Heterogeneity in the distribution of ventilation and blood flow in the lungs, and its effects on pulmonary gas exchange, are well known, and several methods exist for their quantification. This is not the case in skeletal muscle, where heterogeneity in the distribution of both blood flow and O2 consumption has not been directly measurable, rendering its effects on muscle function unable to be evaluated. We used near-infrared spectroscopy (NIRS) to measure the regional distribution of VO2, blood flow (Q), and their ratio (VO2/Q) in six trained cyclists at rest and during constant load exercise (unloaded pedaling, 20%, 50% and 80% of peak watts) in both normoxia and acute hypoxia (FIO2=0.12). From each of six optodes on the skin over the upper, middle and lower vastus lateralis, we recorded a) indocyanine green dye (ICG) inflow after IV injection to measure blood flow, and b) oxygenated Hb/Mb (StO2). Varying both exercise intensity and FIO2 provided a (directly measured) femoral venous O2 saturation (SfvO2) range of about 10 to 70%, and a corresponding range in StO2 of about 35 to 75%. In each subject, a linear relationship was found between mean Q-weighted StO2 over the 6 optodes and SfvO2. We used this empirical relationship to compute local muscle venous blood O2 saturation from StO2 recorded at each optode, from which local VO2/Q ratios could be calculated by the Fick principle. Multiplying regional VO2/Q by Q yielded the corresponding local VO2. Under all conditions, relative dispersion of Q (0.44 ± 0.02) and VO2 (0.48 ± 0.02) were similar, while that for VO2/Q was far less (0.14 ± 0.01), indicating in fit young subjects: a) a strong capacity to regulate Q according to regional metabolic need from rest to heavy exercise in both normoxia and hypoxia, and b) a likely minimal impact of heterogeneity on overall muscle function. Future application of this novel approach, which may require recording from a larger number of optodes, should clarify the extent and importance of heterogeneity in muscle of patients with chronic diseases, and may become useful in the intensive care setting as an indicator of peripheral vascular regulatory integrity.