According to hypertrophy coach Joe Bennett: “Nerds say [hanging leg raises] are not an ab exercise but hip flexor exercise. Meatheads say, ‘I feel my abs, so they’re an ab exercise!’”
The truth is that hanging leg raises can train both effectively. Since six-pack abs are the primary goal for most, Bennett explains how to target these muscles with leg raises and shares his overall favorite ab exercise.
What Do Abs Do?
Determining worthwhile ab exercises begs some fundamental questions:
- What do the abs do?
- What exercises perform these functions most effectively?
“Muscles create tension between an origin and insertion. And what does that tension do? Well, it depends,” Bennett explained. The rectus abdominis, or the six-pack muscles, do two things — curl the pelvis and ribs together, as seen during crunch variations, and contract isometrically (without moving) to resist motion from outside forces.
Exercises that require bending and extending the torso (isotonic reps) are better for building ab muscles. How you perform leg raises favors the abs, hip flexors, or both. Bennett provided a mechanics breakdown for each variation:
[Related: The Best Beginner Workout Plan To Start Your Fitness Journey]
Hanging Leg Raises for Hip Flexors
During hanging leg raises, if the pelvis and spine stay neutral, the hip flexors mostly lift the legs. The abs engage isometrically to stabilize and prevent the pelvis from tilting forward, but this is suboptimal for hypertrophy.
“If you let your pelvis tilt [forward], it’s almost not an ab exercise at all,” Bennett said. This is because there’s minimal ab tension and all hip flexion.
Hanging Leg Raises for Abs
To target the abdominals, tilt the pelvis back by tucking the hips forward and crunch the upper abs toward the pelvis. The motion should come only from the pelvis, without flexing the hips. “That motion is 100% from the abs,” Bennett assured.
If the straight-leg version is too challenging, bend the knees to keep the legs closer to the axis or pelvis. “Shortening the moment arm decreases the load,” Bennett explained. (1)
Are Hanging Leg Raises Worth Doing?
“[Hanging leg raises] for abs is a pretty good exercise,” Bennett said. Part of that is because they can also engage the external obliques — the core muscles on either side of the abdominals — with pelvic action, unlike standard crunches. Hanging leg raises fall short of excellence due to their limited motion and minimal tension during eccentrics.
Loading muscles with maximal tension in their stretched position is believed to be better for hypertrophy.
Better Ab Exercise?
If Bennett had to pick a more optimal ab exercise, it’d be crunches using a curved ab mat for a greater range of motion.
“The ab mat takes you through [full spinal flexion and extension],” he explained. The movement is easier toward the top of the crunch and harder as you lie back due to a longer moment arm. This is more favorable, whereas hanging leg raises are the opposite.
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Reference
- Sherman MA, Seth A, Delp SL. WHAT IS A MOMENT ARM? CALCULATING MUSCLE EFFECTIVENESS IN BIOMECHANICAL MODELS USING GENERALIZED COORDINATES. Proc ASME Des Eng Tech Conf. 2013 Aug;2013:V07BT10A052. doi: 10.1115/DETC2013-13633. PMID: 25905111; PMCID: PMC4404026.
Featured image: @hypertrophycoach on Instagram
