Different types of mastoid vibrations affect the amount and structure of minimum toe clearance variability...

The majority of research primarily examines the role of the vestibular system in regulating balance by assessing gait parameters in the transverse plane while neglecting those in the sagittal plane. The present study aimed to examine the impact of various forms of mastoid vibration (MV) on minimum toe clearance (MTC) and its pattern of variability. This study proposed two hypotheses: 1) the application of MV reduced the MTC, and 2) the application of different forms of MV influenced the amount and structure of MTC variability.

A total of twenty young adults participated in this study. A high-resolution motion capture system with eight cameras captured the minimum toe clearance. Three locomotor tasks were randomly assigned to these young participants: 1) walking normally on the treadmill, 2) walking with unilateral MV, and 3) walking with bilateral MV. The dependent variables were the mean of MTC, the amount, and the structure of MTC variability. The amount of MTC variability was calculated by the coefficient of variation represented, and the structure of MTC variability was measured using a sample entropy measure for a total of 200 MTCs.

Applying unilateral and bilateral MV decreased the MTC significantly (-1.6 %, p = 0.038; -4.3 %, p < 0.001) compared to normal walking. Also, applying unilateral MV increased the amount (11.8 %, p = 0.001) and structure of MTC variability (14.3 %, p < 0.001) compared to normal walking. However, applying bilateral MV decreased the amount (-8.8 %, p = 0.001) and structure of MTC variability (-9.0 %, p < 0.001) compared to regular walking.

Although the statistical differences in MTC and MTC variability were observed in the present study, the mean differences among the different MV conditions were relatively small, thereby requiring meticulous deliberation when extrapolating the results when implementing this MTC in the pathological cohort.