['This study examined the effect of intermittent breath holding (IBH) on physiological response, including oxygenation in working muscle, to moderate-intensity exercise.', 'Thirteen men performed bicycle exercise for 5 min at 65% of peak oxygen uptake with normal breathing (NB) and with IBH. Muscle oxygenation, concentration changes of oxyhemoglobin (ΔOxy-Hb), deoxyhemoglobin (ΔDeoxy-Hb) and total hemoglobin (ΔTotal-Hb), in the right vastus lateralis were continuously monitored using near-infrared spectroscopy (NIRS). Finger capillary blood samples were taken after exercise for analyzing blood lactate concentration (BLa).', 'NIRS parameters showed acute changes to each BH episode in the IBH condition (Total-Hb and ΔOxy-Hb decreased, ΔDeoxy-Hb increased). Accordingly, in the IBH condition, ΔOxy-Hb was lower (P<0.05) and ΔDeoxy-Hb was higher (P<0.05) compared to that in the NB condition, whereas there was no difference in ΔTotal-Hb in the both conditions. BLa levels were greater (P<0.05) in the IBH condition compare to the NB condition.'] Does intermittent breath holding during moderate bicycle exercise provoke consistent changes in muscle oxygenation and greater blood lactate response?