Immediately after exercise, the pulse will still be higher than normal, because the muscle may have used more energy than the blood could supply in the form of oxygen and glucose. The muscle will have to repay this "oxygen debt" by taking in more blood than normal for a time.
Few minutes after exercise, we would expect the pulse rate to be closer to the resting pulse rate than immediately after exercise, as the muscles will have had some time to recover. The time it takes to regain the resting pulse rate after exercise is a useful way of telling a person’s fitness.
The pulse rate indicates how hard your heart is working at any given time. The heart is extremely important for carrying oxygen to all parts of the body. Oxygen is needed when your muscles do work. It is needed to burn up food to produce energy.
Aerobic respiration
During energetic exercise your body may not be able to supply your cells with enough oxygen for aerobic respiration to take place at the required rate. This is called 'oxygen debt'. Your body then begins to produce energy through anaerobic exercise. This then leads to a build-up of potentially painful lactic acid in your muscles. Once the exercise has stopped your body continues to breathe at an increase rate so that the oxygen debt can be recovered and the lactic acid is broken down in a reaction with oxygen to form harmless carbon dioxide and water. It is your brain that detects the level of lactic acid in your blood and causes you to breathe heavily so that oxygen can get into your body as quickly as possible. The amount of time that it takes for your body to return to normal after exercise is called your recovery time.
Aerobic respiration takes place in the presence of oxygen and produces the most energy.
Glucose + Oxygen = Carbon Dioxide + Water + Energy
C6H12O6 + 6O2 = 6CO2 + 6H2O + Energy
Approximately two minutes of exercise, the body responds to supply working muscles with oxygen. When oxygen is present, glucose can be completely broken down into carbon dioxide and water in aerobic respiration. The glucose can come from three different places:
- remaining lactic acid supplies in the muscles
- breakdown of the liver's glycogen into glucose, which gets to working muscle through the bloodstream
- absorption of glucose from food in the intestine, which gets to working muscle through the bloodstream
As you start running. Here's what happens:
- The muscle cells burn off the energy they have floating around in about 3 seconds.
- The ‘phosphagen’ system kicks in and supplies energy for 8 to 10 seconds. This would be the major energy system used by the muscles of a 100-meter sprinter or weight lifter, where rapid acceleration, short-duration exercise occurs.
- If exercise continues longer, then the lactic acid system kicks in. This would be true for short-distance exercises such as a 200- or 400-meter or 100-meter swim.
- Finally, if exercise continues, then aerobic respiration takes over. This would occur in endurance events such as 800-meter, marathon run, rowing, cross-country skiing and distance skating.
Anaerobic respiration
Anaerobic respiration occurs when there is an ‘insufficient’ supply rate of oxygen and lactic acid is produced. If we take strenuous exercise, our muscles need extra oxygen. But we can’t breathe fast enough, nor pump our blood sufficiently quickly to get oxygen to our muscles. So our muscles produce energy by making lactic acid. It is a poison and makes your muscles ache. During a race the lactic acid builds up and it has to be got rid of after the race. This is done, by panting to get more oxygen into the body and converting the lactic acid into carbon dioxide and water. The extra oxygen needed to get rid of the lactic acid is called the oxygen debt.
Anaerobic respiration produces far less energy than aerobic and it cannot go on for long. However, it can mean the difference between life and death.
Anaerobic respiration takes place in the presence of Lactic Acid and produces the least energy.
Glucose = Lactic acid + Energy
For example, running requires a lot of energy to be produced by respiration in the cells and the circulation needs to work hard (faster pumping of the heart etc.) to get the oxygen and glucose where it is needed. Heavier breathing is also needed to supply the oxygen and get rid of the carbon dioxide.
Carbon Monoxide forms a strong bond with the haemoglobin, and does not leave the haemoglobin once it is bonded to it. So it blocks the haemoglobin, and it can’t do its job of carrying around oxygen anymore.
This is a problem for smokers, as they have less ability to carry oxygen around in their blood, and their bodies have to keep on making extra red blood cells to make up for the ones that have been ‘hijacked’ by the carbon monoxide. So, smokers get "out of breath" easily. It is nothing to do with their inability to breathe, but it has a lot to do with their inability to carry enough oxygen around their bodies to the parts that need it.
Now when you exercise you generate heat, which you must lose to prevent you body warming up to much. The skin will respond in a number of ways to cool you down but most importantly the blood flow to the skin increases so that heat can be lost to the air and sweat glands release warm sweat onto the surface of our skin. When the sweat evaporates this cools the skin down and draws heat from the blood so that our core temperature does not get too warm. So you see that although we feel hot during exercise the skin gets colder from the sweat evaporating of it and so cooling our bodies down.
Asthma Attack
Once a person has asthma, a number of things can start an asthma attack. For instance, when a person has asthma, they might get an attack when they have a cold or they might get an attack when they breathe something that irritates the lungs (such as cigarette smoke, dust or feathers). This causes three changes to take place in your lungs: Cells in the air tubes make more mucus than normal. This mucus is very thick and sticky. It tends to clog up the tubes. The air tubes tend to swell and the muscles in the air tubes tighten. These changes cause the air tubes to narrow and make it hard to breathe. Asthma attacks may start suddenly. Or they may take a long time, even days, to develop.
Causes
In a person with asthma, the airways narrow in response to ‘stimuli’ that don't affect the airways in normal lungs. The narrowing can be triggered by many ‘stimuli’, such as pollens, dust mites, animal dander, smoke, cold air, and exercise. In an asthma attack, the smooth muscles of the bronchi go into spasm, and the tissues lining the airways swell from inflammation and secrete mucus into the airways. These actions narrow the diameter of the airways the narrowing requires the person to exert more effort to move air in and out.
