Physical FitnessNCT07873840
Physiological and Performance Characteristics of HYROX Athletes
An observational study of Physical Fitness and Athletic Performance, run by Atlantica - Instituto Universitario at 1 site in Portugal.
Trial summary
HYROX© is a fast-growing fitness competition that combines long-distance running with functional exercises such as sled pushes, rowing, and weightlifting movements. Although the sport has attracted more than a million participants worldwide, little scientific research has looked at the health, body composition, and… Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Physical Fitness, Athletic Performance, Body Composition
- How many people
- 66 participants
- Where
- 1 sitePortugal
- Study dates
- 26 Aug 2026to 30 Nov 2026
- How long will I take part?
- 1 Day
- Phase
- Observational
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult men and women who train for or compete in HYROX©, a hybrid fitness competition combining distance running with functional exercise stations. Participants will be recruited on a voluntary basis via social media advertising and during an official HYROX© competition in Lisbon, Portugal, and classified into two groups: elite athletes (top 15% finishers in their division and age group) and recreational/amateur athletes (>6 months of HYROX© training experience).
Who may be able to join
- Age 18-65 years (both sexes)
- Body mass index (BMI) < 30 kg/m^2
- Willing and able to comply with study procedures
- Able to provide written informed consent
- Elite Athletes group: completed at least 1 official HYROX© event and ranked within the top 15% of their respective category and age group
- Recreational/Amateur Athletes group: more than 6 months of HYROX© training experience, with prior participation in, or expressed willingness to participate in, an official HYROX© competition or a similar hybrid fitness event (e.g., HYROX© simulation or "Hybrid Day")
Who cannot join
- Any medical conditions or health issues that contraindicate exercise
- Failure to meet the minimum requirements for HYROX© participation
- Inability to attend study visits at Atlântica - Instituto Universitário
- Other investigator-determined criteria rendering the participant unsuitable for the study
Trial locations and contacts
1 site in 1 country.
Portugal1 site
Atlântica - Instituto Universitário
Barcarena, Lisbon District, 2730-036
About this study
Official title: Physiological and Performance Characteristics of HYROX Athletes: A Comparison Among Competitive Levels
HYROX© is a fast-growing fitness competition that combines long-distance running with functional exercises such as sled pushes, rowing, and weightlifting movements. Although the sport has attracted more than a million participants worldwide, little scientific research has looked at the health, body composition, and physical fitness of the people who compete in it.
This study will compare body composition, fitness, and performance between two groups of HYROX© participants: those competing at a recreational (amateur) level and those competing at an elite level.
Read more
Adult volunteers (ages 18-65) who train for or compete in HYROX© will be invited to take part. Researchers will measure body composition using a whole-body scan (DXA), skinfold thickness, and muscle ultrasound; resting metabolism; daily physical activity (using a wearable activity tracker); muscle strength and jumping ability; aerobic fitness (a treadmill running test); and short-burst power (a cycling test). Participants will also complete questionnaires about their motivation to exercise, their diet, and their use of dietary supplements, and will wear a heart rate monitor and activity tracker during an official HYROX© competition.
The results will help researchers, coaches, and athletes better understand how the bodies and training needs of HYROX© athletes differ by competitive level, which may support the development of safer and more effective training programs.
Read the detailed description
HYROX© is a standardized hybrid fitness competition, first held in 2017, combining 8 x 1 km runs with high-intensity functional stations (SkiErg, sled push/pull, burpee broad jumps, rowing, farmers carry, sandbag lunges, and wall balls) performed with minimal recovery between efforts. Despite its rapid global growth, peer-reviewed research characterizing the physiological, anthropometric, and performance profiles of HYROX© athletes remains scarce, and no prior study has compared these characteristics across competitive levels within this modality.
This is a single-center, cross-sectional study conducted at the Bettery® LifeLab, Atlântica - Instituto Universitário (Barcarena, Portugal), with an additional field-based assessment during an official HYROX© competition in Lisbon, Portugal. Participants will be classified as elite or recreational/amateur based on their relative finishing rank in official HYROX© events (top 15% of their division and age group for the elite group) and on training/competition history for the recreational group.
Laboratory assessments include: (1) body composition, evaluated through anthropometry (weight, height, 7-site skinfolds), dual-energy X-ray absorptiometry (DXA), and B-mode ultrasonography of the rectus femoris; (2) energy expenditure components, including resting metabolic rate by indirect calorimetry and habitual physical activity by accelerometry; (3) neuromuscular and performance tests, including handgrip strength, countermovement jump height, an incremental treadmill test to determine VO2max and maximal aerobic speed, and a supramaximal Wingate cycling test for anaerobic power; and (4) questionnaires assessing exercise motivation (BREQ-3), dietary intake (three-day food records reviewed by a registered dietitian), and dietary supplement use.
