Relationship between plasma endothelin-1 concentration and cardiovascular responses during high-intensity eccentric and concentric exercise.

The present study investigates the relationship between plasma endothelin-1 (ET-1) concentrations and cardiovascular responses during eccentric (ECC) and concentric (CON) resistance exercises. Eight healthy males (aged 24.3 +/- 1.2 years) performed dynamic forearm exercises for 60 s at an angular velocity of 60 masculine s(-1). Each test comprised 60-s high-intensity (80% of peak torque) bouts of randomly selected ECC and CON contractions, and the plasma ET-1 concentrations were measured before and after each type of contraction. Systolic pressure (SBP), diastolic pressure (DBP), pulse pressure and heart rate (HR) during ECC and CON contraction were also measured. Mean arterial pressure (MAP) was calculated from SBP and DBP. The rate-pressure product (RPP) was calculated from SBP and HR. The plasma ET-1 concentration was significantly increased after CON, compared with ECC contraction (P<0.01). Moreover, SBP, DBP, MAP and RPP were significantly increased (P<0.05, P<0.01, P<0.001, respectively) during CON, compared with ECC contraction. Correlations between plasma ET-1 concentration and MAP were not significant during ECC contraction, but significantly positive during CON contraction (P<0.05). These results showed that CON contraction is associated with ET-1 production and a greater increase in blood pressure compared with ECC contraction.