Effects of medium-chain triglyceride ingestion on fuel metabolism and cycling performance

1996 ◽  
Vol 80 (6) ◽  
pp. 2217-2225 ◽  
Author(s):  
C. G. Van Zyl ◽  
E. V. Lambert ◽  
J. A. Hawley ◽  
T. D. Noakes ◽  
S. C. Dennis
Keyword(s):  
Medium Chain Triglyceride ◽  
Time Trial ◽  
Random Order ◽  
Cycling Performance ◽  
Medium Chain Triglycerides ◽  
O2 Uptake ◽  
Lactate Oxidation ◽  
Medium Chain ◽  
Oxidation Rates ◽  
Fuel Metabolism

On three occasions separated by 10 days, six endurance-trained cyclists rode for 2 h at 60% of peak O2 uptake and then performed a simulated 40-km time trial (T-trial). During the rides, the subjects ingested a total of 2 liters of a [U-14C]glucose-labeled beverage containing a random order of either 10% glucose [carbohydrate (CHO)], 4.3% medium-chain triglycerides (MCTs); or 10% glucose + 4.3% MCTs (CHO+MCT). Although replacing CHO with MCTs slowed the T-trials from 66.8 +/- 0.4 (SE) to 72.1 +/- 0.6 min (P < 0.001), adding MCTs to CHO improved the T-trials from 66.8 +/- 0.4 to 65.1 +/- 0.5 min (P < 0.05). Faster T-trials in the CHO+MCT trial than in the CHO trial were associated with increased final circulating concentrations of free fatty acids (0.58 +/- 0.09 vs. 0.36 +/- 0.06 mmol/l; P < 0.05) and ketones (1.51 +/- 0.25 vs. 0.51 +/- 0.07 mmol/l; P < 0.01) and decreased final circulating concentrations of glucose (5.2 +/- 0.2 vs. 6.3 +/- 0.3 mmol/l; P < 0.01) and lactate (1.9 +/- 0.4 vs. 3.7 +/- 0.5 mmol/l; P < 0.05). Adding MCTs to ingested CHO reduced total CHO oxidation rates from 14 +/- 1 to 10 +/- 1 mmol/min at 2 h and from 17 +/- 1 to 14 +/- 1 mmol/min in the T-trial (P < 0.01), without affecting the corresponding approximately 5 and approximately 7 mmol/min rates of [14C]glucose oxidation. These data suggest that MCT oxidation decreased the direct and/or indirect (via lactate) oxidation of muscle glycogen. A reduced reliance on CHO oxidation at a given O2 uptake is similar to an endurance-training effect, and that may explain the improved T-trial performances.

Effect of carbohydrate or carbohydrate plus medium-chain triglyceride ingestion on cycling time trial performance

2000 ◽  
Vol 88 (1) ◽  
pp. 113-119 ◽  
Author(s):  
Damien J. Angus ◽  
Mark Hargreaves ◽  
Jane Dancey ◽  
Mark A. Febbraio
Keyword(s):  
Performance Enhancement ◽  
Medium Chain Triglyceride ◽  
Time Trial ◽  
Cycling Performance ◽  
Medium Chain Triglycerides ◽  
Carbohydrate Ingestion ◽  
Medium Chain ◽  
Cycling Time Trial ◽  
Carbohydrate Solution ◽  
Trial Performance

This study examined the effectiveness of ingesting a carbohydrate or carbohydrate + medium-chain triglycerides (MCT) on metabolism and cycling performance. Eight endurance-trained men [peak O2 uptake = 4.71 ± 0.09 (SE) l/min] completed 35 kJ/kg as quickly as possible [time trial (TT)] while consuming 250 ml/15 min of either a 6% (wt/vol) carbohydrate solution (C), a 6% carbohydrate + 4.2% MCT solution (C+M), or a sweet placebo (P). Time to complete the set amount of work was reduced in both C and C+M compared with P by 7 and 5%, respectively (C: 166 ± 7 min; C+M: 169 ± 7 min; P: 178 ± 11 min; P < 0.01). Plasma glucose concentration was maintained at or above resting values throughout both C and C+M trials but decreased ( P < 0.05) below resting values in P at the completion of the TT. The estimated rate of carbohydrate oxidation was not different during the first 90 min of exercise but thereafter was reduced ( P < 0.05) in P and was maintained in both C and C+M. These data demonstrate that carbohydrate ingestion during exercise improves 100-km TT performance compared with a sweet placebo, but the addition of MCT does not provide any further performance enhancement.

