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OC2 The Soluble Il-6 Receptor Is Related To Weekly Training Volume And Fatigue In Highly Trained Swimmers
  1. T Cullen1,
  2. AW Thomas2,
  3. R Webb2,
  4. T Phillips3,
  5. MG Hughes1
  1. 1Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, CF23 6XD, UK
  2. 2Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, CF5 2YB, UK
  3. 3University Hospital Wales Cardiff, Cardiff, CF14 4XW, UK


Interluekin-6 (IL-6) plays an important role in immunological, inflammatory and metabolic responses to exercise. The downstream effects of IL-6 signalling are dependent on the binding to its receptors, both soluble (sIL-6R) and membrane bound. There is evidence that sIL-6R concentrations change in response to exercise and are related to exercise load and fatigue. However, considerably less is known about the sIL-6R response to prolonged exercise training. Knowledge of the receptor response to training may provide insight into the mechanisms underlying cytokine regulation of a number of biological processes. This study investigated the effect of a prolonged period of training on sIL-6R and how this related to perceptions of fatigue. Ten (7 females, 3 males) highly trained swimmers participated. sIL-6R was determined from capillary blood samples collected prior to training each week for a period of 18 weeks. Participants also completed a subjective wellbeing-monitoring questionnaire once a week prior to training. sIL-6R was negatively correlated to weekly training volume (r = -0.68, r2 = 0.47, p < 0.005). sIL-6R was 74% higher (25.7 Vs 14.8 ng/ml, p = 0.04) in those reporting lowest Vs highest ratings of fatigue. This study provides a) further evidence for the role of the sIL-6R in sensations of fatigue at rest and b) novel evidence that the sIL-6R is responsive to long-term endurance training and that this response is associated with training volume. sIL-6R appears to be responsive to weekly training mileage, decreasing during periods of increased training mileage and returning to baseline levels when training mileage is reduced. Given that IL-6 in combination with sIL-6R is reported to have a greater sensitising effect with regard to nociception/inflammatory hyperalgesia than IL-6 alone, the observed decline in circulating sIL-6R may provide a mechanism for the impact of exercise on perceptions of fatigue, and hence the ability to adhere to high-mileage training.

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