Acute Effects Of Wobble Board Exercises On Low-frequency Hand Rest Tremor

PURPOSE: Hand rest tremor is a low-frequency, involuntary movement influenced by mechanical and neural factors, including muscle tone and reflexive response, often manifesting in differences in abilities between limbs (i.e., inter-limb asymmetry). Therefore, this study aimed to evaluate the acute effects of wobble board (WB) hand exercise on inter-limb asymmetry of hand rest tremor in healthy subjects. METHODS: 50 subjects (age: 25.0 ± 2.5 yrs) were tested before (PRE) and after (POST) WB hand exercise. Subjects were in a seated position with the tested limb on the armrest. Hand rest tremor was evaluated for 10s using a tri-axial accelerometer (100 Hz sampling rate) fixed under the palm of the hand. The acceleration was recorded along the x, y, and z axes and computed as the square root of the sum of squared accelerations across the axes for each subject. To eliminate noise, a 10 Hz low-pass Butterworth filter was applied. Power spectral density (PSD) was calculated using the fast Fourier transform, with frequency bands of interest at 2-4 Hz and 10-20 Hz (L2-4 and L10-20), corresponding to physiological tremor ranges. The logarithmic values of PSD within these bands were extracted for analysis. A repeated measures ANOVA compared (p < 0.05) tremor asymmetry between the dominant (DOM) and non-dominant (NoDOM) limbs across testing times (PRE vs POST). RESULTS: A significant effect of testing time was found for L2-4 (p < 0.0001), with POST intervention increases in PSD for both DOM (PRE:-7.54 ± 1.77, POST:-4.69 ± 1.44) and NoDOM (PRE:-7.56 ± 1.38, POST:-4.84 ± 1.21) limbs. For L10-20, a smaller effect was observed (p = 0.023), with relatively stable PSD values for both DOM (PRE:-10.68 ± 1.38, POST:-10.32 ± 0.85) and NoDOM (PRE:-10.83 ± 1.42, POST:-10.30 ± 1.03) limbs. CONCLUSIONS: The results suggest that WB hand exercises significantly influenced PSD in L2-4, with increases observed POST intervention, particularly in the DOM limb. This change may reflect improved motor control POST exercise, likely due to enhanced muscle coordination. In contrast, L10-20 showed minimal changes, reflecting the stability of central neural oscillations, which are less influenced by muscle coordination exercises. Findings highlight the potential of WB exercises in enhancing motor function, especially in the DOM limb. Supported by: Olga Papale's and Emanuel Festino’s Ph.D. scholarships are funded by the National Reform for Recovery and Resilience (PNRR) and Pegaso University, CUP: H36E22000130001