Iron DeficiencyEarly Phase 1MyoIRONNCT07084298
Effects of Iron Supplementation on Skeletal Muscle Properties in Females With Suboptimal Iron Storage
A Early Phase 1 study testing Oral iron supplement in people with Iron Deficiency, run by University of Calgary at 1 site in Canada.
Trial summary
The goal of this clinical trial is to learn whether oral iron supplementation will increase skeletal muscle iron storage and its effects on exercise capacity in females with suboptimal iron status. The study will include healthy females, ages 18-40, who either have suboptimal or optimal iron stores. Read more about this study
- Who is it for?
- Ages 18 to 40 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Iron Deficiency
- What is being tested?
- Oral iron supplement
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 36 participants
- Where
- 1 siteCanada
- Study dates
- Aug 2025to Jun 2026
- Phase
- Early Phase 1
- Are there results?
- Not yet: the study is under way
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 40 years
- Women only
- Healthy volunteers accepted
- Adult
Who may be able to join
- biologically female
- between the ages of 18-40 years of age at the time of enrolment
- plasma ferritin ≤ 50 µg/ L (RCT) or >50 µg/L (controls)
- complete Get Active Questionnaire (GAQ: Canadian Society for Exercise Physiology) without contraindication
Who cannot join
- have a body mass index (BMI) > 30 kg/m2
- taking medications that have been shown to affect cardiovascular, respiratory, or metabolic responses to exercise (e.g., β-blockers, anti-inflammatories, anti-coagulants, insulin, etc.)
- hemoglobin ≤ 120 g/L (anemia cut-off for women)
- have known health problems or contraindications that prohibit exercise, including renal or gastrointestinal disorders, metabolic disease, heart disease, vascular disease, arthritis, diabetes, respiratory disease, uncontrolled blood pressure, dizziness, thyroid problems, or any other health conditions that are being treated and deemed likely to confound the results
- dieting for weight loss or following a low-carbohydrate diet (known to affect iron homeostasis)
- history of smoking or using tobacco products
Show all 18Show fewer
- consuming excessive amounts of alcohol (>21 units/week)
- supplementing with iron (>5mg/day) in the last 3 months
- any blood donation or surgeries in the past 3 months
- antibiotic use within the previous four weeks before study enrolment
- current laxative use
- known history of thalassemia
- known bleeding disorder
- chronic use of nonsteroidal anti-inflammatory drugs
- Currently/last 3 months taking prescription medications that are known to affect iron absorption (i.e. Antacids/PPIs (e.g., omeprazole), H2 Blockers (e.g., ranitidine), Tetracycline Antibiotics (e.g., doxycycline), Quinolone Antibiotics (e.g., ciprofloxacin), Cholestyramine, Colchicine, Methyldopa).
- currently pregnant or plans to get pregnant within the duration of the study, and
- do not understand English
- Participants will be removed from the study if they begin taking any other forms of supplemental iron or choose to donate blood
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site
University of Calgary
Calgary, Alberta, T2N 1N4
Martin J MacInnis, (403) 210 - 6554, martin.macinnis@ucalgary.ca
Martin J MacInnis
About this study
Official title: Effects of 12 Weeks of Oral Iron Supplementation on Skeletal Muscle Iron Content, Mitochondrial Function, and Indices of Aerobic Fitness in Healthy Females With Suboptimal Iron Stores
The goal of this clinical trial is to learn whether oral iron supplementation will increase skeletal muscle iron storage and its effects on exercise capacity in females with suboptimal iron status. The study will include healthy females, ages 18-40, who either have suboptimal or optimal iron stores.
The main questions it aims to answer are:
Read more
- Does iron supplementation increase skeletal muscle iron storage and alter the expression of iron-related and mitochondrial proteins?
- Does iron supplementation improve single-leg exercise performance?
- Is serum ferritin correlated with the abundance of iron-related proteins in skeletal muscle?
Researchers will compare outcomes from females with suboptimal iron status who receive oral iron supplementation to those who receive a placebo to see if supplementation improves muscle iron storage, protein expression, and exercise performance. Additionally, a non-intervention control group with optimal iron status will be included to assess baseline differences.
Participants will:
- Be randomly assigned to receive 150 mg elemental iron or placebo (maltodextrin) every other day for 12 weeks
Complete pre- and post-supplementation testing, including:
- Blood draws to assess iron status
- Skeletal muscle biopsies to analyze protein content
- Whole-body and single-leg exercise tests to assess performance
- Controls will undergo baseline-only testing to compare physiological and biochemical markers
Read the detailed description
This study is intended to evaluate the effects of oral iron supplementation on muscle iron levels in females with suboptimal iron status. The design involves both a randomized controlled trial (RCT) for those with low blood iron levels, as well as a cross-sectional component, including only healthy controls. Iron supplementation will be administered to half of those enrolled in the RCT portion to evaluate the effects of iron uptake within the muscle. Therefore, the primary goal of the study is to determine if iron is stored within the muscle in meaningful amounts following an extended period of oral iron supplementation in healthy females with suboptimal iron status.
