White blood cell response to uphill walking and downhill jogging at similar metabolic loads

Summary

The object of this study was to determine whether leukocytosis would occur in response to eccentric exercise, to concentric exercise, and/or to possible increases in serum corticol levels. Eight men performed 2 bouts of exercise at 46%$\dot V_{o_{2max} }$ for 40 min. Subjects initially walked up a 10% grade (UW); 2 weeks later they jogged down a 10% grade (DJ), a form of eccentric exercise known to induce delayed onset muscle soreness (DOMS). Venous blood samples were drawn before and after each exercise bout (0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, and 5 h). Total and differential WBCc and serum cortisol levels were assessed. Results were analyzed using repeated measures ANOVA (2 × 11). Subjects experienced severe DOMS after DJ. There was a significant difference in TWBCc (p<0.0001) between UW and DJ. Post-hoc testing revealed no significant increase over baseline values for UW; after DJ there was a 46% increase over baseline values (p<0.05) initially seen at 1.0 h. These increases in TWBCc were predominantly a reflection of increases in neutrophils which were significant (p<0.0001) when compared to baseline values at 1.0, 1.5 and 2.0 h (∼60%). No significant neutrophil increases were seen after UW. Cortisol levels were similar for both groups pre-exercise (UW=367.1±38.6, DJ=320.2±44.16 mnol · L⁻¹ x±SE) and decreased similarly for both groups after exercise, and thus were not related to the post-exercise neutrophilia. In conclusion, the neutrophilia seen after the DJ appeared to be a response to differences in the exercise, not plasma cortisol levels. Thus a bout of eccentric exercise appears to induce a significant post-exercise increase in neutrophils seen between 1.0 and 2.0 h after the termination of exercise.