During an official HYROX© competition, participants will be equipped with their own heart rate monitors and with accelerometers to characterize external and internal load, finishing time, and, when available, station split times, together with pre- and during-event nutritional intake.
Based on an a priori sample size calculation (large effect size, d = 0.8, for the primary comparison of VO2peak between groups; alpha = 0.05; power = 80%), a target of 66 participants (33 per group) will be recruited to account for an anticipated 20% dropout rate. This characterization is intended to inform the development of training and preparation strategies tailored to athletes' competitive level within the HYROX© modality.
- Conditions
- Physical Fitness, Athletic Performance, Body Composition
- Being tested
- No Intervention: Observational Cohort
- Keywords
- HYROX, hybrid fitness, functional fitness training, athletic performance, body composition, VO2max, cardiorespiratory fitness, muscle strength, elite athletes, recreational athletes, cross-sectional study
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
No Intervention: Observational CohortOther
No intervention
What is being measured
The primary outcome is the main question the study is designed to answer.
Maximal Oxygen Uptake (VO2peak)
Peak oxygen consumption (mL·kg-¹·min-¹), measured via breath-by-breath gas analysis during an incremental treadmill test to volitional exhaustion; compared between elite and recreational HYROX© athletes.
Measured: Baseline (single laboratory assessment)
Secondary outcomes (6)
Body Composition (Fat Mass and Fat-Free Mass)
Total and regional fat mass and fat-free mass will be assessed using dual energy X-ray absorptiometry (DXA) (Hologic Horizon Wi, Waltham, USA). A whole-body scan will be performed according to the manufacter's guidelines. The attenuation of X-rays pulsed between 70 and 140 kV synchronously with the line frequency for each pixel of the scanned image will be measured.
Measured: Baseline
Bone Mineral Density
Bone Mineral Density will be assessed using dual energy X-ray absorptiometry (DXA) (Hologic Horizon Wi, Waltham, USA). A whole-body scan will be performed according to the manufacter's guidelines (Park et al., 2002). The attenuation of X-rays pulsed between 70 and 140 kV synchronously with the line frequency for each pixel of the scanned image will be measured.
Measured: Baseline
Resting Metabolic Rate
Resting Metabolic Rate (RMR) will be assessed using indirect calorimetry with a ventilated canopy open-circuit system (Quark, Cosmed, Italy). Participants will be instructed to arrive in a fasted state (at least 10 hours) and to refrain from exercise for 24 hours prior to their evaluation. At arrival, they will rest in a supine position in a quiet, temperature and humidity-controlled room with a blanket provided as an option. The equipment will be calibrated daily in accordance with the manufacturer's guidelines. Data will be collected for at least 15 minutes, with the initial 5 minutes discarded, following standard protocol. The average RMR (kcal/day) will be calculated based on the 5-minute period showing the lowest coefficient of variation.
Measured: Baseline
Handgrip Strength
Maximal isometric handgrip strength of the dominant hand will be determined using a Jamar®hydraulic hand dynamometer (Jamar, Sammons Preston, Inc, Bolingbrook, IL). The participants will be tested in a standing position with an elbow in full extension. The participant will be asked to squeeze the dynamometer at maximal effort for three trials, with a 30-s break between each trial. The best of the three trials will be considered for data analysis.
Measured: Baseline
Countermovement Jump Height
Jump height will be assessed by a countermovement jump which was performed on a contact-mat jump system controlled by an open-source hardware and software model (Chronojump, Barcelona, Spain). The best attempt out of three will be considered for analysis.
Measured: Baseline
HYROX© Competition Finishing Time
Total race time and, when available, station split times
Measured: Baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Oct 2026
- Study start26 Aug 2026
- Primary completion30 Nov 2026 (estimated)
- Study completion30 Nov 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Physical FitnessStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 66 participants (estimated)
- Target duration
- 1 Day
Sponsor and investigators
- Lead sponsor
- Atlantica - Instituto Universitario
- Sponsor type
- University, hospital or other
- Collaborators
- Bettery S.A.
- Responsible party
- Principal investigator, Catarina L. Nunes, Atlantica - Instituto Universitario
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07873840
- Sponsor's protocol ID
- ATLANTICA-CE-04/2026
- Status last verified
- Oct 2026
- First submitted
- 25 Sep 2026
- Last updated
- 14 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided