COMPONENTS OF PHYSICAL FITNESS

Physical fitness is characterized by the ability to perform occupational and recreational activities without becoming unduly fatigued and to have the capacity to handle unforeseen emergencies.  The following sections focus on cardio respiratory endurance, muscular strength, muscular endurance, flexibility, and body composition.

These characteristics of physical fitness can be categorized as health-related physical fitness.
  Other characteristics, such as speed, power, agility, balance, and reaction time are associated with what would be called performance-related physical fitness.  Although the latter type is most important for competitive athletes, it is the former type that has the most relevance to general population.

Cardio respiratory Endurance

If you were limited to improve only one area of your physical fitness, which would you choose - muscular strength, muscular endurance, or flexibility?  Which would a dancer choose? Which would a marathon runner select? Which would an expert recommend?

The expert, exercise physiologists, would probably say that another fitness dimension is even more important than those listed above.  They regard improve of your heart, lung, and blood vessel function as the key focal point of a physical fitness program.  Cardio respiratory endurance forms the foundation for whole body fitness.

Cardio respiratory endurance increases your capacity to sustain a given level of energy production for a pro-longed period.  It helps your body to work longer and at greater levels of intensity.

Your body can not always produce the energy it needs for long-term activity.  Certain activities require performance at a level of intensity that will outstrip your cardio respiratory system’s ability to transport oxygen efficiently to contracting muscle fibers.  When the oxygen demands of the muscles cannot be met, oxygen debt occurs.  Any activities that continues beyond the point at which oxygen debt begins requires a form of energy production that does not depend on oxygen.

This oxygen-deprived form of energy production is called anaerobic (without oxygen) energy production, the type that fuels many intense, short-duration activities.  For example, rope climbing, weight lifting for strength, and sprinting are short-duration activities that quickly cause muscle fatigue; they are generally considered anaerobic activities.

The key factor is if the energy demand of the activity exceeds the aerobic energy production capability.  Thus, even activities that are typically considered to be aerobic (walking or cycling) can require anaerobic energy if the intensity is high enough.

If you usually work or play at low intensity but for a long duration, you have developed an ability to maintain aerobic (with oxygen) energy production.  As long as your body can meet its energy demands in this oxygen rich mode, it will not convert to anaerobic energy production.  Thus fatigue will not be an important factor in determining whether you can continue to participate.  Marathon runners, serious joggers, distance swimmers, cyclists, and aerobic dancers can perform because of their highly developed aerobic fitness.  The cardio respiratory system of these aerobically fit people have developed a large capacity to take in, transport, and use oxygen.

Besides allowing you to participate in activities such as those mentioned, aerobic conditioning ( cardio respiratory endurance conditioning) may provide certain structural and functional benefits that affect other dimensions of your life.  These recognized benefits have received considerable documented support.  It is now well accepted that regular physical activity that produces aerobic fitness will reduce the risk of heart disease, type 2 diabetes, osteoporosis, obesity, depression, and cancer of the breast and colon.

Muscular Fitness

Muscular fitness is the term used to represent the capabilities of the skeletal muscles to perform contractions.  The capacity of the muscles have two distinct yet integrated characteristics: muscular strength and muscular endurance.  The strength of the muscle is related to its ability to perform at or near its maximum for a short period of time.  Whereas the endurance of the muscles is related to its ability to perform at sub maximal levels for a long period of time.

Muscular fitness is essential for your body to accomplish work.  Your ability to maintain posture, walk, lift, push, and pull are familiar examples of the constant demands you make on your muscles and maintain a level of contraction sufficient to complete tasks.

Muscular strength can be improved best by training activities that use the overload principle.  By overloading, or gradually increasing the resistance (load, object, or weight) your muscles must move, you can increase your muscular strength.  The following three types of training exercises are based on the overload principle.

In isometric (meaning “same measure”) exercise, the resistance is so great that your contracting muscles cannot move the resistance object at all.  So your muscles contract against immovable objects, usually with increasingly greater efforts.  Because of the difficulty of precisely evaluating the training effects, isometric exercises are not usually used as a primary means of developing muscular strength.  These exercises can be dangerous for people with hypertension.

Isotonic resistance exercises, meaning same-tension exercises, are currently the most popular type of strength –building exercises and include the use of traditional free weights (dumbbells and barbells), as well as many resistance exercise machines.  People who perform progressive resistance exercises use various muscle groups to move (or lift) specific fixed resistance or weights.  Although during a given repetitive exercise the weight resistance remains the same, the muscular contraction effort required varies according to the joint angles in the range of motion.  The greatest effort is required at one angle (sticking point) in the range of motion.

Isokinetic ( meaning “same motion”) exercise use mechanical devices that provide resistances that consistently overload muscles throughout the entire range of motion.  The resistance will move only at a preset speed, regardless of the force applied to it.  For the exercise to be effective, a user must apply maximal force.  Isokinetic training requires elaborate, expensive equipment.

Thus the use of isokinetic equipment may be limited to certain athletic teams, diagnostic centers, or rehabilitation clinics.  The most common isokinetic machines are Cybex, Orthotron, Biodex, Mini-Gym, and Exergenie.

Which type of strength-building exercise (machines or free weights) is most effective? Take your choice, since all will help develop muscular strength.  Some people prefer machines because they are simple to use, do not require stacking the weights, and are already balanced and less likely to drop and cause injury.

Other people prefer free weights because they encourage the use to work harder to maintain balance during the lift.  In addition, free weights can be used in a greater variety of exercises than weight machines.

Muscular endurance can be improved by performing repeated contractions of a less than maximal level.  This aspect of muscular fitness is most related to common physical activities (postural muscles, leaf raking, pushing a lawn mower).  Although it is viewed to be as glamorous as the muscular strength component, it is an important part of muscular fitness.  Energy production requires that oxygen and nutrients be delivered by the circulatory system to the muscles.  After these products are transformed into energy by individual muscle cells, the body must remove the potentially toxic waste by-products.

Amateur and professional athletes often wish to increase the endurance of specific muscle groups associated with their sports activities.  This can be achieved by using exercises that gradually increase the number of repetitions of a given movement.  However, muscular endurance is not the physiological equivalent of cardio respiratory endurance.  For example, a world-ranked distance runner with highly developed cardio respiratory endurance of the legs may not have a corresponding level of muscular endurance of the abdominal muscles.

Flexibility

The ability of your joints to move through their natural range of motion is a measure of your flexibility.  This fitness trait, like so many other aspects of structure and function, differs from point to point within your body and among different people.  Not every joint in your body is equally flexible (by design), and over the course of time, use or disuse will alter the flexibility of a given joint.  Certainly, gender, age, genetically determined body build, and current level of physical fitness will affect your flexibility.

Inability to move easily during physical activity can be a constant reminder that aging and inactivity are the foes of flexibility.  Failure to use joints regularly will quickly result in a loss of elasticity in the connective tissue and shortening of muscles associated with the joints.  Benefits of flexibility include improved balance, posture, and athletic performance and reduced risk of low back pain.

As seen in young gymnasts, flexibility can be highly developed and maintained with a program of activity that includes regular stretching.  Stretching also helps reduce the risk of injury.  Athletic trainers generally prefer static stretching to ballistic stretching for people who wish to improve their range of motion.

Body Composition

Body composition is the analysis of what the body is made up of (muscle, bone, fat, water, minerals).  Of particular interest to fitness experts are percentages to body fat and fat-free weight.  Health experts are especially concerned about the large number of people in our society who are overweight and obese.  Increasingly, cardio respiratory fitness trainers are recognizing the importance of body composition and are including strength-training exercises to help reduce body fat.