Wavelet Analysis of the Vertical Ground Reaction Force Acting on the Forefoot (vGRF_F) During the Romberg Test

Introduction. The primary objective of this study was to perform a wavelet analysis of the time-course of the vertical ground reaction force acting on the forefoot (vGRF_F) during the Romberg test. The secondary objective was to conduct a time-frequency energy analysis of this signal. Material and Methods. The study included 93 female volleyball players (age: 15.29 ± 0.49 years, body height: 174.14 ± 7.36 cm, body mass: 62.67 ± 9.41 kg). The participants performed the test on a treadmill (Noraxon FDM-T) equipped with a high-resolution pressure sensor matrix. A time-frequency analysis of the signal originating from the treadmill was conducted using the Morse wavelet. Results. The average percentage contribution of signal energy in three analyzed frequency bands and the inter-band energy flow were determined as a function of eye status (open vs. closed) during the Romberg test. Conclusions. Appropriately preprocessed, the vGRF_F signal can serve as a viable alternative to traditional stabilographic metrics. It possesses high discriminative capability, particularly within the low-frequency range of 0.05 to 1 Hz.