Impact Loading Effect on Bone Biomarkers in Female Runners

Study Overview
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Brief Summary
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This study is a randomized, cross-over intervention study that will evaluate the effect of brief, high-impact loading exercises on biomarkers of bone metabolism in energy-restricted, eumenorrheic female runners. Volunteers will complete two, 5-day experimental conditions in a randomized order separated by one menstrual cycle (approximately 3 weeks). Experimental conditions will include a dietary intervention of energy intake equal to 30 kcal/kg of fat-free mass/d using controlled diets and an exercise intervention of daily treadmill running with or without an additional 50 impact loading exercises.

Detailed Description
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Many long-distance runners struggle to consume enough calories each day to match the number of calories they are burning during exercise and as part of daily living. Undereating for long periods of time is a serious concern because it can have negative effects on general health and sports performance. One of these long-term consequences is related to bone health. With undereating, bone can start to be broken down faster than it can be rebuilt. Even though it can take months, and even years, for bone to be seriously affected, this may lead to weak and brittle bones later in life, if it is left untreated. Typically, athletes are recommended to increase the number of calories they eat to prevent negative health concerns. However, not all athletes may be willing or able to increase their calories based on their performance goals, nutrition knowledge, or concerns with food security. This means that alternative strategies need to be investigated to counteract the negative effects of undereating on bone health. This study proposes to evaluate the effect of adding short bouts of high-impact jumping exercises to typical endurance training to promote healthy bone metabolism. This will specifically involve completing two phases of a supervised treadmill run and consuming a reduced-calorie diet (provided by the research team) on 5 consecutive days. In addition, one of the phases will include performing 5 sets of 10 jumping exercises on 5 consecutive days in addition to the treadmill run. Results of the study will serve as an important first step in helping exercise and medical professionals understand more about how to protect and manage the bone health of female long-distance runners.

Official Title
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The Effect of Impact Loading on Bone Biomarkers in Energy-Restricted Female Runners

Conditions
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Relative Energy Deficiency in Sport

Intervention / Treatment
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* Behavioral: Impact Load Exercises
* Behavioral: No Impact Load Exercises


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Females runners with regular menstrual cycles, not using contraceptives Body Mass Index between 18.5-25.0 kg/m2 Weight stable (+/- 2 kg) for 6 months Running volume of ≥30 miles per week, frequency of at least 5 days per week VO2max of ≥45 ml/kg/min Willing to consume provided meals and snacks Exclusion Criteria: Low Energy Availability in Females Questionnaire (LEAF-Q) score ≥8 Menstrual disturbances measured by progesterone and self-report Using contraceptives (oral contraceptives, injections, intrauterine device, etc.) Low Bone Mineral Density (z-score < -1) Routine engagement in mechanical loading exercises History of fracture in the previous 6 months Recent recovery (within the last 12 months) or still in recovery after eating disorder diagnosis Medication use that could affect bone metabolism (e.g., corticosteroids, anticonvulsants, heparin, gonadotropin-releasing hormone agonists) Pregnancy or lactation Abnormal thyroid-stimulating hormone levels

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 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: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Randomized crossover study design
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Endurance and Jumping Exercises<br>5 days of endurance treadmill running and 5 sets of 10 jumping exercises | Behavioral: Impact Load Exercises<br>* Participants will complete 50-65 min running protocol on treadmill and 5 sets of 10 jumping exercises for 5 consecutive days. Participants will also be provided all meals and snacks to induce a energy-restricted state for the 5-day period.<br>|
| Active Comparator: Endurance Exercise Only<br>5 days of endurance treadmill running | Behavioral: No Impact Load Exercises<br>* Participants will complete only a 50-65 min running protocol on treadmill for 5 consecutive days. Participants will also be provided all meals and snacks to induce a energy-restricted state for the 5-day period.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Bone Remodeling Biomarker - N-terminal propeptide of type 1 procollagen | Levels of N-terminal propeptide of type 1 procollagen will be measured from fasted blood samples drawn before and after each 5-day intervention. The radioimmunoassays (RIA) will be performed on all samples once the study is completed. | 10-minute blood draw in laboratory; samples assessed on intervention day 0 and day 6 | 
| Change in Bone Remodeling Biomarker - C-terminal telopeptide of type 1 collagen | Levels of C-terminal telopeptide of type 1 collagen will be measured from fasted blood samples drawn before and after each 5-day intervention. The enzyme-linked immunosorbent assays (ELISA) will be performed on all samples once the study is completed. | 10-minute blood draw in laboratory; samples assessed on intervention day 0 and day 6 | 
| Change in Blood Metabolic Marker - Parathyroid hormone | Levels of parathyroid hormone will be measured from fasted blood samples drawn before and after each 5-day intervention. These blood samples will be sent out to a local lab service at each timepoint. | 10-minute blood draw in laboratory; samples assessed on intervention day 0 and day 6 | 
| Change in Blood Metabolic Marker - Insulin-like Growth Factor-1 | Levels of insulin-like growth factor-1 collagen will be measured from fasted blood samples drawn before and after each 5-day intervention. The ELISAs will be performed on all samples once the study is completed. | 10-minute blood draw in laboratory; samples assessed on intervention day 0 and day 6 | 
| Change in 24-hour Glucose Patterns | Blood glucose levels will be measured every 15 minutes during each 5-day intervention period using a continuous glucose monitor sensor secured to the arm. The results will provide a descriptive profile of daily glucose patterns while participants are in an energy-restricted state and exercising, either only running on a treadmill daily or running on a treadmill and completing 5 sets of 10 jumping exercises daily. | Continuous collection for 5 consecutive days during each intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Running Economy | Running economy will be measured by collecting and analyzing inspired and expired air continuously during 3 4-minute progressive stages while running on a treadmill. The last two minutes of oxygen consumption and carbon dioxide production data will be used to determine metabolic economy (ml oxygen consumed per kg body weight per minute relative to the set work performed). Running economy will be evaluated in the laboratory at baseline and on the 5th day of each intervention period, three tests total. | 12-minute measurement in laboratory | 
| Change in Body Weight | Body weight will be measured on a digital scale to the closest 0.1 kg. Body weight will be measured the day before, each of the 5 days during, and the day after each intervention. | 1-minute measurement in laboratory | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Bone metabolism, Endurance exercise, Low energy availability, Jump training