SALIVARY ANTIMICROBIAL PROTEIN RESPONSE TO PROLONGED RUNNING

Prolonged exercise may compromise immunity through a reduction of salivary antimicrobial proteins (AMPs). Salivary IgA (IgA) has been extensively studied, but little is known about the effect of acute, prolonged exercise on AMPs including lysozyme (Lys) and lactoferrin (Lac). Objective: To determine the effect of a 50-km trail race on salivary cortisol (Cort), IgA, Lys, and Lac. Methods: 14 subjects: (6 females, 8 males) completed a 50km ultramarathon. Saliva was collected pre, immediately after (post) and 1.5 hrs post race ( 1.5). Results: Lac concentration was higher at 1.5 hrs post race compared to post exercise (p<0.05). Lys was unaffected by the race (p>0.05). IgA concentration, secretion rate, and IgA/Osm were lower 1.5 hrs post compared to pre race (p<0.05). Cort concentration was higher at post compared to 1.5 (p<0.05), but was unaltered from pre race levels. Subjects finished in 7.81 ± 1.2 hrs. Saliva flow rate did not differ between time points. Saliva Osm increased at post (p<0.05) compared to pre race. Conclusions: The intensity could have been too low to alter Lys and Lac secretion rates and thus, may not be as sensitive as IgA to changes in response to prolonged running. Results expand our understanding of the mucosal immune system and may have implications for predicting illness after prolonged running

Prolonged treadmill running in normobaric hypoxia causes gastrointestinal barrier permeability and elevates circulating levels of pro- and anti-inflammatory cytokines

PURPOSE: This study examined the impact of treadmill running in normobaric hypoxia on gastrointestinal barrier permeability and the systemic inflammatory response. METHODS: Ten recreationally-active participants completed two 1h bouts of matched-workload treadmill exercise(65% normoxic VO2max) in counterbalanced order. One bout was performed in normoxia(NORM: FIO2=20.9%) and the other in normobaric hypoxia(HYP: FIO2=13.5%). Minute ventilation(VE), respiratory rate(RR), tidal volume(VT), oxygen consumption(VO2), carbon dioxide production(VCO2), respiratory quotient(RQ), and heart rate(HR) were measured with a metabolic cart. Peripheral oxygen saturation(SpO2) was measured with pulse oximetry. Absolute tissue saturation(StO2) was measured with near-infrared spectroscopy. Fatty acid-binding protein(I-FABP) and circulating cytokine concentrations(IL-1Ra, IL-6, IL-10, TNFα) were assayed from plasma samples collected Pre, Post, 1h-Post, and 4h-Post exercise. Data were analyzed with 2-Way(Condition*Time) RM ANOVAs and Newman-Keuls post hocs were run where appropriate(p<0.05). RESULTS: As compared to NORM, 1h of treadmill exercise in HYP caused greater(p<0.05) changes in VE(+30%), RR(+16%), VT(+10%), VCO2(+18%), RQ(+16%), HR(+4%), SpO2(-16%) and StO2(-10%). Gut barrier permeability and circulating cytokine concentrations were also greater(p<0.05) following HYP exercise, where I-FABP was shown increased at Post(+68%) and IL-1Ra at 1h-Post(+266%). IFABP and IL-1Ra did not change following NORM exercise. IL-6 and IL-10 increased with exercise in both study conditions but were increased more(p<0.05) following HYP exercise at Post(+705% and +127%; respectively) and 1h-Post(+400% and +128%; respectively). KEY FINDINGS: Normobaric hypoxia caused significant desaturation and increased most cardiopulmonary responses by 10-30%. Significant gut barrier permeability and increased pro- and anti-inflammatory cytokine concentrations could promote an "open window" in the hours following HYP exercise