High-Fat Diet versus Habitual Diet Prior to Carbohydrate Loading: Effects on Exercise Metabolism and Cycling Performance

2001 ◽  
Vol 11 (2) ◽  
pp. 209-225 ◽  
Author(s):  
Estelle V. Lambert ◽  
Julia H. Goedecke ◽  
Charl van Zyl ◽  
Kim Murphy ◽  
John A. Hawley ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
High Fat Diet ◽  
Time Trial ◽  
Cycling Performance ◽  
Peak Oxygen Uptake ◽  
High Fat ◽  
Lactate Oxidation ◽  
Cycling Time Trial ◽  
Habitual Diet ◽  
Loading Effects

We examined the effects of a high-fat diet (HFD-CHO) versus a habitual diet, prior to carbohydrate (CHO)-loading on fuel metabolism and cycling time-trial (TT) performance. Five endurance-trained cyclists participated in two 14-day randomized cross-over trials during which subjects consumed either a HFD (>65% MJ from fat) or their habitual diet (CTL) (30 ± 5% MJ from fat) for 10 day, before ingesting a high-CHO diet (CHO-loading, CHO > 70% MJ) for 3 days. Trials consisted of a 150-min cycle at 70% of peak oxygen uptake (V̇O2peak), followed immediately by a 20-km TT. One hour before each trial, cyclists ingested 400 ml of a 3.44% medium-chain triacylglycerol (MCT) solution, and during the trial, ingested 600 ml/hour of a 10% 14C-glucose + 3.44% MCT solution. The dietary treatments did not alter the subjects’ weight, body fat, or lipid profile. There were also no changes in circulating glucose, lactate, free fatty acid (FFA), and β-hydroxybutyrate concentrations during exercise. However, mean serum glycerol concentrations were significantly higher (p < .01) in the HFD-CHO trial. The HFD-CHO diet increased total fat oxidation and reduced total CHO oxidation but did not alter plasma glucose oxidation during exercise. By contrast, the estimated rates of muscle glycogen and lactate oxidation were lower after the HFD-CHO diet. The HFD-CHO treatment was also associated with improved TT times (29.5 ± 2.9 min vs. 30.9 ± 3.4 min for HFD-CHO and CTL-CHO, p < .05). High-fat feeding for 10 days prior to CHO-loading was associated with an increased reliance on fat, a decreased reliance on muscle glycogen, and improved time trial performance after prolonged exercise.

Cycling Performance and Training Load: Effects of Intensity and Duration

2020 ◽  
pp. 1-9 ◽  
Author(s):  
Antonis Kesisoglou ◽  
Andrea Nicolò ◽  
Louis Passfield
Keyword(s):  
Exercise Intensity ◽  
Average Power ◽  
Time Trial ◽  
Exercise Bout ◽  
Random Order ◽  
Cycling Performance ◽  
Training Load ◽  
Subsequent Performance ◽  
Load Effects ◽  
Work Done

Purpose: To examine the effect of cycling exercise intensity and duration on subsequent performance and to compare the resulting acute performance decrement (APD) with total work done (TWD) and corresponding training-load (TL) metrics. Methods: A total of 14 male cyclists performed a 5-minute time trial (TT) as a baseline and after 4 initial exercise bouts of varying exercise intensity and duration. The initial exercise bouts were performed in a random order and consisted of a 5- and a 20-minute TT and a 20- and a 40-minute submaximal ride. The resulting APD was calculated as the percentage change in 5-minute TT from baseline, and this was compared with the TWD and TL metrics for the corresponding initial exercise bout. Results: Average power output was different for each of the 4 initial exercise bouts (; P < .001), and all bouts resulted in an APD. But APD was only different when comparing maximal with submaximal bouts (; P < .001). The APD contradicted TWD and TL metrics and was not different when comparing 5- and 20-minute maximal TTs or the 20- and 40-minute submaximal bouts. In contrast, TL metrics were different for all training sessions (; P < .001). Conclusion: An APD is found after initial exercise bouts consisting of 5- and 20-minute TTs and after 20- and 40-minute of submaximal exercise that is not consistent with the corresponding values for TWD or TL. This discrepancy highlights important shortcomings when using TWD and TL to compare exercise bouts of different intensity and duration.

