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Erythrocyte rheological properties contribute to the dynamic regulation of vascular resistance to flow shear force, facilitating blood delivery from the heart to peripheral tissues. Despite improved physical performance, the effects of eccentric cycling training (ECT) on erythrocyte rheological characteristics remain unclear. This study investigates the distinct effects of ECT and concentric cycling training (CCT) on muscular hemodynamic and erythrocyte rheological responses to exercise. Thirty‐nine sedentary healthy males were randomly assigned to either ECT (n = 13) or CCT (n = 13) at 45%–70% of the maximal workload for 30 min/day, 5 days/week for 6 weeks, or to a control group (n = 13) that did not receive any exercise intervention. A graded exercise test (GXT) was performed before and after the intervention. Muscular hemodynamic and erythrocyte rheological responses to the GXT were determined by near‐infrared spectroscopy and ektacytometry, respectively. Both ECT and CCT significantly enhanced perfusion (Δ[THb]VL) and O2 extraction (Δ[HHb]VL) in vastus lateralis during GXT. Before training, an acute GXT significantly reduced erythrocyte deformability and increased aggregability, whereas after 6 weeks of either ECT or CCT, the extent of erythrocyte rheological changes caused by GXT was diminished. Moreover, CCT elicited higher improvements in cardiac output (CO), VO2, and work‐rate at peak performance than ECT. In hierarchical regression, the change of maximal CO was the most influential factor affecting VO2max following CCT. In contrast, enhanced VO2max was significantly associated with Δ[HHb]VL and erythrocyte aggregability/deformability in ECT. Although CCT is superior to ECT for increasing aerobic capacity, either ECT or CCT effectively enhances aerobic efficiency by improving muscular hemodynamic and erythrocyte rheological responses to exercise. Highlights: Although concentric cycling training (CCT) is superior to eccentric cycling training (ECT) for increasing aerobic capacity, the two regimens effectively enhance aerobic efficiency by improving hemodynamic or/and hemorheological response(s) to exercise.ECT increases blood O2 delivery to and utilization by contracting muscles, while having lower exertional cardiovascular demand compared to CCT.Cardiac hemodynamic function is the most dominant factor affecting the change of aerobic capacity caused by CCT.Muscular hemodynamic and erythrocyte rheological functions are meaningfully associated with aerobic efficiency mediated by ECT. [ABSTRACT FROM AUTHOR]