Another component in our physical fitness definition is agility. It is the ability to rapidly change the body’s momentum from one direction to another. This requires either acceleration in any direction from dead stop or deceleration in the direction one is traveling and acceleration in a new direction. Based on Isaac Newton’s second law, acceleration/deceleration is proportional to the ratio of force to mass. Thus, if two men can exert equal force on the ground, the one with a lower body mass will show greater acceleration. From another point of view, if two individuals have the same body mass, the one who can exert more force on the ground will show greater acceleration. In addition to the ability to accelerate, agility requires a certain degree of flexibility, which aids in going over, under, and around obstacles.
Flexibility refers to the range of motion through which a body joint can be flexed or extended and the ease with which this is accomplished. Some activities like ballet, gymnastics, and Olympic weightlifting require excellent flexibility, while most daily life activities and many sports such as football and boxing do not require great flexibility. More flexibility is not always better. People who are extremely flexible may be susceptible to joint injuries, while those who are less flexible risk muscle injury.Endurancethe capacity of something to last or to withstand wear and tear.