Author(s): ROUSANOGLOU, E., PADERI, F., EMMANOUIL, A., BOUDOLOS, K., Institution: NATIONAL AND KAPODISTRIAN UNIVERSITY OF ATHENS, GREECE, Country: GREECE, Abstract-ID: 1622

INTRODUCTION:
In recent years, wearable sensors (based on miniaturized inertial measurement units) are increasingly used in postural stability studies [2], however, their application on unstable surfaces is still very limited [3].This study aimed to test the validity of postural stability estimation during single-legged standing on unstable surfaces using a with a triaxial accelerometer against the CoP path estimation.
METHODS:
Twenty women (24±3.6 years of age) performed five trials of single-legged standing (40 s each) on the floor and on four unstable surfaces commonly used in postural stability training (pad, disc, air, bosu). The twofold evaluation of postural stability included the 3D recording of the linear acceleration using a triaxial accelerometer (Biopac BN-ACCL3, samling at 100Hz, placed at the side of the tibia) in synchronization with the CoP recording using a force plate (Kistler, 9286AA, sampling at 500Hz). The extracted postural stability variables (absolute values) were the JERK (m/s3, rate of acceleration change) (anteroposterior-AP, mediolateral-ML, vertical direction) as well as the CoP path (m) (AP and ML direction). The percentage difference of each unstable surface relative to the floor (100%) was also calculated (relative values). A linear curve fit analysis was applied to estimate the slope coefficient among the 5 surfaces (scaled: floor, pad, disc, air, bosu) which was used to compare the JERK and the CoP path surface scaling. Statistics included one way ANOVA (surface effect on JERK and CoP path absolute and relative values, respectively) (p ≤ 0.05, SPSS v29.0).
RESULTS:
The surface effect was significant for both the JERK and the CoP path, (AP and ML direction, p < 0.001) indicating an increasing scale from floor, pad, disc, air, bosu. All pairwise differences (absolute and relative values) were also significant (p < 0.001), except for floor versus pad and air versus bosu solely for the CoP path (AP and ML direction). The linear fit was significant for the floor, pad, disc, air and bosu scaling, with a signficant difference between the JERK and the CoP path slope (AP and ML directions, p < 0.01). The JERK slope in the vertical direction differed significantly with the CoP path slope in the AP direction (p < 0.01) but not in the ML one (p = 0.204).
CONCLUSION:
The postural stability estimation using the JERK measure yielded from the linear acceleration obtained with a triaxial accelerometer appears to be valid against the gold standard of the CoP path estimation and yielded the same 3D scaling of the four unstable surfaces concerning the single-leg standing task. The results enhance the limited number of relevant studies [3] concerning the valid use of a portable device as the accelerometer during single-leg standing, which facilitates the in field evaluation of postural stability.
1) Lee et al., Int J Environ Res Public Health, 2020
2) Agostini et al., IEEE 23rd Int Symp Consum Tech, 2019
3) Mayer et al., Front Physiol, 2023