Living high–training low altitude training: effects on mucosal immunity

Secretory immunoglobulin A (sIgA) is the major immunoglobulin of the mucosal immune system. Whereas the suppressive effect of heavy training on mucosal immunity is well documented, little is known regarding the influence of hypoxia exposure on sIgA during altitude training. This investigation examined the impact of an 18-day Living high–training low (LHTL) training camp on sIgA levels in 11 (six females and five males) elite cross-country skiers. Subjects from the control group (n=5) trained and lived at 1,200 m of altitude, whereas, subjects from the LHTL group (n=6) trained at 1,200 m, but lived at a simulated altitude of 2,500, 3,000 and 3,500 m (3×6-day, 11 h day⁻¹) in hypoxic rooms. Saliva samples were collected before, after each 6-day phases and 2 weeks thereafter (POST). Salivary sIgA, protein and cortisol were measured. There was a downward trend in sIgA concentrations over the study, which reached significance in LHTL (P<0.01), but not in control (P=0.08). Salivary IgA concentrations were still lower baseline at POST (P<0.05). Protein concentration increased in LHTL (P<0.05) and was negatively correlated with sIgA concentration after the 3,000 and 3,500 m-phase and at POST (P<0.05 all). Cortisol concentrations were unchanged over the study and no relationship was found between cortisol and sIgA. In summary, data were strongly suggestive of a cumulative negative effect of physical exercise and hypoxia on sIgA levels during LHTL training. Two weeks of active recovery did not allow for proper sIgA recovery. The mechanism underlying this depression of sIgA could be mediated by neural factors.