There are few detailed publications that allow performing associations between the technical aspects and the occurrence of injuries. The purpose of this study was to apply a methodology based in recording material to assess the injury risk factors. Common nage-waza judo techniques during regular training of amateur judokas were used as a case study. Novice students (n=193; 100 men and 93 women) from the University of Vigo during five academic years (2003 to 2008) were filmed during the ordinary training period of the technical execution of ten nage-waza techniques. The obtained data were evaluated using descriptive statistics and t-patterns analysis. Thus, it was possible to identify the presence of typical inaccuracies during execution of the technique uncovering the main temporal sequence of errors allowing us to link our findings with the injury occurrence. In order to narrow the unexpected causes of accidents regarding poor technique performance in regular training, this research provides the hidden temporal sequence of errors of common throw techniques, helping professionals to correct the key technical errors in order to prevent diverse type injuries. The methodology developed here could be easily extended to other martial sports.