Whether you want to develop a six pack or just to be at your strongest, your core is key. The group of muscles that acts as your foundation is made up of your abs, hips, back, and chest, and it does everything from create good posture to stabilize your balance. There’s no strong body without a strong core, and your abs are an important set of muscles within that group.
Crunches and planks both fall under the ab and core exercise category, but is one of them more effective than the other? We asked WeStrive App trainers Phil Catudal, MBA, NASM-CPT and Hailey Andrew for their thoughts.
Meet the Expert
What Are Planks?
Planks are a core exercise that are performed by lying prone on the floor, resting on either your elbows or your wrists and your toes. A plank position looks similar to the beginning of a pushup, but your arms are only used for stability’s sake, and there is no bending of the arms involved. It’s an isometric exercise, which means that you’re isolating specific muscle groups. In this case, those muscles are mostly your core, but planks activate everything from your abs and obliques to your glutes and shoulders. Most experts suggest holding your plank for 10 to 30 seconds. When you do this regularly, your muscles strengthen and you're able to hold the plank position for progressively longer. While one only needs to stay still to do a plank, there are also numerous variations on the position that involve moving your legs, arms, or both, while in the plank position.
Benefits of Planks
Much like how they work numerous muscles, the benefits of planks are manifold.
- Core strength: Your core is an important, foundational muscle group for everyday life, and planks strengthen it.
- Improved posture: A strong core is key to having proper posture.
- Performing other exercises more effectively: By strengthening your core, you set yourself up to be as stable and functional as possible.
Muscles Targeted During Planks
As you may have guessed, a wide variety of muscles are targeted with planks. “Planks work your entire core, with particular emphasis on your abs,” says Catudal. “When you plank properly, you engage and squeeze your abs, lower back, and glutes.” Additionally, he says you’ll “also feel your quads and hip flexors at work, since these are synergistic muscles that connect to and aid your glutes and abs.”
Beyond these muscles, the pull of gravity activates others. Says Catudal: "You’re also in the air resisting as gravity pushes you down, your shoulders, arms, and everything holding you up are also working to support your core." Andrew refers to those supporters as the “accessory muscles involved," noting "the isometric contraction activates the core muscles on the front side and back side of the body almost equally.”
What Are Crunches?
The easiest way to think of crunches is as a simplified and streamlined version of a situp. The main difference is that where a situp has you go from lying flat on your back to sitting fully upright, a crunch has you perform the same activity of lifting your shoulders off the ground, but you stop the exercise before your mid and lower back are also lifted. Crunches are therefore quicker than sit-ups, since they are just the act up lifting your shoulders off the ground and squeezing your upper body in towards your legs, and they don’t target other muscle groups like sit-ups do. “The move is called a crunch because you are essentially crunching your ‘top’ abs into your ‘bottom’ abs," says Catudal. Crunches specifically target just your abs, making them a fast and effective ab exercise.
Benefits of Crunches
- Less stress on other muscles: Crunches strengthen your abs without putting pressure on your shoulders or hips.
- Endurance: Crunches improve your abdominal endurance for other core exercises.
- Toning: By focusing on just one muscle group, you’re able to do many repetitions. This can lead to toning faster than exercises where you do fewer reps.
Muscles Targeted During Crunches
Unlike planks, which target numerous muscles throughout your body, crunches are very specific in their targeting. "Crunches work your abs, with particular emphasis on the upper part of your abdominal wall," says Catudal.
“Running down the center of the body, the rectus abdominis is your six-pack, with the origin at the pubic symphysis/crest and the insertion at the xiphoid process," says Andrew. She thinks crunches are useful because “exercises and motions that create contraction while bringing the origin and insertion closer together engage the rectus abdominis best to create your dream six pack.”
Planks vs. Crunches
These two exercises are very different. Both planks and crunches will strengthen your abs, but planks target many muscles, including your abs, while crunches target only your abs. Both exercises are quick; you can either hold a plank for 30-60 seconds or do a minute’s worth of crunches, and both will be impactful. However, no matter how many crunches you do, you’ll only work your abs. Conversely, when you do planks you improve your abs, but you also strengthen the other muscles of your core, in addition to your upper body because it’s holding you up.
If you have a back injury, planks may be a wiser choice than crunches. That’s because even though crunches put a lot less stress on your back than situps do, there is still pressure on your back involved in order to make the crunching motion. It’s also impossible to do a crunch without putting some amount of pressure on your neck, so if you have neck or upper back injuries, that could be problematic. "Planks are a safe isometric hold for most individuals with lower back problems," says Andrew. "The less range of motion you have to move through tends to be slightly less aggravating on the lower back. By performing proper form in a plank, aggravation can be mostly avoided.” For those with injuries, she suggests a modified plank position. "This could be done by performing the plank from your knees, extending your elbows straight, or widening your feet in order to gain a larger base of support.” If you don’t have an injury but you’re concerned about acquiring one, planks will help to prevent them by strengthening your foundational muscles. Crunches won't have as great an impact.
Both crunches and planks are helpful exercises to strengthen your abs. Crunches will give you more ab endurance, and when paired with proper nutrition, may help you build a six pack. Conversely, planks will improve your body’s foundation, using a wide variety of muscles to strengthen you from shoulders to glutes. To be in the best shape you can be, both are beneficial. Additionally, strength and toning require variety; provided you don’t have an injury, you’ll be best served by doing both of these exercises. If you had to choose one, though, planks could be considered the most beneficial.
Clark DR, Lambert MI, Hunter AM. Contemporary perspectives of core stability training for dynamic athletic performance: a survey of athletes, coaches, sports science and sports medicine practitioners. Sports Med Open. 2018;4(1):32. doi:10.1186/s40798-018-0150-3