Cardio. For some, it’s a dreaded word and for others, it’s a passion they can’t get enough of. Either way, you look at it, cardiovascular exercise is one of the key components that should never be left out of a fitness plan. Here are 8 main benefits of adding some cardio to your fitness routine.
The Cardiovascular System
The cardiovascular system, also called the circulatory system, is a vast system that transports oxygen, nutrients, hormones and metabolic products throughout the entire body. It includes the heart, arteries, veins, capillaries and lymphatic system and has been estimated to be as long as 100,000 km. The average person has 4.7 to 5.7 litres of blood, and the heart pumps this volume every minute at about 70 beats per minute, pumping around 7,600 litres of blood a day (at rest)! The primary role of the cardiovascular system is to provide oxygen to your cells while removing carbon dioxide. As the heart pumps, it moves blood to the lungs where it picks up oxygen and continues back to the heart to be pumped back out to the rest of the body. Oxygen in the blood is absorbed by cells, while carbon dioxide that is produced by the cells is picked up and expelled from the lungs. The blood and cardiovascular system are also important in regulating body temperature and transporting the cells of the immune system around the body.
There are 2 primary forms of cardiovascular training: aerobic and anaerobic, which create different metabolic conditions. During aerobic exercise, the body primarily utilises oxygen to produce energy, with glucose and oxygen converted to carbon dioxide an water during this process. During anaerobic exercise (which is of a higher intensity), there is insufficient oxygen to meet the body’s energy requirements, leading it to seek alternative energy source, whereby glucose is converted to lactic acid…which eventually needs to be oxidised to carbon dioxide and water after returning to aerobic conditions (hence the need for considerable oxygen intake after intense exercise). An anaerobic state generally can’t be maintained for longer than two before aerobic metabolic conditions start to increase.
Anaerobic training, such as high-intensity interval training (HIIT), has been shown to increase glucose metabolism, with metabolism remaining elevated long after exercising, which can lead to increased fat burning.
There are benefits to both styles of training, and which one you focus on will depend on your specific goals.
Strengthens the Heart
With training, the heart becomes stronger and more able to pump blood throughout the body. This is one of the primary reasons that cardio training is so important. The heart is a muscle (one of the strongest and most resilient you have), and like other muscles in your body, it adapts to training stimulus. The muscle cells of the heart, called cardiomyocytes, become larger to compensate for the increased demand placed on them, which is referred to as cardiac hypertrophy. This increase in size allows them to generate more force with each beat of the heart. The majority of this increase occurs around the left ventricle, which is responsible for pushing blood throughout the body. The chambers of the heart also become slightly larger and more flexible, resulting in an increased volume of blood pumped with every heartbeat (also known as the Frank-Starling mechanism).
Improves Resting Heart Rate
The number of times a heart beats per minute while at rest is called a resting heart rate. Regular training can lead to an adaptation where the resting heart rate decreases… so the heart beats less frequently while maintaining the same output (stroke volume), which potentially delays degradation of the muscle. If each heart has a finite number of beats, then reducing the frequency of these beats may extend the lifespan of this important muscle. On average, a person’s heart beats at about 70 times per minute. Elite athletes have measured resting heart rates below 40!
Improves Blood Pressure
Cardio training can reduce and normalize blood pressure, which is especially important for people with hypertension (high blood pressure). Many people today suffer from this condition and it occurs through a variety of mechanisms. Exercise stimulates an increase in blood flow in the peripheries by utilizing the muscles to create a pumping action for the veins. This mobilizes blood and helps open up vessels that may be closed and preventing circulation.
Exercise is thought to lead to angiogenesis, which is the production of new blood vessels, and more blood vessels mean a greater volume is available for the blood, which lowers the overall pressure in the circulatory system. Lastly, another benefit of cardio training is a temporary reduction in blood pressure post-exercise, for as long as 12 hours. All of these positive adaptations help increase health and performance and also help prevent future cardiovascular disease.
Improves Cellular Function OR Increases Red Blood Cells and Mitochondria
Nearly all our cells are reliant on oxygen to produce the required energy necessary for them to survive and maintain their function. This oxygen is transported through the body in our red blood cells (RBC’s), the primary component of the blood. Exercise increases the synthesis of RBC’s, meaning more oxygen can be transported to our cells, which greatly improves our health and function. The body does this through a process called haematopoiesis, where signals from exercise induce the synthesis of more cells from the bone marrow. Along with the increase in RBC’s, training also stimulates the growth of more mitochondria (the “powerhouse” of the cells that produce energy from oxygen). Mitochondria uses fat as energy, so increases in mitochondria should lead to an increased ability to burn fat.
Makes You Feel Good!
Many people who are avid runners often talk about getting a “runners high” – a feeling of energy, exuberance and even happiness. Exercise causes the body to release various hormones – two of which, serotonin and dopamine, promote a feeling of happiness and pleasure, sometimes even during exercise. In the long term, the more we exercise, the more we reinforce these hormone pathways. So it should be no surprise that people who are active and fit are often happy, glowing and full of energy.
The psychological benefits of exercise also extend to the health of our brains. Exercise has been shown to be neuroprotective, meaning that it helps prevent neurological degeneration and disease as we age. It also improves the brain’s ability to think critically and problem solve. So if you’re keen to keep your wits, it’s important to maintain your exercise!
Strengthens the Lungs and Bones
Beyond the cardiovascular system, cardio training also benefits the respiratory system, which comprises the lungs and is intimately linked with the cardiovascular system. As we exercise, aerobically or anaerobically, our demand for oxygen and nutrients increases as well as our demand to breathe out carbon dioxide. This is compensated for by the respiratory system increasing how many breaths we take and how much air we breathe with each breath. As exercise intensity increases, so does our breathing. This trains the muscles that are responsible for respiration, increasing the function of our breathing. Outside the respiratory system, aerobic exercise particularly (such as jogging or running) is excellent for improving bone density. The repetitive forces placed on the bones from small impacts and muscle pulling cause them to adapt and form harder, denser bone. This helps protect against osteoporosis and fractures.
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