Diaphragmatic energetics during prolonged exhaustive exercise.
Abstract: The present study was carried out to examine diaphragmatic O2 extraction and lactate and ammonia production during prolonged exhaustive exercise. Experiments were performed on nine healthy exercise-conditioned ponies in which catheters had been implanted in the phrenic vein previously. Blood-gas variables and lactate and ammonia concentrations were determined on simultaneously obtained arterial and phrenic-venous blood samples at rest and during 30 min of exertion at 15 mph + 7% grade (heart rate, 200 beats/min; approximately 90% of maximum). Arterial O2 tension and saturation were maintained near resting value but CO2 tension decreased markedly with exercise, and because of increased hemoglobin concentration, arterial O2 content rose. Concomitantly, phrenic venous O2 tension, saturation and content decreased markedly (23.6 +/- 1 mm Hg, 24.5 +/- 2%, 5.2 +/- 0.3 ml/dl at 3 min of exertion) and significant fluctuations did not occur as exercise duration progressed to 30 min. Diaphragmatic arteriovenous O2 content difference and O2 extraction rose from 4 +/- 0.3 to 16 +/- 0.5 ml/dl and from 30 +/- 3 to 75 +/- 1% at 3 min of exercise, and significant deviations did not occur as exercise duration progressed. Arterial lactate and ammonia levels increased during exercise, indicating their release from working limb muscles. Phrenic-venous values of lactate and ammonia did not exceed arterial values. Ponies sweated profusely and were unable to keep up with the belt speed in the last 4 to 5 min of exercise. Constancy of phrenic arteriovenous O2 content difference in exercise indicated ability to adjust perfusion in diaphragm so as to adequately meet its O2 needs.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1991-08-01 PubMed ID: 1859069DOI: 10.1164/ajrccm/144.2.415Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the ability of the diaphragm, a primary muscle involved in breathing, to manage oxygen and produce lactate and ammonia during intense, long-lasting exercise using nine trained ponies as subjects.
Methodology
- The researchers chose nine healthy, exercise-adapted ponies for the experiment. These ponies had catheters previously placed in their phrenic vein – a vein that takes deoxygenated blood from the diaphragm back to the heart.
- Through these catheters, the researchers were able to determine blood variables, as well as lactate and ammonia concentrations by drawing blood samples at rest and during 30 minutes of intense exercise. The exercise regime was set at a speed of 15 mph at a 7% incline, simulating exhaustive performance.
Findings
- The study showed that the oxygen tension and saturation in the ponies’ arteries remained stable at resting values throughout the exercise, but carbon dioxide levels decreased notably.
- Despite the intense exercise, the concentration of hemoglobin, the protein in red blood cells that carries oxygen, increased. This increase resulted in a higher arterial oxygen content.
- On the other hand, phrenic venous oxygen tension, saturation, and content declined sharply and remained constant irrespective of the intensity or duration of the exercise. The phrenic vein carries deoxygenated blood away from the diaphragm and back to the heart.
- The researchers found a significant increase of lactate and ammonia in the ponies’ arterial blood during exercise, suggesting these substances were being released from the exercising muscles.
- However, the values of lactate and ammonia in the phrenic vein did not exceed their values in the arterial blood. This indicates that production of these substances in the diaphragm was not significantly contributing to the circulating blood lactate and ammonia levels.
Conclusion
- The study confirmed that the diaphragm in ponies could adjust its blood flow to meet its oxygen needs even during intensive and prolonged exercise. Despite rises in arterial lactate and ammonia, which suggests muscle usage, these increases were not seen in the blood from the diaphragm. This might indicate that the diaphragm isn’t significantly contributing to the production of these substances during laborious exercise.
Cite This Article
APA
Manohar M, Hassan AS.
(1991).
Diaphragmatic energetics during prolonged exhaustive exercise.
Am Rev Respir Dis, 144(2), 415-418.
https://doi.org/10.1164/ajrccm/144.2.415 Publication
Researcher Affiliations
- Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois, Urbana-Champaign 61801.
MeSH Terms
- Aerobiosis / physiology
- Ammonia / metabolism
- Animals
- Diaphragm / physiology
- Heart Rate / physiology
- Horses / physiology
- Lactates / metabolism
- Lactic Acid
- Oxygen Consumption / physiology
- Physical Conditioning, Animal
- Physical Endurance / physiology
- Physical Exertion / physiology
- Work of Breathing / physiology
Citations
This article has been cited 1 times.- McConnell AK, Sharpe GR. The effect of inspiratory muscle training upon maximum lactate steady-state and blood lactate concentration. Eur J Appl Physiol 2005 Jun;94(3):277-84.
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