Balance control, a complex sensorimotor skill, declines with age. Assessing balance is crucial for identifying fall risk and implementing interventions in the older population. This study aimed to measure age-dependent changes in static and dynamic balance using inertial measurement units in a clinical setting. This study included 82 healthy participants aged 20–85 years. For the dynamic balance test, participants stood on a horizontally swaying balance board. For the static balance test, they stood on one leg. Inertial measurement units attached to their bodies recorded kinematic data, with average absolute angular velocities assessing balance capabilities. In the dynamic test, the younger participants had smaller average absolute angular velocities in most body parts than those of the middle-aged and older groups, with no significant differences between the middle-aged and older groups. Conversely, in the single-leg stance tests, the young and middle-aged groups outperformed the older group, with no significant differences between the young and middle-aged groups. Thus, dynamic and static balance decline at different stages with age. These results highlight the complementary role of inertial measurement unit-based evaluation in understanding the effect of age on postural control mechanisms, offering valuable insights for tailoring rehabilitation protocols in clinical settings.

Chronic low back pain (cLBP) compromises daily function, but associated balance deficits remain difficult to quantify using traditional scales. We recruited 50 participants with CLBP (age: 65.68 ± 11.84) and 50 age-matched controls (age: 65.26 ± 10.73) wearing multiple inertial measurement units (IMUs) to evaluate kinematics: average absolute angular velocity ($J\omega$) and linear acceleration ($J\alpha$) across static (single-leg stance), perturbed (balance board), locomotor (walking, tandem gait), and transitional (five times sit-to-stand) tasks. Group differences were assessed using multivariate analysis of variance and Bonferroni-adjusted univariate tests. During the balance board test, $J\omega$ was significantly higher at the chest ($p$ = 0.027) and hip ($p$ = 0.003) in the CLBP group. Conversely, during the sit-to-stand tests, the CLBP group showed significantly lower $J\alpha$ and $J\omega$ (p < 0.0001) at the hip. The CLBP group exhibited globally lower $J\omega$ ($p$ < 0.01) during normal walking, while the ${Amp}_{PR}$ ($p$ = 0.001) was exclusively reduced during tandem gait. These results suggest that multi-sensor IMU-based assessments provide a sensitive tool for detecting subtle, task-specific balance deficits in CLBP, indicating that rehabilitation should target rotational mobility and reactive control rather than core stiffening alone. Larger-scale and longitudinal research is still required to determine their clinical utility.