Study (1999) coconut oil - glycogen use reduction during/post exercise

Preexercise medium-chain triglyceride ingestion does not alter muscle glycogen use during exercise

Preexercise medium-chain triglyceride ingestion does not alter muscle glycogen use during exercise

+ Author Affiliations

1. ¹ Department of Kinesiology and Health Education, The Human Performance Laboratory, The University of Texas at Austin, Austin, Texas 78712

• Submitted 25 May 1999.
• accepted in final form 23 September 1999.

Abstract

This investigation determined whether ingestion of a tolerable amount of medium-chain triglycerides (MCT; ∼25 g) reduces the rate of muscle glycogen use during high-intensity exercise. 

On two occasions, seven well-trained men cycled for 30 min at 84% maximal O₂ uptake. Exactly 1 h before exercise, they ingested either 1) carbohydrate (CHO; 0.72 g sucrose/kg) or 2) MCT+CHO [0.36 g tricaprin (C10:0)/kg plus 0.72 g sucrose/kg]. The change in glycogen concentration was measured in biopsies taken from the vastus lateralis before and after exercise. Additionally, glycogen oxidation was calculated as the difference between total carbohydrate oxidation and the rate of glucose disappearance from plasma (R_d glucose), as measured by stable isotope dilution techniques. 

The change in muscle glycogen concentration was not different during MCT+CHO and CHO (42.0 ± 4.6 vs. 38.8 ± 4.0 μmol glucosyl units/g wet wt). 

Furthermore, calculated glycogen oxidation was also similar (331 ± 18 vs. 329 ± 15 μmol ⋅ kg^{− 1} ⋅ min^{− 1}). The coingestion of MCT+CHO did increase (P < 0.05) R_d glucose at rest compared with CHO (26.9 ± 1.5 vs. 20.7 ± 0.7 μmol ⋅kg^{− 1} ⋅ min^{− 1}), yet during exercise R_d glucose was not different during the two trials.

Therefore, the addition of a small amount of MCT to a preexercise CHO meal did not reduce muscle glycogen oxidation during high-intensity exercise, but it did increase glucose uptake at rest.