Autonomic Dysfunction clinical trials

Upper- and Lower-body Resistance Exercise With and Without Blood Flow Restriction on Hemodynamics and Vascular Function

The American College of Sports Medicine (ACSM) recommends that resistance exercise performed at greater than 70% one repetition maximum (1 RM) is necessary to induce strength gains and muscular hypertrophy (ACSM, 2009). However, previous work has shown resistance exercise at high intensity increases the rate of injury. Blood flow restriction (BFR) exercise is a method that is used to compress the blood vessels to the exercising muscle in order to reduce blood flow to the limb with the use of low-intensity resistance. Researchers have suggested that resistance exercise at intensities as low as 20-30% 1-repetition maximum with BFR increases in muscle mass, muscular endurance, and gains in strength. However, the acute heart and blood vessel changes in response to BFR are not clear. Work by our laboratory (Tai et al., 2016) has demonstrated that immediately following acute resistance exercise at moderate intensity (75% 1 RM) without BFR, there are no changes in aortic and brachial systolic and diastolic blood pressure (BP), but there are increases in the pressure of the reflective wave (augmentation pressure). This suggests that the arterial wall is stiff, and may in turn result in thickening of the arterial wall. However, the data are limited and these responses may not be universally accepted. In addition, these studies used primarily lower-body resistance exercises (squat, leg extension, and leg flexion), and did not assess changes in heart and blood vessel function. Previous researchers have demonstrated that upper-body exercise induces higher BP and heart rate (HR) than lower-body exercise. However, the effects of upper- and lower-body resistance exercise with BFR on heart and blood vessel function are still unclear. Therefore, understanding the effects of upper- and lower-body resistance exercise with BFR on heart and blood vessel function using weight machines, specifically the chess press, latissimus dorsi pulldown, knee extension, and knee flexion may significant impact how the resistance training program is prescribed.