Effects of daily medium-chain triglyceride ingestion on energy metabolism and endurance performance capacity in well-trained runners

The purpose of this study was to assess the effect of medium-chain triglyce ride (MCTG) supplementation on energy metabolism and endurance performance capacity in well-trained runners. Seven men (age 19.4 +/- 1.7 years, maxima l O-2 uptake 67.5 +/- 4.8 ml(.)min(-1.)kg(-1)) were tested before and after MCTG as well as placebo consumption daily for 7 days. The energy and nutri ent intake of the subjects did not differ in MCTG and placebo trial. The ru nning time to exhaustion after dietary intervention was respectively 3916 /- 1225 s in placebo trial and 3498 +/- 559 s in MCTG trial. The concentrat ion of beta -hydroxybutyric acid in plasma was the highest (1.029 +/- 0.67 mmol(.)1(-1)) in post-test samples after MCTG supplementation, significantl y differing from the pre-test concentration in the same trial as well as fr om that observed in post-test blood after placebo treatment. These results suggest that daily MCTG supplementation increases the availability of keton e bodies for oxidation in working muscle during high intensity endurance ex ercise, but does not improve endurance performance capacity. (C) 2001 Elsev ier Science Inc. All rights reserved.