ObjectivesThe purpose of the present study was to utilize ShearWave™ Elastography to assess tissue stiffness by measuring shear wave speed before and after applying the direct Myofascial release (MFR) technique to the lateral gastrocnemius muscle of competitive tennis athletes. MethodsShear wave speed values were measured in the regions of interest within the lateral gastrocnemius fascia and muscle areas from the elastographic images. Measurements were taken in three different situations: before, immediately after and 5 min after MFR protocol. Subsequently, the results from each situation were statistically compared. ResultsThe protocol was administered to a group of eighteen tennis players with a mean age of 18 ± 1.23 years. The shear wave speed values increased for both fascia and muscles sites, after applying the MFR technique: From 3.01 ± 0.64 to 3.33 ± 0.86 m/s in the deep fascia and from 2.23 ± 0.41 to 2.57 ± 0.51 m/s in superficial fascia. In the deep and superficial muscles sites the increases were from 4.12 ± 0.95 to 4.40 ± 1.22 m/s, and from 2.94 ± 0.71 to 3.38 ± 0.95 m/s, respectively. ConclusionThis study showed that after the myofascial manipulation in tennis athletes, the lateral gastrocnemius muscle and fascia tissues stiffness increased, according to elastography, and possible mechanisms were discussed. ShearWave™ Elastography could be utilized to assess the acute effects of applying a direct myofascial release (MFR) technique.