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This study will investigate how ethanol (pure alcohol) influences carbohydrate and fat metabolism during prolonged, moderate intensity exercise. Participants will perform two bouts of cycling exercise with or without prior ingestion of ethanol, in a randomised order, separated by one week.
Very little research has investigated the influence of ethanol on metabolism during prolonged exercise. Evidence suggests that delivery of fat to the working muscles during exercise may be limited with ethanol and therefore this may shift the relative proportions of energy derived from muscle stores of carbohydrate as a result (Jorfeldt & Juhlin-Dannfelt, 1976).
The current study aims to investigate how a small-moderate dose of ethanol influences where energy is derived from during a prolonged bout of moderate intensity cycling exercise.
Participants will visit the lab on three occasions, once for preliminary measurements of fitness and body composition, and twice for the experimental bouts of exercise. Body composition will be assessed using a dual-energy x-ray absorptiometry (DEXA) scan, which will measure lean mass, fat mass, and bone mineral density. Participants will then perform an incremental maximal oxygen uptake test to determine intensity for the experimental bouts of exercise.
The two experimental bouts of exercise include cycling on an exercise bike for 2 hours at 55% of their maximal oxygen uptake (i.e. fitness) following 1 hours rest. This will be performed under two conditions: with and without ethanol ingestion. Pre and post exercise muscle biopsies will be collected to assess muscle metabolism, with regular blood samples and expired breath samples being collected to further investigate fuel delivery and use by the working tissues. The experimental bouts of exercise will be performed 1 week apart in a randomised order.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Ethanol | Experimental | Participants will ingest ethanol (in the form of 40% ethanol) at an ingestion rate of 0.1 grams/kg lean body mass/hour in a solution with water. |
|
| No Ethanol | No Intervention | Participants will ingest a volume matched beverage of water only. |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Ethanol | Dietary Supplement | For one exercise session, participants will be asked to ingest a quantity of ethanol (in the form of vodka) sufficient to maximally stimulate liver alcohol metabolism. |
| Measure | Description | Time Frame |
|---|---|---|
| Change in muscle glycogen content | Muscle biopsy and subsequent biochemical analysis | Change in muscle glycogen content over 2 hours of moderate intensity cycling exercise |
| Blood glucose concentration | Venous blood samples will be taken and biochemically analysed for blood glucose concentration. | Blood samples will be taken every 15 minutes during rest and the first hour of exercise, they will be taken every 30 minutes in the second hour of exercise. |
| Blood non-esterified fatty acid (NEFA) concentration | Venous blood samples will be taken and biochemically analysed for NEFA concentration. | Blood samples will be taken every 15 minutes during rest and the first hour of exercise, they will be taken every 30 minutes in the second hour of exercise. |
| Measure | Description | Time Frame |
|---|---|---|
| Blood ethanol concentration | Venous blood samples will be taken and biochemically analysed for blood ethanol concentration. | Blood samples will be taken every 15 minutes during rest and the first hour of exercise, they will be taken every 30 minutes in the second hour of exercise. |
| Blood lactate concentration |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Harry Smith | University of Bath | Principal Investigator |
| James Betts, PhD | University of Bath | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of Bath | Bath | Somerset | BA2 7AY | United Kingdom |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 594641 | Background | Jorfeldt L, Juhlin-Dannfelt A. The influence of ethanol on human splanchnic and skeletal muscle metabolism during exercise. Scand J Clin Lab Invest. 1977 Nov;37(7):609-18. doi: 10.3109/00365517709100653. No abstract available. | |
| 910908 | Background | Juhlin-Dannfelt A, Ahlborg G, Hagenfeldt L, Jorfeldt L, Felig P. Influence of ethanol on splanchnic and skeletal muscle substrate turnover during prolonged exercise in man. Am J Physiol. 1977 Sep;233(3):E195-202. doi: 10.1152/ajpendo.1977.233.3.E195. No abstract available. |
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| ID | Term |
|---|---|
| D009043 | Motor Activity |
| ID | Term |
|---|---|
| D001519 | Behavior |
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| ID | Term |
|---|---|
| D000431 | Ethanol |
| ID | Term |
|---|---|
| D000438 | Alcohols |
| D009930 | Organic Chemicals |
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Venous blood samples will be taken and biochemically analysed for blood lactate concentration. |
| Blood samples will be taken every 15 minutes during rest and the first hour of exercise, they will be taken every 30 minutes in the second hour of exercise. |
| Carbohydrate Oxidation | Carbohydrate oxidation will be determined through indirect calorimetry via the douglas bag technique. | Expired breath samples will be collected at baseline before beverage consumption and again after 1 hours rest. Samples will collected every 15 minutes during the first hour of exercise and every 30 minutes during the second hour |
| Fat Oxidation | Fat oxidation will be determined through indirect calorimetry via the douglas bag technique. | Expired breath samples will be collected at baseline before beverage consumption and again after 1 hours rest. Samples will collected every 15 minutes during the first hour of exercise and every 30 minutes during the second hour |
| 913043 | Background | Juhlin-Dannfelt A, Jorfeldt L, Hagenfeldt L, Hulten B. Influence of ethanol on non-esterified fatty acid and carbohydrate metabolism during exercise in man. Clin Sci Mol Med. 1977 Sep;53(3):205-14. doi: 10.1042/cs0530205. No abstract available. |