Date of Award

Spring 1-1-2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Integrative Physiology

First Advisor

William C. Byrnes,

Second Advisor

Robert S. Mazzeo

Third Advisor

Rodger Kram

Abstract

Carbon monoxide (CO) interacts with many physiological systems, similar in effect to nitric oxide (NO). Manipulating the NO synthesis pathway through dietary nitrate supplementation decreases oxygen consumption and energy expenditure during submaximal exercise in moderately trained individuals, but the adaptations and acute effects from low-dose CO administration have not been described in full. Our purpose was to quantify any changes to oxidative metabolism, measured by oxygen consumption and energy expenditure during submaximal exercise. Nine recreationally active individuals (ages 20–32 years) familiar with cycling exercise completed four graded submaximal exercise tests, with each test occurring during a separate visit. Subjects received a low dose (1.2 mL·kg-1 body mass) of CO or room-air placebo in a randomized, subject-blind fashion prior to exercise during the first visit in order to study their responses to acute administration. This exercise task was repeated 24 hours later (visit 2) to assess any lasting effects. Subjects returned to the lab after a washout period (2–10 days) to repeat the study procedures with the alternate dose (visits 3 and 4). Acute CO administration did not affect oxygen consumption or energy expenditure during submaximal exercise. However, significant increases in heart rate (P = 0.028; ~4 bpm) and perceived exertion (P = 0.036; 0.36 units) were observed across workloads after acute CO inhalation. Further, the increase in blood lactate concentration from rest after acute CO inhalation was higher than after the placebo intervention at the two highest work rates. No changes to the respiratory exchange ratio or ventilation were observed between visits. In conclusion, acute low-dose CO inhalation temporarily increased heart rate, blood lactate, and perceived effort during submaximal exercise. However, a low-dose of CO had no effects on the energetics of submaximal exercise immediately or 24 hours following its administration.

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