Knowing how to do ab crunches and sit ups with the proper technique can mean the difference between getting a six pack fast or getting a neck strain. Bad posture during sit ups is a constant source of grief for a lot of gym goers and if you are just at the beginning of your journey for a flat and muscular stomach, you'd better pay attention to what we are about to discuss here.
Ab crunches and sit ups are one of the many classic calisthenics exercises, much like push ups (opens in new tab), that everyone thinks they know how to do properly, yet most people fail to do them right. To confuse matters even more, there are a lot of variations and it can be cumbersome to know which works best for you.
If you want to have a well-sculpted six pack, you'll need to do two things: 1) do a killer abs workout (opens in new tab) and 2) lose some weight (opens in new tab) so your abdominal muscles actually show.
New to resistance training? Check out our other how-tos, like how to do deadlifts (opens in new tab), how to do a bench press (opens in new tab), or how to do squats (opens in new tab). Maybe you would like to know how to do an overhead press (opens in new tab) correctly to build bigger arms and shoulders or how to do bent over rows (opens in new tab) for big back gains and strong biceps? We have it all.
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Warm up and diet
Abdominal muscles are high load-bearing muscles which is equally as good as it is bad, depending on the perspective. It's good because they don't need much warm up, which shortens down the time spent with exercising and therefore you can literally spend 5-10 minutes a day working on them.
The downside is, you will need to work them harder for them to take notice. The usual hypertrophy range (the rep range that make muscles grow bigger) of 8-12 reps don't apply to abs. Bomb them with 15-20 reps in each set and you will feel the burn sooner.
As mentioned above, all the abs workouts won't do much good if you aren't paying attention to what you eat. This is especially true to men. The typical dad bod is the result of men building up fat reserves around their waists first. If you want your six pack to show, you will need to lose weight (opens in new tab) as well as work your abs.
Important: if you had some time off exercising and especially if you are just looking into starting exercising for the first time, you might want to ease yourself into it, starting off with less reps and always checking your body metrics. And if you have any concerns about exercising, please consult a medical professional first.
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How to do ab crunches (correctly)
Why are ab crunches so popular? This exercise is easier to perform than sit ups and don't require any external equipment either. To perform ab crunches correctly, you only have to lift your shoulders and head up off the ground just enough to feel your abs flexing. It is very important not to pull with your arms and not to have the arms behind your head either.
Starting position is legs being bent in 90 degrees and upper body on the floor. Arms are either resting next to the body on the floor. Before you move your upper body, engage your core so your back and abs are ready for the movement.
How to do sit ups (correctly)
The main reason sit ups have been banished from abs workouts is because they are performed incorrectly 90% of the people. To do sit ups correctly, you should have some abdominal muscle strength already.
Don't try to do sit ups without leg support either, that'll put way too much pressure on your back. If you are working out at home, get an under door crunch bar (opens in new tab) or a sit up bench (opens in new tab) (maybe a multi-functional weight bench (opens in new tab)).
With sit ups, keep your back straight throughout the movement. Keep your core engaged all the way through the movement and go as far as your hamstrings let you. Also make sure you don't slam your back against the floor as you return to the starting position. Best to get a yoga mat (opens in new tab) and do sit ups (and ab crunches) on a softer surface.
Ab crunch and sit up variations and alternatives
Target your abs from all angles for maximum activation.
- Dead bugs: the best abs exercise if you have back problems. Lay on your back, legs bent in the knee and up in the air. Arms are also in the air, pointing up, extended. In the starting position, you should look like a dead bug (hence the name). Lower one leg and arm (opposite side) down to the floor (arm going above your head) in the same time, then return to the starting position. Do the same on the other side.
- Decline crunch: this variation is performed on a sit up bench. Set the incline to your preference so your head is in a lower position than your legs. Keep your back straight and your core engaged. After reaching the highest point, slowly lower your back down and don't slam your back against the padding.
- Hanging leg raise (opens in new tab): hands down the most challenging abs exercise out there and the one that works all your abs. It requires a strong core and arms muscular enough to be able to hold you during the sets.
- Resistance band kneeling crunches (as featured in our best resistance band workout (opens in new tab) article): this is a great exercise to provide some extra resistance to your abs workout. Make sure you hook the band around an object securely so it won't slap you on your neck as you do the crunches.
- Planks: Planks are notoriously difficult to perform, even for just a short period of time. You won't know how long a minute really is until you tried to hold a plank for 60 seconds. One of the best core strengthening exercises out there.
- Ab rollout (opens in new tab): you can do planks to work your core and your abs but there is a more engaging way to work on your core muscles: ab rollouts. Ab rollers (opens in new tab) are super fun to use and they are also an inexpensive piece of kit. No reason why not to get them.
- Russian twists (as featured in our best 3-exercise abs workout (opens in new tab) article): This is a great exercise to work your obliques. Starting position is sitting on the floor, knees bent, feet on the floor, upper body raised (core engaged!) in a 45-degree angle. Extend your arms in front of you and twist your upper body to the right and then to the left, keeping your arms extended in front of you. For added difficulty, try holding a weight plate, a dumbbell or a kettlebell in your hands. You can also try to lift your feet off the ground, for extra lower-abdominal activation.
- V sit ups: Similar to planks, this is a stationary abs exercise that will really challenge your perception of time, meaning you will reevaluate how long a minute really is. V sit ups are performed sitting on the floor, legs being straight and raised in a 45-degree angle, back straight and also raised in a 45-degree angle. Arms are – wait for it – extended in front of you, parallel to the floor, so pointing away and in front of you. All you have to do is to hold this position. Sounds easy? It isn't. Also, it is advised to stretch your hamstrings before you try doing V sit ups.