Loading rate is an important parameter of running gait as it is commonly associated with increased risk of injury. In this paper we show, that most of the research related to calculating loading rate values from ground reaction force data cannot be directly compared, as the absolute loading rate values and the related first impact peak location and height are highly dependent on the filtering method used, cut-off frequency selected as well as loading rate calculation method selected. The results are based on running trial data from non-forefoot striking long distance runners gathered by the authors.