I have found over the years, this type of split routine works well to burn additional calories in the day and help speed up the metabolism in the evening when it naturally tends to slow down. There are some rules to the two-a-day workout however:

1) Recovery is Important You have to be creative if you do a two-a-day routine. You should either split your cardio exercise from your weights or PT exercises, or do a combination of cardio/stretching and PT in the morning and weights in the evening. If you do exercises like pushups and bench presses in the same day, either do them together in the same workout, or be careful not to do AM pushups and PM bench press for too many weeks in succession. Once a week, it is OK to push your body this way and basically do two chest workouts in the same day, but take at least two days off from repeating those exercises again. And -- do your pushups in the AM and bench in the PM since bench press weights will be more stressful on your muscle fibers if lifting heavy weights. You are right -- you do need to recover. 2) Leg PT is Different I would definitely only do leg workouts once a day, though I would not count a run or bike as a leg workout, but as a cardio workout. So on leg days, I like to do the PT or weights first, then workout the lactic acid produced by a jog, bike or elliptical glide later in the day if you must split the workouts in two. 3) Morning Workout Meal If you are doing cardio in the AM, it is important to drink water prior to exercise. If you are lifting weights or doing challenging PT or pushing the speed of your run and doing intervals or speed workouts, you may want to have fruit or a sport drink prior to running, just to boost your glycogen levels. In high intensity workouts, you may feel dizzy, nauseated, or weak when you run low on your immediate energy source -- glycogen. After your morning workout, replenish your glycogen levels with fruits like bananas, strawberries, apples etc. Also protein should be consumed in the post-workout meal to help rebuild the muscles and speed recovery.

Fullbody Day Option Split AM Workout (Cardio / Leg PT) * Repeat Four Times - Bike 5:00 - Max Squats in 1:00 - Lunges - 25 / leg - Max Crunches - 1:00 * Repeat Ten Times - Jumping Jacks - 10 - Push-ups - 10 PM Workout (Weights /PT) * Repeat Three Times - Bench Press 15 reps - Pullups - Max reps - Biceps Curls -10, 15 - Military - 10, 15 - Tricep Ext -10, 15 - Crunches - 50 Lightweight shoulder workout 5lbs Upperbody Day Option Split AM Workout * Repeat Five Times - Warmup With Crunches - Run/PT - Run 5:00 - Push-ups - 10-20 - Crunches - 20 PM Workout - Push-ups - Max in 2:00 (do knee pushups if you have to) - Rest 2:00 - Sit-ups - Max in 2:00 (or crunches) - Rest 2:00 - Pull-ups - Max - DBs and Weight Machines: (heavy, lightweight like 20#,15# DBs for 10, 15 reps) - Biceps Curls -10, 15 - Military - 10, 15 - Hammer Curl-10, 15 - Tricep Ext -10, 15 - Bench Press - 10, 15 - Pulldowns - 10, 10 Typical Cardio/PT Option AM Workout (Cardio/abs) - Warmup With Crunches - Run, Bike / Elliptical Glide 30:00 PM workout - Circuit Routine - Weight Circuit Three Times - Bench Press - 25 - Tricep ext - 20 - Push-ups - 10 - Sit-ups - 1:00 - Military Press - 20 - Crunches - 50 - Ab Workout Two Times - Regular Crunch - 50 - Right Elbow to Left Knee - 50 - Left Elbow to Right Knee - 50 - Reverse Crunch- 50 - Double Crunch - 50 These are just some of the many ways to split up your routine into a challenging two-a-day workout plan that will get you in great shape and help you lose weight by jump starting your metabolism a second time in the day.