The effect of height of lifting on dynamic postural control in low back pain patients and healthy subjects.

Objectives: The study investigated the influence of starting load position during lifting on postural control in nonspecific chronic low back pain (LBP) and healthy volunteers. Patients and methods: The cross-sectional study included 20 healthy males (mean age: 31.8±7.4 years; range, 18 to 55 years) and 52 male patients (mean age: 33.4±9.2 years; range, 18 to 55 years) with chronic LBP between February 2016 and April 2018. Postural control characteristics were assessed by a force plate system. Center of pressure signals were obtained at a frequency of 100 Hz, and the mean of three trials was calculated. The participants were told to place their feet hip-width apart on the force plate while standing barefoot. They were then asked to lift a box weighing 10% of their body weight from the ground to waist height and then from waist height to overhead with straight elbows. They moved the box at their selected speed. The examinations began upon the examiner's command. Results: Results indicated a significant difference (p<0.001) in all postural control variables in chronic LBP patients who lifted a load at different heights. In addition, there was a significant difference between all of the postural control measures of this study in healthy participants during load lifting at different heights (p<0.05), with the exception of the mediolateral standard deviation of velocity (p=0.067). Conclusion: Different lifting heights impact LBP patients' and healthy people's postural control differently. Postural control was more challenging during waist-to-overhead lifting in the patient group. This may be due to a stiffening strategy. The central nervous system reduces postural sway at higher centers of mass.