The study's rationale extends from the high prevalence of low iron levels among females globally, especially among those who are involved in endurance sports. At the level of the muscle, iron serves in several key biological functions, including oxygen transport, energy production, and even recovery from exercise, making it essential for performance. Although the investigators understand some amount of iron is stored within the muscle, the investigators are currently unaware whether meaningful changes occur following a period of supplementation. Therefore, the proposed protocol outlined below is designed to test the hypothesis that taking iron for a prolonged period at adequate doses will result in meaningful changes.
Participants involved in this study will include biological females aged 18-40 with suboptimal iron status (blood ferritin ≤50 µg/L), who are otherwise healthy, for the RCT portion, or normal iron status (blood ferritin ≥50 µg/L) for healthy controls. Interested participants will be screened, and those eligible for the RCT will be randomly assigned to either an oral iron supplement or a placebo sugar pill, ensuring that the encapsulation is preserved to promote blinding. Participants will consume the assigned treatment once every 2nd day for 12 weeks. Exercise and other biological tests will be performed both before and after supplementation during the RCT, while healthy controls will only participate in baseline testing.
The following is an overview of the study design:
Baseline testing
This phase involves five visits and approximately 6.5 hours of laboratory testing spread over two weeks. Participants in the RCT and those acting as healthy controls will both complete the baseline testing phase.
Visit I: Blood draw
Participants will report to the laboratory in the fasted condition. They will be verbally informed of the methods of this study by the researcher and given time to ask questions before their written consent is obtained. Participants will complete a short survey to characterize their menstrual cycle. Subsequently, an individual trained in phlebotomy will collect venous blood for analysis from an antecubital vein using appropriate techniques. Following analysis of the blood iron markers, participants will be informed whether they are eligible to participate in the RCT or serve as a control. This visit will take approximately 1 hour.
Visit II: Body composition scan and familiarization
Participants will arrive fasted and undergo a body composition scan via dual-energy x-ray absorptiometry (DXA), which takes approximately 10 minutes. They will then be permitted to eat and drink. Participants will complete additional questionnaires (to be repeated before each exercise testing session) detailing perceived rest and food records. They will then be familiarized with a dynamic knee extension (i.e., kicking) task involving 15 minutes of exercise at varying intensities with feedback on technique. Once familiarized, participants will perform a single-leg incremental ramp protocol to determine their quadriceps peak power. In this test, participants will kick at a fixed cadence (e.g., 40 kicks per minute) while resistance gradually increases until they are unable to continue due to fatigue or personal choice. This test will last approximately 10 to 20 minutes. This visit will take approximately 1.5 hours.
Visit III: V̇O₂max and familiarization
On a separate day, at least 24 hours after the last visit, participants will return to the lab without fasting. They will complete an incremental ramp exercise test on a cycle ergometer (double-leg) to measure V̇O₂max, characterizing their aerobic fitness. This test involves gradually increasing resistance until the participant can no longer continue. After a rest period of at least 20 minutes (or longer if needed), participants will perform additional familiarization with the dynamic knee extension exercise, consisting of 30 minutes of kicking at various intensities. This visit will take approximately 1.5 hours.
Visit IV: Lower-body power, quadriceps oxidative capacity, and critical power
On a separate day, at least 24 hours after their last visit, participants will return to the lab without fasting. During this visit, participants will perform countermovement jumps and undergo testing of quadriceps oxidative capacity (OxCap) and critical power (CP) in their dominant leg. They will begin with OxCap testing, which involves a brief isometric contraction of the knee extensor muscles followed by repeated short arterial occlusions using a rapid cuff inflator. This test is performed in duplicate. Next, participants will perform countermovement jumps - a series of vertical jumps on a force plate repeated three times with 60-second rests in between. After resting for 10 to 15 minutes, they will perform three bouts of dynamic knee extension at different intensities to task failure to determine CP. Each bout will last 2 to 20 minutes and be separated by at least 20 minutes of rest. This visit will take approximately 2 hours.
Visit V: Muscle biopsy procedure
On a separate day, at least 24 hours after their last visit, participants will return to the lab in a fasted state for a muscle biopsy. A physician will obtain a small muscle sample using the proper technique, which will later be analyzed for iron-related and mitochondrial protein content. This visit will take approximately 45 minutes.
Supplementation phase
This phase involves two visits and approximately one hour of laboratory testing. Only participants in the RCT will complete this phase.
Participants in the RCT will be randomized to receive either an iron supplement or a placebo in a 1:1 ratio using a concealed allotment procedure. Participants will consume either one iron pill (150 mg elemental iron) or one placebo pill (PolyCal, maltodextrin) every other day for 12 weeks. Each iron supplement contains 50 mg of elemental iron, while the placebo includes none. This dosing protocol is based on prior research showing that alternate-day dosing improves gastrointestinal tolerance. Both iron and placebo pills will be encapsulated within a gelatin capsule for blinding, ensuring no difference in release rate.
Visits VI and VII: Week 4 and 8 blood draws
Participants will visit the lab during weeks 4 and 8 of their supplementation period to provide blood samples. Before each blood draw, they will complete questionnaires about gastrointestinal symptoms and a food record covering the previous three days. Blood will be collected by a trained individual using a standard venipuncture technique. Each visit will take approximately 30 minutes.
Post-supplementation testing
Post-supplementation testing will involve the same procedures as baseline testing, but the visits will be slightly more condensed and re-ordered. In total, participants will visit the lab three times over approximately two weeks for about 5.5 hours of testing. Only RCT participants will complete this phase.
Visit VIII: Blood draw, muscle biopsy, and body composition scan.
After completing supplementation, participants will return to the lab in a fasted state to provide a blood sample and a muscle biopsy, and to undergo a body composition scan. Participants will also repeat familiarization with the single-leg exercise task, using the same procedure from visit II. They will complete questionnaires on gastrointestinal symptoms and their three-day food record. This visit will take approximately 2 hours.
Visits IX and X: Exercise testing
These visits are identical to visits III and IV from the baseline phase and will take the same amount of time (1.5 and 2 hours, respectively) over approximately one week. They will begin a minimum of 48 hours after visit VIII and be separated by at least 24 hours. Before each test, participants will complete questionnaires about rest and their food records for the preceding three days. After all testing is complete, participants and researchers will record their guess about which supplement was consumed to assess the effectiveness of blinding. Participants will then be informed of their group allocation.
- Conditions
- Iron Deficiency
- Being tested
- Oral iron supplement, Placebo
- Keywords
- iron, iron deficiency, athletic performance, female athlete, iron supplements, ferritin, hemoglobin, muscle, muscle ferritin, mitochondria, critical power, aerobic fitness, exercise, placebo
- Medical subject headings
- Iron Deficiencies, Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Oral iron supplementDietary supplement
Encapsulated ferrous sulphate (150mg elemental iron)
PlaceboOther
Encapsulated polysaccharide (maltodextrin)
| Study group | Role | What they receive |
|---|---|---|
| Iron supplement | Experimental | Dietary supplement: Oral iron supplement, encapsulated ferrous sulphate (150mg elemental iron) Receives: Dietary Supplement: Oral iron supplement |
| Placebo | Placebo comparator | Placebo control: Sugar pill, encapsulated polysaccharide substance (malodextrin) Receives: Other: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Muscle Ferritin
Muscle collection: The muscle biopsy involves the removal of a small piece of muscle tissue from the vastus lateralis using a sterile hollow needle. The area over the incision site will be carefully cleaned, and a small amount of local anesthetic will be injected into and under the skin. A small, 4 - 5 mm incision will be made in the skin to create an opening for the biopsy needle.
The biopsy needle will then be inserted through the incision into the muscle, and a small piece of muscle (~50 mg) will be removed, and the needle taken out. A medical doctor will perform this procedure.
Protein analysis: Western blotting will be used to analyze the abundance of ferritin within small sections of the muscle sample.
Measured: At baseline (week 0) and completion of supplementation (week 12)
Secondary outcomes (7)
Serum iron status
A forearm venous blood draw (10ml): Samples will be sent to a third-party laboratory for analysis of blood biomarkers, including ferritin and hemoglobin.
Measured: Every four weeks beginning at baseline (week 0) until completion of supplementation (week 12)
Iron-related proteins
Muscle collection: The muscle biopsy involves the removal of a small piece of muscle tissue from the vastus lateralis using a sterile hollow needle. The area over the incision site will be carefully cleaned, and a small amount of local anesthetic will be injected into and under the skin. A small, 4 - 5 mm incision will be made in the skin to create an opening for the biopsy needle.
The biopsy needle will then be inserted through the incision into the muscle, and a small piece of muscle (~50 mg) will be removed, and the needle taken out. A medical doctor will perform this procedure.
Protein analysis: Small sections of each muscle sample will undergo Western blotting to analyze other iron-related proteins (e.g., transporters)
Measured: At baseline (week 0) and completion of supplementation (week 12)
Mitochondrial proteins
Muscle collection: The muscle biopsy involves the removal of a small piece of muscle tissue from the vastus lateralis using a sterile hollow needle. The area over the incision site will be carefully cleaned, and a small amount of local anesthetic will be injected into and under the skin. A small, 4 - 5 mm incision will be made in the skin to create an opening for the biopsy needle.
The biopsy needle will then be inserted through the incision into the muscle, and a small piece of muscle (~50 mg) will be removed, and the needle taken out. A medical doctor will perform this procedure.
Protein analysis: Small sections of each muscle sample will undergo Western blotting to analyze potential changes to mitochondrial protein content (e.g., transporters). Other sections of the same sample will undergo enzyme assays to quantify the relative changes in protein activity within the sample.
