Physical health does not have a high priority in today's treatment of patients with substance use disorder (SUD) patients have a poor physical health not only due to injuries related to the substance abuse, but also because of the lifestyle that addiction causes. There are today few studies that provide information about SUD patients' physical health. One of the project's aims is to document the physical health of SUD patients in treatment, using objective measures. After completion of various physical tests, an 8 week period of high intensity aerobic training intervention will follow. It will be investigated if the SUD patients are able to engage and participate throughout the whole training intervention, to what degree the participants improve their physical health and the effect of physical health improvement on substance abuse treatment.