dtfs = distance to first symptoms

smartphone app 5r-sts = five-repetition sit-to-stand 6-minute walking test 6wd = 6-minute walking distance 6wt = 6-minute walking test ddd = degenerative disc disease dw = distance wheel gps = global positioning system icc = intraclass correlation coefficient lbp = low-back pain lss = lumbar spinal stenosis ofi = objective functional impairment prom = patient-reported outcome measure ttfs = time to first symptoms tug = timed up and go app = application degenerative disc disease global positioning system lumbar spinal stenosis objective functional impairment