The median frequency (MF) and mean power frequency (MPF) have been confirmed as reliable indicators of muscle fatigue during sustained contractions. The purpose of this study was to explore whether single-monitor arm could release muscle fatigue in neck-shoulder region while maintaining a prolonged seated posture viewing computer screen by measuring MF and MPF. Ten male healthy university students volunteered to participate in the test. Surface electromyography of splenius capitis (SC) and trapezius (TR) were recorded. Each subject performed normal text editing tasks or video watching activities for 120 minutes with different monitor arm positions (Fixed, moving downward and moving upward). Results showed that the MPF of SC and TR had significant decreased trend as monitor arm at fixed position. As monitor arm moving upward, the MF and MPF of both muscles decreased significantly with time and the MF showed the lowest decline rate during the entire testing process. No significant shift of MF and MPF were observed as monitor arm moving downward. Findings of this study may have important implications for people who use computer intensively to release neck-shoulder muscle fatigue.