The purpose of the study was to carry out an immunophenotypical characterization with
a special focus on natural killer cells of junior swimmers from the Hungarian National
Swim Team before and after an intensive acute exercise. Nineteen swimmers, ten females
and nine males, completed the exercise protocol. Sixteen swimmers experienced delayed-onset
muscle soreness. Most of our findings substantiated earlier results, such as the increase
in the percentage of the CD3−/CD56+ natural killer cells and the CD3−/CD56dim+ NK
cells, and the decrease in the percentage of CD3+ T cells among lymphocytes after
the exercise protocol. The drop of natural killer cell activity back to the pre-exercise
level was in line with earlier findings. Interestingly, the percentage of CD3+/CD56+
NKT-like cells did not change significantly in those three swimmers who did not report
delayed-onset muscle soreness. On the contrary, the percentage of CD3+/CD56+ NKT-like
cells among lymphocytes increased in fourteen and decreased in two swimmers reporting
delayed-onset muscle soreness. This study for the first time demonstrated a link between
the delayed-onset muscle soreness and the imbalanced control of CD3+/CD56+ NKT-like
cells among lymphocytes. However, validation of this association in a larger sample
size study will be necessary.
