Clinical trial NCT05241730: Glycaemic Index and Substrate Metabolism
Official title: Influence of a Diet With Different Glycaemic Indices and Carbohydrate Content on Substrate Utilization, Energy Storage, and Performance-related Parameters in Endurance-trained Men
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Substrate Metabolism During Exercise
Lead sponsor: University of Vienna
Sponsor class: OTHER
Collaborators: name: Medical University of Vienna
First posted: 2022-02-16
Enrollment: 65
Sex: MALE
Minimum age (years): 18
Maximum age (years): 40
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

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.


Eligibility criteria: Inclusion Criteria:

* 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

Exclusion Criteria:

* 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

MRI-specific exclusion criteria:

* 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

Primary outcomes:
measure: changes in peak oxygen consumption (measured in ml/min/kg)
timeFrame: Baseline - 10 weeks
measure: changes in 5 km time trial (measured in mm:ss)
timeFrame: Baseline - 10 weeks
measure: changes in muscle glycogen content (measured in mmol/l muscle)
timeFrame: Baseline - 10 weeks
measure: changes in power at lactate turning point 1 (LTP1) and individual anaerobic threshold (IAS) (measured in km/h)
timeFrame: Baseline - 10 weeks
measure: changes in AUC in lactate in the graded exercise test
timeFrame: Baseline - 10 weeks
Secondary outcomes:
measure: changes in fat free mass (measured in kg)
timeFrame: Baseline - 5 weeks - 10 weeks
measure: changes in fat mass (measured in kg)
timeFrame: Baseline - 5 weeks - 10 weeks
measure: changes in skeletal muscle mass (measured in kg)
timeFrame: Baseline - 5 weeks - 10 weeks
measure: changes in body water (measured in l)
timeFrame: Baseline - 5 weeks - 10 weeks
measure: changes in body weight (measured in kg)
timeFrame: Baseline - 5 weeks - 10 weeks
measure: changes in body mass index
timeFrame: Baseline - 5 weeks - 10 weeks
measure: completion time of a half marathon performance (measured in hh:mm:ss)
timeFrame: after 10 weeks
measure: changes in cholesterin and cholesterin subunits (measured in mg/dl)
timeFrame: Baseline - 10 weeks
measure: changes in rated perceived exhaustion (RPE) in 5 km time trial
timeFrame: Baseline - 10 weeks
Other outcomes:
Locations:
city: Vienna
country: Austria
facility: University of Vienna
Study officials:
References: