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 minutes. Continue at this until you have no undue fatigue or muscle soreness the day following the exercise. After that you can lengthen this cardiorespiratory exercise session to 16 to 20 minutes and/or elevate your heart rate by increasing the pace. If you feel breathless slow down to a walk. The preparatory phase for improving muscular endurance and strength through weight training should start easily and progress gradually. Beginning weight trainers should select about 8 to 12 exercises that work all the body’s major muscle groups. You should use only very light weights the first week (that is, the first two to three workouts). This is very important, as you must first learn the proper form for each exercise. Light weights will also help minimize muscle soreness and decrease the likelihood of injury to the muscles, joints, and ligaments. During the second week, you should use progressively heavier weights on each resistance exercise. By the end of the second week (four to six workouts), you should know how much weight will let you do 8 to 12 repetitions to muscle failure for each exercise. At this point the conditioning phase begins. Conditioning Phase To reach the desired level of fitness, you must increase the amount of exercise and/or the workout intensity as your strength and/or endurance increases. To improve cardiorespiratory endurance, for example, you must increase the length of time you run. You should start with the preparatory phase and gradually increase the running time by one or two minutes each week until you can run continuously for 20 to 30 minutes. At this point, you can increase the intensity until you reach the desired level of fitness. You should train at least three times a week and take no more than two days between workouts. For weight trainers, the conditioning phase normally begins during the third week. You should do one set of 8 to 12 repetitions for each of the selected resistance exercises. When you can do more than 12 repetitions of any exercise, you should increase the weight used on that exercise by about five percent so you can again do only 8 to 12 repetitions. This intensity increasing process continues throughout the conditioning phase. As long as you continue to progress and get stronger while doing only one set of each exercise, it is not necessary for you to do more than one set per exercise. When you stop making progress with one set, you should add another set on those exercises in which progress has slowed. As training progresses, you may want to increase the sets to three to help promote further increases in strength and/ or muscle mass. For maximum benefit, you should do strength training three times a week with 48 hours of rest between workouts for any given muscle group. It helps to periodically do a different type of exercise for a given muscle or muscle group. This adds variety and ensures better strength development. The conditioning phase ends when all personal, strength-related goals have been met. Maintenance Phase The maintenance phase sustains the high level of fitness achieved in the conditioning phase. The emphasis here is no longer on progression. A well designed, 45- to 60-minute workout (including warm-up and cool-down) at the right intensity three times a week is enough to maintain almost any appropriate level of physical fitness. These workouts give you time to stabilize your flexibility, cardiorespiratory endurance, and muscular endurance and strength. However, more frequent training may be needed to reach and maintain peak fitness levels. Of course, once you get to this level, maintaining an optimal level of fitness should become part of your life-style and should be continued for life.