Athlete AssessmentNon applicableNCT07878052
Resting Metabolic Rate in Bodybuilders Using Performance-Enhancing Drugs
An observational study of Athlete Assessment and Body Composition, run by Atlantica - Instituto Universitario at 1 site in Portugal.
Trial summary
Bodybuilders present unique body composition profiles, characterized by high fat-free mass and very low levels of body fat. In addition, many competitive and non-competitive athletes use anabolic-androgenic steroids (AAS) and fat-burning pharmacological agents to enhance muscle mass and accelerate fat loss. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Athlete Assessment, Body Composition
- How many people
- 62 participants
- Where
- 1 sitePortugal
- Study dates
- 25 Aug 2026to 18 Oct 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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult competitive or non-competitive bodybuilding and resistance-trained athletes of both sexes, aged 18 years or older, who have engaged in structured resistance training for at least 1 year (with a minimum of 3 training sessions per week) aimed at muscle hypertrophy and body composition optimization. All participants report active and ongoing use of anabolic-androgenic steroids (AAS) and/or fat-burning pharmacological agents for at least 6 consecutive months prior to study enrollment. Participants are recruited via sports clubs, gym facilities, bodybuilding networks, coaches, and digital community platforms.
Who may be able to join
- Male or female individuals aged 18 years or older;
- Current participation in bodybuilding or/and resistance training;
- Minimum resistance training experience of at least 1 year;
- Current self-reported use of AFBPA for at least 6 consecutive months prior to assessment;
- Agreement to maintain usual training and dietary habits prior to assessment;
- Ability to provide informed consent.
Who cannot join
- Present any diagnosed metabolic, cardiovascular, renal, or endocrine disease that may significantly affect RMR;
- Present acute illness or injury at the time of assessment, affecting energy requirements.
- Fail to comply with pre-assessment instructions, including fasting requirements or abstention from exercise, alcohol, or caffeine;
- Present incomplete assessment data.
- Unable to attend the assessments at the laboratory.
- Failure to provide informed consent.
Trial locations and contacts
1 site in 1 country.
Portugal1 site
Atlântica - Instituto Universitário
Barcarena, Lisbon District, 2730-036
About this study
Official title: Development of a Predictive Equation for Resting Metabolic Rate in Bodybuilders Using Anabolic and Fat Burning Pharmacological Agents
Bodybuilders present unique body composition profiles, characterized by high fat-free mass and very low levels of body fat. In addition, many competitive and non-competitive athletes use anabolic-androgenic steroids (AAS) and fat-burning pharmacological agents to enhance muscle mass and accelerate fat loss.
Accurate determination of energy requirements is critical for performance and nutritional planning in this population. Resting metabolic rate (RMR) represents the largest component of daily energy expenditure. While indirect calorimetry is considered the reference method to assess RMR, it is expensive and not widely accessible, making predictive mathematical equations the primary tool used in sports and clinical settings. However, widely used equations (such as Harris-Benedict, Mifflin-St Jeor, and Cunningham) were developed in general or non-athletic populations and may systematically underestimate energy requirements in bodybuilders using performance-enhancing substances.
The primary aim of this cross-sectional study is to measure resting metabolic rate via indirect calorimetry and body composition via dual-energy X-ray absorptiometry (DXA) in adult bodybuilders using anabolic and fat-burning agents. The ultimate goal is to develop and validate a population-specific predictive equation for RMR and compare its accuracy against established predictive formulas.
Read the detailed description
This is a cross-sectional, quantitative observational study conducted at the Bettery® LifeLab, Atlântica - Instituto Universitário (Barcarena, Portugal). The study aims to evaluate bodybuilders of both sexes aged 18 years or older with at least 1 year of consistent resistance training experience and current self-reported use of anabolic-androgenic steroids and/or fat-burning pharmacological agents for at least 6 consecutive months.
Participants complete an online screening and demographic questionnaire assessing training history, competition background, and detailed substance use patterns, including compounds, dosages, administration routes, and duration.
