Effect of Upper Body Negative Pressure on Brachial Blood Flow During Handgrip Exercise

Abstract

Listen

Translate article

Lower body negative pressure (LBNP) has been shown to increase blood pooling in the lower limbs and induce global vasoconstriction. The addition of rhythmic handgrip exercise during LBNP continues to decrease the muscle oxygenation in the arm performing the exercise. However, no studies have used upper body negative pressure (UBNP) to augment blood flow to the exercising muscles. Increasing blood flow, and ultimately shear stress, to the limb vasculature during exercise may improve angiogenesis and have clinical benefits to those with peripheral artery disease. PURPOSE: The purpose of this study was to compare the changes in BBF under normal pressure and -30 mmHg negative pressure at baseline and during three HG intensities. METHODS: The participants lay supine with their right arm in the UBNP box. The top portion of the upper arm was kept out of the UBNP box so the brachial artery could be scanned using Doppler ultrasound. Heart rate (HR) and blood pressure (BP) were recorded continuously throughout the protocol. After a 5 minute baseline period, the participants completed 3 stages (3 minutes each) of HG exercise at 15%, 30%, and 45% of their MVC with one minute of recovery between each stage. This protocol was performed twice, once without negative pressure stimulation and once with -30 mmHg UBNP applied to the exercising limb. BBF was calculated from the blood velocity and vessel diameter for each participant. RESULTS: There were no significant interactions for any of the variables across the pressures and intensities. However, there was a main effect of intensity for BBF (p=0.008) and HR (p=0.002). Both BBF and HR increased as HG intensity increased. UBNP stimulation did not alter HR, MAP or blood flow compared to baseline. CONCLUSIONS: This data indicates that there is an increase in BBF to the arm during handgrip exercise, however UBNP does not augment the blood flow response. Greater negative pressures may be required to increase blood flow during handgrip exercise.