A five-day recovery break between two consecutive weekends of competition is not enough to allow muscle recovery in showjumping horses, a study suggests.
Italian researchers set out to assess the effect of two jumping competitions, over two consecutive weekends, on serum concentrations of the enzymes creatine phosphokinase, aspartate aminotransferase and lactate dehydrogenase. They also measured levels of the nitrogenous waste product urea, and creatinine, which is a breakdown product of creatine phosphate in muscle.
Twelve healthy showjumping horses, comprising seven geldings and five mares, were used in the study. They were aged 9-12 and their average body weight was 500kg.
Blood sampling was performed before the first day of each two-day weekend competition, after each competition, and on the day following.
The study team then analysed the serum in the blood samples to get a picture of how the horses’ muscles stood up to the competitions.
The University of Messina researchers, writing in the journal, Veterinary World, concluded: “Our results suggest that five days recovery period between the two consecutive competition weekends is insufficient to allow muscle recovery and avoid potential additional stress.”
Giuseppe Piccione and his colleagues said the athletic performance of horses was determined by many complicated interdependent biological and physiological processes.
They noted that physiological, blood, and biochemical changes associated with exercise had been extensively analysed in previous studies across several types of horses, including thoroughbreds, eventers, showjumpers, and endurance horses.
One of the organs affected by exercise was the muscle, which can suffer microdamage due to effort under load. Such damage can be assessed by laboratory testing of serum concentrations of urea and creatinine, as well as enzymes such as creatine phosphokinase, aspartate aminotransferase, and lactate dehydrogenase.
“The activity of these enzymes has been studied by several researchers before and after exercise and can be used to detect muscle diseases, characterization of exercise intensity and predicting possible complications that can arise from the exercise,” they said.
Before competing on each of the four days, the Italian Saddle horses in the study each had a 20-minute warm-up consisting of a walk, a trot and a gallop, as well as six jumps ranging in height from 100cm to 140cm.
During the first day of both weekends, horses competed over a jumping course of 550m comprising 13 efforts at 140cm. It was made up of seven verticals and six oxers, including a triple combination.
During the second day of both weekend competitions they competed over a 600m course comprising 15 efforts at 145cm, made up of eight verticals and seven oxers, including a double and a triple.
All horses during the week between both competitions had a daily training schedule which comprised a warm-up – a 10-minute walk, 20 minutes at the trot and 10 minutes of galloping – followed by a showjumping course with seven fences around 80cm in height.
Discussing their findings, the researchers said changes in blood chemistry were found after jumping exercise, with increases in levels of the monitored muscle enzymes.
“These increases are believed to relate either to overt damage or to a change in the muscle fiber membrane causing a transient increase in permeability,” they said.
“However, physiological increases have been also shown to occur without any tissue alteration. The effects of physical effort on serum enzymatic activity may depend on the level of performance of the animal, and the intensity and duration of exercise.”
The researchers found significant increases in both creatine phosphokinase and lactate dehydrogenase after the competitions. Crucially, both were found to be higher at the end of the second jumping weekend, when compared to levels at the end of the first jumping weekend.
They also reported that the horses started the second jumping weekend with higher baseline levels of both enzymes when compared to the baseline levels measured in blood samples before the horses had started in the competitions the previous week.
The findings, they said, seemed to indicate that the two jumping session were timed too close together to allow the horses adequate recovery.
“Our results … underline that the physiological activity of enzymes, if not associated with the adequate recovery period, can increase the probability of muscle damage.”
Their findings, they said, improved knowledge around metabolic changes in horses during competition.
Piccione was joined in the research by Anna Assenza, Simona Marafioti, Fulvio Congiu, Claudia Giannetto, Francesco Fazio, and Daniele Bruschetta.
Assenza A, Marafioti S, Congiu F, Giannetto C, Fazio F, Bruschetta D, Piccione G (2016) Serum muscle-derived enzymes response during show jumping competition in horse, Veterinary World, 9(3): 251-255.