ABSTRACT
Endurance exercises, such as cycling or running, are useful for reducing arterial stiffness. However, individuals with a low physical fitness level, or patients suffering from leg diseases with pain, are unable to perform such moderate-intensity lower-limb exercises for long periods of time. The aim of this study was to evaluate the effects of acute cycling with Electrical muscle stimulation (EMS) on the brachial to ankle pulse wave velocity (ba-PWV). Ten healthy adult men performed 3 sessions, as follows of 20 min: cycling at 50% VO2max (C), cycling at an intensity of 50%VO2max subtracted from VO2 during EMS (LC), and cycling at the intensity of the LC trial while also being combined with EMS (LC+E). The ba-PWV was measured before and after each exercise. In addition, the femoral artery blood flow (BF) was measured in eight healthy adult men before and after exercise using an ultrasound imaging system. In the C and LC+E trials, the ba-PWV significantly decreased immediately after the exercise session, whereas the ba-PWV did not significantly change following the LC trial in any session. Compared with the baseline, the femoral artery BF values significantly increased after all trials. In the C and LC+E trials, the femoral artery BF was significantly greater than that in the LC trial. Acute endurance low-intensity cycling with EMS results in a reduction in the arterial stiffness which is similar to that with moderate-intensity exercise.
ABSTRACT
Endurance exercises such as cycling and running are useful for improving the arterial function and preventing cardiovascular disease (CVD). However, subjects suffering from spinal cord injury (SCI) or lower limb osteoarthritis (OA) cannot perform these kinds of lower limb exercises. Recently, electrical muscle stimulation (EMS) has been shown to be able to increase the muscle strength and blood flow and improve the peripheral circulation. Arm-cranking exercises with EMS may therefore be able to reduce the risk of CVD for patients with SCI and lower OA. However, this point has not been fully clarified. The purpose of this study was to assess the effect of submaximal arm-cranking exercise with EMS on arterial stiffness. Ten healthy young subjects performed submaximal arm-cranking exercise alone (A) and submaximal arm-cranking exercise with EMS (A+E). In the A+E trial, the submaximal arm-cranking exercise was performed at 30%VO2 max for 20 min while EMS was applied to their thigh and calf muscles during the exercise. The brachial-ankle pulse wave velocity (ba-PWV), systolic and diastolic blood pressure (SBP/DBP) and heart rate (HR) were measured before and after each exercise. Immediately after the exercise session, the HR of the subjects in the A+E trial was significantly elevated in comparison to those in the A trial. The SBP and DBP did not differ between the two trials to a statistically significant extent. In the A+E trial, the ba-PWV was significantly reduced immediately after exercise in comparison to the A trial (1082.6 ± 105.9 cm·sec-1 vs. 1191.7 ± 86.7 cm·sec-1, p < 0.05). These findings suggest that arm-cranking exercise with EMS reduces arterial stiffness and might be useful for reducing the risk of CVD.