Incomplete Spinal Cord InjuryNCT05341466

The Effect of Acute Intermittent Hypoxia on Motor Learning

A study testing Acute Intermittent Hypoxia in people with Incomplete Spinal Cord Injury, run by University of Colorado, Boulder at 2 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

The goal of this study is to examine the effect of repetitive acute intermittent hypoxia on motor learning abilities in able-bodied individuals for subsequent study in individuals with incomplete spinal cord injury. Read more about this study

Who is it for?: Ages 18 to 70 yearsHealthy volunteers can take part
Conditions the study is for: Incomplete Spinal Cord Injury
What is being tested?: Acute Intermittent Hypoxia
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 56 participants
Where: 2 sitesUnited States
Study dates: 27 May 2022to 24 Feb 2025
Phase: Interventional
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 70 years
All sexes
Healthy volunteers accepted
Adult, Older adult

Who may be able to join

18 to 70 years old (the latter to reduce likelihood of heart disease);
Medically stable with medical clearance from physician to participate;
Motor-incomplete spinal cord injuries at or below C2 and at or above L5;
AIS A-D at initial screen, or other non-traumatic spinal cord injury disorders (e.g. multiple sclerosis, ALS, tumors, acute transverse myelitis, etc.);
More than 1 year since iSCI to minimize confounds of spontaneous neurological recovery;
Ability to advance one step overground with or without assistive devices;

Who cannot join

Severe concurrent illness or pain;
Recurrent autonomic dysreflexia;
History of cardiovascular/pulmonary complications;
Concurrent physical therapy;
Pregnant at time of enrollment or planning to become pregnant;
Untreated painful musculoskeletal dysfunction, fracture or pressure sore;

Show all 11Show fewer

History of seizures or epilepsy;
Recurring headaches;
Concussion within the last six months;
Depression or manic disorders
Metal implants in the head, or pacemaker.

Trial locations and contacts

2 sites in 1 country.

United States2 sites

University of Colorado, Anschutz Medical Campus
Aurora, Colorado, 80045
University of Colorado
Boulder, Colorado, 80309

Other trials in United States

About this study

Official title: Examining the Relationship Between Changes in Corticospinal Excitability and Motor Learning After Acute Intermittent Hypoxia in Able-bodied Individuals for Subsequent Study in Individuals With Incomplete Spinal Cord Injury.

Conditions: Incomplete Spinal Cord Injury
Being tested: Acute Intermittent Hypoxia, SHAM Acute Intermittent Hypoxia
Keywords: Spinal Cord Injury, Motor Adaptation, Acute Intermittent Hypoxia
Medical subject headings: Spinal Cord Injuries

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Acute Intermittent HypoxiaOther
5 consecutive days of 15, 1.5 min episodes at 9% O2 (AIH) alternating with 21% O2 at 1 min intervals
SHAM Acute Intermittent HypoxiaOther
5 consecutive days of 15, 1.5 min episodes at 21% O2 (SHAM AIH) alternating with 21% O2 at 1 min intervals

Study groups in NCT05341466
Study group	Role	What they receive
Repetitive Acute Intermittent Hypoxia	Experimental	5 consecutive days of 15, 1.5 min episodes at 9% O2 (AIH) alternating with 21% O2 at 1 min intervals Receives: Other: Acute Intermittent Hypoxia
SHAM Acute Intermittent Hypoxia	Sham comparator	5 consecutive days of 15, 1.5 min episodes at 21% O2 (SHAM AIH) alternating with 21% O2 at 1 min intervals Receives: Other: SHAM Acute Intermittent Hypoxia
Control	No intervention	The control group received no AIH exposure.

What is being measured

The primary outcome is the main question the study is designed to answer.

Change in Corticospinal Excitability
Transcranial magnetic stimulation (TMS) can be applied over the primary motor cortex to examine changes in corticospinal excitability. The downstream muscle activation can be recorded with surface EMG as a motor-evoked potential (MEP). The peak-to-peak MEP amplitude (mV) is as an index of corticospinal excitability.
A randomized sequence of TMS intensities can be applied over the primary motor cortex, ranging from 90-140% of the participants' resting motor threshold (RMT). The mean MEP amplitude will be plotted against the corresponding stimulation intensity to produce the recruitment curve. The area under the recruitment curve is an additional index of corticospinal excitability (mV/% RMT).
Measured: We will measure TMS before the start of 5 consecutive days of AIH or SHAM treatment. We will measure TMS within 24 hours of the final treatment.
Step Length Asymmetry
Step length asymmetry will be quantified as the ratio of the normalized difference in step lengths between the fast and slow legs during split-belt motor adaptation: (Fast leg - Slow leg step length) / (Fast leg + Slow leg step length).
Measured: We will compare asymmetry 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).
Step Time Asymmetry
Step time asymmetry will be quantified as the ratio of the normalized difference in step times between the fast and slow legs during split-belt motor adaptation: (Fast leg - Slow leg step time) / (Fast leg + Slow leg step time).
Measured: We will compare asymmetry 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).
Net Metabolic Power
Using expired gas analyses, we will calculate net metabolic power by inputting steady-state values for V̇O₂ and V̇CO₂ into standard regression equations (W), subtracting resting values, and normalizing the result to each participant's body weight (kg).
Measured: We will compare net metabolic power 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

27 May 202224 Feb 2025

First posted22 Apr 2022
Study start27 May 2022
Primary completion31 Jan 2025
Study completion24 Feb 2025

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (2)Papers the sponsor has linked to this study.
Other trials for Incomplete Spinal Cord InjuryStudies 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: Interventional
Phase: Phase N/A
Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Model description: This study design is twofold. The first study examines the effects of AIH on motor learning using an AIH group and a control group (total N = 30). The second part of this study examines corticospinal indices of motor learning using an AIH group and a SHAM group (i.e., blinded normoxia; total N = 26).
Masking: Double blind
Who is masked: Participant, Investigator
Enrolment: 56 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT05341466
Sponsor's protocol ID: 21-3980
Other IDs: P2CHD086844
Status last verified: Apr 2025
First submitted: 11 Apr 2022
Last updated: 14 May 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: No

Publications

Bogard AT, Hembree TG, Pollet AK, Smith AC, Ryder SC, Marzloff GE, Tan AQ. Intermittent hypoxia-induced enhancements in corticospinal excitability predict gains in motor learning and metabolic efficiency. Sci Rep. 2025 Feb 24;15(1):6614. doi: 10.1038/s41598-025-90890-8.
PubMed 39994358
Bogard AT, Hemmerle MR, Smith AC, Tan AQ. Enhanced motor learning and motor savings after acute intermittent hypoxia are associated with a reduction in metabolic cost. J Physiol. 2024 Nov;602(21):5879-5899. doi: 10.1113/JP285425. Epub 2023 Nov 20.
PubMed 37983629

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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All Incomplete Spinal Cord Injury trials

Study at a glance

From the registry record, last updated by the sponsor on 14 May 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Examining the Relationship Between Changes in Corticospinal Excitability and Motor Learning After Acute Intermittent Hypoxia in Able-bodied Individuals for Subsequent Study in Individuals With Incomplete Spinal Cord Injury.
ClinicalTrials.gov ID: NCT05341466
Acronym / sponsor ID: 21-3980
Conditions: Incomplete Spinal Cord Injury
Keywords: Spinal Cord Injury, Motor Adaptation, Acute Intermittent Hypoxia
Study type: Interventional
Recruitment status: Completed
Enrolment: 56 participants (actual)
Lead sponsor: University of Colorado, BoulderUniversity, hospital or other
Collaborators: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), University of Colorado, Denver, Medical University of South Carolina
Study start: 27 May 2022 (actual)
Primary completion: 31 Jan 2025 (actual)
Study completion: 24 Feb 2025 (actual)
First posted: 22 Apr 2022 (actual)
Results: Posted 14 May 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: Double blind (participant, investigator)
Number of arms: 3
Model description: This study design is twofold. The first study examines the effects of AIH on motor learning using an AIH group and a control group (total N = 30). The second part of this study examines corticospinal indices of motor learning using an AIH group and a SHAM group (i.e., blinded normoxia; total N = 26).

Arm	Type	Receives
Repetitive Acute Intermittent Hypoxia	Experimental	Other: Acute Intermittent Hypoxia5 consecutive days of 15, 1.5 min episodes at 9% O2 (AIH) alternating with 21% O2 at 1 min intervals
SHAM Acute Intermittent Hypoxia	Sham comparator	Other: SHAM Acute Intermittent Hypoxia5 consecutive days of 15, 1.5 min episodes at 21% O2 (SHAM AIH) alternating with 21% O2 at 1 min intervals
Control	No intervention	–The control group received no AIH exposure.

