“The main difference between the two is that unlike a sit-up, in a crunch, the lower back never leaves the floor,” explains Katharine Glazer, CPT. Basically, a crunch is a more targeted and isolated exercise that only works your rectus abdominis (primarily your upper six-pack).
Crunches target all three sections of the abdominals - rectus abdominis, external obliques, and internal obliques -- while sit-ups primarily target the rectus abdominis in only one plane of motion (sagittal). For this reason, crunches are considered more effective.
Sit-ups have fallen out of favor among some fitness experts and trainers for several reasons: Spinal Strain: Traditional sit-ups can put a significant strain on the lower back and spine, especially if performed with poor form. This can lead to discomfort or injury over time.
Unfortunately, sit-ups and crunches can't eliminate visceral fat directly. You can't reduce fat from specific parts of your body by exercising that body part; our bodies simply don't work that way. With sit-ups or other abdominal exercises, you're toning the abdominal muscles but not burning intra-abdominal fat.
Abdominal exercises such as crunches or sit-ups do not specifically burn belly fat, but they can help the belly appear flatter and more toned. Other exercises that can help whittle the waistline and tone up the belly include bicycles, planks, and side planks.
Bicycle Crunches
The American Council on Exercise (ACE) ranks bicycle crunches as the best ab exercise [1]. This ab exercise activates multiple parts of the core, including the rectus abdominis, obliques, and the hard-to-reach transverse abdominis deep in the core.
Activities like running, cycling, and high-intensity interval training (HIIT) burn more calories and fat throughout the body, including the upper belly, lower belly, and obliques. So, while ab exercises can help define your core, it's a holistic approach that will help you lose the fat covering those muscles.
How Many Situps Should You Do Every Day? Everyone has different goals, fitness levels, and circumstances, but maxing out at 40 situps daily is a fair goal for most people, says Men's Health fitness director Ebenezer Samuel, C.S.C.S.
Fitness Myth: To get flat abs or six-pack abs, do 100 crunches every day. The crunch is a classic abdominal exercise but only work on the top layer of superficial abdominal muscles that when worked out alone, do not sufficiently achieve visibly trim and ripped abs.
Sit-ups once ruled as the way to tighter abs and a slimmer waistline. Now plank exercises, in which you assume a position and hold it, are the gold standard for working your core, while classic sit-ups and crunches have fallen out of favor.
Myth busted: sit-ups and crunches don't burn belly fat.
In fact, spot reduction isn't possible. The only way to reduce abdominal fat is to reduce overall body fat, and then tone the abdominal muscles through core-strengthening exercises. To burn overall body fat, you need to burn calories.
Men and women: 3–4 sets of 15–25 reps (total 45–100 squats); you can start incorporating variations like sumo squats or goblet squats. Add weights or resistance bands to increase intensity, focus on proper form and allow rest days for recovery.
Crunches or other ab workouts help strengthen your core, but they won't get rid of belly fat. You can't target fat loss in one area. Focus on losing overall body fat with a balanced diet and eating fewer calories.
Aerobic exercise includes any activity that raises your heart rate such as walking, dancing, running or swimming. This can also include doing housework, gardening and playing with your children. Other types of exercise such as strength training, Pilates and yoga can also help you lose belly fat.
Sit-ups are the most popular abdominal exercise, Ball said, but are commonly done with two errors: sitting all the way up, and putting hands behind the neck.
Strength training.
Moderate aerobic exercise includes activities such as brisk walking, biking, swimming and mowing the lawn. Vigorous aerobic exercise includes activities such as running, swimming laps, heavy yardwork and aerobic dancing.