Components of Physical Fitness
"Ultimately, I am what I choose to be; my self-esteem follows the same path." —Anonymous

What does it mean to be physically "fit?" Physical fitness is defined as "a set of attributes that people have or achieve that relates to the ability to perform physical activity" (USDHHS, 1996). In other words, it is more than being able to run a long distance or lift a lot of weight at the gym. Being fit is not defined only by what kind of activity you do, how long you do it, or at what level of intensity. While these are important measures of fitness, they only address single areas. Overall fitness is made up of five main components:

Cardiorespiratory endurance
Muscular strength
Muscular endurance
Body composition
Flexibility
In order to assess your level of fitness, look at all five components together.


What is "cardiorespiratory endurance (cardiorespiratory fitness)?"
Cardiorespiratory endurance is the ability of the body's circulatory and respiratory systems to supply fuel during sustained physical activity (USDHHS, 1996 as adapted from Corbin & Lindsey, 1994). To improve your cardiorespiratory endurance, try activities that keep your heart rate elevated at a safe level for a sustained length of time such as walking, swimming, or bicycling. The activity you choose does not have to be strenuous to improve your cardiorespiratory endurance. Start slowly with an activity you enjoy, and gradually work up to a more intense pace.


What is "muscular strength?"
Muscular strength is the ability of the muscle to exert force during an activity (USDHHS, 1996 as adapted from Wilmore & Costill, 1994). The key to making your muscles stronger is working them against resistance, whether that be from weights or gravity. If you want to gain muscle strength, try exercises such as lifting weights or rapidly taking the stairs.


What is "muscular endurance?"
Muscular endurance is the ability of the muscle to continue to perform without fatigue (USDHHS, 1996 as adapted from Wilmore & Costill, 1994). To improve your muscle endurance, try cardiorespiratory activities such as walking, jogging, bicycling, or dancing.


What is "body composition?"
Body composition refers to the relative amount of muscle, fat, bone, and other vital parts of the body (USDHHS, 1996 as adapted from Corbin and Lindsey, 1994). A person's total body weight (what you see on the bathroom scale) may not change over time. But the bathroom scale does not assess how much of that body weight is fat and how much is lean mass (muscle, bone, tendons, and ligaments). Body composition is important to consider for health and managing your weight!


What is "flexibility?"
Flexibility is the range of motion around a joint (USDHHS, 1996 as adapted from Wilmore & Costill, 1994). Good flexibility in the joints can help prevent injuries through all stages of life. If you want to improve your flexibility, try activities that lengthen the muscles such as swimming or a basic stretching program.


References
U.S. Department of Health and Human Services. Physical activity and health: a report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion; 1996.

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Page last reviewed: May 22, 2007
Page last updated: May 22, 2007
Content Source: Division of Nutrition, Physical Activity and Obesity, National Center for Chronic Disease Prevention and Health Promotion
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Navigation for Physical Activity for Everyone
• Physical Activity for Everyone

Introduction
The Importance of Physical Activity
Why should I be active?
Can everyone benefit from physical activity?
Measuring Physical Activity Intensity
Talk Test
Target Heart Rate
Borg Rating of Perceived Exertion Scale
Metabolic Equivalent (MET) Level
Examples of Activities and Their Intensity Levels
Getting Started
Not Ready for Change
Thinking About Change
Preparing for Action
Taking Action
Maintaining a Good Thing
When is a medical evaluation necessary?
Making Physical Activity Part of Your Life
Tips for Being More Active
Risks to Being Active
Tips for Avoiding Activity-induced Injuries
Overcoming Barriers to Physical Activity
Components of Physical Fitness
Physical Activity Terms
Recommendations
Adults
Young People
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Strength Training for Older Adults
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