A model for the training effects in swimming demonstrates a strong relationship between parasympathetic activity, performance and index of fatigue - Chalencon, S.; Busso, T.; Lacour, J.-R.; Garet, M.; Pichot, V.; Connes, P.; Gabel, C. P.; Roche, F.; Barthélémy, J. C. (PLOS ONE, 2012)