著者

小林 義雄 細井 輝男 竹内 敏子 吉崎 英清

出版者

中京大学

雑誌

中京大学教養論叢 (ISSN:02867982)

巻号頁・発行日

vol.44, no.2, pp.431-443, 2003-10-15

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The concentration of beta-endorphin (B-EP) was measured in 12 male recreational runners before and after marathon running. All subjects could finish 42 km distance and their mean time for finishing was 3 hr and 50 min (3 hr 6 min - 4 hr 22 min). Plasma B-EP significantly (P<0.0001) increased to about 9.8-fold above base line, from 9.1 ± 0.8 (SE) to 88.9±17.0 pg/ml. In addition, B-EP remained above baseline at 30 min and 60 min after the marathon race (43.9 + 12.7 pg/ml; P<0.0001 and 33.6± 6.6 pg/ml; P<0.001, respectively) and dropped to baseline 24 hr following the race. Lactate concentration also significantly (P<0.0001) increased during the marathon race (from 11.8±0.12 to 2.33± 0.18 mmol/L). This value was far below anaerobic threshold levels, 4 mmol/L, and was equivalent to approximately 60-65% VO_2max of our subjects. Previous studies have reported that the peripheral B-EP responses may be intensity dependent and that an exercise intensity of at least 70% VO_2max for 15 min is needed to increase plasma B-EP. Since our subjects performed extremely over-duration exercise and were exhausted after the race, therefore, the undue physical stress might affect the increase in B-EP. In conclusion, plasma B-EP responses may be both intensity and duration dependent.