Clinical trial NCT01848665: The Influence of Cerebral Blood Flow and PETCO2 on Neuromuscular Function During Passive Heat Stress
Official title: The Influence of Cerebral Blood Flow and PETCO2 on Neuromuscular Function During Passive Heat Stress
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Healthy Males
Neuromuscular Function
Lead sponsor: Brock University
Sponsor class: OTHER
First posted: 2013-05-07
Enrollment: 8
Sex: MALE
Minimum age (years): 18
Maximum age (years): 45
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: SINGLE_GROUP
Primary purpose: BASIC_SCIENCE

Brief summary: Increased core temperature (hyperthermia) has been associated with impaired neuromuscular performance; however, the mechanisms associated with these performance decrements and their potential synergies 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 alkalosis (estimated by end-tidal partial pressure of carbon dioxide; PETCO2) remains unexamined. In response to hyperthermia, humans hyperventilate as means of heat dissipation, resulting in a hypocapnia (reduced PETCO2) mediated decrease in CBF and consequently, cerebral alkalosis (increased cerebral pH). 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 decreased PETCO2 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 passive heat stress. The research project will consist of 3 separate experimental trials: (a) poikilocapnic hyperthermia (increased core temperature; decrease CBF; decrease PETCO2), (b) isocapnic hyperthermia (increased core temperature; no change CBF; no change PETCO2) and (c) isocapnic hyperthermia + indomethacin (increased core temperature; decrease CBF; no change PETCO2). During each manipulation, neuromuscular function will be evaluated and compared to baseline (normothermic) conditions using a repeated measures design.

It is hypothesized that changes in PETCO2 and therefore, changes in cerebral alkalosis will contribute to neuromuscular fatigue independent of changes in CBF or increases in core temperature.


Eligibility criteria: Inclusion Criteria:

* 18 to 45 yrs old; healthy males

Exclusion Criteria:

* diagnosed medical condition; NSAID allergy; smoker; high altitude exposure; implants

Primary outcomes:
measure: Resting motor threshold
timeFrame: Change from baseline 90-minutes
measure: H-Reflex Amplitude
timeFrame: Change from baseline 90-minutes
measure: Maximal Voluntary Contraction
timeFrame: Change from baseline 90-minutes
measure: H-Reflex latency
timeFrame: Change from baseline 90-minutes
measure: Voluntary Activation
timeFrame: change from baseline 90-minutes
Secondary outcomes:
measure: Middle Cerebral Artery Blood Flow Velocity
timeFrame: Change from baseline 90-minutes
measure: Blood Pressure
timeFrame: Change from baseline 90-minutes
measure: Heart rate
timeFrame: Change from baseline 90-minutes
measure: End-tidal Gas concentrations
timeFrame: change from baseline 90-minutes
measure: Rectal Temperature
timeFrame: change from baseline 90-minutes
measure: Skin Temperature
timeFrame: change from baseline 90-minutes
Other outcomes:
Locations:
city: St Catharines
country: Canada
facility: Brock University
state: Ontario
Study officials:
References: