Exercise in Patients With Multiple Myeloma

The overall aim is to examine whether early initiated, individualized exercise training in patients newly diagnosed with multiple myeloma, irrespective of age and current performance status, will be beneficial for the patients´physical function, level of physical activity and quality of life, pain and bone disease. The investigators will examine the effect of supervised in-hospital exercise training sessions combined with home-based exercise training, initiated at time of diagnosis. The outcomes of interest are physical function, level of physical activity, QOL, pain and bone disease. Furthermore, to describe the disease in patients with newly diagnosed MM in relation to physical function, level of physical activity, QOL, pain and bone condition at time of diagnosis. The investigators hypotheses are: * Individualized exercise starting at time of diagnosis will have positive effects on physical function, physical activity, QOL and pain. * Individualized exercise starting at time of diagnosis will have positive effects on bone disease (bone markers), bone mineral density (BMD) and lean body mass. * A higher level of physical function is associated with a higher level of physical activity, less pain, better QOL, and higher BMD and lean body mass.