With a view to clarify the effect of a full marathon running on humans, particularly on the liver function, five runners were subjected to a marathon race, and measuring of serum enzymes and liver clearance test (ICG test) were conducted on the day immediately before the race day, on the morning after the race, one week later and two weeks later, with the following rusults.
　1) Each of serum enzymes (GOT, GPT, LDH, CPK) showed a rise immediately after the running and on the following morning, but each of them recovered its initial level one week later.
　2) LDH₄ and LDH₅ of LDH isozymes significantly rose immediately after the running and still remained above their rest levels on the following morning.
　3) ICG plasma concentration significantly decreased both immediately after the running and on the following morning, and a delay in the liver ICG clearance was recognized.
　4) The fluctuation ranges in both the rise of serum activation and the reduction of ICG plasma concentration were slighter, compared with those seen at the race.
　As the above results assure that a full marathon training affects the liver as well as the skeletal muscles, at least two weeks of a rest and adjustment period with less intensified training will assumably be needed after a full marathon running.

DESCENTE SPORTS SCIENCE Vol.9/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE