When Champs get Cramps.
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They’re not getting rid of lactic acid and carbon dioxide efficiently.
An article by Darek Gondor.
Horses of their are born runners, and when their gait quickens to a gallop, they link their breathing to the rhythm hoof beats. During high-intensity exercise, this rhythmic breathing may lower oxygen intake, causing muscles to tire from a buildup of lactic acid and carbon dioxide (CO2) concentration. Now, researchers are developing ways to reduce this buildup and enhance the athletic abilities of these high-performance animals.
To understand how the equine athlete recovers from acid and CO2 buildup in the body, Prof. Henry Staempfli and graduate stu-dent Modest Vengust of the Department of Clinical Studies are looking at CO2 metabo-lism. From the understanding they develop, Vengust will investigate ways to help horses fatigue less and recover faster from strenu-ous workouts.
“When a horse is training, gases such as oxygen and carbon dioxide cycle rapidly through its hard-working muscles,” he says. “Strenuous exercise produces lactic acid in the muscles, which limits the amount of physical activity that can be maintained, creating a situation much like a stitch in your side when running.”
Exercising muscles that don’t receive enough oxygen produce lactic acid and CO2, causing fatigue. To bring the body back to normal, CO2 moves to the bloodstream and is expelled from the lungs. Lactic acid is neu-tralized in various organs, including muscles.
“In general, recovery from lactic acid buildup is momentary and extremely effi-cient when all the body systems are at their best,” says Vengust.
But under certain training circumstances such as repeated overexertion, the recovery process is disturbed. In this situation, acid buildup, called acidosis, further reduces oxygen flow to the muscles, creating long-lasting fatigue — and perhaps permanent muscle damage.
To fully understand how this happens, the researchers looked at the exact physiological mechanisms that transport CO2 from mus-cles to the lungs. Normally, carbonic anhydrase (an enzyme responsible for efficient transport of CO2 from blood to the lungs) allows the body to recover. But to artificially create acid buildup, the researchers used an enzyme blocker called carbonic anhydrase inhibitor. By blocking the enzyme’s actions, Vengust simulated the acidosis experienced by many horses during a race and similar intense exercise.
For this, he worked with horses on a treadmill, with the animals receiving one of three treatments. One group was allowed to recover normally following exercise. A second group received carbonic anhydrase inhibitor several days before exercising. The third group received the inhibitor just before exercising.
In addition, the horses wore a special mask that collected expelled CO2. To follow the progression of CO2 from the muscles, the researchers measured electrolyte and gas concentrations in venous and arterial blood (going into and leaving the heart and lungs).
“All these measurements were taken while the horses were running on the tread-mill at near-maximum speeds,” says Vengust. “This allowed us to closely study gases and electrolytes on both sides of the lungs in a real-life situation.”
Early results show differences among the treatments, he says. In subjects where carbon dioxide exited the cells more quickly, the horse’s bodily functions neared normal, allowing chemical balances to rapidly return to their proper state. Next, the researchers will manipulate the muscle’s acid balance by selectively feed-ing strong electrolytes after exercise. They believe this may speed recovery and keep equine athletes in peak physical condition.
Also involved in this project was McMaster University medical sciences professor George Heigenhauser. This research is sponsored by the Ontario Ministry of Agriculture and Food. R
