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RecruitingNCT06507189M3AXUpdated Aug 10, 2026

Multidimensional Predictive Modeling to Understand Mechanisms of Exercise Response Heterogeneity in Older Adults (M3AX)

An interventional study of Combined endurance and resistance training in Aging and Aging Well, sponsored by Florida Institute for Human and Machine Cognition. Recruiting at 2 sites in United States. Open to participants aged 60 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-10.

Sponsored by Florida Institute for Human and Machine Cognition · Not applicable, Interventional, and Treatment

From the registry’s dates

  • Started Jan 2025; still recruiting 1 year 9 months later.

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Phase
Not applicable
Study type
Interventional
Enrollment
250
Allocation
Randomized
Ages
60 Years and older
Sex
All
01

Study summary

Aging-related functional declines are thought to be caused by hallmark biological processes that ultimately manifest in physical, mental, and metabolic impairments that compromise healthspan and quality of life. Exercise is a multipotent treatment with promise to mitigate most aging hallmarks, but there is substantial variability in exercisƒe responsiveness. Combining endurance and resistance training in alignment with public health guidelines will be used to better understand variable exercise responsiveness in older adults with the ultimate goal of improving each older adult's capacity to attain the many health benefits of exercise.

Read the detailed description

Aging-related functional declines are thought to be caused by hallmark biological processes1 that ultimately manifest in physical, mental, and metabolic impairments - compromising healthspan and quality of life (QoL). Exercise is a multipotent treatment with promise to mitigate most aging hallmarks, but there is substantial variability in individual exercise responsiveness. This inter-individual response heterogeneity (IRH) was first identified and extensively interrogated by Bouchard and colleagues in the context of endurance training (ET). Subsequently, the investigators have demonstrated resistance training (RT) IRH and have studied potential IRH mechanisms. The investigators then led multiple trials in older adults examining dose titration, adjuvant nutrition or medication in attempts to lower poor response rates. Many knowledge gaps remain as summarized in the National Institutes of Aging (NIA) workshop on IRH seeding this Requests for Applications (RFA). The investigators have assembled an interdisciplinary team to address the RFA's central goal, "to better understand factors underlying response variability to exercise training in older adults." Although Health and Human Services (HHS) guidelines specify combined ET and RT to maximize health benefits in aging adults, large-scale exercise trials studying IRH (i.e., HERITAGE, MoTrPAC) have restricted participants to a single exercise mode. For this project, the investigators propose the innovative, but logical, strategy to use combined ET and RT. Low cardiorespiratory fitness (CRF, VO2max) and low functional muscle quality (fMQ; strength/muscle mass) are multi-system manifestations of the deterioration of the cellular hallmarks of aging. Importantly, both CRF and fMQ are modifiable with ET and RT. Thus, the investigators design premise is that combined ET+RT is an excellent strategy for elucidating factors underlying IRH, as it forges a path toward understanding and mitigating IRH in aging with direct translatability to best-evidence public health recommendations.

It is yet to be determined how the hallmarks of aging interact to influence exercise responsiveness. For example, muscle mitochondrial energetics and proteostasis are inextricably linked, and poor responder status may be caused by lack of energetic resources to maintain proteostasis throughout an exercise program. Similarly, aging disrupts circadian clocks, leading to inflammation and disrupted cell signaling, which may also contribute to IRH.

While sources of IRH are a constellation of modifiable and non-modifiable factors, the investigators will test the hypothesis that factors central to aging itself - aging hallmarks such as proteostasis, mitochondrial energetics, and inflammation, as well as systemic and muscle-specific circadian clock function and output - are chief contributors to the multidimensional circuitry that determines whether an individual achieves the minimum clinically important difference (MCID) in CRF and/or fMQ with exercise training. The investigators will also test the hypothesis that altered exercise dosing coupled with lifestyle recommendations will promote attainment of MCIDs among older adults who do not initially respond. With CRF and fMQ as primary clinical outcomes, the investigators will use a 2-phase Sequential Multiple Assignment Randomized Trial (SMART) of combined ET+RT with clinical phenotyping and blood/muscle molecular and cellular analyses.

