Effects of hypoxic preconditioning combined with altitude training on CD55, CD59 and the immune function of swimmers

Hypoxic preconditioning refers to a certain intensity and time of hypoxic exposure before hypoxic stress, which makes the body produce endogenous protection to enhance the body's tolerance to subsequent more severe hypoxia. However, there are few studies on the effects of hypoxic preconditioning combined with altitude training on the immune system of athletes.

Nine swimmers from Shanghai underwent 3-week hypoxic preconditioning [living high-training low (HiLo)] combined with 3-week altitude training. CD55 and CD59 expression in red blood cells (RBCs), CD55 and CD59 expression in white blood cells (WBCs), RBC count, WBC count, T lymphocyte CD3, CD4, CD8 expression, and immunoglobulins IgG, IgM, and IgA were measured 4 times: before the start of hypoxic preconditioning, in the first week of hypoxic preconditioning, at the end of hypoxic preconditioning (i.e., before the start of altitude training), and at the end of altitude training.

CD55 and CD59 expression in RBCs significantly increased in the first week of hypoxic preconditioning (P<0.05), returned to baseline levels at the end of preconditioning, and significantly increased again during altitude training (P<0.05). CD55 and CD59 expression in WBCs decreased significantly during hypoxic preconditioning (P<0.05) and increased significantly during altitude training (P<0.05). CD3 expression first decreased and then increased in the hypoxic preconditioning phase, then decreased again in the altitude training phase. However, there was no significant difference in each phase. CD4/CD8 expression after altitude training was significantly lower than that before altitude training (P<0.05), but was not significantly different from that before the start of hypoxic preconditioning. IgG, IgM, and IgA did not fluctuate significantly throughout the experimental phase.

After hypoxic preconditioning combined with altitude training, the expression of CD55 and CD59 on the surface of RBCs and WBCs increased significantly, and T lymphocyte CD4/CD8 expression also increased. These results suggest an improvement in the complement regulation system and RBC immune function. Hypoxic preconditioning can therefore improve immunity and enhance the physical function of athletes during altitude training.