Expert: Brandon Briggs, MS - 3/12/2008

Question
Is cardiovascular exercise really good for us?  If so, how and why?  How does speeding my heart up to a certain point help me?  And what if I work at a job where I do a lot of "cardio" work?  

I have seen theories that a heart can only beat so many times in a lifetime.  If that is true, then why speed it up?

Doesn't raising the blood pressure and heart rate - even during exercise - cause the same kind of damage to blood vessels as chronic high blood pressure might?

Thanks much,

Shawn  

Answer
First let me start by letting you know that theory of having only so many heart beats with in a life time is a myth. There is no research backing such a statement. However, there is plenty of information regarding the benefits of cardiovascular exercise.

1. Why is cardiovascular exercise good for us?
    To start our heart is a muscle just like our biceps are. We know that to increase muscular endurance or increase strength in a muscle we have to exercise that muscle. Your heart works the same way. When increasing your heart rate you are making the heart increase its contractile force. This can result in higher endurance for the heart muscle. Also by exercising and increasing heart rate and blood pressure you are allowing your vessels to dilate. The more fit you are the longer those vessels stay dilated which can result in lowering blood pressure at rest. When your blood pressure is high or considered hypertensive at rest is when you have a true problem. Another affect on increased cardiovascular endurance gained through exercise is a lower resting heart Rate(HR). A lower HR at rest means that the heart is having to work less at rest when compared to an untrained person. Less work at rest means less strain on the muscle.

2. "Cardio at work"
    Cardiovascular exercise is considered aerobic exercise. The aerobic pathway breaks down fat as fuel. You can think of it as any exercise lasting longer that 3 min in duration that increases the HR and sustains that increase. Any short bursts of exercise use different fuel pathways such as the anaerobic system or the ATP-PCr pathway. The American College Of Sports Medicine (ACSM) recommends that we achieve at least 30 min of cardiovascular exercise most days of the week, meaning 5-6.

3.  Chronic High Blood Pressure
       This is usually due to the vessel being narrowed by plaque which increases the pressure against the walls causing damage. When increasing your BP though exercise your are actually dilating (making a larger opening) the vessel allowing blood to pass through with out damaging the vessel wall.

I hope this has helped if I can explain anything further please let me know.

Best Regards,
Brandon