Who may qualify

Ages: 18 to 70 years
Sex: All
Healthy volunteers: Accepted
Age groups: Adult, Older adult

Key inclusion criteria (6 listed)

18 to 70 years old (the latter to reduce likelihood of heart disease);
Medically stable with medical clearance from physician to participate;
Motor-incomplete spinal cord injuries at or below C2 and at or above L5;
AIS A-D at initial screen, or other non-traumatic spinal cord injury disorders (e.g. multiple sclerosis, ALS, tumors, acute transverse myelitis, etc.);
More than 1 year since iSCI to minimize confounds of spontaneous neurological recovery;

Key exclusion criteria (11 listed)

Severe concurrent illness or pain;
Recurrent autonomic dysreflexia;
History of cardiovascular/pulmonary complications;
Concurrent physical therapy;
Pregnant at time of enrollment or planning to become pregnant;

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
Acute Intermittent Hypoxia5 consecutive days of 15, 1.5 min episodes at 9% O2 (AIH) alternating with 21% O2 at 1 min intervals	Other	Repetitive Acute Intermittent Hypoxia
SHAM Acute Intermittent Hypoxia5 consecutive days of 15, 1.5 min episodes at 21% O2 (SHAM AIH) alternating with 21% O2 at 1 min intervals	Other	SHAM Acute Intermittent Hypoxia

Primary outcome

Change in Corticospinal Excitability
Time frame: We will measure TMS before the start of 5 consecutive days of AIH or SHAM treatment. We will measure TMS within 24 hours of the final treatment.
Transcranial magnetic stimulation (TMS) can be applied over the primary motor cortex to examine changes in corticospinal excitability. The downstream muscle activation can be recorded with surface EMG as a motor-evoked potential (MEP). The peak-to-peak MEP amplitude (mV) is as an index of corticospinal excitability. A randomized sequence of TMS intensities can be applied over the primary motor cortex, ranging from 90-140% of the participants' resting motor threshold (RMT). The mean MEP amplitude will be plotted against the corresponding stimulation intensity to produce the recruitment curve. The area under the recruitment curve is an additional index of corticospinal excitability (mV/% RMT).
Step Length Asymmetry
Time frame: We will compare asymmetry 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).
Step length asymmetry will be quantified as the ratio of the normalized difference in step lengths between the fast and slow legs during split-belt motor adaptation: (Fast leg - Slow leg step length) / (Fast leg + Slow leg step length).
Step Time Asymmetry
Time frame: We will compare asymmetry 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).
Step time asymmetry will be quantified as the ratio of the normalized difference in step times between the fast and slow legs during split-belt motor adaptation: (Fast leg - Slow leg step time) / (Fast leg + Slow leg step time).
Net Metabolic Power
Time frame: We will compare net metabolic power 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).
Using expired gas analyses, we will calculate net metabolic power by inputting steady-state values for V̇O₂ and V̇CO₂ into standard regression equations (W), subtracting resting values, and normalizing the result to each participant's body weight (kg).

Results and safety

Results posted to the registry on 14 May 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Repetitive Acute Intermittent Hypoxia	28	28
SHAM Acute Intermittent Hypoxia	13	13
Control Group	15	15

Primary outcome: Change in Corticospinal Excitability

Time frame: We will measure TMS before the start of 5 consecutive days of AIH or SHAM treatment. We will measure TMS within 24 hours of the final treatment.. Mean (Standard Error). Unit: mV*percentage of RMT

Measure	Repetitive Acute Intermittent Hypoxia n = 13	SHAM Acute Intermittent Hypoxia n = 13
Value	0.528 (0.188)	0.132 (0.188)

Repetitive Acute Intermittent Hypoxia vs SHAM Acute Intermittent Hypoxia: Mean Difference (Net): 0.528, p = 0.0098, Mixed Models Analysis
Repetitive Acute Intermittent Hypoxia: Adjusted R-squared: 0.418, p = 0.014, Regression, Linear
Repetitive Acute Intermittent Hypoxia: Adjusted R-squared: 0.496, p = 0.006, Regression, Linear

Population analysed: A total of 56 participants were enrolled for this study: Part 1: Motor Learning (N = 30; AIH group + control group) \& Part 2: Corticospinal Indices of Motor Learning (N = 36; AIH group + SHAM group). Changes in corticospinal excitability reflect the results from Part 2 of the study, which consisted of an AIH group and a SHAM group (i.e., blinded normoxia).

