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Related Concept Videos

Carbohydrate Catabolism01:30

Carbohydrate Catabolism

Carbohydrate catabolism is a fundamental process in cellular metabolism that enables energy extraction from glucose through two primary pathways: cellular respiration and fermentation. Both pathways begin with glycolysis, which operates independently of oxygen availability.Glycolysis: A Shared Starting PointGlycolysis is an oxygen-independent process that breaks down glucose into two molecules of pyruvic acid. During this process, a net gain of two ATP molecules and two NADH molecules is...
Outcomes of Glycolysis01:13

Outcomes of Glycolysis

Nearly all the energy used by cells comes from the bonds that make up complex organic compounds. These organic compounds are broken down into simpler molecules, such as glucose. As a result, cells extract energy from glucose over many chemical reactions—a process called cellular respiration.
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Overview of Carbohydrate Metabolism01:19

Overview of Carbohydrate Metabolism

Carbohydrate metabolism is a fundamental biochemical process that ensures a constant supply of energy to living cells. The most important carbohydrate is glucose, which can be broken down via glycolysis to enter into the Krebs cycle and eventually lead to the production of ATP through oxidative phosphorylation.
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Fates of Pyruvate01:20

Fates of Pyruvate

Pyruvate is the end product of glycolysis, where glucose is oxidized to pyruvate, simultaneously reducing NAD+ to NADH. Two molecules of ATP are also produced by substrate-level phosphorylation.
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Pyruvate Oxidation01:15

Pyruvate Oxidation

After glycolysis, the charged pyruvate molecules enter the mitochondria via active transport and undergo three enzymatic reactions. These reactions ensure that pyruvate can enter the next metabolic pathway so that energy stored in the pyruvate molecules can be harnessed by the cells.
First, the enzyme pyruvate dehydrogenase removes the carboxyl group from pyruvate and releases it as carbon dioxide. The stripped molecule is then oxidized and releases electrons, which are then picked up by NAD+...
ATP Yield01:31

ATP Yield

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Carbohydrate oxidation from a drink during running compared with cycling exercise.

Beate Pfeiffer1, Trent Stellingwerff, Eric Zaltas

  • 1School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, UNITED KINGDOM.

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Carbohydrate oxidation rates during prolonged running are similar to cycling, suggesting exercise recommendations can be extrapolated. This study compared exogenous carbohydrate (CHO) oxidation during running versus cycling at moderate intensities.

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Area of Science:

  • Sports Science
  • Exercise Physiology
  • Nutritional Science

Background:

  • Current carbohydrate (CHO) intake recommendations for endurance exercise are based on laboratory studies, primarily using cycling.
  • It remains unclear if these findings are directly applicable to running due to differences in exercise mode.

Purpose of the Study:

  • To investigate and compare exogenous CHO oxidation rates during moderate-intensity running versus cycling.
  • To determine if CHO oxidation data from cycling studies can be extrapolated to running.

Main Methods:

  • Eight trained athletes completed four randomized trials: running or cycling at ~60% VO2max for 120 minutes.
  • Participants consumed either a CHO drink (glucose-fructose blend) or water.
  • Exogenous CHO oxidation and substrate utilization were measured.

Main Results:

  • Exogenous CHO oxidation rates were not significantly different between running and cycling trials.
  • Peak and average CHO oxidation showed similar time courses in both exercise modes.
  • Fat oxidation was higher during running compared to cycling, particularly with water ingestion.

Conclusions:

  • Exogenous CHO oxidation is comparable between prolonged running and cycling at similar relative intensities.
  • Findings support the extrapolation of previous CHO oxidation data from cycling studies to running.
  • This has implications for optimizing CHO intake strategies for endurance runners.