pH variation has been investigated in the disease lesion regions, such as tumors, stroke and muscle injury. However, to image the change of the pH level is a challenge. CEST imaging is one of the possible methods using. CEST can efficiently enhance the contrast for small pH variation between solute and water proton by saturation transfer. In this study, fatigue skeletal muscles model of mice by electrical stimulation was investigated. The z-spectra show significant enhancement between the off-resonance frequency of 1 ppm to 2 ppm. CEST images also present a noteworthy contrast in the lesion region while T2 weighed images display a larger lesion which may be due to the temporary increasing blood flow. The pH value in the lesion is believed to be between 6 to 7. According to the magnetic resonance spectroscopy (MRS), main metabolites in the skeletal muscles are creatine and taurine. The acidic environment may enhance the proton exchange between water protons and protons on creatine and taurine. The detailed chemical compositions and acidity in MR images are still needed to be quantified. It will be correlated with fMRI data to differentiate the sensory pain and soreness.