Keynote Lectures

New Technological Possibilities for Swimming Research and Monitoring Training
Bjørn Harald Olstad, Norwegian School of Sport Sciences, Norway, Norway

The Role of Imaging and Simulation Technologies in Understanding the Biomechanics and Loading of the Musculoskeletal System In-vivo
Bill Baltzopoulos, Liverpool John Moores University, United Kingdom, United Kingdom

Biomechanics in Alpine Ski Racing: A Challenge on Performance and Safety
Erich Müller, University of Salzburg, Austria, Austria

Abstract
Swimming is one of the most popular sports in the world and research is growing. The swimming environment is harsh and challenging to sustain, providing technological limitations for research and the daily monitoring of training performance. However, new technologies become more and more advanced and available for providing applied research in the aquatic environment. Technological possibilities are also increasing with the claims of helping swimmers and coaches in their daily work with the promise of improving performance and preventing injuries. 
This presentation will center around five new technological possibilities for swimming research and the daily monitoring of training. 1) race analysis with automatic movement recognition for identifying and improving performance determining factors, 2) a portable winch system for generating load-velocity profiles, anaerobic and strength testing, and passive drag, 3) optical heart rate for monitoring training intensity, 4) inertial measurement units for daily monitoring stroke kinematics, and 5) electromyographic enhancements for identifying muscular activation patterns, fatigue and correspondence to technique/drill exercises.

Abstract
This presentation will highlight our work on using innovative combinations of modern imaging techniques that include X-Ray video, MRI and ultrasound for studying in vivo muscle-tendon and joint function. We have developed techniques that allow the development of accurate and individualised biomechanical models of the musculoskeletal system to study joint and muscle forces and the loading of different tissues during various movements, pathological conditions and sports activities. Our work was the first to combine isokinetic dynamometry with X-Ray video to examine knee joint and muscle in-vivo function in both static and dynamic conditions. This has led to significant advancements in muscle-tendon mechanics knowledge and applications in different areas.  These range from strength assessment using isometric or isokinetic dynamometry to walking or running in children, adults and patients with osteoarthritis using musculoskeletal modelling.  Our results indicate that patellar tendon moment arm length variance, for example, cannot be explained by joint size differences and hence, so imaging-based methodologies are necessary. Furthermore, dynamic moment arms increased significantly with increased muscle contraction intensity leading to different estimates of tendon forces with important implications for musculoskeletal modelling applications. We have also examined various groups of adults and children during different gait speeds on instrumented treadmills. The results show that the gear ratio is affected mainly by the change in external moment arm given its large variation and the relatively constant muscle moment arm. Since the muscle efficiency is optimised when the muscle is working close to isometric conditions without a great change in fascicle length and the gear ratio influences muscle-tendon and fascicle length changes, the differences in gear ratio may affect fascicle length and velocity changes and hence muscle efficiency.

Abstract
Alpine ski racing is known to be a sport with a high risk of injury. Injury rates of more than 36 injuries / 100 athletes per season have been reported, 36% being severe and partly career ending. Ligament injuries in the knee were the most common injuries (36%) in World Cup athletes. Other frequently injured body parts were the lower back (low back pain), sacrum, shoulder and the head. All disciplines were found to be equally dangerous if the effective exposure time was considered. But the injury risks are different. In super-G and downhill, injuries seem to be related to high speed and jumps, whereas injuries in slalom and giant slalom are likely related to high loads during bidirectional turning phases. A maximal loading of 3.16 body weight per turn has been calculated. In addition, overuse injuries related to the back have become a severe problem among top-level alpine ski racers. The mechanisms for this kind of overuse injury seem to be the combined occurrence of frontal bending, lateral bending, and torsion in the highly loaded trunk during turning.  
Athlete-related risk factors are reported to be a) fatigue within a course or training session, b) inappropriate tactical choices, c) insufficient physical fitness, and d) technical mistakes. With respect to physical fitness, insufficient core strength or core strength imbalances, deficits in neuromuscular control, high asymmetries in unilateral leg extension strength, and hamstring / quadriceps strength deficits seem to be the main risk factors in elite ski racers. But considering the very short period of time during which ACL injuries occur, it is not only a question of the strength of the hamstrings and quadriceps, but also a question of the timing of the co-activation of these muscles (feed forward coordination). Apart from athlete related risk factors, equipment (ski side cut radius), course setting and snow conditions (aggressive snow, changing snow conditions), seem to be the main injury risk factors.