1. a National Institute for Working Life – West , P.O. Box 8850, SE-402 72, Gothenburg, Sweden
2. b Human Factors Engineering, Department of Product and Production Development , Chalmers University of Technology , SE-412 96, Gothenburg, Sweden
3. c Ergonomics, Department of Design Sciences , Lund University , P.O. Box 118, SE-22100, Lund, Sweden
4. d Rehabilitation Medicine, Department of Neuroscience and Locomotion, INR, Faculty of Health Sciences , Linköping University , 581 83, Linköping, Sweden