Eccentric exercise-induced muscle damage and inflammation in conjunction with high-altitude decompression in adults

This study aimed to investigate the effect of eccentric exercise on exercise-induced muscle damage (EIMD) and inflammation on high-altitude-induced venous gas emboli (VGE). Subjects were exposed to an altitude of 24,000 ft. for 90 min, with either prior eccentric exercise (ECC) or no exercise (Control) 24 h before. Blood samples were collected at baseline (T₀), before (T₁), and after (T₂) altitude exposures. VGE load was evaluated using the Eftedal-Brubakk (ΕΒ) scale. Creatine kinase (CK) and myoglobin were used to assess muscle damage, while interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), and fibrinogen were used to evaluate inflammation. ECC showed higher EB-scores during altitude exposures [median(range), 3(0-5)] than Control [1(0-4), p = 0.019]. Increases in myoglobin (+35%, p = 0.012), CK (+130%, p < 0.001), IL-6 (+72%, p = 0.02), and CRP (+63%, p = 0.004) were observed from T₀ to T₁ in ECC, but not Control. Significantly higher levels of myoglobin (p = 0.033), CK (p < 0.001), IL-6 (p = 0.016), and CRP (p = 0.002) were noted in the ECC compared to Control at T₁. IL-6 increased from T₁ to T₂ in ECC (p = 0.005), with higher levels than Control at T₂ (p = 0.046). A correlation was found between EB-scores and T₁ myoglobin levels (r_s = 0.450; p = 0.004), and to T₁-T₂ IL-6 changes (r_s = 0.396; p = 0.037). Eccentric EIMD followed by inflammation is associated with a higher decompression strain, with VGE load aggravating systemic inflammation.