In the return of a long-running Sci&Tech series exploring the science behind common student experiences, Treasurer Colby Lazcano explains the effects of exercise on the body

Written by Colby Lazcano
2nd Year Undergraduate - BSc Chemistry with Medicinal Chemistry and Drug Discovery
Published
Images by Geert Pieters

Exercise, as one of the most popular activities done by students, is well-known for its ability to help improve physical wellbeing, such as improving our life expectancy and reducing the future risk of diseases such as, for example, coronary heart disease. However, it can also have a beneficial impact on mental health. During a period of exercise, catecholamines, a type of protein chemical such as noradrenaline and dopamine, are produced; their amount is mainly dependent on the intensity of the exercise done. 

Noradrenaline is produced in the adrenal glands, which are situated just above the kidneys. Physically, their presence in the body causes an increase in heart rate and an increase in blood pressure. Mentally, noradrenaline is able to achieve a number of different results. Firstly, an increase in noradrenaline causes an increase in the ability to wake up after sleep, which is why those who exercise may have a feeling of freshness after they have woken up from sleep. Also, noradrenaline is known to have a positive effect on emotional memory: for example, in an area of a student’s course which the student finds fun, they may experience increased retention. Serotonin, a hormone, is also produced during exercise via the release of tryptophan and its subsequent reaction to form serotonin. Serotonin is known to be a mood-regulating chemical that provides the person who exercises with feelings of elation and satisfaction. Dopamine is known to be similar to serotonin in regards to causing a positive sensation, as it provides a pleasant, reward-like feeling.

Serotonin, a hormone, is also produced during exercise

From exercise, more blood is able to get to the brain. One of the reasons why this is important is that this allows for higher amounts of a chemical called Vascular Endothelial Growth Factor (VEGF) to reach the brain, which stimulates neuroplasticity. Neuroplasticity is the process whereby the brain adapts to both internal and external changes to the body. Through exercise, the brain is better able to incorporate new information, such as notes from a lecture, through the facilitated formation of new connections between neurons. Neuroplasticity is also important for whenever a neuron is injured. When a neuron is injured, the brain is able to reorganise itself in order to create a system of connections that is able to continue the function of the injured neuron.

Through exercise, the brain is better able to incorporate new information

In the area of exercising, the term ‘no pain, no gain’ may be one that comes to mind. The reason why pain is caused by exercise is that while you are exercising, the body repeatedly contracts and relaxes the exerted muscle fibres. This mechanical disruption is then picked up by a pain receptor, which then transports the information from the area and the intensity of the damage caused to the muscle fibres, to the brain. The type of neuron for this muscle pain contains in its structure an insulating layer, called a myelin sheath. This allows the electrical impulse to ‘jump’ from one area to another, making its transport to the brain quicker. This is why the pain from exercise is a quick and sharp pain.

Contrary to popular belief, lactic acid itself does not cause pain during exercise. During exercise, the body must move from normal aerobic respiration (breathing) to a process called anaerobic glycolysis. This provides the energy in the form of ATP, a small energy-storing molecule that releases energy once broken down, but the process is less efficient.

The product (pyruvate) formed from anaerobic glycolysis is then converted into lactate. The burning feeling from the muscles during exercise comes from there being high acidity; lactic acid is produced by the body in order to reduce this acidity and maintain optimal muscle pH. This formation of lactic acid, along with catecholamine, allows the muscles to slow down, protecting them from serious permanent damage.


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