Primary outcome: Step Length Asymmetry

Time frame: We will compare asymmetry 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).. Mean (Standard Deviation). Unit: Ratio

Measure	Repetitive Acute Intermittent Hypoxia n = 15	Control Group n = 15
Value	-0.052 (0.023)	-0.0478 (0.024)

Repetitive Acute Intermittent Hypoxia vs Control Group: Median Difference (Net): -0.0042, p = 0.744, ANOVA

Population analysed: A total of 56 participants were enrolled for this study: Part 1: Motor Learning (N = 30; AIH group + control group) \& Part 2: Corticospinal Indices of Motor Learning (N = 36; AIH group + SHAM group). Changes in step length asymmetry reflect the results from Part 1 of the study, which consisted of an AIH group and a control group.

Primary outcome: Step Time Asymmetry

Time frame: We will compare asymmetry 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).. Mean (Standard Deviation). Unit: Ratio

Measure	Repetitive Acute Intermittent Hypoxia n = 15	Control Group n = 15
Value	0.0781 (0.021)	0.0681 (0.0252)

Repetitive Acute Intermittent Hypoxia vs Control Group: Mean Difference (Net): 0.01, p = 0.269, ANOVA

Population analysed: A total of 56 participants were enrolled for this study: Part 1: Motor Learning (N = 30; AIH group + control group) \& Part 2: Corticospinal Indices of Motor Learning (N = 36; AIH group + SHAM group). Changes in step time asymmetry reflect the results from Part 1 of the study, which consisted of an AIH group and a control group.

Primary outcome: Net Metabolic Power

Time frame: We will compare net metabolic power 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).. Mean (Standard Deviation). Unit: W/kg

Measure	Repetitive Acute Intermittent Hypoxia n = 15	Control Group n = 15
Value	3.87 (0.397)	4.27 (0.766)

Repetitive Acute Intermittent Hypoxia vs Control Group: Median Difference (Net): -0.4, p = 0.020, ANOVA

Population analysed: A total of 56 participants were enrolled for this study: Part 1: Motor Learning (N = 30; AIH group + control group) \& Part 2: Corticospinal Indices of Motor Learning (N = 36; AIH group + SHAM group). Changes in net metabolic power reflect the results from Part 1 of the study, which consisted of an AIH group and a control group. One participant was excluded from metabolic analysis due to RER \> 1.0, violating assumption that primarily oxidative pathways were being utilized.

Adverse events

Time frame: 2 years 6 months. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Repetitive Acute Intermittent Hypoxia	0 of 28 (0%)	0 of 28 (0%)	0 of 28
Control Group	0 of 15 (0%)	0 of 15 (0%)	0 of 15
SHAM Acute Intermittent Hypoxia	0 of 13 (0%)	0 of 13 (0%)	0 of 13

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 14 May 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Results publication: PubMed 39994358Bogard AT, Hembree TG, Pollet AK, Smith AC, Ryder SC, Marzloff GE, Tan AQ. Intermittent hypoxia-induced enhancements in corticospinal excitability predict gains in motor learning and metabolic efficiency. Sci Rep. 2025 Feb 24;15(1):6614. doi: 10.1038/s41598-025-90890-8.
Results publication: PubMed 37983629Bogard AT, Hemmerle MR, Smith AC, Tan AQ. Enhanced motor learning and motor savings after acute intermittent hypoxia are associated with a reduction in metabolic cost. J Physiol. 2024 Nov;602(21):5879-5899. doi: 10.1113/JP285425. Epub 2023 Nov 20.
Related InfoLink provided by the sponsor.
Related InfoLink provided by the sponsor.

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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. This study is not recruiting at the moment.

The record lists no contact. Use the official record to reach the sponsor.

2 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A study testing Acute Intermittent Hypoxia in people with Incomplete Spinal Cord Injury, run by University of Colorado, Boulder at 2 sites in United States.

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 6 inclusion and 11 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: finished, as of the sponsor's last update on 14 May 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 2 sites in United States. 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.

Are results available for this study?

Yes. Results are posted in the registry (first posted 14 May 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change in Corticospinal Excitability (time frame: We will measure TMS before the start of 5 consecutive days of AIH or SHAM treatment. We will measure TMS within 24 hours of the final treatment.). The study lists 4 primary outcomes in all. 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 NCT05341466, which also lists 2 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 14 May 2025.