An Isocaloric Glucose-Fructose Beverage’s Effect on Simulated 100-km Cycling Performance Compared With a Glucose-Only Beverage

2010 ◽  
Vol 20 (2) ◽  
pp. 122-131 ◽  
Author(s):  
Darren Triplett ◽  
J. Andrew Doyle ◽  
Jeffrey C. Rupp ◽  
Dan Benardot
Keyword(s):  
Time Trial ◽  
Endurance Performance ◽  
Cycling Performance ◽  
Peak Oxygen Uptake ◽  
Cycle Ergometer ◽  
Oxidation Rates ◽  
Familiarization Trial ◽  
Competitive Cyclists ◽  
Experimental Trials ◽  
Time Point

A number of recent research studies have demonstrated that providing glucose and fructose together in a beverage consumed during exercise results in significantly higher oxidation rates of exogenous carbohydrate (CHO) than consuming glucose alone. However, there is insufficient evidence to determine whether the increased exogenous CHO oxidation improves endurance performance. The purpose of this study was to determine whether consuming a beverage containing glucose and fructose (GF) would result in improved cycling performance compared with an isocaloric glucose-only beverage (G). Nine male competitive cyclists (32.6 ± 5.8 years, peak oxygen uptake 61.5 ± 7.9 ml · kg-1 · min-1) completed a familiarization trial and then 2 simulated 100-km cycling time trials on an electronically braked Lode cycle ergometer separated by 5–7 d. During the randomly ordered experimental trials, participants received 36 g of CHO of either G or GF in 250 ml of water every 15 min. All 9 participants completed the 100-km time trial significantly faster when they received the GF beverage than with G (204.0 ± 23.7 vs. 220.6 ± 36.6 min; p = .023). There was no difference at any time point between trials for blood glucose or for blood lactate. Total CHO oxidation increased significantly from rest during exercise but was not statistically significant between the GF and G trials, although there was a trend for CHO oxidation to be higher with GF in the latter stages of the time trial. Consumption of a CHO beverage containing glucose and fructose results in improved 100-km cycling performance compared with an isocaloric glucose-only beverage.

Long- and medium-chain triglycerides during parenteral nutrition in critically ill patients

1997 ◽  
Vol 272 (4) ◽  
pp. E550-E555 ◽  
Author(s):  
B. Delafosse ◽  
J. P. Viale ◽  
C. Pachiaudi ◽  
S. Normand ◽  
J. Goudable ◽  
...  
Keyword(s):  
Lipid Oxidation ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Esophageal Resection ◽  
Medium Chain Triglycerides ◽  
Medium Chain ◽  
Clear Cut ◽  
Oxidation Rates ◽  
Isotopic Methods ◽  
Metabolic Conditions

Due to their special metabolic pathway, medium-chain triglycerides (MCT) have been claimed to be oxidized more extensively, compared with long-chain triglycerides (LCT), when administered as a parenteral nutritional support. This enhanced lipid oxidation rate of MCT emulsions could be particularly disclosed in hyperglycemic and hyperinsulinemic conditions. In an attempt to further elucidate this question, we measured substrate oxidation rates in critically ill patients liable to experience such metabolic conditions, that is to say postoperative patients after esophageal resection receiving 1.5 times their measured energy expenditure (n = 12) or after liver transplantation (n = 8). These patients received either LCT or MCT-LCT emulsions. The metabolic measurements were performed simultaneously by two methods, namely indirect calorimetry and isotopic methods based on natural abundance of nutrients. Although both groups of patients were hyperglycemic and hyperinsulinemic, the measured carbohydrate and lipid oxidation rates were not different with whatever type of lipid was administered. The MCT-LCT emulsions did not offer clear-cut advantages over LCT emulsions in critically ill patients when lipid energetic fate was considered.

Metabolic availability of medium-chain triglycerides coingested with carbohydrates during prolonged exercise

1995 ◽  
Vol 79 (3) ◽  
pp. 756-762 ◽  
Author(s):  
A. E. Jeukendrup ◽  
W. H. Saris ◽  
P. Schrauwen ◽  
F. Brouns ◽  
A. J. Wagenmakers
Keyword(s):  
Energy Source ◽  
Prolonged Exercise ◽  
Metabolic Response ◽  
Ingestion Rate ◽  
Work Rate ◽  
O2 Consumption ◽  
Medium Chain Triglycerides ◽  
Medium Chain ◽  
Oxidation Rates ◽  
13Co2 Enrichment

The present study examined the metabolic response to medium-chain triglycerides (MCTs) ingestion with or without carbohydrates (CHOs). Eight well-trained athletes cycled 4 x 180 min at 50% maximal work rate (57% maximal O2 consumption). Subjects drank a bolus of 4 ml/kg at the start and 2 ml/kg every 20 min during exercise of either a 15% (214 g) CHO solution (CHO trial), an equicaloric 149 g CHO-29 g MCT suspension (CHO+MCT trial), 214 g CHO [high CHO (HCHO)]-29 g MCT suspension (HCHO+MCT trial) or 29 g MCT solution (MCT trial). Exogenous MCT oxidation was measured by adding a [1,1,1–13C]trioctanoate tracer to the MCT oil. 13CO2 enrichment of breath samples were measured every 15 min. During the second hour (60- to 120-min period), the amount of MCT oxidized was 72% of the amount ingested during the CHO+MCT trial, whereas during the MCT trial only 33% was oxidized. The rate of MCT oxidation increased more rapidly during the HCHO+MCT and CHO+MCT trials compared with the MCT trial, yet in all three cases the oxidation rate stabilized at 0.12 g/min during 120–180 min of exercise. It is concluded that more MCTs are oxidized when ingested in combination with CHOs. Data do confirm the hypothesis that oral MCTs might serve as an energy source in addition to glucose during exercise because the metabolic availability of MCTs was high during the last hour of exercise, with oxidation rates being approximately 70% of the ingestion rate.

scholarly journals TIME TO EXHAUSTION AT 90 AND 100% VO2MAX AND PHYSIOLOGICAL DETERMINANTS OF 3 KM PERFORMANCE IN ELITE CYCLISTS

2021 ◽  
Vol 6 (10) ◽  
Author(s):  
Zacharogiannis Elias ◽  
Pilianidis Theophilos ◽  
Dallas Giorgos ◽  
Mantzuranis Nikos ◽  
Argitaki Polixeni ◽  
...  
Keyword(s):  
Power Output ◽  
Ventilatory Threshold ◽  
Body Height ◽  
Time Trial ◽  
Random Order ◽  
Cycling Performance ◽  
Training Data ◽  
Time To Exhaustion ◽  
Wide Range

The minimal power that elicits VO2max and the time to exhaustion (tlimit) at this workload appear to determine cyclists’ endurance capabilities, analyze performance and help coaches to design training. Data in the literature are limited so as to elucidate this. The aim of this study was to investigate the tlimit at the power output, which corresponds to 90 (tlimit 90) and 100% VO2max (tlimit 100) in elite endurance cyclists. The contribution of tlimit in 3 km indoor individual time trial was also studied. Subjects were eleven elite male road cyclists (age 17.7  0.5 years, body mass 66.8  4.9 kg, body height 176.3  7.4 cm, VO2max 69.77  2.58 ml.kg-1.min-1). Power output at 90 and 100% VO2max was determined by continuous incremental testing. This protocol had steps of 2 min and increments of 30 W. The exhaustive trials tlimit 90 or tlimit 100 were performed in random order at least five days apart. Five days after the last exhaustive trial, cyclists performed an individual 3 km time trial on an indoor wooden track. Mean sd, tlimit 90 and tlimit 100 were 16:27.73  07:46.6 and 4:48.6  00:53.2 min:sec. Time to exhaustion at tlimit 90 and tlimit 100 ranged between 07:00-30:15 and 03:10-06:00 min:sec, respectively. Tlimit 100, tlimit 90 and VO2max (ml.min-1) did not correlate with 3 km cycling performance (r = 0.08, 0.16 and –0.59, p > 0.05). Tlimit 90 was inversely related (r = –0.49, p = 0.1) with VO2max (ml.min-1). Only power output which corresponded to ventilatory threshold and VO2max correlated significantly with 3 km performance (r = –0.83 and –0.80, p < 0.01). The results of this study indicate that: a) if cyclists’ training intensity is based on %VO2max, individual determination of the tlimit at the %VO2max has to be considered due to a wide range of tlimit to exhaustion; b) 3 km performance directly depends on the power that corresponds with ventilatory threshold and VO2max. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0723/a.php" alt="Hit counter" /></p>

