title: The effect of repeated endurance exercise on IL-6 and sIL-6R and their relationship with sensations of fatigue at rest.
abstract: Strenuous, prolonged exercise increases interleukin-6 (IL-6) release. The effect of IL-6 is dependent on the availability of IL-6 receptors. Few studies have addressed the impact of exercise on IL-6 receptor levels or procalcitonin (PCT), an indicator of systemic inflammation. Changes in these molecules may give insight into cytokine-related mechanisms underlying exercise-related fatigue. Thirteen trained male subjects partook in the study. They cycled a total distance of 468 km over 6 days. Blood samples were obtained prior to and immediately following Day 1 of the study and then each morning prior to exercise. Blood samples were analysed for plasma IL-6, soluble IL-6 receptor (sIL-6R), C-reactive protein (CRP), PCT, creatine kinase (CK) and cortisol concentrations. Subjects also completed mood state questionnaires each day prior to exercise. IL-6 was elevated immediately post-exercise on Day 1 but was unchanged at rest for the duration of the event. In contrast, sIL-6R, CRP, PCT and CK concentrations were unchanged immediately post-exercise on Day 1 but were significantly elevated at rest over the duration of the event compared with pre-event baseline. sIL-6R was highly correlated to CRP. Cortisol concentrations remained unchanged at all time points. In conclusion, strenuous, prolonged exercise stimulated an acute phase response which was maintained throughout the 6-day event. sIL-6R increase is associated with CRP and may affect subjective sensations of post-exercise fatigue at rest.
authors.affiliation: School of Psychology and Sport Sciences, Northumbria University, Northumberland Road, Newcastle NE1 8ST, UK. paula.ansley@unn.ac.uk
authors.forename: Paula
authors.initials: P
authors.lastname: Robson-Ansley
authors.forename: Martin
authors.initials: M
authors.lastname: Barwood
authors.forename: Jane
authors.initials: J
authors.lastname: Canavan
authors.forename: Susan
authors.initials: S
authors.lastname: Hack
authors.forename: Clare
authors.initials: C
authors.lastname: Eglin
authors.forename: Sarah
authors.initials: S
authors.lastname: Davey
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hewitt
authors.forename: James
authors.initials: J
authors.lastname: Hull
authors.forename: Les
authors.initials: L
authors.lastname: Ansley
mesh_terms: D000328:Adult; D001642:Bicycling; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000378:metabolism / Q000523:psychology; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D019947:Receptors, Interleukin-6 / Q000097:blood*; D012677:Sensation / Q000502:physiology*; D011795:Surveys and Questionnaires
chemical_list: D015850:Interleukin-6; D019947:Receptors, Interleukin-6