This study compares the effects of high dose and low dose, high intensity, endurance training and strength training in substance use disorder patients. The hypothesis is that the increase in endurance (measured as maximal oxygen uptake) and strength (measured as maximal strength) will be similar in both the high dose and low dose training groups after 24 training sessions over eight weeks. The rationale for this assumption is based on the patient groups poor physical capacity, supporting that a lesser physical workload is needed to achieve a substantial increase in physical capacity. The practical implication could be higher training attendance, because it is likely easier to motivate the patient group when they only have to perform half the workload. It is paramount for this patient group to increase their physical capacity and consequently augment their physical health status since they are in a high-risk group for developing life-threatening lifestyle related diseases.

Inclusion Criteria:

• Being an inpatient at the clinic
• Free of known cardiovascular disease, pulmonary disease and cancer

Exclusion Criteria:

• Not able to perform a maximal treadmill test
• Not able to perform a maximal strength test in hack squat