Glycaemic Index and Substrate Metabolism

NCT05241730 | Completed

• 1 other identifier: 2105/2021
• Study Type: interventional
• Target: 65
• Locations: 1 country
• Sites: 1

Brief Summary

Substrate metabolism during exercise can be influenced by various nutritional regimes. The effectiveness of the different nutritional regimes, which differ in their carbohydrate content, will be investigated not only by functional tests but also the measurement of the mechanistic processes in the muscle will be explored. Magnetic resonance (MR), better known as magnetic resonance imaging (MRI), has been widely used in clinical practice as a non-invasive imaging technique. Importantly, in addition to producing anatomical images, an MR scanner also offers the possibility to measure the concentrations of a number of metabolic products. This is done through a technique known as magnetic resonance spectroscopy (MRS). This research project asks the following questions:

• Can a diet containing carbohydrates with a low glycemic index achieve the same adaptations in basic endurance/fat metabolism as a high fat, low carbohydrate (ketogenic) diet?
• Does a high-fat, low-carbohydrate diet, compared with a high-carbohydrate diet, prevent improvements in performance in the submaximal and maximal range?
• What is the effect of diets with different carbohydrate content and variable glycemic index on endurance performance in a half marathon and a time trial?
• How do the diets with different carbohydrate content and variable glycaemic index affect the energy and glycogen stores in the muscles? In active recreational athletes, the objectives are: (1) to investigate the effects of different diets with variable carbohydrate content and glycaemic index on substrate metabolism, (2) to determine the effects of the different diets on energy stores using multinuclear dynamic magnetic resonance spectroscopy, and (3) to measure the effects of the different diets on endurance performance.

Conditions

Substrate Metabolism During Exercise

Outcome Measures

Primary Outcomes (5)

• changes in peak oxygen consumption (measured in ml/min/kg)

  VO2peak will be assessed during a graded exercise test on the treadmill.

  Baseline - 10 weeks

• changes in 5 km time trial (measured in mm:ss)

  5 km time trial performance will be assessed during an all out 5 km run on a 400 m running track. The time for completing the 5 km will be assessed.

  Baseline - 10 weeks

• changes in muscle glycogen content (measured in mmol/l muscle)

  Changes in muscle glycogen will be assessed in a thigh muscle using a MR scan.

  Baseline - 10 weeks

• changes in power at lactate turning point 1 (LTP1) and individual anaerobic threshold (IAS) (measured in km/h)

  Changes in power at LTP1 and IAS will be assessed during a graded exercise test on a treadmill.

  Baseline - 10 weeks

• changes in AUC in lactate in the graded exercise test

  Changes in AUS in lactate will be assessed during a graded exercise test on a treadmill.

  Baseline - 10 weeks

Secondary Outcomes (9)

• changes in fat free mass (measured in kg)

  Baseline - 5 weeks - 10 weeks

• changes in fat mass (measured in kg)

  Baseline - 5 weeks - 10 weeks

• changes in skeletal muscle mass (measured in kg)

  Baseline - 5 weeks - 10 weeks

• changes in body water (measured in l)

  Baseline - 5 weeks - 10 weeks

• changes in body weight (measured in kg)

  Baseline - 5 weeks - 10 weeks

Study Arms (3)

Low GI

EXPERIMENTAL

The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from low glycaemic index carbohydrates per day, the other E-% are fats and proteins.

Other: Training intervention; Other: Low Glycaemic Index

High GI

ACTIVE COMPARATOR

The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from high glycaemic index carbohydrates per day, the other E-% are fats and proteins.

Other: Training intervention; Other: High Glycaemic Index

Low Carb High Fat

EXPERIMENTAL

The subjects eat ≥ 65 E-% fats and a maximum of 50 g carbohydrates per day.

Other: Training intervention; Other: LCHF

Interventions

Training intervention OTHER

The training intervention will be a 10 week training plan for endurance runners. The plan consists of five sessions per week (three basic endurance sessions and two interval sessions)

High GI; Low Carb High Fat; Low GI

High Glycaemic Index OTHER

The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from high glycaemic index carbohydrates per day, the other E-% are fats and proteins.

High GI

LCHF OTHER

The subjects eat ≥ 65 E-% fats and a maximum of 50 g carbohydrates per day.

Low Carb High Fat

Low Glycaemic Index OTHER

The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from low glycaemic index carbohydrates per day, the other E-% are fats and proteins.

Low GI

Eligibility Criteria

• Age: 18 Years - 40 Years
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Male gender
• Age between 18 and 40 years
• Recreational active in leisure time (2-3x/week physical activity)
• Motivation for performance testing and structured training plan
• Interest in different diets
• no acute or chronic illnesses

You may not qualify if:

• Contraindications to physical exercise according to ACSM (American College of Sports Medicine) guidelines
• Age \<18 or \>40 years
• Taking medication that could influence the measurements or that is prohibited in training and/or competition according to the WADA (World Anti-Doping Agency) Code
• Competitive athlete with own training plan
• Experience with intervention diets
• Claustrophobia
• Cardiac pacemaker
• cochlear implant
• subcutaneous injection system
• Stents, metal implants, braces, piercings, tattoos
• Body weight of more than 180 kg or BMI of more than 37 kg/m2

Sponsors & Collaborators

• University of Vienna: lead
• Medical University of Vienna: collaborator

Study Sites (1)

University of Vienna

Vienna, 1070, Austria

Location

Related Publications (1)

• Moitzi AM, Krssak M, Klepochova R, Triska C, Csapo R, Konig D. Effects of a 10-Week Exercise and Nutritional Intervention with Variable Dietary Carbohydrates and Glycaemic Indices on Substrate Metabolism, Glycogen Storage, and Endurance Performance in Men: A Randomized Controlled Trial. Sports Med Open. 2024 Apr 10;10(1):36. doi: 10.1186/s40798-024-00705-9.

  PMID: 38600291 DERIVED

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Univ.-Prof. Dr. med., Head of Subunit Nutrition, Exercise and Health

Study Record Dates

• First Submitted: January 25, 2022
• First Posted: February 16, 2022
• Study Start: January 10, 2022
• Primary Completion: April 23, 2023
• Study Completion: April 23, 2023
• Last Updated: November 27, 2023

Record last verified: 2023-11

Data Sharing

• IPD Sharing: Will not share

Locations

AU (1)