Muscle Trauma and Immune Activation after a Downhill Marathon (Tyrolean Speed Marathon)

Abstract

Prolonged physical exercise is associated with multiple changes in the immune status indicating an acute phase response and an activation of the immune system. Eccentric muscle activation (e.g. downhill running) induces micro-trauma of skeletal muscles thus inducing an inflammatory response. At present there are no data to which extent the immune system is activated after a downhill marathon run and if there arc any correlations between immune activation and markers for muscle damage or functional impairment of leg muscles. As model for severe eccentric exercise we selected the Tyrolean Speed Marathon (42 km downhill run, 795 m vertical difference). 13 volunteers (12 male, 1 female; mean running time 224 min [range 193 - 266 min.]) finished the run. Blood from antecubital veins was collected 3-4 days before (T1 ), 3-4 hrs before (T2) and immediately after the marathon (T3) as well as on the morning after the run (T4). We measured serum neopterin concentrations, white blood cell count. C-reactive protein (CRP), creatine kinase (CK), myoglobin (Mb), cardiac troponin I (cTnl) and troponin Τ (cTnT). Moreover, isokinetic muscle tests were performed. Following significant changes were found (before vs. after the run): increase in neopterin, CRP, total leukocyte count, CK. Mb, cTnl, cTnT, whereas isokinetic dynamometry showed a reduction in peak hamstring torque of both thighs after the marathon. There were no significant correlations (Spearman's rank correlation coefficient) between the observed changes in neopterin and CRP, CK, Mb. cTnT, cTnl or between neopterin concentrations and parameters of isokinetic muscle tests. We could demonstrate that a 42 km downhill marathon is associated a) with an activation of the cellular immune system, as evidenced by the increase in serum-neopterin. b) pronounced micro-skeletal muscle damage with high serum creatine kinase and myoglobin, and c) eccentric hamstring fatigue. The absolute changes in neopterin were moderate and similar to other types of exercise (flat course and bicycle marathon, mountain hiking).

Keywords

• neopterin
• muscle damage
• immune activation
• troponin
• eccentric exercise