Erythrocyte rheological properties affect blood viscoelasticity and consequently regulate vascular resistance to flow shear force, whereas rheological impairments of erythrocytes may result in circulatory disorders. The aim of this study was to establish an effective exercise strategy for improving individual aerobic capacity and for simultaneously ameliorating the risk of hemorheological dysfunction evoked by a graded exercise test (GXT) and the hypotheses is exercise intervention will improved hemorheological functions by enhancing deformability of erythrocytes via NO-mediated mechanism. This study included 60 healthy sedentary mens (age 20~30) from Chang Gung university than were randomized into the HIIT [3-min intervals at 40% and 80% V̇O2 reserve (V̇O2R),n=10] and MICT(sustained 60% V̇O2R,n=10)on a bicycle ergometer for 30min·d-1, 5 d·wk-1 for 6 wk.

Recently, the role of erythrocyte has been more emphasized, which also related with endothelial cell. For coronary artery patients, the endothelial nitric oxide synthase activity in red blood cell (RBC-eNOS activity) is lower than age-matched health people, and it is related with dysfunction of endothelial cell. In cardiovascular diseases. the erythrocyte arginase-1 is active and seize L-arginine with eNOS. When the Arg-1 stimulated by reactive oxygen species (ROS), the nitric oxide (NO) bioactivity decrease and produce more ROS, meanwhile, ROS can go around to stimulate Arg-1. When the RBC-NO production is lowering, it will increase the adhesion activity to endothelial cell due to erythrocyte can be quite close to blood vessel well then release Nitric Oxide, induce the dysfunction and oxidative pressure of endothelial cell. The NO can also regulate the deformability of erythrocytes, and extremely affect oxygen supply to tissue once the deformability and aggregation of erythrocyte become abnormal. Besides NO, the deformability will be affected if erythrocyte is continuously exposed to the endogenous or exogenous ROS, which also increase adhesion to endothelial cell with the exposure of phosphatidylserine. Exercise can regulate the mechanism of NO release from erythrocyte, affecting the rheology of erythrocyte, and improve the anti-oxidation ability. Therefore, as mentioned above which make erythrocyte, as many aspects, become an important role on atherosclerosis disease treatment.

Inclusion Criteria:

• Having a sedentary lifestyle (without regular exercise, exercise frequency ≤ once weekly, duration < 20 min).

Exclusion Criteria:

• Exposed to high altitudes (> 3000 m) for at least 1 year.
• Smoker
• Taking medications or vitamins
• Having any cardiopulmonary/hematological risk.