Liver and Muscle Glycogen Replenishment Post-exercise Clinical Trial
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.
| Status | Completed |
| Enrollment | 15 |
| Est. completion date | May 2015 |
| Est. primary completion date | May 2015 |
| Accepts healthy volunteers | Accepts Healthy Volunteers |
| Gender | Male |
| Age group | 18 Years to 35 Years |
| Eligibility |
Inclusion Criteria: - Healthy - Endurance trained cyclists/triathletes - VO2 max = 50 ml/kg/min Exclusion Criteria: - Use of medication - Smoking - Metabolic disorders |
Allocation: Randomized, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Basic Science
| Country | Name | City | State |
|---|---|---|---|
| United Kingdom | Northumbria University | Newcastle upon Tyne | North East |
| Lead Sponsor | Collaborator |
|---|---|
| Northumbria University | Maastricht University, Newcastle University, Sugar Nutrition |
United Kingdom,
| Type | Measure | Description | Time frame | Safety issue |
|---|---|---|---|---|
| Primary | change in liver glycogen concentration | The change in liver glycogen content will be determined post-exercise using 13C magnetic resonance spectroscopy | 5 h | No |
| Secondary | Change in muscle glycogen concentration | The change in muscle glycogen content will be determined post-exercise using 13C magnetic resonance spectroscopy | 5 h | No |
| Secondary | Plasma glucose concentration | 5 h | No | |
| Secondary | Plasma insulin concentration | 5 h | No | |
| Secondary | Plasma lactate concentration | 5 h | No |