The influence of vibration type, frequency, body position and additional load on the neuromuscular activity during whole body vibration

Abstract

This study aimed to assess the influence of different whole body vibration (WBV) determinants on the electromyographic (EMG) activity during WBV in order to identify those training conditions that cause highest neuromuscular responses and therefore provide optimal training conditions. In a randomized cross-over study, the EMG activity of six leg muscles was analyzed in 18 subjects with respect to the following determinants: (1) vibration type (side-alternating vibration (SV) vs. synchronous vibration (SyV), (2) frequency (5-10-15-20-25-30 Hz), (3) knee flexion angle (10°-30°-60°), (4) stance condition (forefoot vs. normal stance) and (5) load variation (no extra load vs. additional load equal to one-third of the body weight). The results are: (1) neuromuscular activity during SV was enhanced compared to SyV (P < 0.05); (2) a progressive increase in frequency caused a progressive increase in EMG activity (P < 0.05); (3) the EMG activity was highest for the knee extensors when the knee joint was 60° flexed (P < 0.05); (4) for the plantar flexors in the forefoot stance condition (P < 0.05); and (5) additional load caused an increase in neuromuscular activation (P < 0.05). In conclusion, large variations of the EMG activation could be observed across conditions. However, with an appropriate adjustment of specific WBV determinants, high EMG activations and therefore high activation intensities could be achieved in the selected muscles. The combination of high vibration frequencies with additional load on an SV platform led to highest EMG activities. Regarding the body position, a knee flexion of 60° and forefoot stance appear to be beneficial for the knee extensors and the plantar flexors, respectively.

A Randomized Trial on the Effect of Bone Tissue on Vibration-induced Muscle Strength Gain and Vibration-induced Reflex Muscle Activity

“…Therefore, the squat or semi-squat position is preferred in WBV exercises performed to increase muscular performance in the lower extremities (6,22). In such positions, the joints are exposed to a significant moment of force due to gravity.…”

“…This position was used during WBV because it exposed the lower-extremity bones to maximum mechanical load while preventing stretching of the extrafusal and intrafusal muscle fibres in the knee flexor and extensor muscles. In most studies of WBV, vibration has generally been applied in a squatting or semi-squatting position; however, intramuscular tension is high in such positions (6,22).…”

The application of whole-body vibration in physiotherapy – A narrative review

“…One of the most thoroughly examined biological effects of WBV is an increase in the activity of striated muscles as detected with surface electromyography (34,54). Mechanical vibrations cause a specific myotatic reflex, commonly referred to in literature as a tonic vibration reflex (TVR) (24).…”

Effect of vibration frequency on agonist and antagonist arm muscle activity

“…In general, WBV exercise resulted in greater EMG activity compared to non-WBV exercise (Cardinale and Lim 2003;Roelants et al 2006). These studies have used vibration frequencies ranging from 20 to 50 Hz and submaximal (Hazell et al 2010;Ritzmann et al 2013) or maximal loads (Ronnestad et al 2012). For WBV, there is some evidence suggesting that EMG activity would increase linearly as a function of the vibration frequency within a range of 5-30 Hz (Berschin and Sommer 2004;Pollock et al 2010;Ritzmann et al 2013), while inconsistent results were obtained within the 25-50 Hz range (Cardinale and Lim 2003;Hazell et al 2007Hazell et al , 2010.…”

“…These studies have used vibration frequencies ranging from 20 to 50 Hz and submaximal (Hazell et al 2010;Ritzmann et al 2013) or maximal loads (Ronnestad et al 2012). For WBV, there is some evidence suggesting that EMG activity would increase linearly as a function of the vibration frequency within a range of 5-30 Hz (Berschin and Sommer 2004;Pollock et al 2010;Ritzmann et al 2013), while inconsistent results were obtained within the 25-50 Hz range (Cardinale and Lim 2003;Hazell et al 2007Hazell et al , 2010. Similarly to WBV, upper limb vibration exercise in the frequency range 23-31 Hz has resulted in greater EMG activity of upper limb muscles compared to non-vibration exercise (Bosco et al 1999;Mischi and Cardinale 2009;Moras et al 2010).…”