Each weekend in the spring , Central Texans have many choices between 5K, 10K and fun runs. Between the time the gun goes off at the start until crossing the finish line most participants are striving for a PR (personal record). This is a test of sorts to determine if training up to that point has produced a level of fitness from which to compete. If a runner won his or her age group or was in the top 50 percent, it could be argued that he or she was physically fit for the race. In our example, the runner was physically fit for the race, but maybe not for cycling 40 miles, lifting body weight on a bench press or even working on a farm or ranch for a day. This begs the question: What is physical fitness and how is it defined?

A Definition Evolving

As the population now lives longer and lifestyles have changed, the working definition of physical fitness has changed with it. What once was a definition of a population engaged in physical labor most days has been changed for a population that now finds itself sedentary, with most of the labor automated or done by low pay laborers. Obesity is now of epidemic proportions and while a person with additional weight can perform certain physical activities, body composition can relate to health problems later in life and must be considered in the definition of physical fitness.

In the last ten years the most often-used definition has been, "A set of attributes that people have or achieve relating to their ability to perform physical activity (U.S. Department of Health & Human Services, 1996)."

Another definition that provides more descriptive information would be, "Physical fitness is a state of well-being with low risk of premature health problems and energy to participate in a variety of physical activities (Howley & Franks, 1997)."

Physical fitness is both multidimensional and hierarchical. So a runner who wins a local 5K may be physically fit for the task of running the race but may lack the endurance to run a marathon, the balance to perform ballet, the agility to play basketball or the reaction time to play tennis. According to The President's Council on Physical Fitness and Sports, health-related physical fitness consists of those components that have a relationship with good health. The components are commonly defined as body composition, cardiovascular fitness, flexibility, muscular endurance, and strength.

Components of Physical Fitness: Definitions*

Body Composition: A health-related component of physical fitness that relates to the relative amounts of muscle, fat, bone and other vital parts of the body.

Cardiovascular Fitness: A health-related component of physical fitness that relates to ability of the circulatory and respiratory systems to supply oxygen during sustained physical activity. Cardiovascular fitness is also referred to as cardiovascular endurance, aerobic fitness and cardiorespiratory fitness. A Max V•O2 test in the laboratory setting is considered to be the best measure of cardiovascular fitness. Commonly administered field tests include the mile run, the 12 minute run, the mile walk, the PACER run for children and various bicycle, step, and treadmill tests.

Flexibility: A health-related component of physical fitness that relates to the range of motion available at a joint. Flexibility is specific to each joint of the body, thus there is no general measurement of flexibility as there is for cardiovascular fitness. Flexibility is typically measured in the lab using measurement devices such as a goniometer, flexometer and in the field with tests such as the sit and reach and the zipper.

Muscular Endurance: A health-related component of physical fitness that relates to the muscle's ability to continue to perform without fatigue. For true assessment of muscular endurance it would be necessary to test each major muscle group of the body. Lab and field tests of muscular endurance are similar and are based on the number of repetitions that can be performed by the specific muscle group being tested (example: repetitions of push-ups or abdominal curls. Muscular endurance can be measured isometrically (static contractions) or isotonically (dynamic contractions).

Strength: A health-related component of physical fitness that relates to the ability of the muscle to exert force. For true assessment it would be necessary to test each major muscle group of the body. Lab and field tests are similar and involve the assessment of one repetition maximum (the maximum amount of resistance you can overcome one time). 1RM tests are typically conducted on resistance machines. Strength can also be assessed using dynamometers. Strength can be measured isometrically (static contractions) or isotonically (dynamic contractions).

Skill-related Physical Fitness: Skill-related physical fitness consists of those components of physical fitness that have a relationship with enhanced performance in sports and motor skills. The components are commonly defined as agility, balance, coordination, power, speed and reaction time. Possession of skill-related fitness abilities enhances ability to perform in sports and games but only has an indirect connection with health.

* from the Surgeon General's Report on Physical Activity and Health

Measurements of Fitness

ExRx.net (Exercise Prescription on the Net) is a free resource for the exercise professional, coach, or fitness enthusiast. ExRx.net is a recommended resource in the ACSM's (American College of Sports Medicine) Resource Manual for Guidelines for Exercise Testing and Prescription. Several of the calculators below will allow you to measure your physical fitness or the fitness of others.

• Body Composition
• Kid's Body Comp
• Target Weight
• Walkport
• 12 Minute Run
• Distance Run
• YMCA Cycle
• Treadmill
• Sit and Reach
• Push Up
• YMCA Bench Press
• Sit Up
• Curl-up / Half Sit-up
• Senior's Chair Stand
• Senior's Arm Curl
• One Repetition Max
• Vertical Jump
• Sprint Speed
• Body Mass Index
• Waist Hip Ratio
• Vitals (BP & HR)
• Target Heart Rate
• Risk Class Calculator

For more information, visit the GoodHealth.com encyclopedia topic on Fitness.