02

Conditions studied

  • Aging
  • Aging Well
03

In context

Lead sponsor

Florida Institute for Human and Machine Cognition is the lead sponsor of 9 studies on the registry; 6 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
60 Years and older
Sexes eligible
All
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. Male or female aged 60 or above
  2. Free of chronic disease
  3. No structured exercise program (2 or more bouts/wk) within previous 12 months
  4. Cognitively capable of providing

Exclusion criteria

Exclusion Criteria:

  1. Neuromuscular or musculoskeletal disorder that would limit ability to perform the exercise and/or testing bouts
  2. Cardiopulmonary disorders or reduced breathing capacity
  3. Metabolic diseases including markers of liver disease ( > 52 U/l) and type 2 diabetes ( = or > 6.5, fasting blood glucose = or > 126 mg/dl)
  4. Any other disease or disorder that would influence exercise response (e.g., chronic kidney disease, dementia, current cancer diagnosis or within 2 yr remission, cerebrovascular disease)
  5. Any current infectious disease
  6. \< 1 year
  7. Insulin sensitizing/blood glucose lowering agents such as metformin or metabolic weight loss agents (e.g. GLP-1 agonists)
  8. High dose statin (dose equivalent of 40 mg/d or higher simvastatin)
  9. Lidocaine allergy
  10. Regular tobacco use and/or vaping
  11. Excessive alcohol consumption (3 drinks/d or 7 drinks/wk for females; 4 drinks/d or 14 drinks/wk for males)
  12. 35.0 kg/m2 or higher
  13. Unable to commit to \~6 months required to complete the study
Terms in these criteria, in plain language(5)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

ALT and AST (liver enzymes)

Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.

Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.

HbA1c

A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.

Life expectancy

The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.

BMI (body mass index)

Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.

What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.

05

Study design

Phase
Not applicable
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Factorial assignment
Masking
Double (Investigator, Outcomes assessor)
Enrollment
250 participants (estimated)

Study arms

  • Experimental
    Phase I (12 weeks)

    In Interrogation, all participants will exercise train using an exercise prescription that is in accordance with current public health recommendations. At the end of Phase I participants will be classified into one of four categories: (1) CRF-/fMQ-, 2) CRF-/fMQ+, 3) CRF+/fMQ- and 4) CRF+/fMQ+).

    Other: Combined endurance and resistance training

  • Experimental
    Phase II (10 weeks)

    Based on the Phase I categories of responsiveness, exercise training will be boosted in the three groups that are non-responsive in one or both outcomes. CRF-/fMQ+ will receive boosted ET, CRF+/fMQ- will receive boosted RT, and CRF-/fMQ- will receive boosting in both. All three of these classifications will also receive education on wearable device data and other free-living recommendations. Participants classified as CRF+/fMQ+ at the end of Phase I will be randomized to either continue the supervised exercise training or to free-living.

    Other: Combined endurance and resistance training

Interventions

  • OtherCombined endurance and resistance training

    ET will consist of 3x/wk training (MWF) with MF being steady state cycling, treadmill, or elliptical at 70-75% HRR for 30 min and the W session being a 20 min high intensity interval session on a cycle ergometer (1 min on/off; 10 cycles) targeting 85-90% HRR. The treadmill and elliptical on M or F will be provided for variety but the mainstay will be cycle ergometry. On MF participants will complete 3 sets x 8-12 repetitions for leg press, knee extension, hamstring curl, chest press, seated row, overhead press, lat pulldown, triceps push-down, and biceps curl in superset fashion \[i.e., alternate between opposing muscle groups without rest (chest press followed by seated row)\] with a 60 s rest between supersets. Sets will be performed with load progression to ensure volitional fatigue in the 8-12 rep range. Core exercises (trunk flexion and extension) will also be included using bodyweight only for 3 sets.

