The health benefits of brightly coloured fruits and vegetables in the human diet have long been established. More recently, however, trials undertaken in New Zealand with endurance horses have revealed a new and exciting role for a particular group of fruit-derived compounds in the training, performance and recovery of competitive horses.
Using a unique combination of red/purple pigments sourced from unique varieties of NZ berry fruits, New Zealand scientist Dr Greg Clark has shown that when taken as part of a horse’s daily diet these compounds can help sustain aerobic performance, reduce muscle fatigue and limit muscle damage.
Flavonoids, as these pigments are called, are responsible for most of the bright red and blue colours in flowers, vegetables and fruits throughout the plant world.
As part of a human diet, flavonoids are an important natural antioxidant source comparative to vitamin C and E but, additionally, flavonoids have been implicated in a functional role in support of the cardiovascular system particularly with respect to improved blood flow to tissues where circulation has been compromised or to muscles undergoing repetitive fatiguing activity.
To assess the potential health benefits of flavonoids to the athletic horse, Dr Clark set up a trial incorporating a number of horses competing in the 160km event at the 2009 New Zealand Endurance National Championships. Two groups of horses were used. Half of these had their normal diet supplemented with a concentrated blend of the specific flavonoid compounds. The supplement was given for a week leading up to the event and at each feeding during the 160km race. The remaining horses were maintained on their normal diets receiving no flavonoid supplementation.
Blood samples were collected from all the horses on the trial the day prior to the event, immediately following it, and for a number of days after the race. These blood samples were analysed for specific markers of physiological and metabolic status and included creatine kinase (CK), aspartate aminotransferase (AST) and lactate.
“CK and AST are proteins found in skeletal muscle cells,” said Clark. “They are often used diagnostically as indicators of muscle stress or trauma as they are leaked into the bloodstream in response to strenuous physical muscle exertion or injury to muscle tissue.”
Plasma lactate levels were used as indicators of the aerobic metabolic status of each horse and were collected immediately following completion of the race. In addition, heart rate recovery at the completion of the race was recorded and used to assess the speed of cardiovascular recovery to resting state.
“Once we analysed the blood samples, some very interesting results were revealed with respect to those horses supplemented with the flavonoid compounds,” added Clark.
“With regards to lactate levels, although levels in both supplemented and non-supplemented horses were typically low, as you would expect from horses of largely Arab bloodlines and an event largely aerobic by nature, there was up to 25% less lactate circulating in the blood plasma of those horses receiving the flavonoids. Not only were their plasma levels for lactate lower, their heart rate recovery was on average at completion of the event 40% quicker.
“Combining these results suggest that the supplemented horses were maintaining a higher aerobic state throughout the event consequently limiting lactate accumulation and reducing the required period for cardiac recovery upon race completion.”
Clark continued to monitor CK and AST levels over the days following the National Endurance Race and these results provided equally supportive data for the inclusion of flavonoids in the diet of endurance horses.
“Horses who didn’t have the supplement added to their diet had, on average, up to three times higher levels of CK and AST present in their blood stream,” said Clark.. “As CK and AST are derived from skeletal muscle cells, and elevated levels indicate muscle cell leakage and potentially muscle tissue damage, these results suggest that a degree of protection or buffering of the skeletal muscle tissues from the stress associated with prolonged muscular activity has occurred in those horses supplemented with flavonoids.”
As well as being indicators of muscle cell leakage CK and AST are proteins with specific functions within the muscle cell required for the efficient performance of the cell and collectively the physical exertion of the horse’s skeletal muscles. Leakage of these proteins from the muscle tissue may not only indicate muscle damage but functionally indicate an impaired muscle system with the likely outcome being a poorer performance.
While these are preliminary results, Clark is excited about the benefits a flavonoid supplemented diet can offer the equine competitor.
“While the physiological mechanisms behind the activity of concentrated forms of flavonoids to the athletic horse is only starting to become apparent, the potential for these natural compounds in the well being, general health and support of race performance of the endurance horse is evident,” he said.
“Although not a vitamin or electrolyte these compounds may be on par when it comes to a support role during competition benefiting both the cardiovascular system and aerobic metabolism, while limiting skeletal muscle damage and supporting performance.”
A recent convert to the benefits of flavonoids is endurance world championship rider Kevin James. After initially supplementing three of his horses’ diets with flavonoids, he now feeds a diet rich in these compounds to all his horses in training.
“Training wise, we are covering up to 50% more distance at this stage of their preparation relative to previous years and the horses seem very settled and are thriving in their work,” James commented. “In their early season events all horses have been breezing through their vet checks with no disqualifications and I have been very pleased with heart rate recoveries and metabolic across the board.”
James has also been positive about being able to supplement his horses’ diet with a natural food source.
“It is likely that in pre-domesticated times, ancestral horses browsed upon plants periodically rich in flavonoids and in doing so may have derived the physiologically and health associated benefits. It may be because of this that horses have a great attraction to red skinned fruits such as apples in which the red skin pigmentation is derived directly from flavonoids and why it makes sense to add these back into our horses diet ,” said Clark.
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