Overview

This trial is active, not recruiting.

Conditions healthy males, neuromuscular function
Treatments indomethacin, placebo
Phase phase 4
Sponsor Brock University
Start date April 2013
End date June 2015
Trial size 10 participants
Trial identifier NCT01830335, 12-167

Summary

Environmental stress, such as low oxygen availability (hypoxia), has been associated with impaired neuromuscular performance; however, the mechanisms associated with these performance decrements remain unclear. While the majority of research suggests that the observed fatigue is related to the central nervous system, the influence of changes in cerebral blood flow (CBF) and associated changes in cerebral pH (partial pressure of carbon dioxide; PCO2) remains unexamined. In response to hypoxic stress, humans hyperventilate to maintain oxygen consumption, resulting in a hypocapnia mediated decrease in CBF and cerebral alkalosis (decreased PCO2). Previous research suggests that hyperventilation induces changes in neural excitability and synaptic transmission; however, it remains unclear if these changes are related to hypocapnia mediated decrease in CBF or cerebral alkalosis or both.

The purpose of the proposed research program is to examine the influence of changes in CBF and cerebral alkalosis on neuromuscular function during environmental stress. The research program will consist of 2 separate projects, summarized below in a table outlining the proposed protocols and resultant physiological manipulations. During each manipulation, neuromuscular function will be evaluated and compared to baseline (normoxic) conditions using a repeated measures design.

The research program will consist of 2 separate projects. Project 1 will examine the changes in CBF and alkalosis by using (a) indomethacin (decrease CBF; no change PCO2) and (b) hypocapnia (decrease CBF; decrease PCO2). Using a similar experimental design, Project 2 will examine the change in CBF and alkalosis during hypoxia by using (a) poikilocapnic hypoxia (decrease PO2; decrease CBF; decrease PCO2), (b) isocapnic hypoxia (decrease PO2; no change CBF; no change PCO2) and (c) isocapnic hypoxia + indomethacin (decrease PO2; decrease CBF; no change PCO2). During each manipulation, neuromuscular function will be evaluated and compared to baseline (normoxic) conditions using a repeated measures design.

Therefore, Project 1 will examine the separate and combined effect of changes in CBF and cerebral alkalosis on neuromuscular function independent of environmental manipulations. Subsequently, Project 2 will examine neuromuscular function during hypoxia while controlling CBF and cerebral alkalosis. It is hypothesized that changes in PCO2 and therefore, changes in cerebral alkalosis will contribute to neuromuscular fatigue independent of changes in CBF and oxygen availability.

United States No locations recruiting
Other Countries No locations recruiting

Study Design

Allocation randomized
Intervention model single group assignment
Masking single blind (subject)
Primary purpose basic science
Arm
(Experimental)
Indomethacin 1.2 mg kg 1 dose
indomethacin
(Placebo Comparator)
flour capsule
placebo

Primary Outcomes

Measure
Resting motor threshold
time frame: Change from baseline 90-minutes
H-Reflex Amplitude
time frame: Change from baseline 90-minutes
Maximal Voluntary Contraction
time frame: Change from baseline 90-minutes
H-reflex latency
time frame: Change from baseline 90-minutes
Voluntary Activation
time frame: Change from baseline 90-minutes

Secondary Outcomes

Measure
Middle Cerebral Artery Blood Flow Velocity
time frame: Change from baseline 90-minutes
Brachial Artery Blood flow
time frame: Change from baseline 90-minutes
Internal Carotid Artery Blood Flow
time frame: Change from baseline 90-minutes
Blood pressure
time frame: Change from baseline 90-minutes
Pulse oximetry
time frame: Change from baseline 90-minutes
Heart Rate
time frame: Change from baseline 90-minutes
End-Tidal Gas Concentrations
time frame: Change from baseline 90-minutes

Eligibility Criteria

Male participants from 18 years up to 25 years old.

Inclusion Criteria: - 18 to 25 yrs old; healthy males Exclusion Criteria: - diagnosed medical condition; NSAID allergy; smoker; high altitude exposure; implants

Additional Information

Official title The Influence of Cerebral Blood Flow and Alkalosis on Neuromuscular Function During Environmental Stress
Principal investigator Stephen Cheung, PhD
Trial information was received from ClinicalTrials.gov and was last updated in January 2016.
Information provided to ClinicalTrials.gov by Brock University.