Carbohydrate Feeding Frequency, Muscle Glycogen and Exercise Capacity in Runners

Study Overview
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Brief Summary
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The aim of this study is to investigate the effects of regular sucrose feeds compared to a single large bolus given late in exercise, on muscle glycogen utilisation, exercise capacity and other markers of metabolism during running

Official Title
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The Effect of Carbohydrate Feeding Frequency on Muscle Glycogen and Exercise Capacity in Runners

Conditions
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Exercise

Intervention / Treatment
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* Other: Regular carbohydrate feeding
* Other: Single carbohydrate bolus


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Self-identify as a trained runner Regularly participate in running activity (>2 times a week) Participated in running based training for a minimum of 2 years Be willing to undertake exercise sessions until volitional exhaustion Be willing to have the necessary samples taken during the testing protocols Not a habitual smoker Have the capacity and willingness to provide informed consent (oral and written) Successful completion of the physical activity readiness questionnaire (PAR-Q) Exclusion Criteria: Female <18 or >50 years old Not regularly participating in running activity (<3 times a week) Experience contraindications to the administration of the proposed anaesthetic (Lidocaine Hydrochloride) Habitual/previously habitual smoker

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 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 |
| --- | --- |
| Active Comparator: Regular carbohydrate feeding<br>Ingestion of 75 g sucrose, given in regular doses for the first 75 minutes of exercise during a time to exhaustion run | Other: Regular carbohydrate feeding<br>* 60 ml of water with 5 g sucrose given every 5 minutes 14 times up until 70 minutes followed by 5 g sucrose after 75 minutes in a 250 ml solution<br>|
| Active Comparator: Single carbohydrate bolus<br>Ingestion of 75 g sucrose, given in a single bolus after 75 minutes of exercise, during a time to exhaustion run | Other: Single carbohydrate bolus<br>* 60 ml of water given every 5 minutes 14 times up until 70 minutes followed by 75 g sucrose after 75 minutes in a 250 ml solution<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Muscle glycogen concentrations | Muscle glycogen concentration at rest, after 75 minutes of treadmill running and at volitional exhaustion. Measured using the bergstrom needle technique for obtaining muscle biopsy samples | Estimated to be between 90 and 145 minutes | 
| Exercise capacity | Time to exhaustion at the pre-determined speed to elicit exhaustion after  90 minutes when ingesting water only | Estimated to be between 90 and 145 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ratings of perceived exertion | Subjective ratings of perceived exertion, during treadmill running. Measured using a borg scale of 6 to 20, where 6 = no exertion at all, and 20 = maximal exertion. | Estimated to be between 90 and 145 minutes | 
| Ratings of stomach discomfort | Subjective ratings of stomach discomfort during treadmill running. Measured using a modified borg scale of 6 to 20, where 6 = no discomfort and 20 = maximal discomfort | Estimated to be between 90 and 145 minutes | 
| Carbohydrate oxidation | Total carbohydrate oxidation during treadmill running. Measured using indirect calorimetry and reported in grams. | Estimated to be between 90 and 145 minutes | 
| Fat oxidation | Total fat oxidation during treadmill running. Measured using indirect calorimetry and reported in grams. | Estimated to be between 90 and 145 minutes | 
| Plasma glucose concentrations | Plasma lactate concentrations during of treadmill running. Measured using colourimetric assay and reported in mmol/L | Estimated to be between 90 and 145 minutes | 
| Plasma lactate concentrations | Plasma lactate concentrations during treadmill running. Measured using colourimetric assay and reported in mmol/L. | Estimated to be between 90 and 145 minutes | 
| Heart rate | Heart rate during treadmill running measured by telemetry and reported in beats per minute | Estimated to be between 90 and 145 minutes | 
| Rate of oxygen consumption | Rate of oxygen consumption during treadmill running. Measured using indirect calorimetry and reported in litres per minute | Estimated to be between 90 and 145 minutes | 
| Rate of carbon dioxide production | Rate of carbon dioxide production during treadmill running. Measured using indirect calorimetry and reported in litres per minute. | Estimated to be between 90 and 145 minutes |