Dietary Macronutrient Manipulation and Substrate Oxidation During Exercise

Study Overview
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Brief Summary
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This study will investigate the effect of dietary macronutrient manipulation on glycogen (stored carbohydrate) levels in the muscle and substrate oxidation during exercise. The investigators will investigate the hypothesis that manipulating the macronutrient content of the diet will alter the levels of glycogen in the muscle and, in turn, substrate oxidation during exercise.

Detailed Description
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One way to help reduce body fat is to expend more energy from the oxidation of fat as a fuel. Exercise is one way to increase fat oxidation. The extent to which exercise facilitates the use of fat as a fuel may be influenced by an individual's dietary intake. This study aims to establish the effect of dietary macronutrient manipulation on muscle glycogen levels and substrate oxidation during exercise. Participants will undertake three separate trial periods. During each trial period participants will consume a diet containing different macronutrient compositions. For each of the trials the investigators will assess how the macronutrient composition of the diet affects muscle glycogen level and substrate oxidation during exercise.

Official Title
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The Effect of Dietary Macronutrient Manipulation and Glycogen Depleting Exercise on Substrate Oxidation at Rest and During Exercise

Conditions
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Dietary Manipulation

Intervention / Treatment
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* Other: Diet with a different macronutrient content A
* Other: Diet with a different macronutrient content B
* Other: Diet with a different macronutrient content C
* Other: Interval treadmill running exercise
* Other: Steady state treadmill running exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Good general health Non-smoking - currently and for the past 5 years Fitness - V̇O2max 40-60 ml/kg/min Body mass index (20-25 kg/m2) Exclusion Criteria: Known or suspected intolerance to the dietary interventions or their stated ingredients. Participation in another clinical study or receipt of an investigational drug within 30 days of the screening visit. Previous participation in this study. Recent history (within the last year) of alcohol or other substance abuse. An employee of the sponsor or the study site or members of their immediate family. Abnormal / extreme habitual dietary practice / intake Recent (≤3 months) dietary practice that may be deemed as low and/or high in macronutrients will be excluded. The taking of any prescribed medication

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 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: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental arm 1<br>One of three 7-day study arms consisting of 3 days of standardised diet followed by 3 days of dietary macronutrient manipulation and 1 day of experimental testing. | Other: Diet with a different macronutrient content A<br>* A diet with altered macronutrient content will be provided to participants on days 4-6 of experimental arm 1.<br>Other: Interval treadmill running exercise<br>* Participants will perform interval treadmill running exercise on days 4 and 5 of all experimental arms.<br>Other: Steady state treadmill running exercise<br>* Participants will perform steady state treadmill running exercise on day 7 of all experimental arms.<br>|
| Experimental: Experimental arm 2<br>One of three 7-day study arms consisting of 3 days of standardised diet followed by 3 days of dietary macronutrient manipulation and 1 day of experimental testing. | Other: Diet with a different macronutrient content B<br>* A diet with a different macronutrient content compared to arm 1 will be provided to participants on days 4-6 of experimental arm 2.<br>Other: Interval treadmill running exercise<br>* Participants will perform interval treadmill running exercise on days 4 and 5 of all experimental arms.<br>Other: Steady state treadmill running exercise<br>* Participants will perform steady state treadmill running exercise on day 7 of all experimental arms.<br>|
| Experimental: Experimental arm 3<br>One of three 7-day study arms consisting of 3 days of standardised diet followed by 3 days of dietary macronutrient manipulation and 1 day of experimental testing. | Other: Diet with a different macronutrient content C<br>* A diet with a different macronutrient content compared to arms 1 and 2 will be provided to participants on days 4-6 of experimental arm 3.<br>Other: Interval treadmill running exercise<br>* Participants will perform interval treadmill running exercise on days 4 and 5 of all experimental arms.<br>Other: Steady state treadmill running exercise<br>* Participants will perform steady state treadmill running exercise on day 7 of all experimental arms.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Muscle glycogen concentration after dietary macronutrient manipulation | Muscle glycogen concentration will be measured after the dietary macronutrient manipulation intervention. | Day 7 of all experimental arms | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Rate of fat oxidation at rest (g/min) | Whole body oxygen consumption (VO2, L/min) and carbon dioxide production (VCO2, L/min) at rest will be measured using indirect calorimetry to calculate the rate of fat oxidation at rest (g/min). | For 20 min on Day 7 of all experimental arms | 
| Rate of fat oxidation during exercise (g/min) | Whole body oxygen consumption (VO2, L/min) and carbon dioxide production (VCO2, L/min) during exercise will be measured using indirect calorimetry to calculate the rate of fat oxidation during exercise (g/min). | During 60 min of exercise on day 7 of all experimental arms | 
| Rate of carbohydrate oxidation at rest (g/min) | Whole body oxygen consumption (VO2, L/min) and carbon dioxide production (VCO2, L/min) at rest will be measured using indirect calorimetry to calculate the rate of carbohydrate oxidation at rest (g/min). | For 20 min on Day 7 of all experimental arms | 
| Rate of carbohydrate oxidation during exercise (g/min) | Whole body oxygen consumption (VO2, L/min) and carbon dioxide production (VCO2, L/min) during exercise will be measured using indirect calorimetry to calculate the rate of carbohydrate oxidation during exercise (g/min). | During 60 min of exercise on day 7 of all experimental arms | 
| Blood glucose concentration | Blood glucose concentration will be assessed in blood samples taken during exercise. | At 0, 20, 40 and 60min into exercise on day 7 of all experimental arms. | 
| Blood insulin concentration | Blood insulin concentration will be assessed in blood samples taken during exercise. | At 0, 20, 40 and 60min into exercise on day 7 of all experimental arms | 
| Blood fatty acid concentration | Blood fatty acid concentration will be assessed in blood samples taken during exercise. | At 0, 20, 40 and 60min into exercise on day 7 of all experimental arms | 
| Change in intramuscular triglyceride (IMTG) content after exercise | IMTG utilisation during exercise (or change in IMTG content pre-post exercise) will be measured by comparing the IMTG content before and after exercise. | IMTG content measured just before and immediately after 60min of exercise on Day 7 of all experimental arms |