Hypoxia causes reduced partial pressure of oxygen in arterial blood and induces
adaptations in skeletal muscle that may affect individuals’ physical performance and muscular
health. These muscular changes are detectable and quantifiable by electromyography (EMG),
an instrument that assesses electrical activity during active contraction at rest. EMG is a relatively
simple and accessible technique for all patients, one that can show the degree of the sensory and
motor functions because it provides information about the status of the peripheral nerves and muscles.
The main goal of this review is to evaluate the scientific evidence of EMG as an instrument for
monitoring different responses of skeletal muscles subjected to external stimuli such as hypoxia and
physical activity. A structured search was conducted following the Preferred Reporting Items for
Systematic Review and Meta-Analyses (PRISMA) guidelines in Medline/PubMed, Scielo, Google
Scholar, Web of Science, and Cochrane Library Plus. The search included articles published in the last
25 years until May 2020 and was restricted to English- and Spanish-language publications. As such,
investigators identified nine articles that met the search criteria. The results determined that EMG
was able to detect muscle fatigue from changes in the frequency spectrum. When a muscle was
fatigued, high frequency components decreased and low frequency components increased. In other
studies, EMG determined muscle activation increased during exercise by recruiting motor units and
by increasing the intensity of muscle contractions. Finally, it was also possible to calculate the mean
quadriceps quadratic activity used to obtain an image of muscle activation. In conclusion, EMG offers
a suitable tool for monitoring the different skeletal muscle responses and has sufficient sensitivity to
detect hypoxia-induced muscle changes produced by hypoxic stimuli. Moreover, EMG enhances an
extension of physical examination and tests motor-system integrity
