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Understanding Hypertension

Most people are generally aware that hypertension is a dangerous condition and is considered to be the “silent killer.” Many can even tell you “high blood pressure makes the heart work harder than it normally has to, that’s why it’s bad!” While these statements are true and important in spreading awareness about high blood pressure, it is important those diagnosed actually physiologically understand their condition.

The main goal of the human circulatory system is to facilitate gas exchange (bringing oxygen in and eliminating carbon dioxide) (Klabunde, 2005). This gas exchange cannot occur without adequate blood flow to working tissues (liver, kidneys, skeletal muscles, etc.). The most important aspect of adequate blood flow is the ability to move from a high pressure to a low pressure. Essentially, it is the job of the heart to receive venous (non-oxygenated blood) and not only replenish the blood’s oxygen supply, but raise the pressure of this blood to assure adequate flow to working tissues (Klabunde, 2005). Systemic arteries will then deliver high pressure oxygenated blood through capillaries to working tissues (smallest vessels where gas exchange directly occurs).

However, these systemic arteries themselves have their own pressure exerted due to the narrowing of arteries (vasoconstriction) controlled by a number of mechanisms and will ultimately raises arterial blood pressure (Klabunde, 2005). Constant vasoconstriction is brought upon by conditions such as stress, physical inactivity, poor diet, and plaque formation all work to increase systemic arterial pressure. Since we have already discussed blood flow works on a pressure gradient (blood flowing from high pressure to low pressure), the heart must increase the pressure of the blood it is sending through systemic flow (Klabunde, 2005). Therefore, the force of each heart contraction has to be greater in order to raise the pressure of ejected blood to assure adequate blood flow via the pressure gradient.

The following article by Cornelissen and Fagard (2005) is a meta-analysis(a research article combining several studies on the topic and giving the general conclusions) and suggests endurance training has shown to be the most effective modality of training for lowering systolic pressure, diastolic pressure, and systemic vascular resistance. Common endurance activities include but are not limited to; running, cycling,  and swimming. Individuals with hypertension are advised to refrain from heavy weight training programs due to the fact it puts added pressure on systemic blood flow. However, endurance weight training (15-20 reps) has shown little adverse effect on blood pressure and vascular resistance. Patients who are considered moderate to high risk for cardiovascular disease should consult with a professional exercise technician to assist with prescribing safe, but effective heart rate zones based on their comorbidities. Especially those with controlled hypertension (medicated). Most blood pressure medications blunt heart rate response to exercise, therefore the common percentage of max heart rate training programs based on age are invalid for these patients and create safety concerns.