Medium-chain Triglycerides with Maltodextrin Increase Fat Oxidation during Moderate-intensity Exercise and Extend the Duration of Subsequent High-intensity Exercise

Abstract: Medium-chain triglycerides (MCT) are useful for increasing fat utilization during exercise. The highest rate of fat oxidation during submaximal exercise tends to precede the lactate threshold in untrained adults. In our previous study, blood lactate concentration was more than 4 mmol/L (onset of blood lactate) in recreational athletes during exercise at a workload corresponding to 60% peak O2 uptake (Vo2), which was below ventilation threshold. In the present study, we investigated the effect of 2 week of ingestion of food containing 6 g MCT on substrate oxidation during moderate-intensity (50% peak Vo2) exercise and high-intensity (70% peak Vo2) exercise in recreational athletes. For comparison, two experimental trials were conducted after participants had been administered isoenergic test foods (MCT-supplemented food with mainly maltodextrin-containing carbohydrate (MCT + CHO) or CHO) for 2 weeks, with a washout period between trials. Participants were instructed to perform cycle ergometer exercise at a workload corresponding to 50% peak Vo2 for 40 min followed by a workload corresponding to 70% peak Vo2 until exhaustion. Fat oxidation was significantly increased in the MCT + CHO trial (13.3 +- 2.7 g/40 min, mean +- SD, p