Comparison between the standard average muscle activation wtith the use of snorkel and without snorkel in breakstroke technique - Conceicao, A.; Gamboa, H.; Palma, S.; Araújo, T.; Nunes, N.; Marinho, D.; Costa, A.; Silva, A.; Louro, H. (Biomechanics and Medicine in Swimming XI - Abstracts, 2010)