We’re all about having a big heart here at DH, both metaphorically and physically, as not only do we genuinely love you all but we also recognise the importance of creating an internal pumping station that would rival the Hoover Dam in its ability to get that blood to those working muscles!
Fortunately, we know a machine that helps do exactly that and we’re pretty fond of sharing the science behind its abilities with you guys.
So sit back and lets dive deep into the understanding of what is affectionately called “Cardiac Hypertrophy”.
The science of getting strong on the inside.
Prolonged participation in aerobic-based activities leads to several changes in cardiovascular function. Specifically, during exercise cardiac output increases (your heart pushes out more blood per beat), whilst at rest heart rate is reduced and stroke volume has increased. These changes are because of cardiac hypertrophy, or an enlargement of the heart muscle. This is often referred to as “athletes heart” as the heart can become up to 25% larger in size. This increase is predominantly due to the enlargement of the ventricles which are responsible for pumping blood more forcefully, and the chambers themselves have become larger, enabling more blood to be ejected with each beat. The increased strength of the heart means that the ventricles can empty more rapidly and more fully.
At rest, stroke volume increases and because the demands of the body at rest are mainly unchanged the heart is able to beat fewer times to meet these demands. While the average resting heart rate of an untrained individual is between 60-80bpm, it is not unusual to see resting heart rates between 40-50bpm, and sometimes lower in elite-level athletes. The slower resting heart rate is a term called ‘bradycardia’, and is the opposite of a high resting heart rate ‘tachycardia’.The increase in maximal cardiac output is the result of the increase stroke volume and results in an increased ability to deliver oxygen, nutrients and hormones around the body.
The increase in potential blood supply from the enlarged heart is supported by an increase in the number of capillaries in the muscles and around the alveoli of the lungs. This increased capillarization ensures that the oxygen and nutrients can be delivered and the waste products such as carbon dioxide and lactic acid, can be quickly removed from the muscle tissue. The increased capillarization reduces the distance that the oxygen has to diffuse from the capillaries to the muscle cells so diffusion can happen more quickly.
It is not clear to what extent cardiac hypertrophy is due to the training effect or to genetics, as it appears some people have naturally low heart rates, to begin with. However, what is clear is that cardiac hypertrophy is not a permanent condition and if aerobic training is not continued, the heart muscle return to its pre-training size. This illustrates the principle of reversibility of training. I.e. if you don’t use it you lose it!!
So, if you ever want to know why we program lots of those aerobic-based sessions there you have it! It’s all about making that heart big and strong, and we want to make you sweat whilst you’re at it also!!
Yours in fitness, education and looking after that heart.
Coach John.
Photo by jesse orrico on Unsplash
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