Short-term Effects of Exercise

When you begin exercising, your heart rate increases. This is because your muscles require more oxygen and nutrients to maintain physical activity. The sweat you produce is your body’s way of cooling down.
There is increased blood flow to the skin. This helps to manage body heat by increasing the blood surface area exposed to the environment.
Blood vessel dilation occurs. This means that the walls of your blood vessels relax and widen, allowing for more blood to flow through them and reach the muscles.
The frequency and depth of breathing increase. This supplies more oxygen to the blood and removes carbon dioxide more swiftly.
There is a temporary increase in blood pressure. This is due to the heart needing to work harder to pump blood around the body during exercise.
Energy stores in the muscles (in the form of glycogen) can be quickly depleted. The body then moves on to utilise the glucose in the blood, and once this is also depleted, it starts to break down fat reserves for energy.
Lactic acid builds up in the muscles, especially during strenuous or prolonged exercise without sufficient oxygen supply (anaerobic exercise). This can lead to muscle fatigue and soreness.
Body temperature rises due to the conversion of chemical energy into thermal and mechanical energy, resulting in sweating to maintain homeostasis.
Exercising strengthens different muscle groups, depending on the type and intensity of the exercise. These muscles may temporarily increase in size immediately after exercise due to increased blood flow (a pump).
Physical activity stimulates the release of endorphins, chemicals in the brain that act as natural painkillers and mood elevators. This is often referred to as ‘runner’s high’.

Keep in mind that the exact changes your body undergoes might vary based on factors such as your overall health, the intensity and type of the exercise, its duration, and the environmental conditions.