Leukocyte mitochondria alterations after aerobic exercise in trained human subjects

Exercise is associated with intensity-dependent immune disturbances. Leukocyte mitochondrial alterations and apoptosis may contribute to this phenomenon. Purpose: To investigate the effects of different intensities of aerobic exercise (AE) on leukocyte mitochondrial transmembrane potential (MTP) and the propensity of apoptosis. Methods: Blood samples were collected from 12 subjects who performed AE for 3 consecutive days (35% maximal oxygen consumption (V̇O_2max)). Leukocyte MTP and apoptosis were measured by flow cytometry. The subjects performed two additional sessions of AE of higher intensities (60% and 85% V̇O_2max) with an intervening 4-wk washout period. The measurements were repeated during each session. Results: Leukocyte MTP declined during daily, repetitive AE at an intensity of 60% and 85% V̇O_2max. Similar changes were not found during a more moderate AE (35% V̇O_2max). Leukocytes increased their propensity of apoptosis a period (3-5 d) after the start of the AE. Conclusion: High-intensity AE has accumulative effects on the mitochondrial energization status and vitality of peripheral blood leukocytes. Leukocyte MTP is a potentially applicable indicator for monitoring immune distress due to overtraining.