A time-course evaluation of inflammatory and oxidative markers following high-intensity exercise in horses: a pilot study

Abstract

Exercise is a physiological stress resulting in reactive oxygen species and inflammatory mediators, the accumulation of which are thought to contribute to degenerative articular diseases. The horse is of particular interest in this regard as equine athletes are frequently exposed to repetitive bouts of high-intensity exercise. The purpose of this study was to provide a detailed description of the response of articular and systemic oxidative and inflammatory biomarkers following high-intensity, exhaustive exercise in horses. A group of horses (Ex) underwent repeated bouts of high-intensity exercise, at a target heart rate of 180 beats/min, until voluntary exhaustion. Baseline plasma and synovial fluid (SF) samples were taken 24 h before exercise and then at 0.5, 1, 2, 4, 8, and 24 h following exercise cessation. This time course was repeated in a group of nonexercised control horses (Co). Plasma and SF samples were analyzed for prostaglandin E (PGE), nitric oxide (NO), total antioxidant status (TAS), and glycosaminoglycans (GAG). The Ex group had significantly higher plasma NO at 0.5, 1, and 2 h; and higher plasma PGE at 0.5 and 1 h compared with Co. SF PGE and GAG were also higher in Ex horses at 8 h compared with Co. It is concluded that high-intensity exercise in horses results in a rapid increase in systemic oxidative and inflammatory markers from 0.5 to 2 h after exercise, which is followed by local articular inflammation and cartilage turnover at 8 h postexercise. NEW & NOTEWORTHY In horses, the influence of exercise systemically and within the articular space remains unclear and requires further detailed characterization. In this study, we identify that an acute bout of high-intensity exercise in horses induces systemic inflammation and oxidative stress within 30 min of exercise cessation, which lasts for ~2 h. Articular inflammation and cartilage turnover were also be observed within the equine carpal joint 8 h following exercise completion.

The Time Course of Inflammatory Biomarkers Following a One-Hour Exercise Bout in Canines: A Pilot Study

“…To our knowledge, this is the first study to report a time-course of post-exercise systemic PGE 2 production in dogs. The duration and intensity of the exercise in this study resulted in a significant increase in PGE 2 one hour after exercise, consistent with our previous study which showed a significant increase in PGE 2 one hour after approximately 30 min of exhaustive galloping exercise in horses [4]. Similarly, human athletes experienced a peak in plasma PGE 2 two hours after a two-hour high-intensity football training bout [12] and one hour after approximately 30 min of exhaustive treadmill running [25].…”

“…Indeed, PGE 2 plays a role in protein synthesis in skeletal muscles following exhaustive eccentric leg exercise in recreationally active human males [32], likely due in part to the stimulatory effect of PGE 2 on the muscle stem-cell function [31], which is impaired in the presence of cyclooxygenase inhibitors [33,34]. The current study demonstrates that one hour of hunt exercise in basset hounds follows an acute temporal pattern of post-exercise increase in PGE 2 that is similar to the pattern reported in humans undergoing resistance exercise [19] and in horses undergoing high-intensity exhaustive sprint exercise [4].…”

“…NO was analyzed using the Griess Reaction. Plasma samples were analyzed as previously described [4]. A linear regression equation was developed from a nitrite standard curve and used to calculate the concentration of NO in each well.…”

“…Transient inflammation induced by exercise is a physiological phenomenon that can be observed in several athletic species, including humans [1][2][3], horses [4,5], and dogs [6][7][8]. Pro-inflammatory cytokines, such as interleukin-1 β (IL-1β) [9,10] and tumour necrosis factor alpha (TNF-α) [1,11], transiently increase following a high-intensity exercise bout, as do pro-inflammatory eicosanoids such as prostaglandin E 2 (PGE 2 ) [4,5,12] and reactive oxygen species such as nitric oxide (NO) [4,5].…”

“…Transient inflammation induced by exercise is a physiological phenomenon that can be observed in several athletic species, including humans [1][2][3], horses [4,5], and dogs [6][7][8]. Pro-inflammatory cytokines, such as interleukin-1 β (IL-1β) [9,10] and tumour necrosis factor alpha (TNF-α) [1,11], transiently increase following a high-intensity exercise bout, as do pro-inflammatory eicosanoids such as prostaglandin E 2 (PGE 2 ) [4,5,12] and reactive oxygen species such as nitric oxide (NO) [4,5]. While it is tempting to characterize this phenomenon as a negative consequence of exercise due to evidence for breakdown of tissues, such as loss of articular glycosaminoglycan [4,5,13], it is becoming increasingly clear that exercise-induced inflammation has a complex and essential role in adaptation (i.e., training) of tissues [14,15], contributing to a net anti-inflammatory effect of repeated exercise bouts over time [14,16,17].…”