It is difficult to detect muscle tension in vivo. In vitro experiments, the young's modulus of human muscle changes with the tension and the shear wave speed is affected by young’s modulus. The tension can be qualified by using the shear wave elastography method. In this paper, the hyperelasticity model for muscles was established. The shear wave speeds in the muscle tissues under tension were studied by applying different statistic loads in the axial direction, and the effect of loads on the shear wave speeds was obtained. The results show that the shear wave speeds increases from 6.1 m/s to 13.1 m/s as the load increases from 0 to 50 kpa, and the speed is linearly related to the load. The shear wave elastography method could be used as a potential non-invasive method to measure the tension in tissues.