WHOLE-BODY VIBRATION EFFECT ON MUSCLE ACTIVATIONS: WHICH ONE IS THE MOST EFFECTIVE, LOW FREQUENCY OR HIGH FREQUENCY?

Abstract

Purpose: Whole Body Vibration (WBV) is a practice that passively applies mechanical oscillations to an individual from a support surface. The tonic vibration reflex response depends on the vibration localization, frequency, amplitude, and initial length of the muscle, but there is no consensus on what the optimal frequency should be. This study was conducted to examine the activation differences of lower extremity muscles at low and high frequencies during squat exercise on WBV. Methods: This study involved 16 healthy individuals (Age = 23.66 ± 2.33 years, Body Mass Index= 22.59 ± 3.86 kg/m2). WBV application was performed on a vertical vibration platform (GLOBUS Physioplate®). Participants performed static half-squats on WBV for 20 seconds under vibrating (20 Hz and 60 Hz; 2-3 mm amplitude) conditions. An 8-channel Electromyography (EMG) Noraxon MiniDTS system was used to measure the activation of the Gluteus Medius (GMed), Gluteus Maximus (GMax), Vastus Lateralis (VL), and Vastus Medialis (VM) muscles. Results: It was observed that there was a difference between the two frequencies for the activation of the VM, VL, and GMed muscles (p = 0.004, 0.001, 0.002, respectively). Vibration frequencies of GMed, VL, and VM muscle activities at high frequency were increased compared to low frequency. GMax did not show any statistically significant change between the two vibration conditions (p=0.013). Conclusions: Physiotherapists and trainers should prefer high frequencies in WBV applications, especially when they need to improve the neuromuscular response in the quadriceps and gluteus medius muscles.