If you complete 100 crunches a day, you might build a little muscle — but, more likely, you'll be left with a sore stomach and not much else.
The crunch and its big brother, the sit-up, can play a role in an abdominal workout routine to boost strength, but they're far from the best exercises you can do — and they won't get you in shape.
Instead, to get in shape — that is, to lose fat and build muscle so you have excellent cardiovascular endurance and muscular strength — you must undertake a comprehensive healthy-eating plan and workout routine that includes both cardio and strength training. Although crunches can be part of that strength training, they shouldn't be the only exercise you do.
If you want to do crunches as part of your workout routine, stick to a moderate number as you would with any other exercise — three sets of 10 to 12 reps is generally sufficient.
Vary your crunches by doing bicycle crunches, reverse crunches and oblique crunches to hit multiple muscles. However, keep in mind that even if you build muscle by doing crunches, you won't see the results if it's hidden under a layer of stomach fat.
Read more: Calories Burned with 300 Crunches a Day
How to Get in Shape
Getting in shape takes more than doing crunches, no matter how many you might do. To lose weight and get in shape, you must eat fewer calories than you burn through activity — it's a simple strategy known as "Calories in, calories out." That catchphrase, however, doesn't tell the whole story.
To truly be "in shape," you need to focus on eating nutrient-rich, satiating foods. This includes an abundance of colorful produce, plenty of fiber and lots of lean protein, including chicken, fish and legumes. You also need to decrease the amount of added sugar you're consuming, as well as salt and saturated fats.
Your Exercise Routine
According to the Centers for Disease Control and Prevention, a weekly minimum of 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity is needed to maintain your body weight. To lose weight, you will likely need more exercise to help contribute to the caloric deficit needed for weight loss.
Additionally, schedule in at least two strength-training sessions per week. Increased lean muscle mass burns more calories at rest. During this time, lift weights — or use weight machines or bodyweight — to target all parts of the body, including arms, back and shoulders, legs and glutes and the core muscles of the abdomen, lower back and hips.
Read more: Sit-Ups Vs. Crunches
Superior Ab Exercises
If you want to strengthen the muscles in your abdomen, there are options that are more effective than crunches.
Get into the same position you would if you were doing a push-up. Bend your elbows and lower your upper body to rest on your forearms. Your body should form a straight line from shoulders to ankles.
Engage your core by contracting your ab muscles. Hold this position for 30 seconds, and work your way up to longer hold times. Release your body to the ground.
2. Bicycle Crunch
Lie on the floor with your hands lightly placed on either side of your head. Press your lower back into the ground. Lift your knees to a 45-degree angle.
Bring your right knee toward your chest, as if it was on the upward swing of pedaling a bike. At the same time, bring your left elbow toward the knee.
Return the elbow back to the starting position and you simultaneously extend your right leg out to a point and bring the left knee toward the chest. Bring your right elbow to the left knee.
Continue to "pedal" your legs and alternate your elbows coming forward for 10 to 15 repetitions.