This chapter contains section titled: The immune response to acute exercise Training Status and the Immune Response to Acute Exercise Training Status and Immune Function at Rest Relationship Between Risk of Infection and Physical Activity Practical Considerations Challenges for Future Research Acknowledgment References The immune response to acute exercise Training Status and the Immune Response to Acute Exercise Training Status and Immune Function at Rest Relationship Between Risk of Infection and Physical Activity Practical Considerations Challenges for Future Research Acknowledgment References