IL6 and hematocrit: However, plasma IL-6 levels increased significantly immediately after the marathon, from 2.8 ± 4.7 to 89.0 ± 25.1 pg/mL in the HT group and 3.3 ± 4.2 to 76.9 ± 30.6 pg/mL in the LT group (p < 0.0001) (Figure 1B).