The aim of this paper was to study the physical performance, pain, pain behavior and disability in patients with subacute low back pain (LBP). The patients were blue-collar workers and had been sick-listed for 8 weeks due to subacute low back pain. A total of 103 patients were randomized, 51 of them to the intervention group and the other to a control group. Recordings of physical performance and complaints of LBP were done before and after treatment in the intervention group. The proportion of patients with no complaints of LBP was significantly greater in the intervention group than in the control group at the one-year follow-up. The patients who intra-individually improved their physical performance also intra-individually decreased their complaints of LBP. The intra-individual improvements were suggested to be important for the individual return to work.