The Effects of Low Intensity Endurance Activity on Various Physiological Parameters and Exercise Induced Oxidative Stress in Dogs

Abstract

The study of canine athlete physiology has focused on endurance sled dog racing and high intensity short duration Greyhound racing, yet the number of dogs competing in low intensity endurance activities is rising due to the increased numbers of hunting and companion dog activities. There is little information on the physiological effect of longer duration low intensity endurance activities. We set out to evaluate the serum biochemistry, oxidative stress, and cortisol response before and after two consecutive days of exercise in ten healthy unconditioned male dogs. Exercise sessions consisted of 120 minutes on an exercise wheel at 11 km/hour on 2 consecutive days. Blood was collected at four time points: 24 hours pre-exercise (sample 1, Day 0, resting); 2 min post-exercise on days 1 and 2, (samples 2 and 3, respectively); and 20 hours post-exercise, collected on day 3(sample 4). Hematocrit, blood gases, serum chemistry, uric acid, cortisol, and F2-isoprostanes were determined. Serum biochemistry and hematocrit suggested hemoconcentration, mild muscle damage and respiratory alkalosis during exercise, which was expected in the unconditioned canine athlete. In addition, plasma indices of oxidative damage (F2-isoprostanes) increased, as did plasma uric acid (an endogenous antioxidant). Importantly, similar to human studies, plasma F2-isoprostanes decreased 24 hours after exercise suggesting a protective effect of exercise. Serum cortisol concentrations were also markedly elevated at the end of exercise on both days suggesting that timing of sampling may play a role in interpreting cortisol results when looking at previous field studies.

Serum concentration of gastrin, cortisol and C-reactive protein in a group of Norwegian sled dogs during training and after endurance racing: a prospective cohort study

“…There was a significant increase in serum cortisol in the competing dogs after racing. These findings are in accordance with previous human, horse and canine studies [ 1 , 8 , 9 , 13 , 17 , 29 ]. Also, anticipation of exercise before racing can cause increase in cortisol in sled dogs [ 30 ].…”

“…Physical exercise promotes release of cortisol in both humans [ 8 , 9 ] and dogs [ 1 , 12 , 13 ]. An association between gastric lesions and an increase in endogenous cortisol has been demonstrated in racing sled dogs.…”

Development of Novel Continuous and Interval Exercise Programs by Applying the FITT-VP Principle in Dogs

“…e increased serum CK after exercise suggests minor musculoskeletal damage [46]. e results are congruent with previous findings of other studies [47,48]. ese outcomes may be influenced by free radicals produced during exercise that cause changes in the permeability of muscle cell membranes, resulting in increased CK, which are the biomarkers of muscle damage [49].…”

“…Another contributing mechanism could be the involvement of an increase in blood urea due to an overload of amino-acid metabolism in the liver and muscles [50]. However, the CK levels returned to the normal range after finishing the exercise program, indicating that the increase could have been a transient phenomenon due to exercise [47].…”

The Effects of Varying Concentrations of Dietary Protein and Fat on Blood Gas, Hematologic Serum Chemistry, and Body Temperature Before and After Exercise in Labrador Retrievers

“…The significant reduction of serum phosphorus concentration in the low-fat diet group appears perplexing; however, again this group was less conditioned for fat metabolism, hence more carbohydrate metabolism as an energy source was utilized. Glucose utilization as a major fuel to meet metabolic demands during this bout of exercise requires phosphorus during glycogenolysis to form glucose-1-phosphate and glucose-6-phosphate potentially leading to an intracellular phosphorus flux during exercise as observed in other exercising canine studies ( 20 , 21 ). The reason for no dietary differences in phosphorus influx is likely due to the exercise bout being well within the range the time range for carbohydrate oxidation, which relies on either glycogenolysis and to a lesser degree protein or fat metabolism ( 22 ).…”