Gorilla Chin/Crunch
Also works: Biceps · Lats
A chin-up and a knee crunch performed as one rep: you hang underhand with the knees already bent to 90 degrees, then pull your chin to the bar while driving the knees up to your chest so both finish together. It is a coordination lift, and the timing is what makes or breaks it.
Own the movement
Set up first, then execute. Every cue below is something you can check on your next set.
Before the first rep
- Take an underhand grip slightly wider than your shoulders — narrower than a standard chin-up feels, but it keeps the elbows in front of the ribs.
- Hang at full stretch, then bend the knees to 90 degrees so the thighs hang vertically and the calves are parallel to the floor.
- Set the shoulders down and back out of your ears before you pull; do not start from a passive dead hang.
- Kill any swing before the first rep — start from a completely still hang.
Every rep
Breathing & tempo — Inhale at the hang, exhale hard through the pull and the crunch together — the forced exhale is what lets the pelvis tuck. Two seconds up, one second at the top, three seconds down.
Before you load it
- An underhand grip at full hang puts the biceps tendon and the elbow in a vulnerable stretched position. Come out of the bottom under control rather than dropping into a dead hang, and skip this movement entirely if you have a history of biceps tendon pain.
Sets, reps & load
Where to start, and what to change when it stops being hard.
You need a strict bodyweight chin-up and a clean hanging knee raise before combining them. Start at 3 sets of 5. Progress by adding reps to 10, then by straightening the legs slightly at the top, and only then by hanging a 5 kg belt weight. Ten synced reps with the chin over the bar and the knees at chest height is the standard worth chasing.
What goes wrong
The errors that show up most often, and the cue that fixes each one.
Slow the whole rep to three seconds up and count the knees and the chin arriving together. If they will not sync, do a set of knee raises and a set of chins separately for a few weeks, then recombine.
Start each rep from a dead stop with the knees already bent, so there is no backswing available. If you cannot get up without one, use a band under the knees or a chin-up assist machine.
Set the standard at nose level with the bar and count only reps that reach it. A half-rep with a knee tuck is not a harder chin-up, it is a shorter one.
End the set two reps before your grip fails, while you can still lower under control. Drop off the bar and rest 2-3 minutes rather than salvaging one ugly rep.
Why bother
Pulling and trunk flexion happen simultaneously, so the lats and the abs are both shortening at the same moment. That is an unusual demand — most gym movements ask one or the other — and it maps directly onto climbing, gymnastics work and anything where you pull yourself over an edge.
Be honest about the trade-off. As a chin-up it is compromised, because the knee tuck shifts your centre of mass and you finish with a shorter, easier pull. As an ab exercise it is compromised too, because your arms are busy and you will stop the set when your biceps quit, not when your abs do. Its value is the coordination, not being the best version of either half.
Where it fits
After your main pulling work, not instead of it. Keep it to 3 sets of 6-10 once or twice a week and treat it as a finisher. If your goal is a bigger chin-up, do strict chin-ups; if your goal is stronger abs, do hanging leg raises. This is for when you want both trained together.
If this one isn't it
No kit, too hard, or too easy — here's where to go instead.
Same job, different kit
Start here instead
When this gets easy
Asked and answered
Does the knee tuck make the chin-up easier or harder?
Easier through the pull itself. Tucking the knees shortens your body and moves your centre of mass closer to the bar, so the pull travels less distance. The difficulty comes from doing both jobs at once, not from the pull being heavier.
Can I use this instead of chin-ups and leg raises?
Not if either one is a priority. You will always be limited by whichever half fails first — usually the grip and biceps — so the abs never see a hard enough set to grow. Keep your strict pulling and your dedicated ab work, and use this as a third thing.
Should I use straps?
Chalk first. Straps are reasonable once your abs are consistently outlasting your grip, because at that point the grip is the wrong limiter. But if you cannot hang for 45 seconds without them, fix the grip — it will hold back your deadlifts and rows too.
Overhand or underhand grip?
Underhand is the version as described, and it lets the biceps contribute so you get more reps. Overhand shifts the load toward the lats and takes strain off the biceps tendon. Both work; pick overhand if your elbows complain at the bottom of the hang.