The basic crunch remains the best entry-level stomach exercise. You can do these exercises anywhere you can find room to lie flat on your back. Clasp your hands behind your head and curl your upper torso up while squeezing your abs. You need to only lift your shoulders off the floor instead of your entire back as with the old-fashioned sit-up.
Isometric Ab Exercise
Isometric ab exercises are even more versatile than crunches. You don't even need room to lie down as you can do this while taking a break from backpacking, standing in line at the exercise equipment store or while you're fishing in a lake. Tighten your ab muscles as much as you can and hold for a count of 10 to 30 seconds. Doing this throughout the day is like setting aside time for crunches every day.
Hanging Knee Raise
Hanging knees raises are an effective way to work your stomach muscles as long as you have a bar from which to hang. This can be done at a gym, on the jungle bars at a neighborhood playground or with a pipe inside your house. Some universal gym machines come with a bar for doing this exercise. This is also an effective exercise to do while camping or hiking. Just find a low enough tree branch that can support your weight. While hanging from the bar with your hands, bring your knees up toward your stomach, hold for a beat and then return to the starting position.
Reverse beetles can be done on your weight bench at home, on your chair at work or on a rock formation when you're out hiking. According to "Basic Weight Training for Men and Women," you do a reverse beetle by getting into a seated position and leaning slightly back while holding onto the sides of the bench or chair, or whatever you are sitting on. Bring your feet up off the floor. Curl your torso by bending your knees and shoulders, and bring the knees up toward your chest before returning to the starting position.
Side Body Lift
The side body lift is an advanced exercise that gives your oblique abs on the side of your body a tough workout. Begin by lying on your side, so you are supporting your body with your left elbow, forearm and hand. Make sure that you have placed your elbow directly beneath your shoulder. Lift your body up slowly, so it forms a diagonal line. Cross your feet to maintain balance and support your balance with your right hand. Once you have mastered this technique, make it tougher by raising your right hand toward the ceiling so that all your support is accomplished with your left forearm and hand. Repeat on your other side.