What Do Leg Raises Do? The Ultimate Core Strength Guide
Walk into any commercial gym, and you will see someone hanging from a pull-up bar, swinging their legs wildly in hopes of getting a six-pack. But if you stop and analyze the mechanics, what do leg raises do actually? Are they purely an abdominal exercise, or is there more going on under the surface?
The short answer is that leg raises are a functional powerhouse, but they are often misunderstood. They don't just target the aesthetic "lower abs"; they are a primary driver for hip flexion strength and pelvic stability. If you perform them incorrectly, however, they become little more than a recipe for lower back strain. Let’s break down the mechanics, the muscles, and the reality of this movement.
Key Takeaways: What Does Leg Raises Do?
If you are looking for the quick answer for your training notes, here is the breakdown of the primary benefits and muscles worked:
- Target the Iliopsoas: This deep hip flexor muscle is the primary mover for lifting your legs above 90 degrees.
- Strengthen the Rectus Abdominis: While they work the whole six-pack, the lower region works hard to stabilize the pelvis against the weight of your legs.
- Improve Grip Strength: If performing the hanging variation, your forearms and lats must work isometrically to keep you suspended.
- Decompress the Spine: Gravity works in your favor during hanging leg raises, potentially alleviating spinal compression.
The Anatomy of the Movement
To understand the effectiveness of this exercise, we have to look at the biomechanics. Many people ask, "what do leg raises workout?" expecting the answer to be strictly "abs." That is only half the story.
The Hip Flexor Dominance
The primary function of lifting your legs from a hanging or lying position is hip flexion. The muscle responsible for this is the iliopsoas. Your abdominal muscles act as stabilizers during the first phase of the movement. They contract isometrically to prevent your lower back from arching (hyperextending).
The abs truly engage dynamically when you curl your pelvis upward at the top of the movement. If you are just lifting your legs to 90 degrees and stopping, you are mostly training your hip flexors, not your abs.
The "Lower Ab" Concept
Physiologically, the Rectus Abdominis is one long sheet of muscle. You cannot isolate the lower portion entirely. However, leg raises apply more mechanical tension to the lower region because of the leverage. Since the pivot point is the hips, the lower portion of the muscle must work harder to curl the pelvis than it does during a standard crunch.
Why You Should Incorporate Them
Beyond the mirror muscles, functional strength is the real ROI here.
Midline Stability
A strong core isn't about doing a thousand crunches; it's about the ability to transfer force between your upper and lower body. Leg raises force your core to stabilize the weight of your legs—which are heavy levers—preventing energy leaks during compound lifts like squats or overhead presses.
Grip and Lat Engagement
When a client asks what does leg raises do for the upper body, I point to the hanging variation. To stop yourself from swinging, you must engage your lats (pulling down on the bar) and your grip. This has a direct carryover to your pull-up performance.
Common Mistakes That Kill Progress
Leg raises are easy to cheat. Here is why most people fail to see results.
The Momentum Swing
Using momentum to kick your legs up bypasses the core entirely. If you are swinging back and forth, you are using physics, not muscle. You need to control the eccentric (lowering) phase for at least two seconds to kill momentum.
Arching the Lower Back
This is the danger zone. If your lower back peels off the floor (in lying raises) or arches excessively (in hanging raises) as your legs lower, your abs have disengaged. This places massive shear force on the lumbar spine. If you cannot keep your back flat, bend your knees to shorten the lever arm.
My Training Log: Real Talk
I want to share my personal experience with what do leg raises do, specifically regarding the learning curve. When I first started taking hanging leg raises seriously, the limiting factor wasn't my abs—it was the excruciating burn in my forearms.
I remember hanging from the knurled bar, and by rep eight, my grip was failing long before my core was fatigued. I also struggled with the "swing." I’d kick my legs up, and my body would pendulum backward. I had to learn to actively engage my lats—literally pulling the bar down into my palms—to create a rigid torso.
Another unpolished detail people don't mention: the hip cramping. There is a specific, sharp cramp right in the crease of the hip (the TFL muscle) that hits you if you don't warm up your mobility first. It feels like a guitar string snapping tight. Once I started doing dead hangs and hip circles before the raises, that cramping vanished, and I could finally feel the deep burn in the lower stomach area rather than just my hip crease.
Conclusion
So, what do leg raises do? They bridge the gap between hip mobility and core stability. They are one of the few exercises that challenge the abs vertically while simultaneously testing your grip and hip strength. Stop swinging, control the descent, and focus on curling the pelvis, not just lifting the feet. Your core will thank you, even if your hip flexors hate you tomorrow.
Frequently Asked Questions
Why do my hips pop when I do leg raises?
This is usually caused by a tight psoas muscle snapping over a bony prominence in the pelvis. It is generally not dangerous unless accompanied by pain, but it indicates tight hip flexors. Stretching and reducing the range of motion can help.
Are hanging leg raises better than lying leg raises?
Hanging raises are superior for athletic development because they engage the lats and grip while decompressing the spine. However, lying leg raises are better for beginners because the floor provides feedback for spinal alignment, making it easier to prevent lower back arching.
Can leg raises burn belly fat?
No exercise can spot-reduce fat. While leg raises will build the muscle underneath the fat, revealing that definition requires a caloric deficit and overall fat loss. You cannot crunch or leg-raise away a specific area of body fat.
