Effects of concentric and eccentric exercise regimens on bioenergetic efficiency of lymphocytes in sedentary males

Eccentric exercise training (EET) increases physical performance while having lower metabolic demand than concentric exercise training (CET). Whether EET influences bioenergetic efficiency in peripheral blood mononuclear cells (PBMCs) remains unclear. This study investigates the effects of EET and CET on PBMC phenotypes and mitochondrial functions in blood. Thirty three sedentary healthy males were randomly assigned to either EET (n = 11) or CET (n = 11) that performed at progressively increased from 60% to 80% of maximal absolute workload for 30 min/day, 5 days/week for 6 weeks, or a control group (n = 11) that did not receive any exercise intervention. A graded exercise stress test (GXT) was performed before and after the intervention. PBMC phenotypes and mitochondrial respiratory capacity were analyzed using flowcytometry and high-resolution respirometry, respectively. In the same absolute workload, EET elicited lower heart rate and rating of perceived exertion than CET. However, EET as CET increased the VO₂ level at the ventilatory threshold. Notably, both EET and CET increased central memory (CD45RO⁺/CD62⁺/CD3⁺) T cells and decreased effector memory T cells reexpressing CD45RA (CD45RA⁺/CD62^-/CD3⁺). Moreover, the two exercise regimens diminished the loss of mitochondrial membrane potential (ΔΨm) caused by GXT, increased maximal/reserve O₂ consumption rates (OCR), and bioenergetic health index in intact PBMCs and enhanced complex I-/II-related OCR in PBMCs with a substrate-rich environment. EET improves aerobic fitness with a lower cardiovascular response to exercise than CET. Moreover, EET as CET reduces senescent T-cell distribution in blood and improves PBMC bioenergetic efficiency by stabilizing ΔΨm and increasing capacity of oxidative phosphorylation.