Effects of concentric and eccentric cycling training on muscular hemodynamic and erythrocyte rheological responses to exercise in sedentary males

Erythrocyte rheological properties significantly contribute to the dynamic regulation of vascular resistance to flow shear force, whereas impaired rheological functions of erythrocytes lead to circulatory disorders and exercise intolerance. This study investigated whether eccentric (ECE) and concentric (CCE) cycling exercise regimens influence hemorheological/hemodynamic responses to hypoxic stress in sedentary males. Twenty-two healthy sedentary men were randomized to either ECE (n=11) or CCE (n=11) group. These subjects progressively performed ECE or CCE at 45% to 70% VO2max on a bicycle ergometer for 40 min/day, 5 days/week for 6 weeks. Erythrocyte rheological and central/peripheral hemodynamic characteristics at rest and after hypoxia exercise test (HE, 100W under 12% O-2 for 40 min) were determined by laser diffraction ektacytometer and bioreactance-based device/near infrared spectrometer, respectively. The result demonstrated that HE reduced erythrocyte deformability and increased erythrocyte aggregability under shear flow whereas CCE rather than ECE attenuated the extents of erythrocyte rheological impairment caused by HE. Although cardiac hemodynamic responses to exercise in the ECE group were smaller than those in the CCE group, the percentages of blood distributed to frontal cerebral lobe and vastus lateralis muscle in ECE group were larger than those in CCE group. Hence, we conclude that CCE effectively increases the resistance to hemorheological impairment evoked by HE, whereas ECE prominently enhances cerebral/muscular hemodynamic adaptions to exercise in sedentary males.