Electromyographic analysis of the swim start: Bilateral comparison of the front-weighted and rear-weighted track start from the OMEGA OSB11 starting block

Previous swim start studies involving electromyography (EMG) consistently comprised unilateral measurements and the attachment of the swimmer via cables to a computer. Therefore the present work aims for an overall picture of the muscle activation pattern during the swim start by conducting bilateral measurements with minimal restriction of motion. On that account a multichannel surface EMG device with a wireless Bluetooth connection and videography is utilized in order to assess the nowadays most common start dive techniques of competitive swimming events - differently weighted track starts from the OMEGA OSB11 starting block. The data analysis identified that the normalized muscle activation levels were higher during the front-weighted than during the rear-weighted start - probably caused by shorter block times and less contribution of the arms. Furthermore the onset of the muscle activation seems to be different in between start dive techniques, as for instance the muscles of the rear leg commence contracting earlier while the muscles of the front leg start later in the rear-weighted compared to front-weighted starts. It is highly likely that this originates in the position of the center of mass relative to the muscles. A general overview over the coordination of the different muscles could also be obtained: It became obvious that some muscles are the main drivers of the swim start (vastus lateralis, soleus) whereas others rather exerted supportive actions (gluteus maximus, semitendinosus, erector spinae longissimus)