What Is Considered Physically Fit?

Approximately 30 percent of American adults are obese and 16 percent of teenagers are considered overweight. These numbers show a stark lack of physical fitness in the American population. At a time when physical activity is declining due to technological advances, musculoskeletal injuries and chronic diseases are up. Obesity leads to many other chronic diseases, including cancer, cardiovascular disease, arthritis and diabetes -- and physical fitness has been proven to reduce your risk of obesity.

Physical fitness is succinctly described as a condition that helps you look, feel and do your best, according to the President's Council on Physical Fitness and Sports. If this description seems ambiguous, it is rightfully so -- even if you look and feel good, your body is probably not performing as well as it could. Even the Council's lengthier definition -- the ability to perform daily activities vigorously and alertly and still have energy for leisure and emergency -- leaves room for interpretation. True physical fitness means meeting several prerequisites, none of which is simple.

Cardiorespiratory Endurance

Cardiorespiratory endurance refers to your body's ability to deliver oxygen and nutrients, and remove waste, over an extended period of time. Cardiorespiratory endurance benefits your health -- your weight goes down, stamina goes up, immune system is boosted, heart becomes stronger, your mood improves and you'll live longer, according to the Mayo Clinic. Swimming, cycling, brisk walking, dancing and any other activity that elevates your heart rate can contribute to building your cardiorespiratory endurance.

Muscular Endurance

Muscular endurance is the ability of a muscle, or group of muscles, to produce low levels of force and maintain them for extended periods of time. Muscular endurance is crucial for minimizing unnecessary joint stress and preventing injury, not only during exercise, but as you accomplish your daily tasks. Muscular endurance enhances posture throughout the day, as well as during exercise. Pushups, situps and pullups are common exercises you can use to develop your muscular endurance.

Muscular Strength

Muscular strength is the ability of the neuromuscular system to produce internal tension to overcome an external force, according to the National Academy of Sports Medicine. The "internal tension" is supplied by the muscles and connective tissue that pull on your bones. Building muscular strength doesn't just help you lift heavy grocery bags, it improves bone density and insulin sensitivity and boosts your metabolism due to increased lean muscle mass. Muscular strength is frequently developed through weight training.

Flexibility

Flexibility is the ability to use joints and muscles in their full range of motion -- and it's the most undervalued component of physical fitness, but one of the most important in preventing injuries. According to the National Academy of Sports Medicine, several studies have demonstrated a correlation between decreased flexibility and increased injury. The results of inactivity are muscle imbalances, poor posture, improper movement and injury. Flexibility training can correct muscle imbalances and increase your range of motion, improving your body's overall functioning. Flexibility exercises include self-myofascial release -- foam rolling -- and stretching. Yoga is a popular form of exercise that incorporates strength, balance and flexibility training.

Body Composition

Body composition compares the amount of fat in your body to the amount of lean mass. Body composition is an important objective measurement because obesity-related health problems are more prevalent in people with higher percentages of fat in their bodies. Body fat can be measured using skin-fold calipers, circumference measurements, bioelectrical impedance or underwater weighing.

Other Considerations

If you've attained optimum levels of all the fitness components above, you are considered physically fit. However, there are several other areas of fitness training that you can work on further developing to help your body function better. Balance training will improve your ability to stabilize joints during movement. Power, or plyometric, exercises improve your neuromuscular system's reactivity and rate of force production. Speed, agility and quickness drills are often used by athletes to improve their performance on the playing field, but they can also benefit your fitness level.