A method for assessing and diagnosing traumatic brain injury (e.g.concussion)fromelectromyographic (EMG) signal. The method includes placing an electrode setcoupled to anamplifier unit on the subject's skin that overlying muscle(s), acquiring EMGsignals from thesubject through the electrode set, processing the acquired EMG signals using asignalprocessing algorithm that including Fourier transformation. The powerfrequency spectrum(also power spectrum) is obtained and used to determine anomaly in EMG fromsubjects whohad traumatic brain injury.