Author(s): ARIPPA, F., LEBAN, B., PITTALIS, A., ANEDDA, G., PAU, M., Institution: UNIVERSITY OF CAGLIARI, Country: ITALY, Abstract-ID: 2690

INTRODUCTION:
Quantitative biomechanical assessment of athletes is usually limited to laboratory/elite settings due to high equipment costs and complex setups. Consequently, data are rarely collected in youth or sub-elite sports, despite their importance for performance optimization and injury prevention.
Wearable inertial measurement units (IMUs) offer a low-cost, portable solution for field-based sport biomechanics. While IMU-based methods to estimate lower-limb strength from vertical jumps are well established, most focus on jump height alone. In sports requiring frequent jump–landing tasks, post-landing neuromuscular control is crucial and can be assessed through Time to Stabilization (TTS), a measure of post-landing stability. Despite its relevance, this feature has received less attention than jump metrics in IMU-based applications. We therefore aimed to develop and validate an affordable, single-IMU framework for the integrated assessment of vertical jump performance and dynamic postural stability.
METHODS:
Fifty-five volleyball athletes (41 F), spanning youth, non-professional, and professional levels participated in the study. Vertical jump performance was assessed using Squat Jump (SJ) and Countermovement Jump (CMJ), while post-landing stability subsequent to a submaximal jump was evaluated through the TTS. A single IMU secured at the lumbar level with a semi-elastic belt while the athlete stood onto a laboratory-grade force platform, so to acquire trunk accelerations and ground reaction forces (GRF) simultaneously. Jump height was calculated from GRF using the flight-time method, while IMU-based estimates were derived using the same biomechanical model with calibrated take-off and landing detection. Dynamic stability was evaluated using a standardized submaximal forward jump with bipedal take-off and single-leg landing. TTS was computed from force data as the time required to return within ±5% of body weight for 1 s. IMU-TTS was derived using a similar criterion applied to the resultant acceleration (±5% of g for 1 s). Pearson correlations were computed between GRF- and IMU-derived parameters.
RESULTS:
Both approaches detect jump height increases with age and competitive level, with CMJ consistently exceeding SJ across groups and competitive levels. IMU- and GRF-derived values were strongly correlated for CMJ+SJ (r = 0.875, p < 0.001), CMJ (r = 0.874, p < 0.001), and SJ (r = 0.852, p < 0.001). TTS ranged from 1.3 to 1.7 s and was comparable between methods, although IMU-derived values were slightly lower overall. Greater inter-individual variability was observed in youth athletes. IMU-TTS showed a significant moderate-to-strong correlation with force-based TTS (r = 0.778, p < 0.001).
CONCLUSION:
The proposed framework provides a low-cost, single-IMU solution for the integrated assessment of jump performance and dynamic stability, supporting field-based and longitudinal monitoring for athletes’ profiling and injury-risk management where traditional instrumentation is unavailable.