Nazarov ABT-199 chemical structure and Zilinsky (1984) reported that stretch exercises with vibration gave a greater increase in simple clinical measures of flexibility than stretch exercises alone. In a more recent study, Fagnani and colleagues (2006) demonstrated that whole body vibration also may increase flexibility alone without any further stretching exercises. These studies were focused on athletic subjects and showed enhancement of athletes’ flexibility as a result of vibration in both short-term and long-term protocols. However, further investigations

examining the passive mechanical properties of muscles are required to determine whether the changes are due to true alterations in muscle ‘length’. The underlying selleck products mechanisms of the effect of vibration on flexibility might involve a shift of the pain threshold and the stimulation of muscle spindle and Golgi tendon organs, causing the inhibition of the contraction (Issurin et al 1994), which involves neural circulatory and thermoregulatory factors (Mester et al

1999). Vibratory stimulation of the muscle spindle may produce Ia input, which modulates the recruitment thresholds and firing rates of motor units. Issurin (2005) has proposed that vibration enhances excitatory inflow from muscle spindles to the motor neuron pools and depresses the inhibitory impact of Golgi tendon organs due to accommodation to vibration stimuli. Ribot-Ciscar and colleagues (1998) demonstrated that after tendon vibration, a stretched muscle was perceived as being less stretched than it actually was, which indicates that vibration produces centrally first localised neural changes. They demonstrated

that the static stretch sensitivity of the muscles was decreased during the 3 sec following vibration exposure, due to a decreased spontaneous firing rate in the muscle spindle primary endings after vibration. This may contribute to the increased flexibility after vibration. The level of Golgi tendon organ excitation is therefore a possible mechanism for the muscle flexibility after vibration (Bosco et al 1999, Issurin et al 1994). Lundeberg and colleagues (1984) showed that the application of vibration to muscles produces analgesic effects during and after the procedure. This may delay the start of pain, which serves as a natural barrier to muscle elongation techniques, although it was shown that vibration has no effect on the pain perception in the vibrated muscles (Sands et al 2008). The use of vibration in pathological conditions such as muscle shortening remains an exciting area for further research. However, research in these fields is in its early stage. Much research is still needed on the optimal frequencies, amplitudes, and vibration durations to improve each of these factors. More studies are also needed to provide further knowledge about the optimal frequency and progression of the vibration.