To quantify levels of IL-6 and CRP, 10ml of blood were collected into EDTA tubes (Becton–Dickinson, Franklin Lakes, NJ), held on ice, and centrifuged within 2 hours of collection for 15 minutes at 1500g. Plasma was then aspirated, aliquoted, and frozen at −80 °C until assay. Plasma levels of IL-6 were quantified using Quantikine High Sensitivity human IL-6 kits (R&D Systems, Inc., Minneapolis, MN), an enzyme-linked immunosorbent assay (33 (link)) with an intra-assay coefficient of variation of 4% and inter-assay coefficient of variation of 10%. The minimal detectable level of IL-6 was 0.156 pg/ml. CRP was measured using the Dade Behring N High Sensitivity CRP turbidimetric immunoassay (Dade Behring Diagnostics, Marburg, Germany) on the BN ProSpec. We excluded data from 8 participants with both IL-6 values above 10 pg/ml and CRP values above 10mg/L, in order to rule out participants who were likely to be experiencing an acute infection at the time of data collection (34 (link)). To address non-normal distribution, IL-6 and CRP variables were transformed using a natural log function.