The nervous system:
The nervous system intervenes at all stages of a physical activity: it controls the movements and the cardiorespiratory activity. The central nervous system is the "command center" and the nerves connect it to the organs.
Cardiac system and respiratory system:
During a muscular effort, the functioning of the body is modified: the heart and respiratory rates accelerate.
These changes and those affecting the blood vessels can bring more blood to the muscles. They are thus supplied according to their needs in dioxygen and nutrients during an effort. These answers allow adaptation to the effort. The heart will increase its frequency of beat as well as its force of contraction in order to convey the nutrients and the oxygen more quickly towards the organs such as the muscles. The lungs will increase their frequency and intensity of breathing to increase the oxygen supply inside the body.
The muscular system
Muscles are responsible for consumption, energy expenditure, and disposal. Muscle, by its mass and its power, dissociates, disintegrates and oxidizes all the nutritive materials. Its activity, if it is powerful and continuous enough, ensures the humoral and blood detoxification, the perfect oxygenation of all tissues, and the circulation of pure blood, rich and bright red, throughout the body.
The digestive system.
The liver is a vital organ that plays a key role in energy metabolism, protein synthesis, and waste disposal. The digestive tract goes into sleep mode during intense activities to preserve the energy for use by the muscles. Because the body pumps more blood to the muscles, it removes systems and functions that are not at this time a priority, such as digestion. This can cause stomach ache. Movement, absorption, and secretion in the stomach and intestines can be affected.
The urinary system
The intensity of your exercise can affect the rate at which the kidneys filter the blood. After intense exercise, the kidneys allow more protein to be filtered in the urine. They also facilitate the absorption of water, thus decreasing the urine, presumably to help you stay as hydrated as possible.
The endocrine system:
*The pituitary gland
This control center in the brain prevents the adrenal glands from producing the hormones needed for movement. It also diffuses growth hormones. As the body searches for more fuel to burn after tapping into your glycogen stores, it will turn to either muscle or fat, says Cameron. In humans, growth hormone acts as a safety agent for the muscles, telling the body to burn fat instead for energy.
*The adrenal glands
Many of the hormones known as "stress hormones" that release these glands are actually fundamental during exercise. Cortisol, for example, helps the body to mobilize its energy reserves like fuel. And adrenaline helps the heart to beat faster, so it spreads blood faster through the body.