Components of Physical Fitness
Fitness is a general term for a concept that consists of many distinct and individual components. Each component will determine the ability of an individual to successfully perform specific tasks. Below is a list of the components of physical fitness. Each component is defined and some examples of activities requiring each component have been provided.

Aerobic Fitness:
Aerobic fitness is often referred to as cardiovascular fitness, cardio-respiratory fitness, or endurance. Aerobic fitness is related to the ability to perform exercises or dynamic activities involving large muscle groups, performed at moderate intensities for prolonged periods of time (ACSM, 2000).

The general public is likely to associate aerobic conditioning with 'being fit' as it is the component of fitness that allows individuals to walk, run, swim and cycle for prolonged periods of time. These modes of exercise are common and the ability to perform them is desirable to those who struggle to perform physical activity without getting very short of breath. When most non-exercising individuals resolve to 'get fit' they are more likely to throw themselves into jogging or cycling than getting to the gym and participating in resistance training or some other mode of exercise.
Examples of activities requiring aerobic fitness include marathon running, cross-country skiing, long distance cycling and walking briskly for prolonged periods.

Anaerobic Fitness:
Anaerobic fitness is associated with the ability to produce energy without oxygen. If the body is trained consistently using exercises that challenge the anaerobic energy pathways, adaptations will occur that allow the individual to delay the onset of fatigue or perform exercise at a higher intensity prior to fatigue.
Examples of activities that require anaerobic condition vary greatly. They range from extremely short but intense contraction of up to 10 seconds in duration, to activities that are less intense but may last up to approximately 2 minutes in duration.
Some examples of anaerobic activities include sprinting, weight training, jumping and team / racquet sports involving multiple short sprints and changes of direction.

Muscular Strength:
Knutten and Kreamer (1987 cited in Fleck and Kreamer 1997), define strength as:
"...the maximum amount of force a muscle or muscle group can generate in a specified movement pattern at a specified velocity of movement."
The development of enhanced muscular strength is useful for two key reasons. Firstly, the individual is able to produce a greater maximal force when required to do so. Secondly, with enhanced levels of strength everyday sub-maximal tasks require a lesser percentage of individual's maximal effort, thus making the task easier.
Examples of activities requiring maximal strength include heavy weightlifting and lifting / moving heavy objects.

Muscular Endurance:
Heyward (1997), defines muscular endurance as:
"...the ability of a muscle group to generate sub-maximal force for extended periods."
The vast majority of everyday situations that require an individual to exert force require sub-maximal contraction. One-off maximal contractions (i.e. express maximal strength) are performed very rarely. It could therefore, be argued that the majority of 'regular' individuals would derive more benefit from muscular endurance training than from strength training. The development of muscular endurance would enhance the ability of an individual to perform commonplace everyday tasks.
Activities requiring muscular endurance include: carrying shopping, walking up stairs, maintaining a good postural position, gardening, high repetition resistance training and downhill skiing.

Power:
Power can be defined as follows:

Power =

Force x Distance Time

Power requires strength to be expressed at speed. The faster a given load can be lifted the higher the power output. Many sporting endeavours require a high degree of power for successful performance.
Examples of activities requiring power include sprinting, jumping, throwing, Olypic weightlifting (clean and jerk) and running up a flight of stairs.

Flexibility:
"Flexibility is the ability to move a joint through its complete range of motion." (ACSM 1997)
It is common practice for flexibility to be largely ignored as an important component of fitness. Many individuals only dabble with flexibility by including a few generic stretches as part of a warm-up or cool-down. A significant percentage of exercising individuals perform no flexibility training at all.

The importance of development and maintaining an appropriate range of motion at all joints should not be underestimated. The body operates as a kinetic chain with all joints contributing to freedom of movement. If uncorrected this process can lead to altered movement patterns, dysfunction, pain and injury.

For example, if the range of dorsiflexion available at the ankle is limited (possibly due to tight soleus muscles) the ability to squat with a normal movement pattern will be lost. In order to perform a squatting movement with limited dorsiflexion the body will naturally compensate by increasing the amount of hip flexion generated as the individual descends into the torso and increases the stress on the lumbar spine. By adopting this compensatory movement pattern, it is clear to see how a lack of ankle flexibility can indirectly lead to back pain.

Examples of activities and sports that require flexibility include gymnastics, dance, yoga and everyday normal function.

Motor Skills:
Proprioception, Balance, Co-ordination:
Motor skills are general term for a group of abilities that contribute to controlled and efficient human movement.

Proprioception is a component of fitness that informs an individual where all the components of their musculoskeletal system are, and what they are doing relative to one another in a space and time (Siff, 2003). It can be simply viewed as an innate sense of positional awareness.

Balance can be defined as the ability to maintain the centre of mass within the base of support (Schumway-cook & Woolacott, 2001)

Co-ordination can be defined as a controlled interaction between two or more body parts that produces a desired movement under the control of neuromuscular system

Balance, co-ordination and Proprioception contribute to the ability of an individual to effectively perform established movement patterns. They may also determine how effectively an individual is able to learn and establish new movement patterns (i.e. a new exercise).

Motor skills, like all other components of fitness can be improved through appropriate training and feedback.

All human movement requires some degree of motor skills. The more complex the movement-based task, the higher the motor skill requirement. Sports and activities that require well developed
motor skills include gymnastics, juggling, skiing, team sports, table tennis and golf. It is important to note that each activity requires different combinations of motor skills.