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13:30   Adaptive sports; wheelchairs and handcycling Chair: Johan Molenbroek 13:30 20 mins QUANTIFYING BODY SEGMENT PARAMETERS USING DUAL-ENERGY X-RAY ABSORPTIOMETRY: A PARALYMPIC WHEELCHAIR CURLER CASE REPORT Brock Laschowski, John McPhee Abstract: The body segment parameters of a Paralympic wheelchair curler were experimentally investigated; the athlete has an incomplete cervical spinal cord injury. Two-dimensional body segment parameters (i.e., mass, length, position vector of the center of mass, and principal mass moment of inertia about the center of mass) were quantified using dual-energy x-ray absorptiometry (DXA). In addition to measuring the body segment parameters in the interests of developing a subject-specific multibody biomechanical model, the mass of each body segment as measured via the DXA imaging was compared with that reported by previous research of able-bodied cadavers. In general, there were significant differences in the body segment masses between the different methods. The composition of each body segment (i.e., percentage of skeletal muscle, bone mineral content, and adipose tissue) was additionally investigated. 13:50 20 mins MUSCULOSKELETAL MODELLING OF ELITE HANDCYCLING MOTION: EVALUATION OF MUSCULAR ON- AND OFFSET Eduard M. Felsner, Stefan Litzenberger, Franziska Mally, Anton Sabo Abstract: Handcycling, as a competitive sport, has been a Paralympic discipline since 2004 and is performed by handicapped athletes with impairments of the spine or brain. In this work a musculosketal model of a handcyclist is developed in the software AnyBody 6.0.5 (AnyBody Technology, Aalborg, Denmark) using the MoCapModel of the AnyBody Managed ModelRepository 1.6.3 (AMMR). Kinematic data from a previous study of handcycling, where one male elite handbiker (class: H3.2, age: 44 yrs., height: 172 cm, weight: 62 kg, multiple medal-winner in Paralympic Games and World Championships) volunteered as a subject, is used for driving the kinematics of the model. The course of the crank torque over a crank revolution was adapted from literature. The model was successfully implemented in AnyBody and muscular activity was simulated. Using Matlab 7.11.0.548 (The Mathworks Inc., Natick, USA) single rotations were isolated, normalised to 360 degrees and averaged. The on- and offset timing of several muscles of the upper body (left and right of: m. pectoralis, m. deltoideus, m. biceps brachii and m. triceps brachii) were calculated with different thresholds and compared to similar calculations performed on sEMG measurements recorded during the previously mentioned subject study. It could be shown, that the mean overlap of muscle activation times was between a satisfying 64% and 75% depending on the threshold used. In most cases a threshold of 10% or 20% of the local maximum muscle activation proved best. However, especially for m. deltoideus a very different on- offset behaviour was observed in the simulation than in the sEMG measurements. As reasons for these differences the positioning of the electrodes in the subject study on one specific branch of the m. deltoideus and insufficient knowledge about the actual course of the crank torque for this specific athlete were identified. Nonetheless it could be shown, that using musculoskeletal modelling based on actual data of handcycling can yield results similar to actual measurements and that these results improve with improving quality and accuracy of input parameters. Thus – given sufficient accuracy of input parameters - musculoskeletal modelling could be used to predict changes in muscle activity timing for different handcycle setups. 14:10 20 mins PUSH CHARACTERISTICS IN WHEELCHAIR COURT SPORT SPRINTING Rienk van der Slikke, Monique Berger, Daan Bregman, Dirkjan Veeger Abstract: Short sprints are important components of most wheelchair court sports, since being faster than the opponent often determines keeping ball possession or not. Sprinting capacity is best measured during a field test, allowing the athlete to freely choose push strategies adapted to their own wheelchair setting, physical ability, classification and speed changes during a sprint. The key test outcome is sprint duration, but there are various ways to accomplish the same sprint time. So can different push strategies be identified in a wheelchair sport and how do they relate to athlete level/classification and wheelchair configuration? These relationships were investigated by field tests of 30 male wheelchair basketball athletes during a 12 meter sprint in their own wheelchair. A recently developed method for ambulatory measurement was used to calculate wheelchair kinematics [1], providing outcomes on displacement, speed, acceleration and pushes. Additionally maximal isometric push force was recorded and rear seat height was noted. Within the measured athletes, internationals were expected to be faster due to a better physical training status and technique, allowing them to sprint with fewer (but more powerful) pushes. Likewise, athletes of higher classification were expected to be faster due their superior physical capacity, but the effect on the number of pushes used was not that evident. Video analysis was added to validate push detection of the ambulatory measurement system. Mutual correlations and competition level differences of sprint characteristics were calculated. General Linear Models (GLM) were drawn to determine the effect of competition level and classification on sprint time and number of pushes. In the overall dataset sprint characteristics did not correlate significantly with classification, but if split by competition level, there were significant correlations with sprint time (r=-0.715, p=0.006) and number of pushes (r=-0.647, p= 0.017) in the national level athletes. Sprint time, number of pushes and isometric push force differed significantly between national and international level wheelchair basketball athletes. Competition level showed to be a significant (p<0.05) factor in univariate GLMs for sprint time and number of pushes, whereas classification did not. The interaction of competition level and classification as a factor in univariate GLMs was significant. As hypothesized, international level athletes were faster with fewer pushes, even though their higher average seat height was less optimal for propulsion [2]. The interaction effect of competition level and classification in the GLM indicates that the effect of classification on sprint time and number of pushes is different between competition levels. Indeed, in the national level athletes there was a clear relationship between classification and sprint time / number of pushes, but not in internationals. This difference is pointing at a more professional level of wheelchair configuration or better technique of the international athletes regarding sprint performance. Given the correlation between seat height and classification, the seat height of lowly classified athletes seemed optimized for sprinting, whereas seat height of highly classified athletes with already adequate sprinting capacity was optimized for upward reach. Future research based on larger groups with more even distribution over classifications could provide more solid models and reveal more detailed insight in push strategy efficacy. Given the proven reliability of the inertial sensor based method [1] and the proven reliability for push detection in sprinting, this research could well be performed using this easy to use ambulatory method. Although more challenging than well controlled experimental research, the field based setting in this research revealed additional information not only describing the relation between wheelchair setting and performance, but also describing its practical applications if other game demands were taken into account. The results of this approach is believed to assist athletes, coaches and wheelchair experts in decision making concerning wheelchair configuration and athlete training.