The acute effects of wobble board performance on hand tremor: how much is it functional?

Purpose: A range of wearable sensors has been used to capture human movements such as fine motor skills. Specifically, inertial measurements unit (IMU) have been used for the assessment of physical symptoms such as Hand Tremor (HTR), crucial to perform fine motor skills. Although training proved to be effective in improving HTR, little is known on the acute effects of specific hand exercises on HTR. Therefore, this study aimed to investigate the acute effects of 30 min hand exercises on HTR also in relation to sex. Methods: 16 healthy subjects (Men(M) = 10; Women(W) = 6; age: 25.4 ± 2.9yrs) were asked to sit on a chair and extend their dominant upper limb forward with an IMU fixed under the palm at the middle finger level while resting the contralateral limb on the armrest. HTR was recorded for 10 s PRE and POST hand exercises. The exercises comprised four 15 s trials (antero-posterior, medio-lateral, clockwise, counterclockwise) performed on a computerized wobble board (WB), with a 30 s recovery period in between. The trained limb was positioned at a 90° on the WB placed on a table, and a monitor displaying the real-time performance of the WB was positioned at eye level. Subjects were instructed to maintain a motion marker within a target zone, displayed on the screen, for as long as possible during each trial. The IMU’s Acceleration (A) data on the z axis were downloaded using a USB connecting cable with proprietary software. Linear repeated mixed models were utilized to examine the effects of WB exercises on subject’s Az axis HTR, in relation to sex. Significance level was set at p < 0.05. Results: The analysis showed a significant main effect (p < 0.034) for sex on the Az axis, with M showing higher values than W. Specifically, significant differences were found between sex in PRE (M: 3.18 ± 0.4 cm/s2; W: 2.65 ± 0.2 cm/s2; p = 0.039) and POST (M: 3.23 ± 0.4 cm/s2; W: 2.63 ± 0.2 cm/s2; p = 0.013) evaluations. However, hand exercises led to distinct patterns in Az at different time points, with M increasing their HTR, and W decreasing it. Conclusions: In line with the literature, findings showed that M had higher HTR than W. Although the implementation of training interventions to improve fine motor skills in healthy individuals is essential, future studies should evaluate the acute effects on gesture accuracy to understand whether this increase in HTR in M is a limiting factor on the performance of fine motor skills or a physiological adjustment that could improve precision and accuracy.