Influence of a Diet With Different Glycaemic Indices and Carbohydrate Content on Substrate Utilization, Energy Storage, and Performance-related Parameters in Endurance-trained Men
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- University of Vienna
- Enrollment
- 65
- Locations
- 1
- Primary Endpoint
- changes in peak oxygen consumption (measured in ml/min/kg)
Study Overview
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.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Basic Science
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 40 Years (Adult)
- Sex
- Male
- Accepts Healthy Volunteers
- Yes
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
Arms & Interventions
Low GI
The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from low glycaemic index carbohydrates per day, the other E-% are fats and proteins.
Intervention: Training intervention (Other)
Low GI
The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from low glycaemic index carbohydrates per day, the other E-% are fats and proteins.
Intervention: Low Glycaemic Index (Other)
High GI
The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from high glycaemic index carbohydrates per day, the other E-% are fats and proteins.
Intervention: Training intervention (Other)
High GI
The subjects eat 55-60 E-% carbohydrates with ≥ 65 % from high glycaemic index carbohydrates per day, the other E-% are fats and proteins.
Intervention: High Glycaemic Index (Other)
Low Carb High Fat
The subjects eat ≥ 65 E-% fats and a maximum of 50 g carbohydrates per day.
Intervention: Training intervention (Other)
Low Carb High Fat
The subjects eat ≥ 65 E-% fats and a maximum of 50 g carbohydrates per day.
Intervention: LCHF (Other)
Outcomes
Primary Outcomes
changes in peak oxygen consumption (measured in ml/min/kg)
Time Frame: Baseline - 10 weeks
VO2peak will be assessed during a graded exercise test on the treadmill.
changes in 5 km time trial (measured in mm:ss)
Time Frame: Baseline - 10 weeks
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.
changes in muscle glycogen content (measured in mmol/l muscle)
Time Frame: Baseline - 10 weeks
Changes in muscle glycogen will be assessed in a thigh muscle using a MR scan.
changes in power at lactate turning point 1 (LTP1) and individual anaerobic threshold (IAS) (measured in km/h)
Time Frame: Baseline - 10 weeks
Changes in power at LTP1 and IAS will be assessed during a graded exercise test on a treadmill.
changes in AUC in lactate in the graded exercise test
Time Frame: Baseline - 10 weeks
Changes in AUS in lactate will be assessed during a graded exercise test on a treadmill.
Secondary Outcomes
- 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 body weight (measured in kg)(Baseline - 5 weeks - 10 weeks)
- changes in skeletal muscle mass (measured in kg)(Baseline - 5 weeks - 10 weeks)
- changes in rated perceived exhaustion (RPE) in 5 km time trial(Baseline - 10 weeks)
- changes in body mass index(Baseline - 5 weeks - 10 weeks)
- changes in body water (measured in l)(Baseline - 5 weeks - 10 weeks)
- completion time of a half marathon performance (measured in hh:mm:ss)(after 10 weeks)
- changes in cholesterin and cholesterin subunits (measured in mg/dl)(Baseline - 10 weeks)
Investigators
Daniel König
Univ.-Prof. Dr. med., Head of Subunit Nutrition, Exercise and Health
University of Vienna