Trails directed at investigating differences in injury risk in relation to the focus of the running schedule have been conducted without any firm conclusions. People engaged in recreational running or choosing running as a new and active lifestyle needs guidance on which running schedules minimize the injury risk, aiding their chance of an active lifestyle and possibly reversing the increase in people developing a lifestyle disease. To develop running schedules minimizing the risk of injury, an understanding of the mechanisms that the different training variables impose on the human body is necessary. The existing literature on running intensity and the development of injuries show conflicting result. More studies are necessary to ascertain if there is a relationship between the intensity of running. In such studies, it is important to include other training variables in the analysis and to quantify running exposure using an objective method of measuring the relative intensity and absolute volume.