Independence of exercise hypocapnia and limb movement frequency in ponies.
Abstract: The objective of this study was to determine whether changes in limb motion per se influence arterial CO2 partial pressure (PaCO2) during muscular exercise in ponies. Fifteen ponies were studied at rest and during 8 min of treadmill exercise when the work load was constant or when the work load was increased after the 4th min. Five different treadmill settings were selected to provide for a range of metabolic rate achieved with primary changes in either speed or grade (1.8 mph at 3, 8, and 15% grade; or 3 and 6 mph at 3% grade). The ponies exercised either on all four legs or on only the hindlegs. Step frequencies were 49, 66, and 99 at 1.8, 3, and 6 mph, respectively. During all work tasks PaCO2 decreased maximally 30-60 s after the work task was initiated from rest or from a less intense level of exercise. This nadir in PaCO2 was followed by some recovery with a stable level of mild hypocapnia (delta PaCO2) maintained after 3-4 min. The delta PaCO2 was directly related to O2 consumption (VO2) (P less than 0.01). The delta PaCO2-VO2 regression slopes did not differ between speed and grade VO2 changes nor between four- and two-legged exercise (P greater than 0.10). These data suggest that neither frequency of limb movement nor the number of limbs moving are major factors in the PaCO2 (and alveolar ventilation) response to exercise in ponies. We conclude that the apparent difference in PaCO2 regulation during exercise between ponies (hypocapnia) and humans (isocapnia during walking and bicycling) is not related to a species difference in the number of limbs employed in the exercise task.
Publication Date: 1984-12-01 PubMed ID: 6439708DOI: 10.1152/jappl.1984.57.6.1885Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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This study aimed to find out if changes in limb movement during exercise impacts levels of arterial carbon dioxide (PaCO2) in ponies. The researchers found that the frequency of limb movement or the number of limbs moving did not significantly affect PaCO2 levels during exercise, suggesting that the difference in PaCO2 regulation between ponies and humans during exercise is not due to the number of limbs used.
Objective and Methodology
- The research aimed to examine whether changes in limb motion independently influence arterial carbon dioxide (PaCO2) during muscle exercise in ponies.
- A total of 15 ponies were studied both at rest and during 8 minutes of treadmill exercise. The workout load was either kept constant or intensified after the 4th minute.
- Five different treadmill settings were used to offer a range of metabolic rates achieved primarily by speed or grade adjustments.
- The ponies exercised either on all four legs or just the hindlegs. The step frequencies were set at 49, 66, and 99 for 1.8, 3, and 6 mph, respectively.
Key Findings
- Across all exercise tasks, there was a swift decrease in PaCO2 levels, usually within 30-60 seconds after the onset of exercise. This was followed by a slight recovery, again stabilizing to milder hypocapnia levels (lower than normal carbon dioxide levels).
- This drop in PaCO2 was directly related to oxygen consumption.
- The change in PaCO2-oxygen consumption regression slopes did not vary significantly between speed and grade changes, or between exercising on all four or just two legs.
Conclusion
- These findings suggest that neither the frequency of limb movement nor the number of limbs used in exercise are major contributors to the PaCO2 (and alveolar ventilation) response in ponies during exercise.
- Thus, the researchers concluded that the apparent discrepancy in how PaCO2 is regulated during exercise in ponies and humans is not due to a species difference in the number of limbs used during the exercise task.
Cite This Article
APA
Forster HV, Pan LG, Bisgard GE, Flynn C, Dorsey SM, Britton MS.
(1984).
Independence of exercise hypocapnia and limb movement frequency in ponies.
J Appl Physiol Respir Environ Exerc Physiol, 57(6), 1885-1893.
https://doi.org/10.1152/jappl.1984.57.6.1885 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Arteries
- Carbon Dioxide / blood
- Carotid Body / physiology
- Chemoreceptor Cells / physiology
- Denervation
- Extremities
- Female
- Heart Rate
- Horses / physiology
- Hydrogen-Ion Concentration
- Hyperventilation / physiopathology
- Male
- Movement
- Oxygen Consumption
- Partial Pressure
- Physical Exertion
- Sodium Cyanide
- Time Factors
Grant Funding
- 15473 / PHS HHS
Citations
This article has been cited 1 times.- Art T, Lekeux P. Pulmonary mechanics during treadmill exercise in race ponies.. Vet Res Commun 1988;12(2-3):245-58.
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