The Impact of Sucrose Ingestion Post-Exercise on Liver and Muscle Glycogen Repletion.

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 our ability to perform intense/prolonged endurance exercise. Therefore, it is important to replete these stores after an intense/prolonged endurance exercise session in order to recover and perform optimally during a subsequent exercise bout, especially if the next exercise session is within 24h (e.g. stage races such as the Tour de France, tournament-style competitions such as the Olympic games and ultra-endurance events). Carbohydrate intake has been shown to increase the availability of glycogen in the muscle and liver after exercise. The carbohydrates typically found in sports drinks are glucose and sometimes fructose. It has been observed that the ingestion of glucose will lead to a maximum rate of absorption of approximately  1 g/min. However, if we also provide a different source of carbohydrate (fructose) then this is absorbed through a different pathway and therefore we can absorb up to  1.75 g/min of carbohydrate. In addition, both carbohydrate sources are metabolised differently in the human body. By supplementing both glucose and fructose, we can potentially replenish the liver and muscle glycogen stores at a faster rate than ingestion of glucose only. 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 post-exercise when supplemented in relatively high amounts. Therefore the aim of this study is to assess whether relative high amounts of sucrose ingestion will improve liver and muscle glycogen repletion after endurance exercise.

Conditions
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Liver and Muscle Glycogen Replenishment Post-exercise

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


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy Endurance trained cyclists/triathletes 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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sucrose<br>Sucrose ingestion post-exercise | Dietary Supplement: Glucose<br> <br> |
| Active Comparator: Glucose<br>Glucose ingestion post-exercise | Dietary Supplement: Sucrose<br> <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 content will be determined post-exercise using 13C magnetic resonance spectroscopy | 5 h | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in muscle glycogen concentration | The change in muscle glycogen content will be determined post-exercise using 13C magnetic resonance spectroscopy | 5 h | 
| Plasma glucose concentration |  | 5 h | 
| Plasma insulin concentration |  | 5 h | 
| Plasma lactate concentration |  | 5 h |