The relationship between respiratory exchange ratio, plasma lactate and muscle lactate concentrations in exercising horses using a valved gas collection system.
Abstract: A valved gas collection system for horses was validated, then used to examine the relationship between the respiratory exchange ratio (RER), and plasma and muscle lactate in exercising horses. Four healthy Standardbred horses were trained to breathe through the apparatus while exercising on a treadmill. Comparisons of arterial blood gas tensions were made at 3 work levels for each horse, without (control), and with the gas collection system present. At the highest work level, the arterial oxygen tension (PaO2) was significantly lower (P < 0.05), and the arterial carbon dioxide tension (PaCO2) was significantly higher (P < 0.05), than control levels when the apparatus was present; however arterial oxygen content remained unchanged. The horses completed a standardized incremental treadmill test on 4 occasions to determine the repeatability of measurements of oxygen consumption (VO2), carbon dioxide production (VCO2), inspired minute ventilation (VI), respiratory exchange ratio (RER), ventilatory equivalent for oxygen (VI/VO2), tidal volume (VT), and ventilatory frequency (VF). All gas exchange and respiratory measurements showed good reproducibility with the mean coefficient of variation of the 4 horses ranging from 3.8 to 12%. We examined the relationship between 3 indices of energy metabolism in horses performing treadmill exercise: respiratory exchange ratio (RER), central venous plasma and muscle lactate concentrations. A relationship between RER and plasma lactate concentration was established. To compare muscle and plasma lactate concentrations, the horses completed a discontinuous exercise test without the gas collection apparatus present. Significant relationships (P < 0.05), between plasma lactate concentration and RER, and between plasma and muscle lactate concentration, were described for each horse. The valved gas collection system produced a measurable but tolerable degree of interference to respiration, and provided reproducible measurements of gas exchange and ventilatory measurements. It was concluded that measurements of both gas exchange and blood lactate may be used to indicate increased glycolytic activity within exercising skeletal muscle.
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The research paper is focused on exploring the relationship between respiratory exchange ratio (RER), plasma lactate, and muscle lactate in exercising horses using a valved gas collection system. The study further validates the use of this system for such analysis.
Methodology
The study was conducted on four healthy Standardbred horses which were trained to breathe through a specifically designed apparatus while exercising on a treadmill.
A comparison of arterial blood gas tensions was performed at three different work levels for each horse, without (control) and with the gas collection system.
At the highest work level, arterial oxygen tension was found to be lower while the arterial carbon dioxide tension was higher than control levels when the apparatus was in use. However, the arterial oxygen content remained constant.
The horses underwent a standardized incremental treadmill test four times to check the repeated measurements accuracy of oxygen consumption, carbon dioxide production, inspired minute ventilation, tidal volume, and ventilatory frequency along with RER.
Findings
The study revealed good reproducibility with all the gas exchange and respiratory measurements.
The relationship between three energy metabolism indices in horses, i.e., RER, plasma lactate, and muscle lactate concentrations, was studied.
A link was found between RER and plasma lactate concentration.
To compare muscle and plasma lactate concentrations, the horses underwent a discontinuous exercise test without the gas collection apparatus.
Significant relationships were established between plasma lactate concentration and RER, as well as between plasma and muscle lactate concentration for each horse.
Conclusion
The study concluded that the valved gas collection system interferes minimally with respiration and provides productive measurements of gas exchange and ventilatory measurements.
It further established that both gas exchange and blood lactate measurements can be used to indicate increased glycolytic activity within exercising skeletal muscle of horses.
Cite This Article
APA
Gauvreau GM, Young SS, Staempfli H, McCutcheon LJ, Wilson BA, McDonell WN.
(1996).
The relationship between respiratory exchange ratio, plasma lactate and muscle lactate concentrations in exercising horses using a valved gas collection system.
Can J Vet Res, 60(3), 161-171.
Wasserman K, Beaver WL, Whipp BJ. Mechanisms and patterns of blood lactate increase during exercise in man.. Med Sci Sports Exerc 1986 Jun;18(3):344-52.