High intensity exercise training (HIT) accelerates V’O2 kinetics (VO2k) in older subjects. It is controversial whether IRT may elicit the same adaptation. We explored the effect of HIT and IRT on VO2k and muscle deoxygenation during moderate intensity exercise in older, healthy men. 12 men (68 yy ± 4) were exposed to 8 weeks (3 times a week) of: i) HIT, and, after 4 months, ii) IRT performed with an isoinertial YoYo. Before and after training we measured: i) V’O2 peak (V’O2p); ii) breath-by-breath V’O2 and fractional muscle O2 extraction (∆HHb) of vastus lateralis by quantitative NIRS during step-exercise transitions of moderate intensity. VO2k was modeled by means of a double - exponential function to obtain the time constant (Tau) of its primary component. The normalized ∆HHb to ∆V’O2 ratio (∆HHb/∆V’O2) was calculated as and index of the matching between muscular O2 delivery (VO2m) and uptake (QaO2). V’O2p increased after HIT (29.9 mL min-1 kg-1 ± 4.3 - 32.6 mL min-1 kg-1± 6.0, p<0.05); it was not affected by IRT. Tau decreased after HIT (26.97 s ± 5.54 - 19.63 s ± 4.31, p<0.05); it did not change after IRT. Peak ∆HHb/∆V’O2 was smaller after HIT (1.83 ± 0.63 - 1.23 ± 0.37, p<0.05); it was not affected by IRT. 8 weeks of HIT accelerated V’O2k and improved the matching between QaO2 and VO2m. IRT did not lead to any improvement of ∆HHb/∆V’O2 and left V’O2k unchanged. Results suggest that the acceleration of V’O2k was mainly due to the improved matching of VO2m to QaO2.