Fig. 1

Exercise protocol and blood sampling. Heathy donors (n = 12) were separated into two groups and underwent two different training programs on two occasions separated by 14 days. In the first week group 1 (n = 6) completed a single bout of continuous exercise (CONT: 30 min at 50% of individual maximum capacity), whereas group 2 (n = 6) underwent a single bout of high-intensity interval training (HIT: 20 min of 30 s at maximum capacity followed by a 30 s pause, 5 min before and after HIT at 50% of individual maximum capacity). On the second visit exercise protocols were interchanged for both donor groups (week 3). Intravenous blood samples were collected before, directly, 1 h, and 24 h after exercise. The cellular immune status was determined directly in whole blood and specific T-cell responses were obtained in isolated peripheral blood mononuclear cells (PBMCs) using established immunoassays