VARIABLE-FREQUENCY MICRO-VIBRATION ON THE LOWER EXTREMITY INDUCES IMMEDIATE IMPROVEMENT IN SINGLE-LEG STANDING BALANCE

L.-W. Chou¹, T.-H. Chan¹, C.-H. Lin²

¹National Yang Ming Chiao Tung University, Physical Therapy and Assistive Technology, Taipei, Taiwan, ²Taipei Medical University, Master Program in Long-Term Care, Taipei, Taiwan

Background: Aging induces significant decline of the neuromuscular function, for example, slowness of motor reaction and weakness of muscle force output. Sensory afferent inputs are important in sensorimotor control, and sensory inputs have been used as a neuromodulation tool for improving motor function. Vibration applied on the skin and muscle belly induces cutaneous and proprioceptive afferent inputs into the central nervous system (CNS). Because sensory system is easily adaptive to constant mechanical stimuli, vibration with variable intensities and frequencies could be beneficial in providing consistent sensory afferent inputs for modulating CNS. For the development of wearable device that can be easily worn during daily lives, micro-vibrator with low energy requirements and light-weight are better suited.

Purpose: Investigating the effects of lower extremity variable-frequency micro-vibration on the performance of single-leg stance.

Methods: The study recruited 10 healthy adults without neuromuscular injuries in the past six months. Participants were asked to stand on a force plate with the dominant leg and perform 60-sec single leg stance test under 5 different vibration conditions, including no vibration, vibration, immediate after vibration, 10-min after vibration, and 20-min after vibration. Micro vibrators were placed and secured on the gastrocnemius muscle belly (1 on medial head, 1 on lateral head) and Achille’s tendon. The pattern and frequency of vibration is randomized and range from 125 to 300Hz. Participants were asked to perform 60 second single leg stance test twice with 1-minute break between conditions. COP data was analyzed by calculating the ellipse area of COP, and analyze mean and peak velocity in 2 directions (COPx, COPy). These parameters of 5 condition were compared analyzed using the Friedman test. The level of statistical significance was set at 0.05.

Results: The study found that the ellipse area of COP was the smallest in the during vibration condition. The area decreased from 773.59 to 629.69(mm²). Also, after vibration the area increased from 629.69 to 846.27(mm²). In addition, the mean and peak velocity of COPx and COPy didn’t change during or after vibration.

Conclusions: Micro vibration with variable frequency on calf may improve balance performance on COP area. However, this type of vibration does not induce improvement on either mean or peak COP velocity.

Implications: Micro vibrator is small and portable, and appears to be an effective device for improving balance during daily life

Funding acknowledgements: Taiwan Minister of Science and Technology: MOST 110-2221-E-A49A-501 -MY3

Keywords:
Vibration
Balance
Neuromuscular control

Topics:
Musculoskeletal
Neurology

Did this work require ethics approval? Yes

Institution: National Yang Ming Chiao Tung University

Committee: IRB

Ethics number: YM111060E