Measured: At baseline (week 0) and completion of supplementation (week 12)
Whole body aerobic fitness (VO2max)
Exercise: Participants will complete an incremental ramp exercise test on a cycle ergometer (double-leg) to measure V̇O2max, serving to characterize participants' aerobic fitness. For this test, participants will cycle on a stationary bicycle while the resistance increases gradually until the participants are unable to continue because they are fatigued and/or wish to stop (~10-20 min)
Metabolic analysis: For whole-body exercise tests, participants will wear a face mask attached to a metabolic cart (Quark CPET, COSMED, Rome, Italy) that will analyze the volume and content of expired breath to determine oxygen uptake, carbon dioxide production, and minute ventilation. The maximal whole-body rate of oxygen consumption (V̇O2max) will be determined as the highest 30s average from a ramp incremental test.
Measured: At baseline (week 0) and completion of supplementation (week 12)
Single-leg critical power
Exercise: Participants will perform three bouts of dynamic knee extension exercise at differing intensities to task failure to determine their CP. Each bout of kicking will last between 2 and 20 minutes and be separated by a minimum of 20 minutes of rest.
Critical power determination: The two parameters of the intensity-duration relationship, CP (W) and W' (J), will be calculated using three equations: the linear work-time model, the inverse linear model, and the hyperbolic model.
Linear work-time model: W = CP × t + W' Inverse linear model: P = W' × (1/t) + CP Hyperbolic model: t = W' / (P - CP)
Where P represents power output and W represents the total work completed. The equation with the highest coefficient of determination (R2) and lowest standard error of the estimate will be selected to determine CP and W' for each participant.
Measured: At baseline (week 0) and completion of supplementaton (week 12)
Muscle oxidative capacity
Exercise: Participants will complete oxidative capacity testing, which involves performing a brief isometric contraction of the knee extensor muscles followed by repeated, transient (5 s) arterial occlusions with a rapid cuff inflator. This protocol will be performed in duplicate.
Oxidative measure: Near-infrared spectroscopy (NIRS) will be used to non-invasively measure muscle oxidative capacity. The NIRS device will be held in place with two-sided tape and a tensor bandage on the vastus lateralis muscle, and a blood pressure cuff will be wrapped around the upper portion of the thigh, proximal to the NIRS device. During transient (5 s) arterial occlusions following a brief exercise stimulus, NIRS will be used to measure changes in the concentration of oxygenated and deoxygenated hemoglobin. Using these measures, the rate at which muscle oxygen uptake recovers following a series of brief contractions, a surrogate for the oxidative capacity of the muscle, can be determined.
Measured: At baseline (week 0) and completion of supplementation (week 12)
Countermovement jump test
Exercise: Participants will perform a countermovement jump that involves completing a series of short-burst vertical jumps on a force plate to assess lower-body power and explosiveness. This activity will be repeated twice more, separated by 60 s of rest, before resting for several (~10-15) mins.
Measured: At baseline (week 0) and completion of supplementation (week 12)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Jul 2025
- Study startAug 2025 (estimated)
- Primary completionMay 2026 (estimated)
- Study completionJun 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (20)Papers the sponsor has linked to this study.
- Other trials for Iron DeficiencyStudies of the same condition, open and under way.
- More trials run by University of CalgaryThe sponsor's other registered studies.
- 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
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 36 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Calgary
- Sponsor type
- University, hospital or other
- Collaborators
- Natural Sciences and Engineering Research Council, Canada
- Responsible party
- Principal investigator, Martin MacInnis, University of Calgary
- Investigators
- Martin J MacInnis, Principal investigator, University of Calgary
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07084298
- Sponsor's protocol ID
- REB25-0927
- Acronym
- MyoIRON
- Status last verified
- Jul 2025
- First submitted
- 16 Jul 2025
- Last updated
- 6 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Rineau E, Gueguen N, Procaccio V, Genevieve F, Reynier P, Henrion D, Lasocki S. Iron Deficiency without Anemia Decreases Physical Endurance and Mitochondrial Complex I Activity of Oxidative Skeletal Muscle in the Mouse. Nutrients. 2021 Mar 24;13(4):1056. doi: 10.3390/nu13041056.
PubMed 33805065Paul BT, Manz DH, Torti FM, Torti SV. Mitochondria and Iron: current questions. Expert Rev Hematol. 2017 Jan;10(1):65-79. doi: 10.1080/17474086.2016.1268047. Epub 2016 Dec 12.
PubMed 27911100Ohira Y, Hegenauer J, Strause L, Chen CS, Saltman P, Beinert H. Mitochondrial NADH dehydrogenase in iron-deficient and iron-repleted rat muscle: an EPR and work performance study. Br J Haematol. 1982 Dec;52(4):623-30. doi: 10.1111/j.1365-2141.1982.tb03938.x.
PubMed 6291576Moretti D, Goede JS, Zeder C, Jiskra M, Chatzinakou V, Tjalsma H, Melse-Boonstra A, Brittenham G, Swinkels DW, Zimmermann MB. Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women. Blood. 2015 Oct 22;126(17):1981-9. doi: 10.1182/blood-2015-05-642223. Epub 2015 Aug 19.
