Fitness and Exercise Improve Your Body's Systems

Fitness and the Musculoskeletal System

Author: J. Flowers Health Staff

Physical fitness is important for health and wellness because exercise has a beneficial effect on most systems in the body. Unfortunately, many people do not get adequate exercise. According to 2017 data, only, 53.3% of U.S. adults engaged in the amount of aerobic exercise that the Centers for Disease Control and Prevention (CDC) recommends for good health, and only 23.2% got a sufficient amount of both aerobic and strengthening exercise.¹
Most people would benefit from getting more exercise, because of the ways it improves overall health.

According to exercise science, fitness has a positive impact on the musculoskeletal system. It can increase the size and strength of muscle fibers, as well as ligaments and tendons. It also increases the number and size of mitochondria.

Two types of strength training that have these specific effects are isometric exercise and isotonic exercise. With isotonic exercise, muscle contracts against a load, such as when someone lifts weights. With isometric exercise, muscle contracts without a person moving. For instance, staying still in a squat position is an example of an isometric exercise.

Benefits of Isotonic Exercise

The research has shown the benefits of isotonic exercise. A 2014 study in the European Journal of Applied Physiology found that isometric knee exercises increased muscle thickness and improved strength. In fact, one type of isometric exercise performed over eight weeks increased muscle thickness by 9% – 14%.²

Benefits of Isometric Exercise

While isometric exercise can increase muscle thickness and strength, the International Sports Sciences Association (ISSA), has explained that there are also benefits associated with aerobic training. This is because this form of exercise positively affects the mitochondria, which are within the body’s cells and are responsible for creating energy. With aerobic exercise, people experience an increase in mitochondria density. This means the body has more oxygen available for use and can convert it to energy.³ This and the benefits for muscle size and strength are just several of the reasons exercise is good for you.

Main Systems Impacted by Fitness and Exercise

Immune System Benefits with Exercise

In addition to its benefits for the cardiovascular system, exercise also has a positive effect on the functioning of the immune system. It is thought to flush bacteria, strengthen antibodies, prevent bacteria growth, and reduce stress hormones that can make a person sick.

A research report in a 2019 edition of the Journal of Sport and Health Science found that exercise improves the immune system functioning so much that people who exercise moderately are less likely to become ill. One study found that compared to those who got a low amount of exercise, those who got a high amount of exercise were 18% less likely to become sick over a four-month period.⁵ In fact, research shows that moderate-intensity exercise, performed almost daily, is more effective for preventing illness than most medications and supplements.⁵

Exercise's Effects on the Nervous System

Another reason that exercise is good for you is that it improves the functioning of the nervous system. In the central nervous system, exercise has a beneficial effect on the brain, as it promotes the growth of new cells, according to research. Over the long-term, exercise can increase the activity of brain-derived neurotrophic factor. This can promote improved learning and reduce the risk of Alzheimer's disease.⁵

Exercise also has a positive influence on the sympathetic nervous system, as it can reduce the activity of this system. This is important because excessive activity in the sympathetic nervous system can be linked to high blood pressure and heart failure. Physical fitness is likely to improve the way that the nervous system controls circulation.⁶

More Systems Impacted by Exercise and Fitness

Fitness and the Endocrine System

Physical fitness also has a beneficial effect on the body’s endocrine system, which is responsible for making the hormones that carry out a variety of important functions, including metabolism. Exercise, whether it is strength training or anaerobic exercise, increases the metabolic rate, so the body burns more calories. This can help you to manage your weight.

In addition to improving metabolism, exercise can make you more sensitive to a hormone called insulin, which helps to regulate blood sugar levels. During exercise, blood sugar levels may drop. Because of these effects, regular physical activity can reduce the risk of developing type 2 diabetes, which is yet another way that exercise is medicine.

According to the CDC, exercise can reduce the risk of both diabetes and metabolic syndrome, which is a condition that occurs when a person has excess abdominal fat, elevated blood pressure, and high levels of blood sugar, triglycerides, and bad cholesterol.

The Impact of Exercise on the Digestive System

Fitness is also good for its effects on the digestive system. For instance, exercise stimulates the gut and increases blood flow to muscles in the digestive system, helping the body to digest food efficiently. You may find that physical fitness prevents you from suffering from complications such as constipation or upset stomach.

Exercise also affects the millions of microbes called the gut microbiota within the digestive system. These microbes are thought to affect health, and studies have supported this belief. For example, research has found that women who exercise for three or more hours per week have greater levels of a type of gut bacteria that is associated with improved metabolic health and leanness. There is also some evidence that exercise increases the variety of bacteria in the digestive system, which can improve health.⁷

Respiratory System Benefits of Exercise

Another benefit of fitness is that it improves the functioning of the respiratory system. Not only does it strengthen the muscles used in breathing; it also helps the body to use oxygen more efficiently. For example, with intense anaerobic exercises, such as fast running or jumping rope, the VO₂ max will increase. This means that the body will be able to use greater amounts of oxygen during exercise and therefore able to produce more energy in the body. This can make daily activities such as walking up the stairs or carrying items around the house seem less taxing, as you will not be as fast to run out of breath when exerting yourself. In summary, just like exercise can make the heart and muscles stronger, it can improve the strength of the lungs.

Exercise and a Healthy Mind

Beyond its other numerous benefits, exercise is good for you because it improves psychological functioning. According to research, moderate-intensity exercise lowers stress and anxiety, improves self-image, and has a positive effect on mood. In fact, the impact of exercise is so strong that it can reduce depression. It also reduces cognitive decline during older adulthood.⁵

Exercise can improve the functioning of the mind in several ways. For instance, it can improve focus by reducing the impact of distractions, per the results of research. Furthermore, as mentioned, exercise increases levels of the brain-derived neurotrophic factor. This can improve memory and help with learning. Research with animals shows that just one week of voluntary running can improve the capacity for learning.⁵

Fitness and Physical Literacy

In addition to its benefits for the body’s various systems, exercise improves a construct known as physical literacy. According to researchers, this term describes the degree to which a person is able and committed to being physically active. A 2019 study in the journal BMC Public Health found that when sedentary adults participated in a weekly exercise training program for 15 weeks, their physical literacy scores improved by about 12%. Beginning to participate in physical exercise can help people to develop a commitment to fitness.⁸

Fitness Impacts All Your Body’s Systems

Given the information that researchers have learned from exercise science, it is clear that exercise is medicine and is beneficial for both physical and mental health. Increasing your physical fitness is good for you and can also improve flexibility. A variety of exercises are beneficial and should be incorporated into your regular routine, including anaerobic exercise, isometric exercise, and isotonic exercise. If you are wondering how to tone your body, you would benefit from beginning a fitness program that includes strength training as well as some high-intensity anaerobic exercise. With the right exercise program, you will not only improve your physical and mental health but also achieve a toned body that makes you feel confident.