Conventionally Neuromuscular Electrical Stimulation (NMES), delivered on the muscle belly at low frequency and short pulse duration, is used in rehabilitation protocols to prevent muscle atrophy. However, conventional NMES causes rapid on-set of fatigue and possibly activates muscle fibers in a synchronous, spatially fixed order (i.e. reverse of the size principle). To overcome these limitations, in the past years, a novel approach that utilizes both high frequency (100Hz) and long pulse duration (1000µs) (Wide Pulse High Frequency Stimulation, WPHF) was proposed. During WPHF NMES muscle contraction is achieved via afferent nerve fibers, allowing the reflexive discharge of motor units, with the contribution of spinal circuitries, and mimic the recruitment order of a voluntary effort (i.e. first type I fibers). PURPOSE: Evaluating muscle oxygen consumption via Near-Infrared Spectroscopy (NIRS) technique during two NMES bouts at fixed frequency (100Hz), applying Short (200µs) and Long (1000µs) Pulse duration, while concurrently matching the external force output. METHODS: Two 5 minutes intermittent (1 sec on - 3 sec off) NMES bouts at Short and Long pulse duration were delivered on the right quadricep muscle of 14 healthy subjects while sitting on an isometric chair. NIRS recorded oxygen extraction (i.e. Deoxygenated Hemoglobin - Myoglobin) from the vastus lateralis of the stimulated limb. Equal muscle force between protocols was achieved by carefully selecting the individual stimulation intensity. RESULTS: We selected 10 consecutive contractions for Short and Long Pulse NMES in order to have equal muscle output and evaluate the corresponding oxygen consumption. In the selected contractions, Peak Force was 15.3 ± 5.7 and 15.4 ± 5.6 % (p: ns) of the Maximal Voluntary Contraction while Force Time Integral was 1522.6 ± 593.4 and 1539.4 ± 597.3 Nm*s (p: ns) for Short and Long Pulse respectively. At the same force output, Long Pulse NMES exhibited higher oxygen consumption, in percentage of the physiological calibration, than Short Pulse NMES (36.71 ± 11.82 % vs 28.79 ± 17.07 %, p:0.041). CONCLUSION: Applying Long Pulse NMES can elicit higher muscle oxygen utilization compared to Short Pulse duration, suggesting preferential recruitment of oxidative, type I muscle fibers, likewise to a voluntary contraction.