PubMed 26289639MacInnis MJ, Zacharewicz E, Martin BJ, Haikalis ME, Skelly LE, Tarnopolsky MA, Murphy RM, Gibala MJ. Superior mitochondrial adaptations in human skeletal muscle after interval compared to continuous single-leg cycling matched for total work. J Physiol. 2017 May 1;595(9):2955-2968. doi: 10.1113/JP272570. Epub 2016 Aug 3.
PubMed 27396440Jacobs A. Tissue changes in iron deficiency. Br J Haematol. 1969 Jan-Feb;16(1):1-4. doi: 10.1111/j.1365-2141.1969.tb00372.x. No abstract available.
PubMed 5795211Hinton PS, Giordano C, Brownlie T, Haas JD. Iron supplementation improves endurance after training in iron-depleted, nonanemic women. J Appl Physiol (1985). 2000 Mar;88(3):1103-11. doi: 10.1152/jappl.2000.88.3.1103.
PubMed 10710409Frise MC, Holdsworth DA, Johnson AW, Chung YJ, Curtis MK, Cox PJ, Clarke K, Tyler DJ, Roberts DJ, Ratcliffe PJ, Dorrington KL, Robbins PA. Abnormal whole-body energy metabolism in iron-deficient humans despite preserved skeletal muscle oxidative phosphorylation. Sci Rep. 2022 Jan 19;12(1):998. doi: 10.1038/s41598-021-03968-4.
PubMed 35046429DellaValle DM, Haas JD. Iron supplementation improves energetic efficiency in iron-depleted female rowers. Med Sci Sports Exerc. 2014 Jun;46(6):1204-15. doi: 10.1249/MSS.0000000000000208.
PubMed 24195864Stugiewicz M, Tkaczyszyn M, Kasztura M, Banasiak W, Ponikowski P, Jankowska EA. The influence of iron deficiency on the functioning of skeletal muscles: experimental evidence and clinical implications. Eur J Heart Fail. 2016 Jul;18(7):762-73. doi: 10.1002/ejhf.467. Epub 2016 Jan 21.
PubMed 26800032Newhouse IJ, Clement DB, Taunton JE, McKenzie DC. The effects of prelatent/latent iron deficiency on physical work capacity. Med Sci Sports Exerc. 1989 Jun;21(3):263-8.
PubMed 2733574Melenovsky V, Hlavata K, Sedivy P, Dezortova M, Borlaug BA, Petrak J, Kautzner J, Hajek M. Skeletal Muscle Abnormalities and Iron Deficiency in Chronic Heart FailureAn Exercise 31P Magnetic Resonance Spectroscopy Study of Calf Muscle. Circ Heart Fail. 2018 Sep;11(9):e004800. doi: 10.1161/CIRCHEARTFAILURE.117.004800.
PubMed 30354361McDougall RM, Tripp TR, Frankish BP, Doyle-Baker PK, Lun V, Wiley JP, Aboodarda SJ, MacInnis MJ. The influence of skeletal muscle mitochondria and sex on critical torque and performance fatiguability in humans. J Physiol. 2023 Dec;601(23):5295-5316. doi: 10.1113/JP284958. Epub 2023 Oct 30.
PubMed 37902588Hinton PS. Iron and the endurance athlete. Appl Physiol Nutr Metab. 2014 Sep;39(9):1012-8. doi: 10.1139/apnm-2014-0147. Epub 2014 May 27.
PubMed 25017111Finch CA, Miller LR, Inamdar AR, Person R, Seiler K, Mackler B. Iron deficiency in the rat. Physiological and biochemical studies of muscle dysfunction. J Clin Invest. 1976 Aug;58(2):447-53. doi: 10.1172/JCI108489.
PubMed 956378
Study at a glance
From the registry record, last updated by the sponsor on 6 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of 12 Weeks of Oral Iron Supplementation on Skeletal Muscle Iron Content, Mitochondrial Function, and Indices of Aerobic Fitness in Healthy Females With Suboptimal Iron Stores
- ClinicalTrials.gov ID
- NCT07084298
- Acronym / sponsor ID
- MyoIRON / REB25-0927
- Conditions
- Iron Deficiency
- Keywords
- iron, iron deficiency, athletic performance, female athlete, iron supplements, ferritin, hemoglobin, muscle
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 36 participants (estimated)
- Lead sponsor
- University of CalgaryUniversity, hospital or other
- Collaborators
- Natural Sciences and Engineering Research Council, Canada
- Study start
- Aug 2025 (estimated)
- Primary completion
- May 2026 (estimated)
- Study completion
- Jun 2026 (estimated)
- First posted
- 24 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this clinical trial is to learn whether oral iron supplementation will increase skeletal muscle iron storage and its effects on exercise capacity in females with suboptimal iron status. The study will include healthy females, ages 18-40, who either have suboptimal or optimal iron stores.
The main questions it aims to answer are:
- Does iron supplementation increase skeletal muscle iron storage and alter the expression of iron-related and mitochondrial proteins?
- Does iron supplementation improve single-leg exercise performance?
- Is serum ferritin correlated with the abundance of iron-related proteins in skeletal muscle?
