Effects of Exercise on the Renin-angiotensin System

Overview

Angiotensin converting enzyme-2 (ACE2) is part of the renin-angiotensin system (RAS), which is involved in maintaining blood flow and electrolyte balance. It has been shown in obese and hypertensive individuals that levels of another molecule Angiotensin converting enzyme (ACE) are much higher, leading to inflammation, fibrosis, vasoconstriction and high blood pressure. ACE2 has a protective effect from ACE, leading to anti-inflammatory, anti-fibrotic and vasodilating effects. In animal models, it has been shown that aerobic exercise can increase levels of ACE2, while decreasing levels of ACE and offers protection to the cardiovascular system by keeping these two molecules balanced. Although the effects of exercise on the classical arm of the RAS have been studied significantly, ACE2 is a relatively new discovery and has not been studied as extensively in humans. The purpose of this research is to determine the effects of exercise training status on the RAS, specifically on ACE2 and its products.

The design of the proposed study is an intervention study, where participants are selected into either a physically active group or a sedentary group. The physically active group will be set as our control, as the physiological stress of the exercise protocol should be lower in the physically active group and limit the magnitude of the response. Both groups will be exposed to the same experimental procedure. Participants will be placed in their group based on their responses to the CSEP Get Active questionnaire. Individuals who do not accumulate less than 75 minutes of moderate to vigorous physical activity a week will be placed in the sedentary group, while those who accumulate more than 150 minutes will be placed in the active group. Participants will be asked to avoid anti-Inflammatory medications, drugs, alcohol and smoking 48 hours prior to any of the sessions. Participants in both groups will undergo the same testing procedure. Tests will include densitometry and a graded exercise test to measure maximum VO2 and associated parameters. Venipuncture (10 ml) will be performed before, after and 30 minutes post VO2 max test. The proposed study analysis will be conducted using a dependent groups ANOVA and Tukey's post hoc testing.