Author(s): RIZZATO, A., FAGGIAN, S., PAOLI, A., BOZZATO, M., MARCOLIN, G. , Institution: UNIVERSITÀ OF PADOVA, Country: ITALY, Abstract-ID: 860

INTRODUCTION:
Understanding the postural control mechanisms in dynamic balance training is warranted. We primarily aimed to study whether a four-week training with unstable boards could influence a transfer of balance ability to (i) a more challenging task and (ii) an untrained balance task (i.e., unexpected perturbation of the base of support). Moreover, we aimed to understand, through a non-linear center of pressure (CoP) analysis (i.e., Sample Entropy), whether a shift from voluntary to automatic postural mechanisms could occur in trained and untrained balance tasks.
METHODS:
Thirty-four young adults participated in the study and were randomly divided into a training (TR; N=17; 27.45±3.41yrs; 1.74±0.08m; 69.35±10.8kg) and a control (CTRL; N=17; 28±4.37yrs; 1.73±0.07m; 68.3±10.79kg) group. TR and CTRL were assessed for postural balance at the beginning of the study (T0) and after one month (T1) consisting of: static balance (SB); dynamic balance on unstable boards of easy (DBE) and hard (DBH) level; balance under unexpected perturbation of the base of support (PER). For each condition, subjects performed five trials over a force plate (AMTI BP400600, US) to measure the CoP trajectory. During SB, the subjects quietly stood in an upright posture. During DBE and DBH, subjects stood on the unstable board, aiming to maintain it parallel to the ground. During PER, subjects received an unexpected perturbation of the base of support (direction: forward; displacement: 50mm; ramp rate: 200mm/s). During DBE and DBH, an inertial measurement unit recorded the angular displacement of the board to calculate three parameters of balance performance: full (FB), fine (FiB), and gross (GB) balance. During PER, the mean velocity, the first peak, and the maximal oscillations (CoPMax) of the CoP trajectory were calculated in the 2.5s window after the perturbation. Moreover, the CoP trajectory was quantified in terms of regularity (Sample Entropy) in SB, UBE, and UBH conditions. The TR group underwent a month (T0-T1) of training (3 days/week) with increasing difficulty only using the easy-level unstable board.
RESULTS:
Two-way ANOVA showed improvements in balance performance (T0 vs. T1) in the TR group for FB (p<0.001), FiB (p<0.05), and GB (p<0.01) both in DBE and DBH. Similarly, the PER task had significant increases (T0 vs. T1) in the first peak (p<0.01) andCopMax (p<0.05). Sample Entropy parameters were significantly higher (p<0.001) after the training (T1) in DBE and DBH conditions.
CONCLUSION:
The one-month training successfully improved dynamic balance performance. A transfer of the balance ability was observed towards a more difficult (i.e., easy to hard) and to an untrained (i.e., unexpected perturbation) balance task. The non-linear CoP measure showed a shift from voluntary to automatic postural control mechanisms also in the task where no training occurred.

REFERENCES:
1. Rizzato et al., Hum Mov Sci., 2023.
2. Paillard et al., Biomed Res Int., 2015.