The Effects of Combined Energy and Carbohydrate Restriction on Exercise Capacity
- Conditions
- Overweight and Obesity
- Interventions
- Other: Calorie-restriction with low carbohydrateOther: Calorie-restriction with moderate carbohydrate
- Registration Number
- NCT06381908
- Lead Sponsor
- University of Aarhus
- Brief Summary
The effect of calorie restriction combined with low or moderate carbohydrate availability on exercise capacity, metabolism and metabolic health indicators will be measured in a randomized parallel group design. Forty overweight (BMI 25-30) and relatively inactive women (20-35 of age) will be included. These will be randomized into one of two experimental groups both receiving a calorie-restricted diet (-1000 kcal) combined with either low carbohydrate availability or moderate carbohydrate availability across a 10 day period. Laboratory-based physical capacity tests and blood and muscle sampling will be performed before and after the intervention. In addition, an additional follow-up test day will be performed after continuing the diet for another 48 h and then standardizing the pre-testing carbohydrate availability before repeating the tests of physical capacity.
- Detailed Description
Overweight (BMI 25-30), but healthy premenopausal women aged 20-35 years (n=40) will be included in the trial, which is structured as a randomized, parallel group design where participants are randomized to either consume a hypocaloric diet (-1000 kcal) with concurrent carbohydrate restriction (low carbohydrate, L-CHO, n=20) or a similar hypocaloric diet with moderate carbohydrate availability (moderate carbohydrate, M-CHO, n=20). The trial will be single-blinded since it might be transparent to the participants which diet they are consuming, whereas the test personnel collecting and processing test results will be blinded to diet allocation. Diet handling will be managed by specific individuals in the research group who do not partake in executing the physical capacity tests. Additionally, the direction of the trial's primary hypothesis will not be disclosed to the participants to avoid creating preconceived expectations about the effects.
After an initial screening interview and two familiarization visits, participants will complete the intervention period consisting of 10 days with the allocated diet manipulation with preceding and subsequent test days with a series of tests. The tests before and after each test period include measurements of the participants' physical capacity level and energy metabolism in the laboratory as well as blood and muscle sampling. In addition, resting metabolism and body composition will be measured. During each test period, participants' habitual activity level will be monitored with an accelerometer attached to the wrist (Axivity). There will also be monitoring of the activity level with an accelerometer in a 7-day cycle before the start of the trial as a baseline measurement.
Similarly, a glucose monitor will be placed on the upper arm for continuous glucose readings via a Freestyle Libre2 sensor during the trial period.
Recruitment & Eligibility
- Status
- RECRUITING
- Sex
- Female
- Target Recruitment
- 40
- Age: 20-35
- BMI: 25-30
- Irregular menstruation within the last 6 months (shorter end 24 days or longer end 35 days cycle)
- Injuries / pain in the lower body, which prevents participation in intense cycling
- Medication consumption that may affect primary outcome measures.
- Smoking
- Pregnancy
- Systematic physical activity more than 2 hours per week
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Low-carbohydrate calorie-restriction Calorie-restriction with low carbohydrate Minimum of 3 g carbohydrate/kg body weight/day and a \~1000 kcal calorie restriction Moderate-carbohydrate calorie-restriction Calorie-restriction with moderate carbohydrate Maximum of 1 g carbohydrate/kg body weight/day and a \~1000 kcal calorie restriction
- Primary Outcome Measures
Name Time Method Time to exhaustion Pre, post (day 11 of the intervention) and follow-up (day 2 after the post measurement) Time to exhaustion at 85% VO2max
Sprint performance Pre, post (day 11 of the intervention) and follow-up (day 2 after the post measurement) Peak and mean 15-s sprint performance
Muscle glycogen levels Pre and post (day 11 of the intervention) Muscle glycogen levels obtained from biopsy sample
Exercise tolerance Pre, post (day 11 of the intervention) and follow-up (day 2 after the post measurement) Ratings of perceived exertion (Borg scale) during standardized-intensity exercise from 6 (lowest exertion) to 20 (highest exertion)
- Secondary Outcome Measures
Name Time Method Maximal fat oxidation capacity Pre, post (day 11 of the intervention) and follow-up (day 2 after the post measurement) Maximal fat oxidation measured in the laboratory
Muscle metabolic enzyme activity Pre and post (day 11 of the intervention) Activity of key enzymes involved in carbohydrate and fat metabolism
Continuous glucose levels 14 days from the day before the intervention, throughout the intervention (days 1 to 11) and 2 days after the intervention (follow-up) Glucose levels measured continuously across the trial + during exercise tests
Fasting blood glucose and insulin Pre and post (day 11 of the intervention) Insulin sensitivity (Homa 2 IR)
Long-term glycemic control (HbAc1) Pre and post (day 11 of the intervention) Measured from fasting blood
Physical activity level During the intervention (days 1 to 11 of the intervention) Measured with accelerometer during the intervention
Blood lipid profile Pre and post (day 11 of the intervention) High-density lipoproteins, low-density lipoproteins, very-low-density lipoproteins, cholesterol, free fatty acids and triglycerides
Trial Locations
- Locations (1)
Section for Sport Science, Department of Public Health, Aarhus University
🇩🇰Aarhus C, Denmark