Trunk Curls Start this exercise by lying face-up on the floor with your knees comfortably bent (about 45 degrees). Place your hands loosely behind your head for support with your elbows out to the sides. Curl your head, shoulders and upper back off the floor very slowly (10 seconds), and return back to the starting position in five full seconds. You will be barely moving but your abdominal muscles (rectus abdominis) will be fully activated throughout the entire repetition. Begin with two repetitions in 30 seconds, rest for 30 seconds, and complete two more repetitions in 30 seconds. Work your way up to four repetitions in 60 seconds, rest for 30 seconds, and do four more repetitions in 60 seconds.

Push-Ups The key to properly performed push-ups is straight body position which requires substantial midsection strength to prevent sagging. Begin in the up position with your hands slightly wider than shoulder-width apart and your arms straight. Lower your torso slowly by bending your elbows, taking five full seconds to touch your chest to the floor. Push yourself up very slowly and deliberately, counting from one-thousand-one to one-thousand-ten before reaching the top position. Push-ups address several upper body muscle groups, including the chest (pectoralis major), front shoulders (anterior deltoids) and rear arms (triceps). Try to do two slow push-ups separated by a 15-second rest period. Work your way to four slow push-ups separated by 15-second rest periods. When this can be accomplished, reduce the rest periods to 10 seconds, then to five seconds, until you are capable of completing four successive slow push-ups in 60 seconds.

Bar-Dips My favorite exercise is bar-dips, which simultaneously work the chest (pectoralis major), front shoulders (anterior deltoids), rear arms (triceps), and upper back (latissimus dorsi) muscles. Unfortunately, bar dips require parallel bars or two stable kitchen chairs for proper execution. Start in the up position, with your arms straight, your body straight, and your knees bent if you are using kitchen chairs. Slowly lower your body by bending your elbows until your upper and lower arm form a 90 degree angle. The lowering phase should take five seconds. Pause momentarily, and push up slowly (10 full seconds) to the starting position. Because this is a demanding exercise, I suggest doing just one bar dip at a time with 30-second rests between repetitions. When four separate repetitions can be completed, gradually reduce the rest periods. When you can perform four slow bar-dips in 60 seconds, you have achieved a very high level of muscular fitness in your upper body pushing muscles.

Chin-Ups Without question, the most difficult of the bodyweight exercises is chin-ups. This exercise involves your upper body pulling muscles, including the upper back (latissimus dorsi), rear shoulders (posterior deltoids), front arms (biceps) and, surprisingly, the abdominals (rectus abdominis). Of course, a chinning bar, or properly positioned tree limb, is necessary to perform this exercise. Begin by grasping the bar with an underhand, shoulder-width grip, and hanging with your arms fully extended. Pull your chin above the bar slowly, taking 10 seconds for the upward movement. Once there, lower yourself to the starting position in five seconds. Try for two slow chin-ups in two-minutes, taking a 90-second rest between repetitions. Gradually, reduced the recovery period until you can complete three consecutive chin-ups in 45 seconds.