A routine is a specific combination of exercises prescribed for a given body part. A split routine is the working of a given number of body parts on one day, and a given number of other body parts on the next day. A routine can be split into two or three workout days. The purpose of the split routine is to allow the exercised muscle the required forty-eight hours to recuperate from a workout. If it's not allowed this amount of rest time, a muscle may become exhausted from overtraining, and development may be hindered or reversed. The split routine allows you to workout everyday if you so choose because you never exercise the same body parts on two consecutive days. In most workouts, the routine is split into the lower and middle body workout on opposite days. Once you've established a routine, a workout plan is vital to the success of your fitness program. Whether you have minimum or maximum time to spend on your fitness regimen, it's a good idea to write out a weekly plan and to follow it, so that your routine can quickly become a habit, something that you do without thinking and without negotiating the issue. What ever routine you devise, there are some specific rules you'll want to keep in mind when developing a workout plan : *Never exercise the lower body two days in a row. *Don't exercise the upper body two days in a row. - For optimum development, your upper and lower body muscles need forty-eight hours rest before working out again. *The middle body (your abdominals) can be exercised every day, any day. *And aerobics can be done every day, any day. For more information on establishing a routine or a workout plan, talk with a fitness professional.