Researchers will compare outcomes from females with suboptimal iron status who receive oral iron supplementation to those who receive a placebo to see if supplementation improves muscle iron storage, protein expression, and exercise performance. Additionally, a non-intervention control group with optimal iron status will be included to assess baseline differences.
Participants will:
- Be randomly assigned to receive 150 mg elemental iron or placebo (maltodextrin) every other day for 12 weeks
Complete pre- and post-supplementation testing, including:
- Blood draws to assess iron status
- Skeletal muscle biopsies to analyze protein content
- Whole-body and single-leg exercise tests to assess performance
- Controls will undergo baseline-only testing to compare physiological and biochemical markers
Detailed description
This study is intended to evaluate the effects of oral iron supplementation on muscle iron levels in females with suboptimal iron status. The design involves both a randomized controlled trial (RCT) for those with low blood iron levels, as well as a cross-sectional component, including only healthy controls. Iron supplementation will be administered to half of those enrolled in the RCT portion to evaluate the effects of iron uptake within the muscle. Therefore, the primary goal of the study is to determine if iron is stored within the muscle in meaningful amounts following an extended period of oral iron supplementation in healthy females with suboptimal iron status.
The study's rationale extends from the high prevalence of low iron levels among females globally, especially among those who are involved in endurance sports. At the level of the muscle, iron serves in several key biological functions, including oxygen transport, energy production, and even recovery from exercise, making it essential for performance. Although the investigators understand some amount of iron is stored within the muscle, the investigators are currently unaware whether meaningful changes occur following a period of supplementation. Therefore, the proposed protocol outlined below is designed to test the hypothesis that taking iron for a prolonged period at adequate doses will result in meaningful changes.
Participants involved in this study will include biological females aged 18-40 with suboptimal iron status (blood ferritin ≤50 µg/L), who are otherwise healthy, for the RCT portion, or normal iron status (blood ferritin ≥50 µg/L) for healthy controls. Interested participants will be screened, and those eligible for the RCT will be randomly assigned to either an oral iron supplement or a placebo sugar pill, ensuring that the encapsulation is preserved to promote blinding. Participants will consume the assigned treatment once every 2nd day for 12 weeks. Exercise and other biological tests will be performed both before and after supplementation during the RCT, while healthy controls will only participate in baseline testing.
The following is an overview of the study design:
Baseline testing
This phase involves five visits and approximately 6.5 hours of laboratory testing spread over two weeks. Participants in the RCT and those acting as healthy controls will both complete the baseline testing phase.
Visit I: Blood draw
Participants will report to the laboratory in the fasted condition. They will be verbally informed of the methods of this study by the researcher and given time to ask questions before their written consent is obtained. Participants will complete a short survey to characterize their menstrual cycle. Subsequently, an individual trained in phlebotomy will collect venous blood for analysis from an antecubital vein using appropriate techniques. Following analysis of the blood iron markers, participants will be informed whether they are eligible to participate in the RCT or serve as a control. This visit will take approximately 1 hour.
Visit II: Body composition scan and familiarization
Participants will arrive fasted and undergo a body composition scan via dual-energy x-ray absorptiometry (DXA), which takes approximately 10 minutes. They will then be permitted to eat and drink. Participants will complete additional questionnaires (to be repeated before each exercise testing session) detailing perceived rest and food records. They will then be familiarized with a dynamic knee extension (i.e., kicking) task involving 15 minutes of exercise at varying intensities with feedback on technique. Once familiarized, participants will perform a single-leg incremental ramp protocol to determine their quadriceps peak power. In this test, participants will kick at a fixed cadence (e.g., 40 kicks per minute) while resistance gradually increases until they are unable to continue due to fatigue or personal choice. This test will last approximately 10 to 20 minutes. This visit will take approximately 1.5 hours.
Visit III: V̇O₂max and familiarization
On a separate day, at least 24 hours after the last visit, participants will return to the lab without fasting. They will complete an incremental ramp exercise test on a cycle ergometer (double-leg) to measure V̇O₂max, characterizing their aerobic fitness. This test involves gradually increasing resistance until the participant can no longer continue. After a rest period of at least 20 minutes (or longer if needed), participants will perform additional familiarization with the dynamic knee extension exercise, consisting of 30 minutes of kicking at various intensities. This visit will take approximately 1.5 hours.
Visit IV: Lower-body power, quadriceps oxidative capacity, and critical power
On a separate day, at least 24 hours after their last visit, participants will return to the lab without fasting. During this visit, participants will perform countermovement jumps and undergo testing of quadriceps oxidative capacity (OxCap) and critical power (CP) in their dominant leg. They will begin with OxCap testing, which involves a brief isometric contraction of the knee extensor muscles followed by repeated short arterial occlusions using a rapid cuff inflator. This test is performed in duplicate. Next, participants will perform countermovement jumps - a series of vertical jumps on a force plate repeated three times with 60-second rests in between. After resting for 10 to 15 minutes, they will perform three bouts of dynamic knee extension at different intensities to task failure to determine CP. Each bout will last 2 to 20 minutes and be separated by at least 20 minutes of rest. This visit will take approximately 2 hours.
