Postural control and trunk mobility impairments in adults with long COVID: A cross-sectional study using computerized posturography and clinical biomechanical tools.

Long COVID is increasingly associated with persistent neuromuscular and functional impairments, including deficits in balance and trunk control. This cross-sectional study examined postural stability and trunk biomechanics in adults with Long COVID, comparing them to matched healthy controls. A total of 128 participants (64 per group) underwent computerized posturography to assess sway area, sway velocity, and stability index under varying sensory conditions. Trunk range of motion and isometric muscle strength were measured, along with fatigue, pain sensitivity, and physical function, using validated patient-reported outcomes. Compared to controls, individuals with Long COVID demonstrated significantly larger sway area (eyes closed on foam: 8.12 ± 1.87 cm2 vs. 6.01 ± 1.65 cm2, p < 0.001), higher sway velocity (1.23 ± 0.34 cm/s vs. 0.98 ± 0.29 cm/s, p < 0.001), and lower stability index (78.45 ± 5.67 vs. 83.21 ± 6.12, p < 0.001). Trunk flexion and extension were reduced (p < 0.001), as were flexor and extensor strength (p < 0.001). Fatigue was markedly elevated (FSS: 5.72 ± 1.03 vs. 2.34 ± 0.98, p < 0.001). Multivariate analysis identified trunk extensor strength (β = 0.34, p = 0.001), fatigue severity (β = -0.38, p = 0.002), and physical function (β = 0.28, p = 0.015) as independent predictors of postural instability. These findings underscore the need for integrated rehabilitation that addresses both trunk biomechanics and symptom burden in Long COVID.