06

What researchers measure

Primary outcomes

  1. Cardiorespiratory fitness (CRF)

    A primary outcome of this investigation is cardiorespiratory fitness (CRF). The CRF is the amount of oxygen (ml/kg) that is used during exercise and how efficient you are using that oxygen. The exercise used to measure oxygen uptake is a stationary bicycle with increasing intensity until you are able to maintain pace. Your expired air is collected with a mask or mouthpiece and analyzed with an oxygen and carbon dioxide sensor.

    Time frame: 23 weeks

  2. Functional muscle quality (fMQ)

    A primary outcome of this investigation is functional muscle quality (fMQ). This is a ratio of knee extension strength to thigh leanness. Knee extension strength is the maximum amount of weight you can successfully lift one time. Thigh lean mass is measured with the dual energy x-ray absorptiometry (DEXA). This is a common tool used to measure bone density, but it is very efficient at determining fat and lean masses partitioned in the body.

    Time frame: 23 weeks

Secondary outcomes

  1. Balance

    Balance will be assessed with tools such at the short physical performance battery (SPPB). The SPPB is a clinical test used to measure balance in three areas of balance: stand-in balance, gait speed and chair stand time. The overall higher score you have is an indicator of better balance.

    Time frame: 23 weeks

  2. Cognitive performance

    An assessment such as the Trail Making Task (TMT)is used to measure reaction times at the beginning of and after the exercise intervention.

    Time frame: 23 weeks

  3. Body composition

    Body composition will be measured four times pre and post to exercise intervention.

    Time frame: 23 weeks

  4. Metabolic health

    A clinical assessment such as continuous glucose monitoring (CGM) will be use to measure metabolic health at the beginning, the middle, and end of intervention time points. CGM will monitored for seven days pre and post to the exercise intervention. This can be used to determine blood glucose response before and after exercise.

    Time frame: 23 weeks

  5. Metabolic health

    The HOMA-IR will is test used to determine protein turn over or how efficient you are at processing proteins.

    Time frame: 23 weeks

07

Study locations

2 of 2 sites recruiting
08

References and documents

Individual participant data

Plan to share: Yes — Data Entry and Management System. Regarding the data entry and management system (DEMS) used for data management, we will customize one of the DEMS platforms developed by the team at IHMC using Smartabase, which is a federally approved, secure cloud-based environment we are currently using in other federally funded observational studies and clinical trials. We have experienced Smartabase builders on the team led by Dr. McAdam who will create custom programs and forms for the study that facilitate data collection and entry while also having the infrastructure to provide access to real-time data summaries and comparisons across all performance sites. Importantly, we have established numerous streamlined approaches for direct electronic data transfer to Smartabase from testing instruments (e.g., DXA, metabolic carts, strength dynamometers, EMG systems) via APIs to eliminate manual data entry errors.

Supporting information: Study protocol, Statistical analysis plan, Clinical study report

Time frame: Data will be transferred and monitored on the day of acquisition. Data will be identified with unique study identity.

No publications or documents are linked to this record.

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Started Jan 2025 (actual). Primary completion is estimated for Jul 2028, 42 months after the start.

How these figures are worked out, and which studies are left out of them.

Registered
Jun 27, 2024
First posted
Jul 18, 2024
StartActual
Jan 27, 2025
Primary completionEst.
Jul 31, 2028
CompletionEst.
Aug 31, 2029
Last update
Aug 10, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Aug 10, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT06507189
Lead sponsor
Florida Institute for Human and Machine Cognition
Collaborators
University of Florida, Oklahoma Medical Research Foundation
Responsible party
Sponsor
First posted
Jul 18, 2024
Start date
Jan 27, 2025
Primary completion
Jul 31, 2028 (estimated)
Completion
Aug 31, 2029 (estimated)
Last update
Aug 10, 2026

Study contacts

Craig Tuggle
Contact
ctuggle@ihmc.org
205-352-6036
Marcas Bamman, PHD
Contact
mbamman@ihmc.org
Marcas Bamman
principal investigator · Florida Institute for Human and Machine Cognition

Oversight

Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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