Eligible participants attend a single laboratory testing session lasting approximately 90 minutes under strictly standardized morning conditions:
Fasting for at least 8 to 10 hours; Abstention from moderate-to-vigorous physical activity, alcohol, and caffeine for at least 24 hours prior to evaluation; Maintenance of normal hydration and avoidance of acute diuretic use.
Data collection procedures include:
Resting Metabolic Rate (RMR): Measured via indirect calorimetry using an open-circuit ventilated canopy system (Quark, Cosmed, Italy) in a quiet, thermoneutral room after supine rest. Gas exchange is monitored, and RMR is determined from steady-state respiratory gas parameters.
Body Composition: Evaluated using whole-body Dual-energy X-ray Absorptiometry (DXA; Hologic, USA) to quantify fat-free mass, fat mass, and bone mineral content.
Bioelectrical Impedance Analysis (BIA): Assessed using a phase-sensitive analyzer (BIA-101, RJL/Akern Systems) to quantify body water compartments, such as total body water, intracellular water, and extracellular water.
Anthropometry: Body weight, height, circumferences, and skinfold thickness measured according to International Society for the Advancement of Kinanthropometry (ISAK) standards.
Statistical Analysis:
Multiple linear regression modeling will be conducted to develop a new predictive RMR equation using body composition parameters (notably DXA-derived fat-free mass), anthropometrics, and pharmacological variables as predictors. Internal model stability and generalizability will be evaluated using leave-one-out cross-validation (LOOCV). Agreement between measured RMR and values derived from both the newly developed equation and existing standard predictive formulas will be examined using paired statistical tests and Bland-Altman plots.
- Conditions
- Athlete Assessment, Body Composition
- Being tested
- No Intervention: Observational Cohort
- Keywords
- bodybuilding, athlete, body composition, resting energy rate, resting energy expenditure, indirect calorimetry, Anabolic androgenic steroids, predictive equation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
No Intervention: Observational CohortDiagnostic test
Observational study with no administered clinical intervention. The study involves a one-time laboratory evaluation assessing resting metabolic rate through indirect calorimetry, body composition via DXA and BIA, anthropometry, and self-reported background regarding training and current use of anabolic and fat-burning pharmacological agents.
What is being measured
The primary outcome is the main question the study is designed to answer.
Resting Metabolic Rate
Measured via indirect calorimetry using an open-circuit ventilated canopy system (Quark, Cosmed, Italy). Assessment is performed in a quiet, thermoneutral room after supine rest, following an overnight fast of 8-10 hours and at least 24 hours of abstention from exercise, caffeine, and alcohol. The average RMR will be calculated from the 5-minute steady-state period showing the lowest coefficient of variation.
Measured: Baseline
Secondary outcomes (5)
Fat-Free Mass (FFM)
Assessment of whole-body fat-free mass (kg) using a whole-body DXA scanner (Hologic, USA) following standardized positioning protocols.
Measured: Baseline
Fat Mass (FM)
Assessment of whole-body fat mass (kg) using a whole-body DXA scanner (Hologic, USA) following standardized positioning protocols.
Measured: Baseline
Total Body Water
Assessment of total body water (liters), intracellular water (liters), and extracellular water (liters) using a phase-sensitive bioimpedance device (BIA-101, RJL/Akern Systems).
Measured: Baseline
Sum of 7 Skinfolds
Measurement of subcutaneous fat thickness (sum of 7 skinfolds in millimeters using a Harpenden caliper) assessed by a certified anthropometrist according to International Society for the Advancement of Kinanthropometry (ISAK) guidelines.
Measured: Baseline
Body Circumferences
Measurement and body circumferences (waist, hip, arm, thigh, calf in centimeters) assessed by a certified anthropometrist according to International Society for the Advancement of Kinanthropometry (ISAK) guidelines.
Measured: Baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Oct 2026
- Study start25 Aug 2026
- Primary completion18 Oct 2026 (estimated)
- Study completion18 Oct 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Athlete AssessmentStudies 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
- Cross-sectional
- Enrolment
- 62 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
- NCT07878052
- Sponsor's protocol ID
- ATLANTICA-CE-14/2026
- Acronym
- Non applicable
- Status last verified
- Oct 2026
- First submitted
- 7 Oct 2026
- Last updated
- 16 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No