Maintaining a good level of physical fitness is something that we should all aspire to do. But what does fitness actually entail? What does being physically fit mean?
According to the United States Department of Health and Human Services,1 physical fitness is defined as "a set of attributes that people have or achieve that relates to the ability to perform physical activity."
This description goes beyond being able to run long distances or lift heavy weights at the gym. Despite being important, these attributes only address single areas of fitness. Fitness is more than simply a question of listing which activities you do or how long you do them for.
This article provides details of the five main components of physical fitness:
Contents of this article:
Fast facts on fitness
Here are some key points about fitness. More detail and supporting information is in the main article.
- Maintaining physical fitness can help ward off a number of diseases.
- Different types of muscle fiber develop depending on the type of activity completed.
- Body composition can change drastically without an associated change in weight.
- Athletes' hearts show different changes dependent on their chosen sport.
- Muscle strength increases by fiber hypertrophy and neural changes.
- Body composition can be ascertained in a number of ways.
- Stretching to increase flexibility can ease a number of medical complaints.
Running is one exercise that can help improve your cardiorespiratory endurance.
Cardiorespiratory endurance indicates how well our body can supply fuel during physical activity via the body's circulatory and respiratory systems.
Activities that help improve your cardiorespiratory endurance are those that cause an elevated heart rate for a sustained period of time.
These activities include swimming, brisk walking, jogging, and cycling. It is important to begin these activities slowly and then gradually increase the intensity.
Exercising increases cardiorespiratory endurance in a number of ways. Essentially, the heart muscle is strengthened so that it is able to pump more blood per heartbeat.
At the same time, additional small arteries are grown within muscle tissue so that blood can be delivered to working muscles more effectively when needed.
Heart changes with exercise
The fact that the heart changes and improves its efficiency after persistent training is well known. However, more recent research shows that different types of activity change the heart in subtly different ways.
All types of exercise increase the heart's overall size, but there are significant differences between endurance athletes, like rowers, and strength athletes like footballers.
Endurance athletes' hearts show expanded left and right ventricles, whereas strength athletes show thickening of their heart wall, particularly the left ventricle.2
Changes within the lungs
While the heart steadily strengthens over time, the respiratory system does not adjust to the same degree. Lung function does not drastically change, but oxygen that is taken in by the lungs is used more effectively.3
In general, exercise encourages the body to become more efficient at taking on, distributing and using oxygen. This improvement, over time, increases endurance and overall health.
The American College of Sports Medicine recommends aerobic exercise 3-5 times per week for half an hour to an hour, at an intensity that keeps the heart rate at 65-85% of the maximum heart rate.4
On the next page, we look at muscular strength and endurance.