Introduction: Stress due to repeated exposure to hypoxia affects the mucosal immune system, as reflected in a reduced salivary concentration of immunoglobin-A (sIgA) (Tiollier et al. 2005). Moreover, adding a hypoxic stress to a very intensive form of training (i.e. repeated sprint training in hypoxia (RSH)) induced superior performance benefits compared to repeated sprint training in normoxia (RSN) (Faiss et al. 2013). With a positive correlation between decrease in sIgA and incidence of respiratory tract infection, we hypothesized that RSH may alter immune function and increase infection risk to a greater extent than RSN in elite cross-country skiers. Methods: Within a two-week period 17 elite cross-country skiers performed 6 sessions on a double-poling ergometer (Concept2), under either normobaric hypoxia (RSH, FiO2=13.8%, 3000m, n=9) or normoxia (RSN, FiO2=20.9%, 300m, n=8). Each session consisted of 10-s repeated sprints (4 sets of 5) interspersed with 20 s of recovery. Before (Pre-) and after (Post-) training, performance was assessed by a repeated sprint test (RSA) with 10s all-out sprints interspersed with 20 s of recovery until peak power output fell below 70% of the best sprint. Saliva was collected on a rest day before Pre- and the first and sixth training day in specific polyethylene tubes (SaliTubes, Eppendorf) at five times during the day: immediately and 30 min after awakening, before and after the training session as well as immediately before going to bed. These samples were stored at -20°C until being analyzed for sIgA (DRG Instruments). Results: In Post- compared to Pre-, power output in RSA was improved (p<0.01) similarly in both groups (25% vs. 21%, NS), whereas the number of sprints completed before task failure was increased in RSH (10.9±5.2 vs. 17.1±6.8, p<0.01) but not in RSN (11.6±5.3 vs. 11.7±4.3). Groups did not differ in any measured parameter on the rest day (p=0.35). Further, in RSH vs. RSN, saliva flow rate (0.50±0.10 vs. 0.54±0.07 and 0.51±0.04 vs. 0.52±0.08 mL/min, NS), sIgA (103.1±59.1 vs. 89.8±31.3 and 121.3±57.1 vs. 99.9±59.5 ìg/mL, NS), and sIgA secretion rate (47.9±25.4 vs. 45.2±12.1 and 61.1±30.6 vs. 50.8±31.1 ìg/min, NS) were unaffected on the day of the first and sixth training session, respectively. Conclusion: We conclude that for elite cross-country skiers repeated sprint training in hypoxia is more beneficial than identical normoxic training without compromising mucosal immunity.
© Copyright 2014 19th Annual Congress of the European College of Sport Science (ECSS), Amsterdam, 2. - 5. July 2014. Julkaistu Tekijä VU University Amsterdam. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator