The Impact of Sucrose Ingestion During Exercise on Liver and Muscle Glycogen Concentration.

Study Overview
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Brief Summary
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Carbohydrate is stored in the body as glycogen, which is mainly found in the liver and muscle. During endurance exercise, muscle glycogen is used as fuel for the working muscles and liver glycogen is broken down to provide glucose to maintain blood glucose (sugar) levels. Both liver and muscle glycogen are important for the ability to perform intense/prolonged endurance exercise. Therefore, nutritional strategies which can maximise the availability of glycogen in muscle and liver can benefit endurance exercise capacity. The carbohydrates typically found in sports drinks are glucose and sometimes fructose. If glucose only is ingested during exercise, then the maximum rate at which can be absorbed from the intestine into the blood stream is  1 g/min. However, if different sources of carbohydrate (fructose) are used, which are absorbed through a different pathway, absorption of carbohydrate can be up to  1.8 g/min. With more carbohydrate available as a fuel, this translates into an improvement in performance. Sucrose is a naturally occurring sugar that is made up of a single glucose and single fructose molecule. Therefore, theoretically, this can use the two different pathways of absorption and also maximise carbohydrate delivery. It is not yet known however, what impact this has on our liver and muscle glycogen stores during exercise. Therefore the aim of this study is to assess whether sucrose ingestion influences liver and muscle glycogen depletion during endurance exercise.

Conditions
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Liver and Muscle Glycogen Use During Exercise.

Intervention / Treatment
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* Dietary Supplement: Glucose ingestion
* Dietary Supplement: Sucrose ingestion


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy Male 18 - 35 years of age Endurance trained cyclist/triathlete VO2 max ≥ 50 ml/kg/min Exclusion Criteria: Use of medication Smoking Metabolic disorders

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Glucose ingestion<br>Glucose ingestion during exercise at a rate of 1.8 g/min. | Dietary Supplement: Glucose ingestion<br>* Glucose ingestion during exercise at 1.8 g/min<br>|
| Experimental: Sucrose ingestion<br>Sucrose ingestion during exercise at a rate of 1.8 g/min. | Dietary Supplement: Sucrose ingestion<br>* Sucrose ingestion during exercise at 1.8 g/min<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in liver glycogen concentration | The change in liver glycogen concentration will be determined pre-to-post 3 h of exercise using 13C magnetic resonance spectroscopy. | 3 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plasma glucose concentration. | Plasma glucose concentrations will be determined every 30 min during 3 h of exercise. | 3 hours | 
| Plasma lactate concentration | Plasma lactate concentrations will be determined every 30 min during 3 h of exercise. | 3 hours | 
| Plasma non-esterified fatty acid concentration | Plasma non-esterified fatty acid concentrations will be determined every 30 min during 3 h of exercise. | 3 hours | 
| Indirect calorimetry | Measurements of oxygen consumption, carbon dioxide production and respiratory exchange ratio through indirect calorimetry measured every 30 minutes during exercise. | 3 hours | 
| Muscle glycogen concentration | The change in muscle glycogen concentration will be determined pre-to-post 3 h of exercise using 13C magnetic resonance spectroscopy. | 3 hours | 
| Change in intramyocellular lipid concentration | The change in intramyocellular lipid concentration will be determined pre-to-post 3 h of exercise using 1H magnetic resonance spectroscopy. | 3 hours |