Type III/IV Muscle Afferents in Airway and Thermoregulatory Responses
Northern Arizona University
Summary
Exercise places serious demands on the body. These demands are fundamentally caused by increases in oxygen demand and the consequent increase in body temperature. These demands are met by several physiological responses, including increases in heart rate, blood pressure, breathing and blood flow. These responses must be proportional to the increase in demand and some signal must relay information from the muscle to the brain. Group III/IV afferents do just this. They relay information about the muscle (movement, temperature, acidity, etc.) up to the brain so that appropriate responses are mounted. There is strong evidence in animals that group III/IV afferents play a key role in making breathing easier (decreasing airway resistance) and initiating sweating and blood flow responses. There has been no research on the role of group III/IV afferents on these fundamental exercise responses in humans. The investigators propose to isolate the role of group III/IV afferents on regulate airway resistance, sweating and blood flow responses to exercise in humans.
Description
Group III/IV afferents are nerves that relay information from the muscles to the central nervous system. This afferent activity acts as negative feedback to minimize the overall strain placed on muscles . Without this negative feedback, locomotor muscles become damaged during intense exercise. It is well-established that group III/IV afferents are required for normal breathing and blood pressure responses to physical activity. In certain disease states, such as chronic obstructive pulmonary disease, heart failure and hypertension, group III/IV afferents become dysfunctional and lead to exercis…
Eligibility
- Age range
- 18–40 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion Criteria: * regularly physically active as determined via questionnaires (Par-Q \& You) * maximal aerobic power 30 mL/min/kg (female), 40 mL/kg/min (male) Exclusion Criteria: * current smokers * acute bronchial asthma * diabetics * chronic back pain * peripheral neuropathy * chronic obstructive airway or status asthmaticus * obese (body mass index \> 30 kg/m2) * convulsive disorders * requiring daily medications that may affect responses to exercise (e.g. anti-hypertensive, anti-arrhythmogenics, blood thinners) * history of drug abuse * history of disease/dysfunction that could ca…
Interventions
- DrugEXERCISE TRAINING WITH OR WITHOUT MEDICATION
Cycling exercise with group III/IV afferent feedback blocked via drug
Location
- Northern Arizona UniversityFlagstaff, Arizona