Beat Göpfert : Laboratory of Orthopaedic Biomechanics, CM & BE, University of Basel, Switzerland
Jacqueline Romkes : Laboratory for Movement Analysis, CM & BE, University Children's Hospital Basel, Switzerland

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Two Vicon systems (a 6 camera MX13 system and a 460 with 6 MCAM1's plus an MX Control) have been used to capture the movements of the Swiss National Fencing Team enabling the team to better understand and improve their performances as well as reduce the risk of injury.

Precise movement, reaction and speed required by the athlete make fencing a very challenging area to study. The focus of this project is on the coordination between the movement and muscular activation of the leg and shoulder muscles. We used a whole body marker set up (Romkes 2007) with two additional markers on the pelvis, three markers on the weapon and the target. The fencers aim to hit the target as precisely as possible while the activation of 14 muscles is recorded by surface electromyography (EMG) and the signals analyzed using the wavelet transformation method according to von Tscharner (von Tscharner 2000). Reaction time is a key element in fencing. Athletes start when a light at the target goes on. The target is equipped with an additional load cell to record the impact force of the weapon.

We use a test setup that closely simulates training and competition conditions. An athlete reacts to the movements of his/her opponent and performs the correct movement to hit the opponent first, in order to score a point and win the bout. In this project, the athletes make small vertical bounces while standing with each foot on one of the force plates. As soon as the light on the target goes on they have to perform a flèche attack and try to hit the target in the centre. Athletes are required to perform ten successful trials where they aim to hit the target perfectly.

View in Workstation of an athlete performing a flèche attack

We have analyzed the kinematics, kinetics and the wavelet transformed EMG of eight male fencers from the Swiss National Team. The wavelet transformed from EMG enables us to determine each stage of the movement, in which frequency band and at what intensity a muscular activation occurs. Overall we observed different movement strategies among the 8 fencers while performing a flèche attack. The more experienced fencers execute the forward movement of the trunk and arm more parallel than the less experienced fencers, where the movement is sequential.

Overview of University of Basel
The Laboratory of Orthopaedic Biomechanics and the Laboratory for Movement Analysis are part of the Clinical Morphology & Biomedical Engineering Department (CM & BE) of the Medical Faculty at the University of Basel. The Laboratory of Orthopaedic Biomechanics was founded in 1990 by Professor Erwin W. Morscher, a pioneer in orthopaedic surgery. Its main focus is biomechanical research from macro (e.g. implant testing and development) to nano scale (e.g. material stability and surface reaction) and is equipped with different material testing machines (MTS, Calorimeters) to help answer questions on biomedical engineering.

Preparing Marcel Fischer for the pilot test by Beat Göpfert (left) and Corina Nüesch (middle) under the critical observation of the national coach

The Laboratory for Movement Analysis was established in the late 1960s, as the first clinical gait lab in Europe specializing in clinical gait analysis of individuals with complex movement disorders for both clinical and research purposes. The laboratory is equipped with two Vicon systems.
• A Vicon 460 system with 6 MCAMs
• A Vicon MX system with 6 MX13s plus
• a MX Control
• Two Kistler force plates
• Three EMG systems
• Vicon Workstation, Nexus, Polygon, BodyBuilder, as well as Matlab software

The close collaboration between the laboratories also allows Master and PhD students from various backgrounds to gain experience in human movement sciences and related fields. The biomechanics of fencing is just one of the many projects being carried out at the University of Basel.

Outlook
The combined analysis of kinematics, kinetics, and wavelet transformed EMG is a standard procedure in the majority of our projects related to human movement sciences. It helps us to understand the interaction between movement and muscular activation and the tuning of complex movements. For our sports biomechanics projects, our goal is not only to understand the performance but also to improve the athletes' performance and reduce the risk of injuries.

Mean Multi-Muscle Intensity pattern of three muscles for 10 flèche trials from one subject. The grey scale indicates the intensity of the muscular activation (low: white, high: black) MS: Start of the movement; HT: Hit of the target; MBE: Maximum bending of the épée

Acknowledgment
The fencing project was supported by the ProMotio Foundation in Basel and the Robert Mathys-Foundation (RMS) in Bettlach, Switzerland.

Literature
Romkes et al, J Pediatr Orthop B.,16:175-180, 2007.
von Tscharner, J Electromyogr Kinesiol,10:433-445, 2000.

Working on the Fencing Project
Marcel Fischer (MD),
Julien Frere (M.Sc.),
Niklaus F. Friederich (MD),
Beat Göpfert (MEng, EMBA),
Corina Nüesch (M.Sc.),
Jacqueline Romkes (Ph.D),
Dieter Wirz (MD),