Low-Back Pain and Knee Position-Related Differences on Postural Control Measures During a One-Legged Stance in Athletes.

Abstract

Chronic low-back pain (CLBP) may be associated with changes in postural balance in athletes as poor postural control during sports practice. To compare the postural control of athletes with and without CLBP during 2 one-legged stance tasks and identify the center of pressure (COP) cutoff values to determine the main differences. Designed: A cross-sectional study. Laboratory of functional evaluation and human motor performance. A total of 56 male athletes, 28 with and 28 without CLBP (mean age = 26y). The one-legged stance with knee extension and with the knee at 30° flexion tasks were measured and analyzed on a force platform. The participants completed three 30-second trials (30s of rest between each trial). The COP parameters: the area of COP, mean COP sway velocity in both the anteroposterior and mediolateral directions, and total COP displacement were computed, and a receiver operating characteristics curve analysis was applied to determine the group differences. Athletes with CLBP had poorer postural control (P < .01) in both tasks. The 30° knee flexion reported more postural instability than the knee extension for all COP parameters (a large effect size d = 0.80).The knee extension cutoffs identified were >7.1 cm2 for the COP area, >2.6 cm/s for the COP sway velocity in the anterior-posterior direction, and >3.2 cm/s for the mediolateral direction. Whereas, the 30° knee flexion cutoffs were >10.9 cm2 for the COP area, >2.9 cm/s for the COP sway velocity in the anterior-posterior direction, and >4.1 cm/s for the mediolateral direction. Both measures showed enough sensitivity and specificity (ie,area under the curve = 0.88 in and 0.80, respectively) to discriminate both groups. The athletes with CLBP had poorer postural control than the healthy athletes and obtained specific cutoff scores from the COP values.