Comparison of Trunk and Leg Sway During Single Leg Stance

Purpose/Hypothesis: A force platform is a commonly used instrument to evaluate body sway. However, such a platform is not able to analyze how different body parts respond during static single-leg stance. The purpose of this study was to use a small wearable gyroscope-based balance assessment instrument, Balance Gear, to investigate how different body parts respond during static single-leg stance. We hypothesized that measurements at the knee would exhibit more sway than measurements taken at the lumbar level. Materials and Methods: Nineteen (10 males and 9 females) healthy young graduate students from the principal investigator’s institution were screened and recruited for this study. The Balance Gear (BG) was secured at two locations: L4 level (LUM), and popliteal fossa (KN) of the dominant leg. Testing location was randomized in order to avoid fatigue effect. Subjects were asked to perform static single-leg stance on the dominant leg for 30 seconds. Data of the subject’s body sway (direction, range, velocity, and acceleration) were recorded and transmitted wirelessly to a computer for data storage and analysis. Paired t-tests were used for data processing. Results: Subjects with the BG at KN showed a statistically significant difference in body sway range, velocity, and acceleration in the antero-posterior plane (p.05). Also, both LUM and KN sway posteriorly, but KN showed significantly larger range, velocity and acceleration compared to sway at LUM (all p Conclusions: It is the very first time the sway of different body parts were assessed during static single-leg stance. During stance, the KN is larger in range, velocity, and more posterior direction than the LUM sway.