Visit V: Muscle biopsy procedure
On a separate day, at least 24 hours after their last visit, participants will return to the lab in a fasted state for a muscle biopsy. A physician will obtain a small muscle sample using the proper technique, which will later be analyzed for iron-related and mitochondrial protein content. This visit will take approximately 45 minutes.
Supplementation phase
This phase involves two visits and approximately one hour of laboratory testing. Only participants in the RCT will complete this phase.
Participants in the RCT will be randomized to receive either an iron supplement or a placebo in a 1:1 ratio using a concealed allotment procedure. Participants will consume either one iron pill (150 mg elemental iron) or one placebo pill (PolyCal, maltodextrin) every other day for 12 weeks. Each iron supplement contains 50 mg of elemental iron, while the placebo includes none. This dosing protocol is based on prior research showing that alternate-day dosing improves gastrointestinal tolerance. Both iron and placebo pills will be encapsulated within a gelatin capsule for blinding, ensuring no difference in release rate.
Visits VI and VII: Week 4 and 8 blood draws
Participants will visit the lab during weeks 4 and 8 of their supplementation period to provide blood samples. Before each blood draw, they will complete questionnaires about gastrointestinal symptoms and a food record covering the previous three days. Blood will be collected by a trained individual using a standard venipuncture technique. Each visit will take approximately 30 minutes.
Post-supplementation testing
Post-supplementation testing will involve the same procedures as baseline testing, but the visits will be slightly more condensed and re-ordered. In total, participants will visit the lab three times over approximately two weeks for about 5.5 hours of testing. Only RCT participants will complete this phase.
Visit VIII: Blood draw, muscle biopsy, and body composition scan.
After completing supplementation, participants will return to the lab in a fasted state to provide a blood sample and a muscle biopsy, and to undergo a body composition scan. Participants will also repeat familiarization with the single-leg exercise task, using the same procedure from visit II. They will complete questionnaires on gastrointestinal symptoms and their three-day food record. This visit will take approximately 2 hours.
Visits IX and X: Exercise testing
These visits are identical to visits III and IV from the baseline phase and will take the same amount of time (1.5 and 2 hours, respectively) over approximately one week. They will begin a minimum of 48 hours after visit VIII and be separated by at least 24 hours. Before each test, participants will complete questionnaires about rest and their food records for the preceding three days. After all testing is complete, participants and researchers will record their guess about which supplement was consumed to assess the effectiveness of blinding. Participants will then be informed of their group allocation.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Iron supplement | Experimental | Dietary Supplement: Oral iron supplementDietary supplement: Oral iron supplement, encapsulated ferrous sulphate (150mg elemental iron) |
| Placebo | Placebo comparator | Other: PlaceboPlacebo control: Sugar pill, encapsulated polysaccharide substance (malodextrin) |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- biologically female
- between the ages of 18-40 years of age at the time of enrolment
- plasma ferritin ≤ 50 µg/ L (RCT) or >50 µg/L (controls)
- complete Get Active Questionnaire (GAQ: Canadian Society for Exercise Physiology) without contraindication
Key exclusion criteria (18 listed)
- have a body mass index (BMI) > 30 kg/m2
- taking medications that have been shown to affect cardiovascular, respiratory, or metabolic responses to exercise (e.g., β-blockers, anti-inflammatories, anti-coagulants, insulin, etc.)
- hemoglobin ≤ 120 g/L (anemia cut-off for women)
- have known health problems or contraindications that prohibit exercise, including renal or gastrointestinal disorders, metabolic disease, heart disease, vascular disease, arthritis, diabetes, respiratory disease, uncontrolled blood pressure, dizziness, thyroid problems, or any other health conditions that are being treated and deemed likely to confound the results
- dieting for weight loss or following a low-carbohydrate diet (known to affect iron homeostasis)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Oral iron supplementEncapsulated ferrous sulphate (150mg elemental iron) | Dietary supplement | Iron supplement |
| PlaceboEncapsulated polysaccharide (maltodextrin) | Other | Placebo |
Primary outcome
Muscle Ferritin
Time frame: At baseline (week 0) and completion of supplementation (week 12)
Muscle collection: The muscle biopsy involves the removal of a small piece of muscle tissue from the vastus lateralis using a sterile hollow needle. The area over the incision site will be carefully cleaned, and a small amount of local anesthetic will be injected into and under the skin. A small, 4 - 5 mm incision will be made in the skin to create an opening for the biopsy needle. The biopsy needle will then be inserted through the incision into the muscle, and a small piece of muscle (~50 mg) will be removed, and the needle taken out. A medical doctor will perform this procedure. Protein analysis: Western blotting will be used to analyze the abundance of ferritin within small sections of the muscle sample.
