Barbell Spider Curl

What the barbell spider curl actually trains

A barbell spider curl is a biceps isolation exercise performed lying face down on a steep incline bench, with the upper arms hanging vertically and the bar curled up towards the shoulders.

The biceps brachii is the prime mover, both the long head on the outside of the upper arm and the short head on the inside. The brachialis, which sits underneath the biceps and pushes it upwards as it grows, works hard throughout. The brachioradialis in the forearm assists, though less than it would with a neutral or pronated grip.

What defines the spider curl is where the resistance is hardest. Because your upper arms hang straight down towards the floor, the moment arm is longest when the forearms are horizontal, which happens near the top of the curl. The exercise is therefore hardest in the contracted position and close to free at the bottom.

That is the exact mirror of a preacher curl, where the pad angles the upper arms forwards and the hardest point arrives near full extension.

It is worth being blunt about this. Preacher, incline and spider curls are not three different exercises with three different purposes. They are the same movement with the resistance peak shifted to a different part of the range. Choose on the basis of which part you want loaded, not on folklore about peaks and separation.

The other genuine feature is that the bench removes cheating. With your chest pinned to a pad you cannot swing the bar, lean back or use your hips, so what the bar does is what your elbow flexors did.

Setting up and executing

Set an adjustable bench to a steep incline, somewhere around sixty degrees, and lie face down with your chest against the pad.

Position your armpits over the top edge of the bench so the arms can hang cleanly without the pad blocking the elbows.

Have someone hand you the bar, or stand it on end in front of the bench and pick it up once you are in position.

Let the arms hang straight down with a supinated grip at roughly shoulder width.

Curl the bar up towards your shoulders, keeping the upper arms vertical and still. Do not let the elbows drift forwards to make the top easier.

Squeeze for a beat at the top, then lower over two to three seconds until the elbows are completely straight, and start the next rep from a dead stop.

The mistakes that cost you the most

Letting the elbows drift forwards is the fault that ruins this exercise. Because the top is the hardest position, the body wants to shorten the lever by swinging the upper arms forwards, which turns the hard part into the easy part. Keep the upper arms pointing straight at the floor for the whole set.

Not extending fully at the bottom is easy to get away with here, since the bottom is unloaded and a short rep is invisible. Pallares and colleagues found full range training produced better strength and hypertrophy outcomes than partial range work, so the free part of the range is still worth doing properly.

Going too heavy shows up as a bar that stalls halfway and a lower back that lifts off the pad. The spider curl loads a position where you have poor leverage, so the honest weight is well below what you use standing.

And rushing the descent throws away the eccentric. Schoenfeld and colleagues found concentric and eccentric actions produce broadly similar hypertrophy when volume is equated, but control on the way down is the cheapest quality you can add to a curl, and here it costs nothing.

Sets, reps and rest by goal

Curls respond to volume and effort far more than to variation, so keep the programming simple.

For muscle gain, three sets of ten to fifteen with sixty seconds rest. For strength, three sets of eight to twelve with ninety seconds, though biceps strength as a goal is mostly a proxy for size. In a fat loss phase, three sets of twelve to twenty with forty five seconds.

Higher reps suit this variation better than heavy work. The peak resistance sits where the biceps is short and mechanically weak, and grinding very heavy sets there is unpleasant without being more productive.

Schoenfeld and colleagues found a dose response between weekly hard sets and hypertrophy, and the practical version for arms is that total weekly curl volume matters more than which curl you picked. Six to twelve hard sets a week across all your biceps work suits most people.

Refalo and colleagues found stopping a rep or two short of failure produces comparable growth to going all the way. On a spider curl the last rep before failure is usually the last one you can complete without the elbows creeping forwards, which is a convenient place to stop.

Where it fits in your split

Late in a session, after the pressing or pulling that actually needs your energy.

On push, pull and legs it goes on pull day, after the rows and pulldowns. On an upper and lower split it belongs at the end of the upper sessions. On a bro split it is arm day work. On a full body programme it is optional filler if time allows.

No session should be built around it. The biceps already get substantial work from every row, pulldown and chin-up you do, and direct curls supplement that rather than form the foundation of it.

If you already have another curl in the same session, think before adding this one. Two curls that differ only in where the resistance peaks are close to redundant, and the second mostly adds fatigue. A spider curl next to a preacher curl in the same workout is a good example of what not to do.

Twice a week is plenty.

Variations worth knowing

The dumbbell spider curl swaps the bar for two dumbbells, which lets each arm work independently and lets the hands rotate as they curl.

The preacher curl uses the same principle in reverse, with the pad angling the upper arms forwards so the hardest point sits near full extension.

The incline dumbbell curl goes to the other extreme, with the arms hanging behind the body and the biceps loaded in its longest position.

The EZ bar spider curl is the same exercise with an angled bar, which most wrists prefer and which changes nothing else.

A cable spider curl, lying on a bench in front of a low pulley, keeps tension more even through the range and removes the free bottom position.

And the standing barbell curl is the simplest alternative of all, doing more total work with less setup, and the one to keep if you are only keeping one.

What the evidence says

Marcolin and colleagues compared electromyographic activity of the biceps brachii and brachioradialis across three curl variants and found the differences between them were modest, which is the evidence based reason not to treat curl selection as a high stakes decision.

Vigotsky and colleagues cautioned that surface electromyography amplitude does not straightforwardly indicate muscle growth, which is worth holding in mind whenever a curl variation is sold on the strength of an activation study.

Pallares and colleagues found full range training produced better strength and hypertrophy outcomes than partial range work, supporting full extension at the bottom even though that part of a spider curl feels unloaded.

Pedrosa and colleagues found that partial ranges carried out at long muscle lengths produced more favourable adaptations than the same partials at short lengths. That is a point against the spider curl specifically, since its resistance peak sits at the short end of the range.

Schoenfeld and colleagues found concentric and eccentric actions produce broadly similar hypertrophy when volume is equated, so the slow lowering here is about control rather than a special stimulus.

Schoenfeld and colleagues also found a dose response between weekly hard sets and hypertrophy, and Refalo and colleagues found stopping short of failure produces comparable growth, which together set the volume and effort targets.

Common questions

Is a spider curl better than a preacher curl?

No, it is the mirror image. A preacher curl is hardest near full extension, a spider curl is hardest near full contraction. If you want the stretched position loaded, which the evidence on long muscle lengths mildly favours, the preacher is the better pick. If you want a hard contraction with no cheating, take the spider.

Do I actually need this exercise?

Not really. It is a curl, and your biceps mostly care about how many hard sets you do rather than which curl produced them. Its niche is that the bench makes cheating impossible, which is genuinely useful if your standing curls turn into a hip driven swing.

Straight bar or EZ bar?

EZ bar unless your wrists are perfectly comfortable with a straight one. The angled grip reduces the strain at the wrist without meaningfully changing what the elbow flexors do, so there is nothing to gain by suffering through a straight bar.

Will this build a biceps peak?

No. Peak is a matter of muscle length and insertion points, both fixed. What you can do is grow the whole muscle, along with the brachialis underneath it, which changes how the arm looks far more than any attempt to target a shape.

How steep should the bench be?

Steep enough that your upper arms hang close to vertical, which is usually around sixty degrees or more. If your arms rest against the pad rather than hanging free, the bench is too flat and you are doing an incline curl instead.