Event-Specific Adaptations to CrossFit and Running-Based HIIT in Elite Distance Runners at Modera… (NCT07675577) | Clinical Trial Compass
CompletedNot Applicable
Event-Specific Adaptations to CrossFit and Running-Based HIIT in Elite Distance Runners at Moderate Altitude
Iran36 participantsStarted 2021-09-01
Plain-language summary
The goal of this clinical trial is to compare the effects of two high-intensity training programs on physical performance and physiological adaptations in elite male middle- and long-distance runners aged 25 to 35 years who live and train at moderate altitude (approximately 1,400 meters above sea level).
The main questions it aims to answer are:
Does running-based high-intensity interval training improve aerobic fitness and race performance in elite distance runners? Does CrossFit training improve muscle strength, power, and physiological markers in elite distance runners? Researchers will compare running-based high-intensity interval training (HIIT) with CrossFit training to determine how each program affects aerobic capacity, strength, running performance, and selected blood markers.
Participants will:
Be randomly assigned to either a running-based HIIT program or a CrossFit training program Train five days per week for six weeks under supervision Complete exercise testing before and after the training period, including treadmill fitness testing and timed running trials Provide blood samples before and after the intervention to measure selected physiological markers
Who can participate
Age range
25 Years – 35 Years
Sex
MALE
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion Criteria:
* Nationally ranked elite male middle- or long-distance runner
* Ranked within the national top 10 in their respective primary competitive event
* Aged between 25 and 35 years
* Minimum of six months of structured high-intensity training prior to enrollment, defined as more than five supervised sessions per week
* Living and training year-round at moderate altitude (approximately 1,400 m) in Zahedan, Iran
* Competing in one of the following event categories: middle-distance (800-3,000 m) or long-distance (≥5,000 m)
* Willing and able to provide written informed consent prior to participation
* Able to commit to five supervised training sessions per week for the full six-week intervention period
Exclusion Criteria:
* Musculoskeletal injury within the three months preceding enrollment
* Current or recent use of performance-enhancing substances
* Use of new nutritional supplements during the study period
* Any medical condition or physical limitation that could interfere with safe participation in high-intensity exercise training
* Inability to complete the required number of training sessions due to scheduling conflicts or other commitments
* Incomplete study application or failure to meet all inclusion criteria
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Lactate Threshold (LT)
Timeframe: Baseline and immediately after 6 weeks of intervention
2
Maximal Oxygen Uptake (VO₂max)
Timeframe: Baseline and immediately after 6 weeks of intervention
3
1,500-Meter Time Trial Performance
Timeframe: Baseline and immediately after 6 weeks of intervention
4
5,000-Meter Time Trial Performance
Timeframe: Baseline and immediately after 6 weeks of intervention