What happens to our body when we exercise? Reveal!

This text was written by a TecMundo columnist; Learn more at the end.

Isn’t it hard to get off the couch and exercise? Understand this, The incredible process that happens in your body when you move.

Physical exercise is by definition a stressor because it disrupts the body’s normal physiological balance, but it is not like other stressors that have negative negative effects. The stress caused by adequate amounts of exercise is one of the best stresses we can create for the human body. Understand in detail here how this process occurs, which provides many health benefits.

Prof. Guilherme Weiss Freccia, PhD in Human Movement Sciences and exercise physiologist, explains: “Exercise greatly disrupts the physiological balance, and therefore different organs (and their constituent cells) must communicate in harmony and simultaneously with the demands of the imposed effort.”

Freccia says we must take into account that it is almost impossible to understand the exact temporal sequence of physiological events, especially since we can respond to very different intensities, durations and types of exercise.

first steps

According to Freccia, “It all starts in the motor cortex, a set of specialized cells in the brain that respond to the decision to perform the movement by sending signals to the muscles that need to be activated precisely and in an organized manner through the motor neurons.” Before or simultaneously with the voluntary movement of the muscles, the body prepares fuel.Through central command, it activates concerted cardiovascular and respiratory responses to prevent any lack of energy substrate and oxygen in currently active muscles. To achieve this, more blood and more oxygen now feed the working muscles (like the hips when cycling), the heart and the respiratory muscles.”

The nervous system reacts very quickly. The conduction speed of a motor neuron’s nerve signal is 70 m/s (this is approximately 10 times faster than Bolt, the world record holder in the fastest athletics event, in the 100 m dash). This refers to the ability to respond to the stress of high-speed exercise. But the nervous system continues – as long as the effort continues – to monitor whether survival is at imminent risk by maintaining muscles, joints, tendons and, for example, blood sugar and body temperature.

According to the professor, “The endocrine system, like the nervous system (but slightly slower), seeks metabolic adjustments. Initially, there is a decrease in circulating insulin and an increase in levels of glucagon – a hormone that stimulates glucose production in the body.” liver. This reduction in insulin is paradoxical but important because this energy must be directed to active muscle and cannot be “wasted” on other tissues that need it less.. “Therefore, the muscle cell activates the entry of this sugar into the circulation through the GLUT-4 glucose transporters present in the cell membrane.”

This internal mechanism of muscle contraction appears to be important for people diagnosed with type II diabetes, as it is independent of the amount of insulin present in the blood.

Professor Guilherme Freccia also says: “The contracting muscle produces a lot of metabolic heat, which can negatively affect the activity of the enzymes responsible for energy conversions in metabolic processes. Therefore, the nervous system is already monitoring the inside of the muscle to cool the machinery by releasing anti-diuretic hormone (ADH) ) secretes and aldosterone, which in turn works to preserve water wastage and prevent the loss of important electrolytes.“

“When muscle temperature becomes too high, some of the blood flow will be directed to the dermis, allowing better heat exchange with the environment through sweating, resulting in loss of plasma volume (water in the blood).” Therefore, hydration needs to be maintained at all times, especially in a hot environment. Thirst, as the physiologist points out, is an important symptom of dehydration..

So what are the differences between exercise types?

Freccia comments: “In general, these responses from the heart, circulation and lungs are more pronounced in exercises that we call aerobic, such as running or cycling in the park, and are named this because oxygen joins a large part of the body. energy conversion processes.”

But in exercises where we need to lift and/or support weights, such as going to the gym, your ability to build muscular strength is constantly at the center. (This does not mean that the cardiopulmonary apparatus is no longer used, because everything works simultaneously and integrated).

The nervous system participates more actively and more intensively in strength training, as special muscle fibers must be used. Generally, there are two types of fiber in our body:

• write the letter i (also known as red or oxidative fibers) do not produce much force but are quite resistant;
• as type II (white or glycolytic), produces a lot of power but tires quickly.

Like the roots of a tree branching out from its trunk, the motor neuron connects to many muscle fibers of the same type; We call this the motor unit.

When this motor neuron is activated, all the fibers it innervates contract. For example, in bodybuilding we almost always use type II fibers, which require significant stimulation from the nervous system.

“In other words, just as we choose to use some of the fibers that resist fatigue to travel long distances, we may also choose to additionally use other segments of fibers that produce great force (but unfortunately tire quickly).”

If such changes occur immediately in our body, many other chronic adaptations occur when we constantly repeat the stimulus (training), such as strength gain, mitochondrial biogenesis, increased maximum oxygen consumption, greater bone density, etc., which translates into a stronger person. It is both more resistant to fatigue and healthier. Physical exercise is probably the best daily stressor we can have.

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Fábio Dominski He holds a PhD in Human Movement Sciences and a degree in Physical Education from Santa Catarina State University (UDESC). He is a university professor and researcher at the Laboratory of Sport and Exercise Psychology (LAPE/CEFID/UDESC). He is the author of the book Exercising Físico e Ciência – Fatos e Mitos and hosts the program Exercising Físico e Ciência on UDESC joinville radio (91.9 FM); in the program Available as a podcast on Spotify.