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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
8
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.
University of Bath
Bath, Somerset, United Kingdom
Change in muscle glycogen content
Muscle biopsy and subsequent biochemical analysis
Time frame: 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.
Time frame: 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.
Time frame: 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 ethanol concentration
Venous blood samples will be taken and biochemically analysed for blood ethanol concentration.
Time frame: 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
Venous blood samples will be taken and biochemically analysed for blood lactate concentration.
Time frame: 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.
Time frame: 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
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Fat Oxidation
Fat oxidation will be determined through indirect calorimetry via the douglas bag technique.
Time frame: 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