Intermittent Hypoxia and Inspiratory Threshold Loading to Enhance Inspiratory Muscle Function
Condition: Intermittent Hypoxia
MeSH terms: Respiratory Aspiration; Hypoxia
Study type: Interventional

Summary: 
      Rehabilitation approaches introduce a stimulus to a motor system, with the goal to enhance
      motor function to patients. For example, exposure to brief and intermittent episodes of mild
      hypoxia has shown to strengthen synaptic pathways to respiratory and skeletal muscle motor
      neurons. In humans with spinal cord injury, exposure to intermittent hypoxia (IH) alone or in
      combination with rehabilitative strategies has shown enhanced motor function. Another
      strategy known as inspiratory threshold loading, which involves breathing against pressure
      threshold loads, results in improved inspiratory muscle strength. Although there is evidence
      supporting the use of IH alone or in combination with other rehabilitative strategies in
      improving motor function in humans, the impact of exposure to IH or IH with inspiratory
      threshold loading on inspiratory muscle function and ventilation in humans is unknown.
    

Detailed description: 
      Investigators will test whether exposure to IH alone and in combination with inspiratory
      threshold loading (ITL) will result in increased inspiratory muscle strength and ventilation.

      Investigators will use a Latin square, repeated measures design which will consist of 12
      subjects participating in four experimental conditions.There will be an interval of 1 week
      between each of the four conditions, which will serve as a washout period.

      At the end of each of the 5 sessions, the subjects will rest in a reclining chair for 15
      minutes while their heart rate, blood pressure, oxygen saturation and breathing are
      monitored. Subjects that have a blood systolic blood pressure > 140 or diastolic pressure >
      90 or SPO2 < 92% will be asked to remain in the laboratory for 15 additional minutes and the
      vital signs will be repeated. If the blood pressure and/or peripheral capillary oxygen
      saturation (SPO2) remain outside of the criteria mentioned above, the subject will be
      instructed to seek assessment by their health provider and the incident will be reported to
      the Institutional Review Board. Subjects will also be asked to report any discomfort.
    

Intervention name(s): Intermittent Hypoxia; Inspiratory Threshold Loading; Sham Intermittent Hypoxia
Intervention type(s): Other; Other; Other
Intervention description(s): A single session of IH will last for 45 minutes and will consist of alternating phases of hypoxia(FiO2 :9%-11%) and hyperoxia (FiO2 :22%-38%).
Each hypoxic interval will last for 2 minutes whereas the hyperoxic interval lasts for 1 minute each (15, two-minute episodes of hypoxia and 15, one-minute episodes of hyperoxia).; Subjects will undergo inspiratory threshold loading using a commercially available Threshold IMT device (Power breathe®). ITL will be administered at an intensity of 80% of the individual's maximal inspiratory pressure (MIP). The subjects will be instructed to take 10 deep, forceful breaths through the threshold device followed by at least 2 minutes of rest. The process will be repeated 4 more times for a total of 5 sets of 10 breaths each.; Subjects will be exposed to a session of sham Intermittent hypoxia.This will consist of breathing room air for 45 minutes through a hypoxicator.
Other intervention name(s): IH; ITL; Normoxia
Allocation: Randomized
Intervention model: Factorial Assignment
Intervention model description: Latin square, repeated measures design to study the effects of IH administered alone and in combination with inspiratory threshold loading on the above stated respiratory parameters.
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: Inspiratory threshold loading