Delayed increase in inflammation and thenar VO₂ in marathon runners

Introduction

The muscle-specific inflammatory response after strenuous exercise has some similarity with those observed in sepsis and it is used as a mirror of sepsis-specific inflammatory response. Near-infrared spectroscopy (NIRS) has been used to quantify sepsis-induced metabolic alterations by measuring variations of tissue oxygen saturation (StO₂) during a vascular occlusion test (VOT). We aimed to investigate whether NIRS dynamic variables could reflect the magnitude of inflammatory process that follows strenuous exercise in marathon runners.

Methods

VOT-NIRS (InSpectra Model 650) measurement was performed before, at the finish line and on the day after the marathon in 13 runners (10 males/three females). VOT-derived NIRS traces were analyzed for StO₂-downslope (R_decStO₂) and StO₂-upslope (R_incStO₂). Blood samples were collected to measure C-reactive protein (CRP), procalcitonin (PCT), white blood cells (WBC), creatine kinase (CK), and lactate. Data are mean ± SD (in Table 1, median (IQR)). P < 0.05 was considered statistically significant.

Table 1 NIRS and hemodynamic variables

Results

The results of NIRS dynamic and hemodynamic variables are shown in Table 1. R_decStO₂ was significantly increased in the day after the marathon. Significant increases in lactate (2.7 ± 0.5 vs 1.2 ± 0.3) and WBC (14 × 10³ ± 4 vs 5 × 10³ ± 2) were observed after the completion of the marathon. Serum CRP, PCT and CK were significantly increased on the day after the marathon (0.6 ± 0.6 vs 12 ± 8; 0.09 ± 0.2 vs 0.7 ± 0.9; 398 ± 198 vs 1,932 ± 1,620), indicating the muscle-specific inflammatory response as a result of muscle damage.

Conclusions

Delayed increase in thenar VO₂ is associated with muscle-specific inflammatory response after strenuous exercise as a result of the muscle damage.