Effects of carbohydrate (CHO) and fat supplementation on CHO metabolism during prolonged exercise

Jul 1, 1996Metabolism: clinical and experimental

How carbohydrate and fat supplements affect carbohydrate use during long exercise

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

No significant differences in muscle glycogen breakdown were detected among the carbohydrate and medium-chain triglyceride supplementation trials during exercise.

Muscle glycogen levels were similar across all trials, with values of 277 +/- 14 mmol/kg for CHO, 249 +/- 20 for CHO + MCT, and 240 +/- 18 for HCHO + MCT.
Mean exogenous carbohydrate oxidation rates during the final hour of exercise were measured at 0.79, 0.63, and 0.73 g/min for the respective trials.
No significant differences were found in the respiratory exchange ratio during exercise across the trials.
Plasma free fatty acid concentrations reached approximately 500 micromol/L and were consistent across all trials.
Plasma ketone concentrations increased significantly after medium-chain triglyceride ingestion compared to the carbohydrate trial.

AI simplified

The aim of the study was to examine carbohydrate (CHO) utilization in subjects receiving CHO or CHO + medium-chain triglycerides (MCT) supplements during 180 minutes of exercise at 50% maximal aerobic work rate ([Wmax] 57% maximal oxygen consumption [VO2max]). In a double-blind crossover design, nine trained athletes cycled four times. Subjects received a bolus of 4 mL x kg(-1) at the start and 2 mL x kg(-1) every 20 minutes during exercise of either a 150-g x L(-1) CHO solution (CHO trial), an equicaloric 70 energy% (en%) CHO-30 en% MCT suspension containing 29 g MCT (CHO + MCT trial), or a 150-g x L(-1) CHO (high-CHO [HCHO]) solution plus 20 g MCT (HCHO + MCT trial). A fourth trial consisted of a 13C-background control trial (CON). The four trials were randomized. Before and after the exercise bout, muscle biopsies were taken from the quadriceps muscle and muscle glycogen levels were determined. During exercise, breath samples were collected for estimation of exogenous and endogenous CHO oxidation. No significant differences were detected in glycogen breakdown among the trials (277 +/- 14 mmol x kg dry weight(-1) CHO, 249 +/- 20 CHO + MCT, and 240 +/- 18 HCHO + MCT) or in the respiratory exchange ratio during exercise. Mean exogenous CHO oxidation rates during the final hour of exercise were 0.79, 0.63, and 0.73 g x min(-1), respectively. No differences were observed between the trials regarding exogenous or endogenous CHO oxidation. Plasma free fatty acid (FFA) concentrations were elevated during exercise to a level of approximately 500 micromol x L(-1) and were comparable in all trials, whereas plasma ketone concentrations significantly increased after MCT ingestion as compared with the CHO trial. It is concluded that 29 g MCT co-ingested with CHO during 180 minutes of exercise does not influence CHO utilization or glycogen breakdown.

Full Text

Full text is available at the source.

View full text (XML) ↗View full text ↗

Effects of carbohydrate (CHO) and fat supplementation on CHO metabolism during prolonged exercise

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief