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Fitness for Older Adults: part four - The Heart

August 19, 2019

This week we're going to look at how ageing affects the cardiovascular system. Put simply, how changes to the heart and blood flow affect our ability to exercise.

 

Before you read this, understand this very important fact: active older people have not been reported to demonstrate the same levels of declines as inactive people. In fact, regular exercise has been suggested to slow down these responses to ageing by 50%. This means that you can make a major impact on all the changes you'll read about below and you can never start too late (or early!)

 

 

Firstly, the heart. How does it work and what happens to it as we get older?

 

The heart is a muscle. As this muscle contracts it sends oxygen rich blood to our other muscles. As it relaxes in between contractions the heart muscle itself is fed with oxygenated blood. When we look at blood pressure readings, the first (systolic) tells us the pressure at which the blood is being pumped around our body to the other muscles and the second (diastolic) tells us the pressure at which the heart itself is being fed.  As we age, our bodies spend less time in the second (diastolic) phase where the heart muscle itself is receiving oxygenated blood. This means that our hearts receive less blood per pump. Our heart muscle becomes weaker as a result. Maintaining a normal blood pressure helps us keep our hearts strong.

 

One way to do this is to puff and pant regularly. People who take regular aerobic exercise will have a lower heart rate than those who don't and each beat will force a greater amount of blood around the body. The amount of blood that is pumped with each contraction is called the Stroke Volume. High blood pressure or a lack of aerobic activity may reduce the heart's ability to sufficiently pump. The body still needs the same volume of blood to be pumped every minute (this is called Cardiac Output) so will raise our heart rate and pump the blood in smaller batches. The resulting faster and shallower heart beat leaves less time for the heart muscle itself to be fed with oxygenated blood during the diastolic phase. Therefore, a low and strong heartbeat is a good indicator of cardiovascular fitness.

 

As we age, changes also occur to our maximum heart rate (max HR) reducing our ability to perform aerobically challenging activities. Max HR is the maximum exertion rate at which we can tolerate exercise. While our resting heart rate can remain relatively the same, Max HR decreases by 5-10 beats per decade. This decrease is attributed to changes in nerve stimulation and exercise cannot influence this change. When we have a large difference between our resting and maximum heart rate it gives us greater scope for intensive exercise. We can maintain this greater difference long term by keeping our resting heart rate low. This mean more aerobic or puff'n'pant activity. 

 

There's a bit of a puff'n'pant pattern here!

 

So on to the vessels which carry the blood.

 

As we age, calcium deposits are laid down in the arteries which make the vessels themselves stiffer and less able to respond to the changes in blood flow. This prevents the same volume of blood from being pumped around the body in each stroke and raises the blood pressure. As we saw before, this weakens the heart muscle and increases resting heart rate. It also prevents the other muscles from receiving blood when needed and so further limits exercise capacity. 

 

Another ageing issue is the build up of fatty plaques in the walls of the arteries which further compress the size of the arteries and therefore the blood flow which is able to circulate. This makes it harder to feed the heart, to send the oxygenated blood into or from the heart or to respond to the pressure changes throughout the journey of the blood around the body. This is what happens to your arteries if you have high cholesterol.

 

Fortunately, having a low resting heart rate helps clear out these vessels as the greater amount of blood in each pump removes some of the calcium deposits (like a pressure hose) and increasing the malleability of the vessels. Maintaining your fitness can also help change your body's cholesterol levels, removing the fatty plaques and normalising the blood pressure.

 

It's a closed system and as a result changes to one area knock on to the rest. This means that improving your cardiovascular health has a major impact on your life quality and it's simple to do. Try to spend around 150 minutes every week slightly out of breath. You should be able to speak a few sentences but then need to catch your breath before continuing. It doesn't matter what you do to achieve this (unless it's something illegal like robbing banks) as long as you're comfortably panting away.

 

The only different advice here is if you have a respiratory condition which interferes with your breathing and makes aerobic activity difficult. We'll look at that next week.

 

How do you puff and pant? (Clean) answers on the Making Change Stick Facebook group please!

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