A physical fitness training program is divided into three phases: preparatory, conditioning, and maintenance. The starting phase for different individuals will vary depending on their age, fitness levels, and previous physical activity.
Young, healthy persons may be able to jump right into the conditioning phase, while those who have been exercising regularly may already be in the maintenance phase. Factors such as extended inactivity, injury or illness can drop you from a maintenance to a conditioning phase. Persons who have not been physically active, especially if you are age 40 or older, should start with the preparatory phase.
Preparatory Phase
The preparatory phase helps both the cardiorespiratory and muscular systems get used to exercise, preparing the body to handle the conditioning phase. The work load in the beginning must be moderate. Progression from a lower to a higher level of fitness should be achieved by gradual, planned increases in frequency, intensity, and time.
Initially, poorly conditioned persons should run or, walk if need be, three times a week at a comfortable pace that moderately elevates their heart rate for 10 to 15...