Abstract: Thirty-six male basketball athletes performed oral HCO₃^-and placebo tests respectively (with one week interval between tests) followed by an high-intensity interval sprint trial (5×10 s with 60 s recovery) after 60 min, and average power output (APO) as well as peak power output (PPO) were recorded. Before ingestion and training, immediately after training and 5 min after training, acid-base equilibrium indexes were determined in arterial blood samples. Before ingestion, training, immediately after training, 60 and 120 min after training, plasma oxidative stress indicators were measured in venous blood. The results displayed:APO increased by supplement of HCO₃^- during high-intensity interval sprint trial compared with placebo (P<0.05);pH andHCO₃^- raised whileH⁺ reduced before, immediately and 5 min after training by supplement of HCO₃^- compared with placebo (P<0.05); compared with before training, plasma MDA heightened (P<0.05) in all time points after training by oral placebo, although no significant change of all oxidative stress indexes by HCO₃^- ingestion (P>0.05). The findings indicated that supplement of HCO₃^- before training improved exercise capacity following high-intensity interval sprint training in young males possibly through maintainance of acid-base equilibrium but unlikely to be due to a decreased oxidative stress.