Influence of Low Energy Availability on Skeletal Muscle and Cardiovascular Health

Study Overview
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Brief Summary
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The project is designed as a randomized controlled intervention trial in which 60 young trained (n = 30) (Population A) and recreationally active (n = 30) women (Population B) with regular menstruation are divided into four groups. Population A will receive a low-calorie diet + exercise or an energy balanced diet + exercise over 10 days. Population B will receive a low-calorie diet without exercise, or an energy balanced diet over 10 days. The participants are matched in pairs based on training history and randomized. Before the diet period, the groups will undergo a 6-day control period, during which all participants must take an energy-balanced diet (± training). After the 10 days of the diet intervention period, the groups will receive an energy-balanced diet for 2 days. Before, during, and after the trial period, participants will perform performance tests. In addition, 3 muscle biopsies, 2 adipose biopsies, blood samples, urine samples will be taken during the period, as well as resting metabolic rate, electrocardiogram, flow-mediated vasodilation, and body composition over the trial period. Muscle protein synthesis rate will be measured over the period using stable isotope technique, which includes ingestion of heavy water (D2O) and collection of saliva samples daily (days 0 to 16). The primary measurement parameter is changes in muscle protein synthesis rate.

Official Title
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Influence of Low Energy Availability on Performance and Health in Trained and Recreationally Active Women

Conditions
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Diet; Deficiency, Exercise Intervention

Intervention / Treatment
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* Other: Diet intervention - caloric restriction
* Other: Exercise intervention
* Other: Diet intervention - Energy balance


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age 18-30 BMI 18.5-30 Regular training at least 4 times a week and a maximum of 10 times a week (≥1 times strength training, ≥1 times endurance training / interval training or interval-based sports Exclusion Criteria: • Irregular menstruation within the last 6 months (shorter end 24 days or longer end 35 days cycle) Used hormonal contraception within the last 3 months for the trial. Injuries / pain in the lower body, which prevents participation in intense strength training Medication consumption that may affect protein metabolism and inflammatory parameters. Diabetes Smoking Unstable weight / major weight loss (weight fluctuations of more than 5 kg in the last six months) Do not eat animal products Eating disorder Pregnancy Blood donor within the last month Cannot read or understand Danish

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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Female

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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Energy balance group vs. energy restriction
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Energy balance<br> | Other: Diet intervention - Energy balance<br>* Energy balance is set to 50 kcal / kg fat-free mass<br>|
| Experimental: Energy restriction<br> | Other: Diet intervention - caloric restriction<br>* Energy restriction is set to 25 kcal / kg fat-free mass<br>|
| Active Comparator: Energy balance + exercise<br> | Other: Exercise intervention<br>* Exercise will consist of supervised resistance training, interval training and moderate intensity cycling<br>Other: Diet intervention - Energy balance<br>* Energy balance is set to 50 kcal / kg fat-free mass<br>|
| Experimental: Energy restriction + exercise<br> | Other: Diet intervention - caloric restriction<br>* Energy restriction is set to 25 kcal / kg fat-free mass<br>Other: Exercise intervention<br>* Exercise will consist of supervised resistance training, interval training and moderate intensity cycling<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in muscle protein synthesis |  | 10 days of diet+exercise intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Markers of muscle protein synthesis and breakdown |  | before and after 10 days of diet+exercise intervention | 
| Muscle glycogen and lipid levels |  | before and after 10 days of diet+exercise intervention | 
| Sarcoplasmic reticulum function |  | before and after 10 days of diet+exercise intervention | 
| Macrophage content in adipose tissue |  | before and after 10 days of diet+exercise intervention | 
| Adipocyte area and cell size in adipose tissue |  | before and after 10 days of diet+exercise intervention | 
| Expression of fat oxidative proteins in adipose tissue |  | before and after 10 days of diet+exercise intervention | 
| Maximal isometric and dynamic muscle strength |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Maximal vertical jump height |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Repeated sprint ability |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| 4-minute time trial performance |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Sex hormone levels |  | During the course of the whole intervention period (18 days) | 
| Cortisol Levels |  | During the course of the whole intervention period (18 days) | 
| Inflammatory levels |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Bone turnover levels |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Electrocardiogram - Qt interval |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Flow mediated vasodilation |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Resting metabolic rate |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance | 
| Body composition |  | before and after 10 days of diet+exercise intervention and 2 days of energybalance |