Bicycle Crunches

Flatten and Firm Your Abs

By Stephen E. Alway, Ph.D., FACSM

With pool parties and beach plans, there is no hiding your waist shape. However, there is no cause for panic because you can do a few things that will be effective enough to put the finishing touches on firming your entire waistline. Importantly, if you are committed to get your flatten your abs, you may want to raise your aerobic portion of your workout, to twice each day if possible. That does not mean you need to live in the gym, as the second aerobic piece could be a brisk 40-minute walk in the evening. The goal is to raise your metabolic rate to burn more fat, and when you do, the benefits of your direct abdominal training will be all the more evident.

The best abdominal exercises shorten the fibers in the front and sides of the abdominal wall and they do not stretch these muscles.1 Bicycle crunches will create strong shortening contractions while also challenging your core.2 The bonus for this exercise is that there is no need for any specialized equipment to effectively begin to reshape your abdominals.3

Bicycle Crunches - Flatten and Firm Your Abs

Exercise: Bicycle Crunches

1. Lie on your back on a mat. Flex your knees so that your feet are flat on the floor. Place your hands behind your head (avoid clasping or intertwining your fingers). Alternatively you can gently contact your fingertips to the temple on each side of your temple.

2. Press your lower back into the mat and tighten your abdominal muscles. Lift your head, shoulders and upper back from the floor.

3. Move your right elbow and left knee toward each other while straightening your right leg. Do not let the leg that is straightening contact the floor mat.

4. In a smooth transition, flex the hip and knee so that your right knee moves back toward your chest and twist so that your left elbow and right knee move toward each other. Straighten your left knee as the right knee is flexed.

5. Twisting the elbow to the right and left knee in the sequence is considered one full repetition.

6. Make the transition between twisting to the right and left, and flex and extend the knees in a fluid and continuous fashion, much like pedaling a bicycle (hence its name). You should work up to three sets of 25-30 repetitions.

Bicycle Crunches - Flatten and Firm Your Abs

The twist from one side, then the other as you are coming upward on successive repetitions, fully activates the internal and external oblique muscles.6 The rectus abdominis is contracted almost constantly throughout the entire set. The smaller size and the lower attachments make the most inferior part of the rectus abdominis harder to develop. However, bicycle crunches strongly activate this lower area.

As you progress and your abdominals are getting firmer and stronger, you can make the exercise more challenging by holding a light weight behind your head as you do the exercise. However, do not cut the repetitions down just to lift a heavier weight in this exercise.

The old adage that once you learn to ride a bike you will not forget is fairly accurate when it comes to bicycle crunches. Once you get the handle on the exercise, you are going to want to keep “pedaling” your way to a firm and shapely abdominal wall. The exercise is challenging and effective but it is not terribly difficult to perform, especially once you get your legs moving smoothly. If you tighten your diet, increase the frequency of your aerobics, and hit bicycle crunches as part of your regular abdominal training (maybe even throwing in a few sets at home between workouts), you’ll be able to sculpt a new thin, flat and firm abdomen.

Illustrations by William P. Hamilton, CMI


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  1. Nelson GA, Bent-Forsythe DA, Roopchand-Martin SC: Electromyographic activity of the rectus abdominis during a traditional crunch and the basic jackknife exercise with the Ab Lounge. J Strength Cond Res 2012;26:1584-1588.
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