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Chien J-H1, Lu J1, Siu K-C1
1University of Nebraska Medical Center, Physical Therapy Education, Omaha Nebraka, United States
Background: Approximate one-third of Americans (about 69 million) aged 40 years and older have some types of vestibular problems. These declining functionalities of the vestibular system affect quality of life. These difficulties in performing daily activities eventually increase the potential risk of falling. Therefore, patients with vestibular disorders have a nearly 8-fold increase in the risk of falls in comparison with age-matched controls. The role of vestibular system has been widely investigated in walking and standing. In real life, human not only walk on flat surface but also walk on inclined surface. Therefore, there is a need to understand the role of vestibular system while walking on the inclined surface.
Purpose: To avoid unnecessary exposure of patients with vestibular disorders to untested procedures, several investigators have evaluated healthy individuals by using the caloric or galvanic stimulation. However, the usability of these simulations to study the effects of the vestibular system on balance control during walking is questionable due to the induced discomfort. Therefore, in current study, we used our previously validated approach using mastoid vibration (MV) without discomfort to investigate the role of the vestibular system on gait during treadmill walking at different angles of inclination.
Methods: Ten subjects participated in this study (5 Females and 5 males, average height: 1.68±0.11 m, average weight: 64.5±12.8 kg). Retro-reflective markers were placed on the toe and heel of both legs to determine the stride length and stride interval using an 8-camera motion capture system. The MV was generated by mechanical vibrotactile stimulus on the mastoid process. Eight treadmill walking conditions were randomly introduced to all subjects (level: 0%, 3%, 6%, and 9% grade with/without MV). The long-range correlation was used to understand the subtle change of stride-to-stride fluctuation during gait, a higher alpha value (a) is indicated as higher long-range correlation. A two-way repeated ANOVA was used to investigate the effect of MV on the long-range correlation of stride length (aSL) and stride interval (aSI). A Pearson's correlation was used to understand the association between different angles of inclination and the a of gait parameters.
Results: A significant MV effect was found in aSL (F3,27 = 10.61, p > 0.05), only the present of MV changed the long-range correlation of stride length. The linear relationship between different angles of inclination and aSI was positive without MV (R2 = 0.57) and with MV (R2 = 0.51). However, the linear relationship between different angles of inclination and aSL was negative without MV (R2 = 0.05) and with MV (R2 = 0.71).
Conclusion(s): Applying MV on inclined walking could require an adaptive control of stride-to-stride fluctuation. Moreover, the need of such adaptive control increases as the angle of inclination increases during treadmill walking.
Implications: Combining MV with inclined treadmill, a simple and inexpensive approach without discomfort, maybe an optimal way to challenge the vestibular system during walking in clinical settings.
Keywords: Treadmill walking, Mastoid vibration, gait variability
Funding acknowledgements: This work is supported by the NASA Nebraska Space Grant Program (Mini-Grants #NNX15A109H and NNX15AK50A) and NASA Nebraska EPSCoR Program.
Purpose: To avoid unnecessary exposure of patients with vestibular disorders to untested procedures, several investigators have evaluated healthy individuals by using the caloric or galvanic stimulation. However, the usability of these simulations to study the effects of the vestibular system on balance control during walking is questionable due to the induced discomfort. Therefore, in current study, we used our previously validated approach using mastoid vibration (MV) without discomfort to investigate the role of the vestibular system on gait during treadmill walking at different angles of inclination.
Methods: Ten subjects participated in this study (5 Females and 5 males, average height: 1.68±0.11 m, average weight: 64.5±12.8 kg). Retro-reflective markers were placed on the toe and heel of both legs to determine the stride length and stride interval using an 8-camera motion capture system. The MV was generated by mechanical vibrotactile stimulus on the mastoid process. Eight treadmill walking conditions were randomly introduced to all subjects (level: 0%, 3%, 6%, and 9% grade with/without MV). The long-range correlation was used to understand the subtle change of stride-to-stride fluctuation during gait, a higher alpha value (a) is indicated as higher long-range correlation. A two-way repeated ANOVA was used to investigate the effect of MV on the long-range correlation of stride length (aSL) and stride interval (aSI). A Pearson's correlation was used to understand the association between different angles of inclination and the a of gait parameters.
Results: A significant MV effect was found in aSL (F3,27 = 10.61, p > 0.05), only the present of MV changed the long-range correlation of stride length. The linear relationship between different angles of inclination and aSI was positive without MV (R2 = 0.57) and with MV (R2 = 0.51). However, the linear relationship between different angles of inclination and aSL was negative without MV (R2 = 0.05) and with MV (R2 = 0.71).
Conclusion(s): Applying MV on inclined walking could require an adaptive control of stride-to-stride fluctuation. Moreover, the need of such adaptive control increases as the angle of inclination increases during treadmill walking.
Implications: Combining MV with inclined treadmill, a simple and inexpensive approach without discomfort, maybe an optimal way to challenge the vestibular system during walking in clinical settings.
Keywords: Treadmill walking, Mastoid vibration, gait variability
Funding acknowledgements: This work is supported by the NASA Nebraska Space Grant Program (Mini-Grants #NNX15A109H and NNX15AK50A) and NASA Nebraska EPSCoR Program.
Topic: Human movement analysis; Human movement analysis
Ethics approval required: Yes
Institution: University of Nebraska Medical Center
Ethics committee: IRB
Ethics number: 379-17-EP
All authors, affiliations and abstracts have been published as submitted.
