Previous research studies have reported that spectral compression of the surface Electromyogram (SEMG) towards lower frequencies is associated with onset of localized muscle fatigue. One reason for this spectral compression has been attributed to motor unit synchronization in literature. According to this, motor units are pseudo randomly excited during muscle contraction, and the recruitment pattern changes during the onset of muscle fatigue, such that the firing of motor units becomes more synchronized. While this theory is widely accepted, there is little experimental proof of the phenomenon. This paper has used source dependence properties and measures developed in research related to independent component analysis (ICA) to test for synchronization. This paper has also determined that the global matrix can be used as a measure for estimating localized muscle fatigue during cyclic movements.