Oxygen uptake and blood metabolic responses to a 400-m run

This study aimed to investigate the oxygen uptake and metabolic responses during a 400-m run reproducing the pacing strategy used in competition. A portable gas analyser was used to measure the oxygen uptake (V̇O ) of ten specifically trained runners racing on an outdoor track. The tests included (1) an incremental test to determine maximal V̇O (V̇O) and the velocity associated with V̇O(v - V̇O), (2) a maximal 400-m (400T) and 3) a 300-m running test (300T) reproducing the exact pacing pattern of the 400T. Blood lactate, bicarbonate concentrations [HCO], pH and arterial oxygen saturation were analysed at rest and 1, 4, 7, 10 min after the end of the 400 and 300T. The peak V̇O recorded during the 400T corresponded to 93.9 ± 3.9% of V̇O and was reached at 24.4 ± 3.2 s (192 ± 22 m). A significant decrease in V̇O (P < 0.05) was observed in all subjects during the last 100 m, although the velocity did not decrease below v - V̇O. The V̇O in the last 5 s was correlated with the pH (r = 0.86, P < 0.0005) and [HCO] (r = 0.70, P < 0.05) measured at the end of 300T. Additionally, the velocity decrease observed in the last 100 m was inversely correlated with [HCO] and pH at 300T (r = -0.83, P < 0.001, r = -0.69, P < 0.05, respectively). These track running data demonstrate that acidosis at 300 m was related to both the V̇O response and the velocity decrease during the final 100 m of a 400-m run. © Springer-Verlag 2010.