101 kms. in 24 hours is a sporting test organised by the Legion, of the Spanish Army, since 1995 in Serran\u00eda de Ronda (Andaluc\u00eda). It has been achieving an increasing expectation, until, in the 5th edition in May 1999, there were 2.694 participants including soldiers and civilians. The raking of data, both quantitative and qualitative, in this edition, allows us to think about questions such as: is the search for extreme limits, generalised behaviour in the human being? and if so, do extreme sports contribute to satisfy these aspirations? Do the 101 kms. in 24 hours constitute a ritual of pass or of solidarity? Do the objectives of the organisers coincide with the motivation of the participants? To what point can we see society reflected in the structure and dynamics of this sporting test? On all this questions we bring data and ideas, with the intention of increasing the understanding of a sporting event, already converted into a social phenomenon.<\/p>\n