| Popis: |
During long distance races, abrupt acceleration results in a sudden energy requirement in runners.The aim of this study was to determine whether prior different-speed running affected the oxygen uptake kinetic and tissue oxygenation during subsequent high-speed running.Eight healthy male volunteers (mean±SD: age, 19.6±1.4 yr; height, 169.3±4.9 cm; weight,67.9±7.39 kg) performed a velocity-incremental maximal test and 2 transient submaximal running tests. From the results of the maximal test, running velocities corresponding to ventilation threshold (VT) and maximal oxygen uptake (VO2peak) were estimated. Subjects performed two 12 min continuous running tests that consisted of a 1st stage (6 min) and a 2nd stage (6 min). First stage running velocity corresponded to either 80%VT or VT. The 2nd stage of running velocity corresponded to ⊿ 40% (VT + (VO2peak ? VT)×0.4). Therefore, Subjects performed 80%VT → 2nd stage running (Sub-1) and VT → 2nd stage running (Sub-2). During transient running tests, pulmonary gas exchange parameters were measured by breath-by-breath, and a non-linear regression technique was used. The oxygenation status of the vastus lateralis muscle of the left leg was monitored using a commercially-available near- infrared spectroscopy (NIRS) system, and a surface electromyogram (EMG) was obtained from the vastus lateralis muscle of the right leg during submaximal tests.The time constant of VO2 response in primary phase was significantly longer during sub-2 than during sub-1 (p < 0.05). Slow component amplitudes were 173.0±103.2 (sub-1) and 178.4±154.1 (sub-2). NIRS-derived deoxygenated hemoglobin during both submaximal tests (sub-1 and sub-2) |
