The Effect of Acute Intermittent Hypoxia on Motor Learning

University of Colorado, Boulder56 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Incomplete Spinal Cord Injury

Interventions

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

Eligibility

Sex: ALLMin age: 18 YearsMax age: 70 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Locations (2)

University of Colorado, Anschutz Medical Campus

Aurora, Colorado, United States

University of Colorado

Boulder, Colorado, United States

Outcomes

Primary Outcomes

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).

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.

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).

Time frame: 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).

Time frame: 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).

Time frame: We will compare net metabolic power 15 minutes after the final AIH treatment to asymmetry following no treatment (control group).

Data from ClinicalTrials.gov

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