Biceps brachii muscle oxygenation in electrical muscle stimulation

Summary The purpose of this study was to compare between electrical muscle stimulation (EMS) and maximal voluntary (VOL) isometric contractions of the elbow flexors for changes in biceps brachii muscle oxygenation (tissue oxygenation index, TOI) and haemodynamics (total haemoglobin volume, tHb = oxygenated‐Hb + deoxygenated‐Hb) determined by near‐infrared spectroscopy (NIRS). The biceps brachii muscle of 10 healthy men (23–39 years) was electrically stimulated at high frequency (75 Hz) via surface electrodes to evoke 50 intermittent (4‐s contraction, 15‐s relaxation) isometric contractions at maximum tolerated current level (EMS session). The contralateral arm performed 50 intermittent (4‐s contraction, 15‐s relaxation) maximal voluntary isometric contractions (VOL session) in a counterbalanced order separated by 2–3 weeks. Results indicated that although the torque produced during EMS was approximately 50% of VOL (P