[Background] Altitude training has often been conducted just before main competition games in many sports. An increase in the frequency of upper respiratory tract infections and gastrointestinal infections due to an altitude-induced suppression of the immune system has been reported after altitude training. Salivary secretory immunoglobulin A (SIgA) is the major immunoglobulin of the mucosal immune system. A suppressive effect of heavy training on SIgA has been reported. However, little is known regarding the effects of repetitive altitude training and hypoxic exposure on SIgA. The objective of this study was to evaluate the changes in SIgA in swimmers undergoing repetitive altitude training at 1,900 m.
[Methods] Nine collegiate swimmers who experienced their first altitude training experience (FT group) were compared to nine swimmers who experienced repetitive training (RT group) and non-training subjects (Con group). Saliva was collected before ascent and eight times every 2 days during altitude training. SIgA levels were measured by enzyme-linked immunosorbent assays.
[Results] Compared to the Con group, SIgA levels and the secretion velocity were decreased after ascent and were slowly restored in both the FT and RT groups. The chronological trends in SIgA levels were similar, even though the decline in SIgA levels in the FT group was larger than that in the RT group.
[Conclusion] Altitude training and experience with altitude training may be one of the factors influencing SIgA.