Chronic low back pain (DLC) is associated with changes in postural control and is highly prevalent in the elderly. Research shows that aging and DLC are described as important factors that affect postural control. The postural control impairments increase the risk of falls. Researches evaluating the postural control in elderly people with DLC are still necessary for greater effectiveness in balance rehabilitation programs to prevention falls in this population. The objective of this study is to verify whether anticipatory postural adjustments (APAs) and compensatory postural adjustments (CPAs) are affected by DLC in elderly people by assessing their postural control during a self-initiated perturbation paradigm induced by rapid upper arm movement when pointing to a target. Elderly people were divided into: Group with DLC (GDLC) (n = 15) and Control Group (CG) (n = 15). The participants’ lower limb muscle onset and center of pressure (COP) displacements were assessed prior to perturbation and throughout the entire movement. T0 moment (i.e., the beginning of the movement) was defined as the anterior deltoid (DEL) onset, and all parameters were calculated with respect to it. The rectus femoris (RT), semitendinosus (ST), and soleous (SOL) showed delayed onset in the GDLC group compared with the control group: RF (control: -0.094 ± 0.017 s; GDLC: -0.026 ± 0.012 s, t = 12, p < 0.0001); ST (control: -
0.093 ± 0.013 s; GDL: -0.018 ± 0.019 s, t = 12, p < 0.0001); and SOL (control: -0.086±
0.018 s; GDL: -0.029 ± 0.015 s, t = 8.98, p < 0.0001). In addition, COP displacement was delayed in the GDLC group (control: -0.035 ± 0.021 s; GDL: -0.015 ± 0.009 s, t = 3; p = 0.003) and presented a smaller amplitude during APA COPAPA [control: 0.444 cm (0.187; 0.648); GDLC: 0.228 cm (0.096; 0.310), U = 53, p = 0.012]. The GDLC group required a longer time to reach the maximum displacement after the perturbation (control: 0.211 ± 0.047 s; GDLC 0.296 ± 0.078 s, t = 3.582, p = 0.0013). This indicates that GDLC elderly patients have impairments to recover their postural control and less efficient anticipatory adjustments during the compensatory phase. Our results suggest that people with GDL have altered feedforward hip and ankle muscle control, as shown from the SOL, ST, and RT muscle onset. This study is the first study in the field of aging that investigates the postural adjustments of an elderly population with GDLC. Clinical assessment of this population should consider postural stability as part of a rehabilitation program.
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