Effects of Medium-Chain Triglyceride Ingestion on Carbohydrate Metabolism and Cycling Performance

1994 ◽  
Vol 87 (s1) ◽  
pp. 30-31 ◽  
Author(s):  
C Van Zyl ◽  
EV Lambert ◽  
TD Noakes ◽  
SC Dennis
Keyword(s):  
Carbohydrate Metabolism ◽  
Medium Chain Triglyceride ◽  
Cycling Performance ◽  
Medium Chain

Effects of Medium-Chain Triacylglycerol Ingested With Carbohydrate on Metabolism and Exercise Performance

1999 ◽  
Vol 9 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Julia H. Goedecke ◽  
Richard Elmer ◽  
Steven C. Dennis ◽  
Ingrid Schloss ◽  
Timothy D. Noakes ◽  
...  
Keyword(s):  
Exercise Performance ◽  
Plasma Insulin ◽  
Gastrointestinal Symptoms ◽  
Time Trial ◽  
Peak Oxygen Consumption ◽  
Serum Free Fatty Acid ◽  
Medium Chain ◽  
Fuel Metabolism ◽  
Plasma Insulin Levels ◽  
Trial Performance

The effects of ingesting different amounts of medium-chain triacylglycerol (MCT) and carbohydrate (CHO) on gastric symptoms, fuel metabolism, and exercise performance were measured in 9 endurance-trained cyclists. Participants, 2 hr after a standardized lunch, cycled for 2 hr at 63% of peak oxygen consumption and then performed a simulated 40-km time trial (T trial). During the rides, participants ingested either 10% 14C-glucose (GLU), 10% 14C-GLU + 1.72%MCT(LO-MCT), or 10% l4C-GLU + 3.44%MCT(HI-MCT) solutions: 400 ml at the start of exercise and then 100 ml every lOmin.MCTingestiondid not affect gastrointestinal symptoms. It only raised serum free fatty acid (FFA) and ß-hydroxybutyrate concentrations. Higher FFA and ß-hydroxybutyrate concentrations with MCT ingestion did not affect fuel oxidation or T-trial performance. The high CHO content of the pretrial lunch increased starting plasma insulin levels, which may have promoted CHO oxidation despite elevated circulating FFA concentrations with MCT ingestion.

scholarly journals Impact of Parenteral Lipid Emulsion Components on Cholestatic Liver Disease in Neonates

Nutrients ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 508
Author(s):  
Gregory Guthrie ◽  
Douglas Burrin
Keyword(s):  
Fatty Acid Composition ◽  
Parenteral Nutrition ◽  
Fish Oil ◽  
Lipid Emulsion ◽  
Medium Chain Triglyceride ◽  
Cholestatic Liver Disease ◽  
Lipid Emulsions ◽  
Medium Chain Triglycerides ◽  
Medium Chain ◽  
Life Saving

Total parenteral nutrition (TPN) is a life-saving intervention for infants that are unable to feed by mouth. Infants that remain on TPN for extended periods of time are at risk for the development of liver injury in the form of parenteral nutrition associated cholestasis (PNAC). Current research suggests the lipid component of TPN is a factor in the development of PNAC. Most notably, the fatty acid composition, vitamin E concentration, and presence of phytosterols are believed key mediators of lipid emulsion driven PNAC development. New emulsions comprised of fish oil and medium chain triglycerides show promise for reducing the incidence of PNAC in infants. In this review we will cover the current clinical studies on the benefit of fish oil and medium chain triglyceride containing lipid emulsions on the development of PNAC, the current constituents of lipid emulsions that may modulate the prevalence of PNAC, and potential new supplements to TPN to further reduce the incidence of PNAC.

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