The Effects of High‐ and Moderate‐Intensity Exercise on Epithelial Integrity Markers and Inflammatory Responses in Healthy Young Men

The effects of exercise intensity on airway epithelial integrity markers and inflammatory responses remain unknown. Therefore, we investigated the effects of high- and moderate-intensity exercise on airway epithelial integrity markers (club cell protein 16 [CC16], surfactant protein D [SP-D], and the CC16/SP-D ratio), along with systemic inflammation assessed via high-sensitivity C-reactive protein [hs-CRP] in healthy young men. Twenty healthy young men were randomly divided into two groups: high-intensity (n = 10) and moderate-intensity (n = 10) and both groups completed 20-min of continuous intensity treadmill exercise. The exercise intensities for the high-intensity and moderate-intensity groups were 85%-90% and 65%-70% of maximum heart rate, respectively. Serum was collected before and at +1 and + 24 h after exercise. CC16, SP-D, and hs-CRP concentrations were measured using enzyme-linked immunosorbent assay. A two-way repeated measures analysis of variance suggested that CC16, SP-D, CC16/SP-D ratio, and hs-CRP changed significantly over time (p < 0.05). Time × group interaction effects were observed for CC16 (p = 0.032) and CC16/SP-D ratio (p = 0.010) but not for SP-D (p = 0.824) and hs-CRP (p = 0.422) concentrations. Post hoc analysis revealed that CC16 concentrations at +1 h (p = 0.002) and the CC16/SP-D ratio at +24 h (p = 0.005) were higher for the high- compared to the moderate-intensity group. Our findings suggest for the first time that exercise intensity has a significant impact on CC16 and the CC16/SP-D ratio but does not affect the release of SP-D or hs-CRP.