The purpose of this study was to examine the biochemical features of the slump period in female distance runner. Six female distance runners (19-20 years old) were examined to provide data concerning hemoglobin concentration, serum glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), creatine phosphokinase (CPK), blood lactate disappiarance, and Vo₂ in running at submaximal constant speed during the slump period and the period of good condition.
　The results obtained were summarized as follows;
1) In the slump period, Vo₂ in running at submaximal constant speed was higher than that in the period of good condition.
2) The significant correlation (r= 0.63 P< 0.05) was found between blood hemoglobin concentration and running performance in various conditions, The data suggest that mild anemia might be major causes of the slump period.
3) No remarkable change of serum GOT, and GPT was found in any case. They remained in the normal range or lower value.
4) Serum CPK showed the higher value and was over the normal range in all subjects. But there was no significant correlation between serum CPK and running performance in various condition.
5) Blood lactate disappiearance tended to show the higher value in the period of good condition than that in slump period. But the correlation was not significant statistically.

DESCENTE SPORTS SCIENCE Vol.11/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE