Plasma LDH Isozyme Runners after 400-m Sprinting in Long-distance and Untrained Subjects

The blood lactate concentration is generally considered an indicator for evaluating anaerobic work capacity in man. It has been reported that the peak blood lactate concentration measured after supramaximal exercise lasting for about 1 min highly correlated with running time for the 400-m sprint in untrained subjects and long-distance runners (FUJITSUKA et al., 1982; OIKUWA et al., 1984a). We observed recently that, in well-trained sprint runners, there is a significant relationship between mean velocity in the 400-m sprint and lactate dehydrogenase (LDH) isozyme in the plasma, but the mean velocity did not correlate with the peak blood lactate concentration or plasma LDH activity (OHKUWA et al., 1984b). However, there are no available data concerning the relationship between mean velocity of the 400-m sprint and LDH activity or LDH isozyme in the long-distance and untrained subjects. The purpose of this study was to confirm whether LDH activity after the 400-m sprint is correlated with the physical performance of the 400-m sprint run in long-distance runners and untrained subjects. The subjects in this study were 8 male long-distance runners and 7 untrained male students. Their mean ages, height, and weight were 20.1 yr, 170.1 cm, and 58.1 kg for the long-distance runner group and 22.8 yr, 170.0 cm, and 67.6 kg for the untrained group, respectively. The long-distance runners regularly trained 3 to 4 h daily, 6 days a week throughout the year and continued training for at least 4 years. The experiments were conducted approximately 3-4 h after the last meal. All