Carbohydrate Intake and Gut Hormone Release During Exercise

Study Overview
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Brief Summary
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It is well known that following a single session of moderate-to-high intensity exercise individuals experience a temporary suppression of hunger and a delay in the commencement of eating. This effect is believed to be due to changes in blood concentrations of specific hormones released from the gut that influence appetite. Individuals undertaking physical activity often consume foods immediately before exercise in order to improve their performance. However, it is currently unknown whether this eating practice influences the gut hormone response to exercise as well as how hungry an individual feels post-exercise. Therefore, the aim of this study is to investigate the effect of consuming a sugary (carbohydrate) drink immediately before starting an exercise session on the concentration of these gut hormones as well as the amount of food eaten in the hours following exercise completion.

Detailed Description
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It is well established that following an acute bout of moderate-to-high intensity exercise individuals experience a transient suppression of hunger and a delay in the commencement of eating - a phenomenon referred to as exercise-induced anorexia. Acute exercise modulates the concentrations of gut hormones known to influence satiety, including the anorexigenic hormones glucagon-like peptide 1 (GLP-1) and peptide tyrosine tyrosine (PYY), as well as the acylated form of the orexigenic hormone ghrelin. These alterations in gut hormone concentrations have consequently been hypothesised to play a key role in exercise-induced anorexia. Despite suppressing hunger and delaying eating, acute exercise does not appear to alter short-term energy intake in the immediate hours following exercise completion. The absence of a compensatory response therefore creates an energy deficit capable of inducing weight loss. Strategies that augment the gut hormone response to acute exercise may thus increase the potency of exercise as a weight-loss tool. Research investigating the effect of exercise on appetite has frequently utilised participants in a fasting state. Undertaking exercise in this physiological condition contradicts current practices, as athletes often consume a carbohydrate source immediately prior to exercise in an attempt to maximise performance. It is currently unknown as to whether the consumption of carbohydrate during this period may further enhance the gut hormone response to exercise, and thus research into a potential additive effect is warranted. High-intensity exercise increases sympathetic nervous system activity and catecholamine release. Catecholamine concentrations are negatively correlated with acylated ghrelin concentrations and may directly stimulate GLP-1 and PYY release via activation of β-receptors located on L-cells. The decrease in gastric emptying rate that is observed during high-intensity exercise is also attributed to this increase in sympathetic activity. Consequently, an increase in sympathetic nervous system activity has been postulated as a key mechanism underlying exercise-induced changes in gut hormone concentrations. However, to our knowledge, no study has directly measured the relationship between sympathetic nervous system activity and anorexigenic gut hormone release during exercise. Therefore, the aim of this study is to examine any potential additive effects of carbohydrate ingestion immediately prior to exercise on gut hormone release and post-exercise appetite suppression. Furthermore, this study will look to investigate the mechanisms underlying changes in gut hormone concentrations experienced during exercise.

Official Title
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Carbohydrate Intake and Gut Hormone Release During Exercise

Conditions
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Obesity

Intervention / Treatment
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* Dietary Supplement: Maltodextrin (carbohydrate)
* Other: Exercise
* Other: Rest
* Other: Water


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male Age between 18-40 years (inclusive) Body mass index (BMI) of 18-30 kg/m2 Willingness and ability to give written informed consent and willingness and ability to understand, to participate and to comply with the study requirements Exclusion Criteria: Abnormal ECG Screening blood results outside of normal reference values Current smokers Current or history of substance abuse and/or excess alcohol intake Diabetes Cardiovascular disease Cancer Gastrointestinal disease e.g. inflammatory bowel disease or irritable bowel syndrome Kidney disease Liver disease Pancreatitis Started new medication within the last 3 months likely to interfere with energy metabolism, appetite regulation and hormonal balance, including: anti-inflammatory drugs or steroids, antibiotics, androgens, phenytoin, erythromycin or thyroid hormones. Participation in a research study in the 12 week period prior to entering this study. Any blood donation within the 12 week period prior to entering this study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 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
Interventional Model Description: Participants perform all four trials in a randomized order
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: No Carbohydrate Drink + Rest<br>Participants will consume the no carbohydrate drink (300ml water) followed by a rest session | Other: Rest<br>* 30 minutes laying on a bed<br>Other: Water<br>* A drink containing 300ml of water<br>|
| Active Comparator: No Carbohydrate Drink + Exercise<br>Participants will consume the no carbohydrate drink (300ml water) followed by an exercise session (75% VO2 max on a cycle ergometer) | Other: Exercise<br>* 30 minutes on a cycle ergometer working at 75% VO2 max<br>Other: Water<br>* A drink containing 300ml of water<br>|
| Active Comparator: Carbohydrate Drink + Rest<br>Participants will consume the carbohydrate drink (300ml water + 75g maltodextrin) followed by a rest session | Dietary Supplement: Maltodextrin (carbohydrate)<br>* A drink containing 300ml of water and 75g of maltodextrin<br>Other: Rest<br>* 30 minutes laying on a bed<br>|
| Experimental: Carbohydrate Drink + Exercise<br>Participants will consume the carbohydrate drink (300ml water + 75g maltodextrin) followed by an exercise session (75% VO2 max on a cycle ergometer) | Dietary Supplement: Maltodextrin (carbohydrate)<br>* A drink containing 300ml of water and 75g of maltodextrin<br>Other: Exercise<br>* 30 minutes on a cycle ergometer working at 75% VO2 max<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in GLP-1 concentration | Changes in GLP-1 concentration between exercise and resting conditions, and between carbohydrate and control conditions | During the study visit, 165 minutes | 
| Changes in PYY concentration | Changes in PYY concentration between exercise and resting conditions, and between carbohydrate and control conditions | During the study visit, 165 minutes | 
| Changes in acylated ghrelin concentration | Changes in acylated ghrelin concentration between exercise and resting conditions, and between carbohydrate and control conditions | During the study visit, 165 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in energy intake | Differences in energy intake at an ad libitum meal between exercise and resting conditions, and between carbohydrate and control conditions | During the study visit, 165 minutes | 
| Changes in Energy expenditure | Differences in energy expenditure between exercise and resting conditions, and between carbohydrate and control conditions. | During the study visit, 165 minutes | 
| Changes in energy balance | Differences in energy balance between exercise and resting conditions, and between carbohydrate and control conditions. | During the study visit, 165 minutes | 
| Glucose homeostasis | Changes in glucose homeostasis between exercise and resting conditions, and between carbohydrate and control conditions. | During the study visit, 165 minutes | 
| Changes in subjective nausea | Changes in subjective feelings of nausea as measured by visual analogue scales between exercise and resting conditions, and between carbohydrate and control conditions. Visual analogue scales will range from 0 mm to 100 mm with a higher score indicating a higher degree of nausea. | During the study visit, 165 minutes | 
| Changes in subjective appetite | Changes in subjective feelings of appetite as measured by visual analogue scales between exercise and resting conditions, and between carbohydrate and control conditions. Visual analogue scales will range from 0 mm to 100 mm with a higher score indicating a higher degree of fullness. | During the study visit, 165 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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carbohydrate, exercise, PYY, GLP-1, ghrelin, hormones