Knee posture and low back pain-related differences on postural control measurements in athletes. A case control study

Introduction Compare postural control in athletes, with and without chronic low back pain (CLBP), during two one-legged stance tasks and identify center of pressure cut-off differences. Material and methods Fifty-six male athletes, 28 with and 28 without CLBP (mean age = 26 years) performed on a force platform: – one-legged stance with knee extension; – one-legged stance with the knee at a 30° flexion, both tasks with eyes open. Participants completed three 30-s trials (with 30-s of rest between each trial), and the mean across trials was used for subsequent analysis. Results Athletes with CLBP had poorer postural control (P   7.1 cm2 for COP area, > 2.6 cm/s for COP sway velocity in the anterior-posterior direction and > 3.2 cm/s for medio-lateral direction. In the knee flexion position, these variables were related to: > 10.9 cm2 for COP area, > 2.9 cm/s for COP sway velocity in the anterior-posterior direction and > 4.1 cm/s for the medio-lateral direction. Both measures showed enough sensitivity and specificity (i.e., area under curve = 0.88 in extension and 0.80 in flexion). Conclusions Athletes with CLBP had poorer postural control than healthy athletes. Athletes with CLBP obtained specific cut-off scores on COP values for early detection of the effects of low back pain on balance.