensional plane had two degrees of freedom. These were the crank angle and the ankle angle, when the greater trochanters were supposed to be stopped during cycling pedaling. In previous researches, the ankle angle during cycling pedaling was obtained directory from the image analysis using the high-speed cameras. This relationship does not require the image-analysis software with the high-speed camera. From the lower limbs model, all position of lower limb segments, joint torques and joint torque powers were calculated. Analytical system of cycling pedaling was composed of cleat-shape biaxial load cells and evaluation program for pedaling effectiveness, joint torque and joint torque power. The plastic cleats between shoe-sole and binding pedal were replaced to the biaxial load cells which measured biaxial-forces of right and left leg independently. Evaluation of joint torques of lower limb were conducted with some male subjects to show applicability of our proposed methods.