Liver and Muscle Glycogen Use During Exercise.
Conditions
Brief summary
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.
Interventions
DIETARY_SUPPLEMENTGlucose ingestion
Glucose ingestion during exercise at 1.8 g/min
DIETARY_SUPPLEMENTSucrose ingestion
Sucrose ingestion during exercise at 1.8 g/min
Sponsors
University of Newcastle Upon-Tyne
Maastricht University
Sugar Nutrition, UK
Javier Gonzalez, PhD
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
MALE
Age
18 Years to 35 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in liver glycogen concentration | 3 hours | The change in liver glycogen concentration will be determined pre-to-post 3 h of exercise using 13C magnetic resonance spectroscopy. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Plasma lactate concentration | 3 hours | Plasma lactate concentrations will be determined every 30 min during 3 h of exercise. |
| Plasma non-esterified fatty acid concentration | 3 hours | Plasma non-esterified fatty acid concentrations will be determined every 30 min during 3 h of exercise. |
| Plasma glucose concentration. | 3 hours | Plasma glucose concentrations will be determined every 30 min during 3 h of exercise. |
| Muscle glycogen concentration | 3 hours | The change in muscle glycogen concentration will be determined pre-to-post 3 h of exercise using 13C magnetic resonance spectroscopy. |
| Change in intramyocellular lipid concentration | 3 hours | The change in intramyocellular lipid concentration will be determined pre-to-post 3 h of exercise using 1H magnetic resonance spectroscopy. |
| Indirect calorimetry | 3 hours | Measurements of oxygen consumption, carbon dioxide production and respiratory exchange ratio through indirect calorimetry measured every 30 minutes during exercise. |
Countries
United Kingdom
Outcome results
None listed