Plasma ammonia and lactate responses using incremental and constant speed exercise tests.
Abstract: Plasma NH3, formed during intense exercise, results principally from the deamination of AMP in muscle. Its formation during exercise may be influenced both by the pool of fibres recruited and by changes in the intracellular environment affecting ADP homeostasis. This study compared incremental and constant speed exercise as possible protocols for the investigation of plasma NH3 accumulation with intense exercise. Six trained Thoroughbred horses, one of which had recently been operated on for recurrent laryngeal neuropathy, undertook a step-wise treadmill test with 1 min incremental steps of 6, 8, 10, 11 and 12 m/s (7.5% incline). Two and 4 weeks later horses performed a constant-speed, maximum-exercise tolerance test at 115% VO2max (7.5% incline). Blood samples from the jugular vein were drawn at 20 s intervals in all 3 tests, for plasma NH3 and lactate. There were marked differences between and within horses in their time dependant lactate and NH3 responses to exercise. Three of the 6 horses studied showed a distinct threshold for onset of plasma NH3 accumulation with incremental exercise. Distinct thresholds for the onset of NH3 accumulation were apparent also in 5 of the 6 horses during exercise at constant rate. The present study demonstrates clearly the practicality of measuring NH3 concentration curves, even during a short incremental step test which has the advantage that other measures relating to cardiovascular and respiratory functions can be measured simultaneously.
Publication Date: 2000-02-05 PubMed ID: 10659315DOI: 10.1111/j.2042-3306.1999.tb05281.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates the production of plasma ammonia during intense exercise, comparing its accumulation during incremental and constant speed exercise. It involves six trained Thoroughbred horses, one of which had undergone recent surgery for recurrent laryngeal neuropathy.
Methodology
- The researchers conducted a step-wise treadmill test where the speed was increased incrementally for six Thoroughbred horses. The speed increased in 1-minute intervals, going from 6, 8, 10, 11, and 12 m/s, maintaining a 7.5% incline.
- Two and four weeks later, the horses performed a constant-speed, maximum-exercise tolerance test at 115% of their maximum oxygen uptake (VO2max), maintaining the same incline.
- Blood samples were drawn from the jugular vein every 20 seconds during all three tests to measure plasma ammonia and lactate levels.
Findings
- There were pronounced differences observed between the horses and within the individual horses’ responses to exercise: namely, how lactate and ammonia were produced over time.
- Among the six, three horses revealed a distinct threshold for the onset of plasma ammonia accumulation with incremental exercise.
- Five out of the six horses showed distinct thresholds for ammonia accumulation during the constant speed exercise.
Conclusion
- This study underscores the feasibility of assessing ammonia concentration curves, even during a short incremental step test. This method has a further advantage as it allows for the simultaneous measurement of other factors related to cardiovascular and respiratory functions.
Cite This Article
APA
Harris RC, Harris DB, Dunnett M, Harris PA, Fallowfield J, Naylor JR.
(2000).
Plasma ammonia and lactate responses using incremental and constant speed exercise tests.
Equine Vet J Suppl(30), 546-551.
https://doi.org/10.1111/j.2042-3306.1999.tb05281.x Publication
Researcher Affiliations
- Exercise Research Group (E.R.G.), Royal Veterinary College, University of London, Hatfield, UK.
MeSH Terms
- Ammonia / blood
- Animals
- Female
- Horses / blood
- Lactic Acid / blood
- Male
- Oxygen Consumption
- Physical Conditioning, Animal
- Time Factors
Citations
This article has been cited 3 times.- Vissing J, MacLean DA, Vissing SF, Sander M, Saltin B, Haller RG. The exercise metaboreflex is maintained in the absence of muscle acidosis: insights from muscle microdialysis in humans with McArdle's disease. J Physiol 2001 Dec 1;537(Pt 2):641-9.
- Reemtsma FP, Giers J, Horstmann S, Stoeckle SD, Gehlen H. Concentration Changes in Plasma Amino Acids and Their Metabolites in Eventing Horses During Cross-Country Competitions. Animals (Basel) 2025 Jun 22;15(13).
- Massie S, Bayly W, Ohmura H, Takahashi Y, Mukai K, Léguillette R. Field-training in young two-year-old thoroughbreds: investigating cardiorespiratory adaptations and the presence of exercise induced pulmonary hemorrhage. BMC Vet Res 2024 Apr 26;20(1):159.
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