Unaccustomed eccentric exercise has a profound impact on muscle structure and function. However, it is not known whether associated microvascular dysfunction disrupts the matching of O₂ delivery (QO₂) to O₂ utilization (VO₂). Near infra-red spectroscopy (NIRS) was used to test the hypothesis that eccentric exercise-induced muscle damage would elevate the muscle QO₂ : VO₂ ratio during severe intensity exercise whilst preserving the speed of the VO₂ kinetics at exercise onset. Nine physically active men completed 'step' tests to severe-intensity exercise from an unloaded baseline on a cycle ergometer before and 48 h after eccentric exercise (100 squats with a load corresponding to 70% of body mass). NIRS and breath-by-breath pulmonary VO₂ were measured continuously during the exercise tests and subsequently modeled using standard non-linear regression techniques. There were no changes in phase II pulmonary VO₂ kinetics following the onset of exercise (time constant, pre: 25 ± 4; post: 24 ± 2 s; amplitude, pre: 2.36 ± 0.23; post: 2.37 ± 0.23 L/min; all P>0.05). However, the primary (pre: 14 ± 3; post: 19 ± 3 s) and overall (pre: 16 ± 4; post: 21 ± 4 s) mean response time of the [HHb] response was significantly slower following eccentric exercise (P<0.05). The slower [HHb] kinetics observed following eccentric exercise is consistent with an increased QO₂ : VO₂ ratio during transitions to severe-intensity exercise. We propose that unchanged primary phase VO₂ kinetics are associated with an elevated QO₂ : VO₂ ratio that preserves blood-myocyte O₂ flux.