Why do fit people have quicker heart rate recovery?

Answer 1

First of all, 'How does the body detect when we're exercising?'. Chemoreceptors detect particular changes in the body's environment; in particular it reacts to chemical stimuli. When we're exercising, our body changes chemically. One of these changes is the change in concentration of carbon dioxide and oxygen in the bloodstream. Therefore these chemoreceptors, both central chemoreceptors and peripheral chemoreceptors detect these chemical stimuli in the environment.

The process I have just described is a neuron pathway. The first time a nerve impulse travels along a particular pathway, a neuron pathway is formed. New experiences set up new neuron pathways. If the experience is repeated, in this case, if concentrations of carbon dioxide and oxygen in your body changes, in other words if the subject exercises more, then his neuron pathway would be much stronger than pathways of those less fit than the subject. The more frequently this pathway is stimulated, the quicker a response can come about. In other words, the subjects with higher fitness levels will be able to react to changes in their body's environment and come about with a response much quicker than those who are less fit. Therefore as people with higher levels of fitness start recovering from the exercise quicker than those with lower levels; overall they will recover more quickly as they have already had some time recovering before the less fit people.

The neuron impulses picked up by the chemoreceptors are then transmitted to the cardiovascular centre situated within the hypothalamus, within the brain. The hypothalamus is the area of the brain responsible for carrying out all homeostatic procedures including the concentration of carbon dioxide and oxygen within the body.

Once the hypothalamus receives these neuron impulses, it sends chemical messages to the autonomic nervous system which can be sub-categorised into one of the nervous systems below:

o Sympathetic nervous system- A series of nerves responsible for carrying out many particular functions within the body as a result of up and down homeostatic mechanisms e.g. heart rate. Effects include the activation of sweat glands, the increase in heart rate and the dilation of pupils - all three of these effects occur when the subject it exercising

o Parasympathetic nervous system(via vagus nerve stimulation) - A series of nerves responsible for the stimulation of particular functions within the body whilst the body is resting e.g. salivation

The sympathetic nerve may be referred to as the accelerator as it causes an increased pulse rate whereas the vagus nerve may be referred to as the decelerator as it causes a decreased pulse rate.

Both systems are a patch of cells located in the heart which receives messages from the cardiovascular centre and convert these chemical messages into electrical messages and transmit to the sinoatrial node, otherwise known as the pacemaker. This is the part of the heart organ which brings about a response to a detected stimulus.

The heart is myogenic, meaning that it beats at its own accord. If, for example, we took the heart out of an individual and placed it on a table, it would continue to beat. This is because the heart beat rate is initiated in the heart within the sympathetic and parasympathetic nervous systems, and is carried out within the sinoatrial node. It only needs a nervous input to determine the rate, at which the heart should beat, therefore if the autonomic nervous input ceases to exist, or is disconnected to the nervous system, it would continue beating, just without guidance of the speed at which it should beat at.