| Popis: |
During long-distance races, an attribute of physiological responses to change in running speed could determine race performance. This study investigated whether prior knowledge about increase in running speed affected cardiorespiratory responses when running. Eight healthy male volunteers (mean ± SD: age, 20 ± 1 years; height, 167.3 ± 3.9 cm; weight, 63.2 ± 8.3 kg) participated in this study. Initially, they performed a velocity-incremental maximal test. From the results of the maximal test,running velocities corresponding to the ventilation threshold (VT) and maximal oxygen uptake (VO2peak) were calculated. Second, the subjects carried out two types of 10-min transient submaximal running tests: those who had prior knowledge about running speed increase while running (aware) and those who did not (unaware). The 10-min transient running consisted of pre-increase (4 min) and post-increase (6 min) continuous running. The running velocity during the pre-increase time corresponded to the velocity at VT while the running velocity during the post-increase time corresponded to the velocity of Delta 40% (VT + [VO2peak ? VT] x 0.4). Pulmonary gas exchange parameters and heart rate were measured during all exercise tests. Local muscle oxygenation profiles of the left vastus lateralis muscle were obtained using near-infrared spectroscopy. The mean value of VO2peak was 3318 ± 448.4 mL/min. The actual VO2 at pre-increase was 2083 ± 405 mL/min (63% of VO2peak) for those aware and 2021 ± 411 mL/min (61% of VO2peak) for those unaware, and that at post-increase was 2846 ± 447 mL/min (86% of VO2peak) for those aware and 2768 ± 385 mL/min (83% of VO2peak) for those unaware. There were no differences in cardiorespiratory responses prior to and at the onset of speed-up running between the aware and unaware groups. This suggests the following two possibilities: 1) descending signals from higher brain centers capable of influencing cardiorespiratory responses were absent or decreased because of intense exercise, and/or 2) imagination following the knowledge of speed-up was insufficient to drive cardiorespiratory responses while running. |
