Exercising your abs is not about how many reps you can do at a time. It is about really targeting the muscles and making them work. You will feel your abs working when you target them with the right exercises. Plus, when your lower abs begin to get tired from too much of a workout, you may start to not feel them as much. Listen to your body. Do not over strain them or you will be paying for it the next day.
A great lower ab exercise that specifically targets your abs targets your transverse ab muscles. The Transverse Abdominal runs horizontally under the Rectums Abdominal (muscles that run vertically and pull your front pelvis up towards the belly button) and are the muscles that pull your belly button in towards your spine. This exercise is preformed by kneeling on the floor with your palms flat on the floor in front of you. You simply pull your belly button in as much as you can using your abs. Try to relax the rest of your body to ensure that the work is being done by your lower abs. If you are a beginner, start by holding the position for 10 seconds then relax. As your body gets used to using these muscles, you can lengthen the exercise to holding the position until you can not feel it anymore or for up to 2 minutes or you start feeling other muscles contracting more. If you are a beginner and you are unsure if you are performing the exercise correctly, test yourself my lying face down flat on the floor and performing the same exercise. This position will allow you to be able to feel your lower abs better therefore ensuring the exercise is done correctly.
Another great lower ab exercise starts with you lying flat on the floor on your back. This exercise works by moving your legs and targeting your lower abs. The goal here is to keep your abs tight throughout the exercise. Once you stop feeling the tightness in your abs or you feel pain in your lower back, stop the exercise. To perform the exercise, one leg is kept on the ground and the other leg is kept in a bent position. Keep the thigh muscle of your bent leg perpendicular to the ground. Using your lower abs, move your leg towards the ground until your foot touches the floor. Work both legs with this exercise. As the exercise gets easier for you and you are looking for more of a challenge, you can straighten your leg in order to increase the demand on your lower abs. To further increase demand on lower abs, lower both legs straight at the same time. Keep in mind that this exercise should be done slowly and with a lot of concentration. Perform 2 to 3 sets of 10 to 15 reps each.