7 secondary outcomes
Serum iron status
Time frame: Every four weeks beginning at baseline (week 0) until completion of supplementation (week 12)
Iron-related proteins
Time frame: At baseline (week 0) and completion of supplementation (week 12)
Mitochondrial proteins
Time frame: At baseline (week 0) and completion of supplementation (week 12)
Whole body aerobic fitness (VO2max)
Time frame: At baseline (week 0) and completion of supplementation (week 12)
Single-leg critical power
Time frame: At baseline (week 0) and completion of supplementaton (week 12)
Muscle oxidative capacity
Time frame: At baseline (week 0) and completion of supplementation (week 12)
Countermovement jump test
Time frame: At baseline (week 0) and completion of supplementation (week 12)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Aug 2025.
- Background: PubMed 33805065Rineau E, Gueguen N, Procaccio V, Genevieve F, Reynier P, Henrion D, Lasocki S. Iron Deficiency without Anemia Decreases Physical Endurance and Mitochondrial Complex I Activity of Oxidative Skeletal Muscle in the Mouse. Nutrients. 2021 Mar 24;13(4):1056. doi: 10.3390/nu13041056.
- Background: PubMed 27911100Paul BT, Manz DH, Torti FM, Torti SV. Mitochondria and Iron: current questions. Expert Rev Hematol. 2017 Jan;10(1):65-79. doi: 10.1080/17474086.2016.1268047. Epub 2016 Dec 12.
- Background: PubMed 6291576Ohira Y, Hegenauer J, Strause L, Chen CS, Saltman P, Beinert H. Mitochondrial NADH dehydrogenase in iron-deficient and iron-repleted rat muscle: an EPR and work performance study. Br J Haematol. 1982 Dec;52(4):623-30. doi: 10.1111/j.1365-2141.1982.tb03938.x.
- Background: PubMed 26289639Moretti D, Goede JS, Zeder C, Jiskra M, Chatzinakou V, Tjalsma H, Melse-Boonstra A, Brittenham G, Swinkels DW, Zimmermann MB. Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women. Blood. 2015 Oct 22;126(17):1981-9. doi: 10.1182/blood-2015-05-642223. Epub 2015 Aug 19.
- Background: PubMed 27396440MacInnis MJ, Zacharewicz E, Martin BJ, Haikalis ME, Skelly LE, Tarnopolsky MA, Murphy RM, Gibala MJ. Superior mitochondrial adaptations in human skeletal muscle after interval compared to continuous single-leg cycling matched for total work. J Physiol. 2017 May 1;595(9):2955-2968. doi: 10.1113/JP272570. Epub 2016 Aug 3.
- Background: PubMed 5795211Jacobs A. Tissue changes in iron deficiency. Br J Haematol. 1969 Jan-Feb;16(1):1-4. doi: 10.1111/j.1365-2141.1969.tb00372.x. No abstract available.
- Background: PubMed 10710409Hinton PS, Giordano C, Brownlie T, Haas JD. Iron supplementation improves endurance after training in iron-depleted, nonanemic women. J Appl Physiol (1985). 2000 Mar;88(3):1103-11. doi: 10.1152/jappl.2000.88.3.1103.
- Background: PubMed 35046429Frise MC, Holdsworth DA, Johnson AW, Chung YJ, Curtis MK, Cox PJ, Clarke K, Tyler DJ, Roberts DJ, Ratcliffe PJ, Dorrington KL, Robbins PA. Abnormal whole-body energy metabolism in iron-deficient humans despite preserved skeletal muscle oxidative phosphorylation. Sci Rep. 2022 Jan 19;12(1):998. doi: 10.1038/s41598-021-03968-4.
- Background: PubMed 24195864DellaValle DM, Haas JD. Iron supplementation improves energetic efficiency in iron-depleted female rowers. Med Sci Sports Exerc. 2014 Jun;46(6):1204-15. doi: 10.1249/MSS.0000000000000208.
- Background: PubMed 26800032Stugiewicz M, Tkaczyszyn M, Kasztura M, Banasiak W, Ponikowski P, Jankowska EA. The influence of iron deficiency on the functioning of skeletal muscles: experimental evidence and clinical implications. Eur J Heart Fail. 2016 Jul;18(7):762-73. doi: 10.1002/ejhf.467. Epub 2016 Jan 21.
- Background: PubMed 2733574Newhouse IJ, Clement DB, Taunton JE, McKenzie DC. The effects of prelatent/latent iron deficiency on physical work capacity. Med Sci Sports Exerc. 1989 Jun;21(3):263-8.
- Background: PubMed 30354361Melenovsky V, Hlavata K, Sedivy P, Dezortova M, Borlaug BA, Petrak J, Kautzner J, Hajek M. Skeletal Muscle Abnormalities and Iron Deficiency in Chronic Heart FailureAn Exercise 31P Magnetic Resonance Spectroscopy Study of Calf Muscle. Circ Heart Fail. 2018 Sep;11(9):e004800. doi: 10.1161/CIRCHEARTFAILURE.117.004800.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Martin J MacInnis principal investigator
University of Calgary
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing Oral iron supplement in people with Iron Deficiency, run by University of Calgary at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 6 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Alexander L Isidori (6475173560, alex.isidori1@ucalgary.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Muscle Ferritin (time frame: At baseline (week 0) and completion of supplementation (week 12)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07084298, which also lists 20 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Aug 2025.