THE EFFECT OF ACUTE EXERCISE ON THE PRODUCTION OF REACTIVE OXYGEN SPECIES AND INFLAMMATORY MARKERS IN HEALTHY PRE-PUBERTAL AND ADULT MALES

Abstract

<p>An acute bout of exercise causes short-term changes in the immune system in both children and adults. It has been well-established that exercise induces an inflammatory response. Especially in children, cytokines play an important role in balancing anabolic and catabolic processes of growth. Existing evidence suggests cross-talk between inflammation and oxidative stress. Reactive oxygen species are also found to transiently increase in response to exercise, affecting muscle adaptation post-exercise. Characterizing the exercise-induced inflammatory and oxidative stress responses in children compared to adults will start clarifying the transition from the child phenotype to that of an adult. Ten children aged 8-10 and 12 adults aged 19-21 performed 2×30min bouts of continuous cycling, separated by a 6min rest period, at a target work rate of 60% of their maximum aerobic capacity. Blood samples were collected pre-exercise and immediately post-exercise, and analyzed for<strong> </strong>neutrophil count, systemic oxidative and inflammatory markers (tumor necrosis factor alpha, interleukin 6, protein carbonyls, malondialdehyde, elastase), intracellular neutrophil-derived reactive oxygen species (using 3 fluorescent markers detected by flow cytometry), and <em>in vitro</em> production of neutrophil-derived myeloperoxidase and interleukin 8. Compared to the post-exercise increase in absolute neutrophils in men, boys showed no change. However, intracellular neutrophil reactive oxygen species production increased for boys and not for men. Boys also demonstrated higher overall protein carbonyl levels, whereas men showed higher overall malondialdehyde. Both boys and men showed a positive correlation between tumor necrosis factor alpha and elastase, with a steeper slope seen in boys. Although there were other correlations observed in boys and men, no others existed in both. The differences observed in the exercise-induced inflammatory and oxidative stress response may indicate growth-mediated adaptive responses to exercise during childhood development.</p>