The impact of soccer training on the immune system.

OBJECTIVE

The aim of this study was to evaluate whether the level of some immune markers changed in soccer players during pre-season and during playing-season.

DESIGN

An observational study for one soccer season (one year).

SETTING

Professional soccer players.

PARTICIPANTS

Thirteen professional soccer players (age: 26.3 +/- 3.7 years).

MEASURES

The effect of 11 months of soccer training sessions and matches on circulating leukocyte and lymphocyte subpopulations was investigated. Blood samples were taken before the season and also 6 weeks, 6 months and 11 months later. All samples were taken at 08:00 h.

RESULTS

Total lymphocyte counts did not change in all samples. During the pre-season, however, the concentrations of some inflammatory lymphocyte subpopulations were changed: CD4CD45RA+ was elevated and CD57 and CD8CD57 showed a significant decrease (p < 0.05), At the competitive period, CD4 and CD8 were increased. At the end of the season there were significant changes in some immune cells: total leukocyte and neutrophil number and CD8+ cell concentration was increased compared to pre-season values and the CD4/CD8 ratio was decreased.

CONCLUSIONS

The results suggest that athletes exposed to a long-term training periods can exhibit variations in some immune cells. The clinical significance of these variations requires more detailed investigation.