Abstract
PurposeTo compare the effects of endurance exercise performed in the morning and evening on inflammatory cytokine responses in young men.MethodsFourteen healthy male participants aged 24.3 ± 0.8 years (mean ± standard error) performed endurance exercise in the morning (0900–1000 h) on one day and then in the evening (1700–1800 h) on another day with an interval of at least 1 week between each trial. In both the morning and evening trials, the participants walked for 60 minutes at approximately 60% of the maximal oxygen uptake () on a treadmill. Blood samples were collected to determine hormones and inflammatory cytokines at pre-exercise, immediately post exercise, and 2 h post exercise.ResultsPlasma interleukin (IL)-6 and adrenaline concentrations were significantly higher immediately after exercise in the evening trial than in the morning trial (P < 0.01, both). Serum free fatty acids concentrations were significantly higher in the evening trial than in the morning trial at 2 h after exercise (P < 0.05). Furthermore, a significant correlation was observed between the levels of IL-6 immediately post-exercise and free fatty acids 2 h post-exercise in the evening (r = 0.68, P < 0.01).ConclusionsThese findings suggest that the effect of acute endurance exercise in the evening enhances the plasma IL-6 and adrenaline concentrations compared to that in the morning. In addition, IL-6 was involved in increasing free fatty acids, suggesting that the evening is more effective for exercise-induced lipolysis compared with the morning.
Highlights
IntroductionHormonal changes, including increases in the plasma concentrations of several hormones (e.g., adrenaline and cortisol), occur in response to exercise and are known to have immunomodulatory effects [1,2]
Hormonal changes, including increases in the plasma concentrations of several hormones, occur in response to exercise and are known to have immunomodulatory effects [1,2]
Serum free fatty acids concentrations were significantly higher in the evening trial than in the morning trial at 2 h after exercise (P < 0.05)
Summary
Hormonal changes, including increases in the plasma concentrations of several hormones (e.g., adrenaline and cortisol), occur in response to exercise and are known to have immunomodulatory effects [1,2]. The reduction of lymphocytes post exercise is mediated by both catecholamines and cortisol [6] These findings suggest that exercise stimulates immunoendocrine responses, with its effects on the inflammatory response in particular being mediated by activation of the sympathetic nervous system, and the hypothalamic-pituitary-adrenal axis [7]. Catecholamines and cortisol concentrations are increased by acute endurance exercise, but the responses are different for morning and evening exercise [8,14,15,16]. Catecholamines are known to be involved in the secretory stimulation or inhibition of IL-6 [17,18,19] This response can be considered to have different possibilities depending on whether acute endurance exercise is performed in the morning or evening
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