Dumbbell Spider Curl

What the dumbbell spider curl actually trains

A dumbbell spider curl is a biceps isolation exercise performed lying chest down on an incline bench with the arms hanging straight below the shoulders, curling the dumbbells up towards the shoulders.

The biceps brachii flexes the elbow and holds the forearm supinated, with the brachialis beneath it and the brachioradialis contributing from the forearm. That is the same cast of muscles as every other curl, so the interesting question is not which muscles work but when they work hardest.

Here the answer is unusual. Because your upper arms hang vertically and a dumbbell is pulled straight down, the load on the elbow is close to zero at the bottom, where the arm is straight and the weight sits directly below the joint. It rises steadily as you curl and peaks near the top, with the forearm horizontal.

That is the opposite of a preacher curl, where the sloped pad puts the hardest part near the bottom, and it is the opposite of an incline curl, where the arm hangs behind the torso and the stretched position takes the load.

This is worth stating plainly because the three exercises are usually described in mystical terms. They differ in where the resistance peaks. That is it. There is no separate role, no special fibre, no unique growth mechanism.

If anything, the spider curl is the least fashionable of the three by current thinking. Pedrosa and colleagues found that training at long muscle lengths produced favourable hypertrophy outcomes compared with short length training, and the spider curl deliberately loads the short end. It is not a bad exercise, but it is not the one to build a programme around.

What it does well is make cheating difficult. Lying face down, there is nowhere to swing from, which is why some people find it the most honest curl they own.

Setting up and executing

Set an incline bench to roughly forty five degrees. Steeper is fine if it suits your height; much flatter is not.

Take a dumbbell in each hand and lie chest down against the pad, with your feet on the floor for balance.

Let the arms hang straight below the shoulders and set an underhand grip with the palms facing forward. Brace the abs so your torso stays on the pad throughout the set.

Curl both dumbbells up towards the shoulders, keeping the upper arms vertical rather than letting the elbows drift backwards.

Pause for a beat at the top, which is where the load is heaviest, then lower under control over two to three seconds until the arms are completely straight.

The mistakes that cost you the most

Letting the chest come off the pad turns a spider curl into an ordinary curl done in an awkward position. If your torso lifts to help the last reps, the shoulders and upper back are doing part of the job. Stay pinned.

Swinging the upper arms backwards is the same problem in a subtler form. Drifting the elbows behind the shoulders shortens the lever right at the top, which is the only part of this movement carrying a real load.

Using too much weight is more punishing here than elsewhere. The peak resistance sits at the contracted end, where the biceps is shortest and weakest, so the honest working weight is noticeably lighter than what you handle standing.

Half repping the bottom is tempting because the bottom of a spider curl feels like nothing. It is close to nothing in terms of load, but Schoenfeld and Grgic's review of range of motion found fuller ranges generally favour muscle development, and there is no reason to shorten a range that costs you nothing to complete.

Bench angle too low is the setup mistake. A near flat bench puts your face into the pad and makes the arm position awkward. Around forty five degrees is the sensible default.

Sets, reps and rest by goal

Moderate loads, higher repetitions, and no ego.

For muscle gain, three sets of ten to fifteen with ninety seconds rest. For strength, three sets of eight to twelve with two minutes, though nobody has ever needed a strong spider curl. In a fat loss phase, three sets of twelve to twenty with a minute.

Because the top of the range is where the resistance lives, the pause is worth taking seriously here in a way it is not on a low cable curl.

Control the descent over two to three seconds. Roig and colleagues found eccentric training produced greater strength gains than concentric training, and while the hypertrophy case is weaker, a controlled lowering costs nothing.

Schoenfeld and colleagues found a dose response between weekly hard sets and hypertrophy. Before adding this as a third curl, count the sets your biceps already receives from rows, pulldowns and chin-ups.

Refalo and colleagues found stopping a rep or two short of failure produces comparable growth to going to failure, which is a reasonable default on an exercise where the failure rep usually involves your chest peeling off the bench.

Where it fits in your split

Last in a pulling or arm session, after the heavier work.

On push, pull and legs it goes at the end of pull day. On an upper and lower split it fits at the close of either upper session. On a bro split it belongs on arm day, after a heavier curl. On a full body programme it is rarely worth the bench setup unless arms are a stated priority.

The honest way to use it is as a second curl rather than a first. Pair it with something that loads the stretch, an incline curl or a low cable curl, so the biceps is loaded hard at both ends of its range. Running it alongside a preacher curl gives you two exercises pulling in similar directions and one wasted slot.

If your gym is busy and the incline benches are always taken, skip it without regret. This is a nice option, not an important one.

Variations worth knowing

The incline dumbbell curl uses the same bench the other way round, lying face up so the arms hang behind the torso, which loads the stretched position instead of the contracted one and is arguably the more useful of the pair.

The preacher curl rests the upper arms on a sloped pad and puts the hardest part near the bottom, making it the mirror image of this exercise.

A barbell spider curl is steadier and easier to load but fixes the wrists in one position.

The single arm spider curl exposes differences between arms that a two dumbbell version hides.

A spider hammer curl keeps a neutral grip, shifting emphasis towards the brachialis and brachioradialis.

And the standing dumbbell curl remains the default, with the resistance peaking in the middle of the range, which is a perfectly reasonable place for it to peak.

What the evidence says

Marcolin and colleagues compared electromyographic activity of the biceps brachii and brachioradialis across three curl variants and found only modest differences between them, which is a good reason to treat curl selection as a question of resistance profile and comfort rather than recruitment.

Pedrosa and colleagues found that training at long muscle lengths produced favourable hypertrophy outcomes compared with short length training, which is a point against building a biceps programme around an exercise that loads the short end.

Schoenfeld and Grgic reviewed range of motion and muscle development and found fuller ranges generally favour growth, supporting a complete extension at the bottom even where the load there is light.

Vigotsky and colleagues cautioned that surface electromyography amplitude does not map neatly onto hypertrophy, which is worth remembering whenever a curl variation is sold on activation figures.

Schoenfeld and colleagues found a dose response between weekly hard sets and hypertrophy, which remains the most useful principle in arm training.

Refalo and colleagues found stopping short of failure produces comparable hypertrophy to training to failure, so the last grinding rep is optional.

And Roig and colleagues found eccentric training produced greater strength gains than concentric training, which supports controlling the lowering phase rather than dropping out of the top.

Common questions

Why does this feel so much harder than a normal curl?

Because the resistance peaks where the biceps is shortest and weakest, and because you cannot swing. A standing curl lets you use momentum and loads the middle of the range where you are strong. Expect to use noticeably less weight.

Is the spider curl better for the biceps peak?

No. Peak is a function of the muscle's shape and where its tendons attach, neither of which training alters. Making the muscle bigger is the only lever you have, and total hard sets does that more reliably than exercise choice.

How is this different from a preacher curl?

They are near opposites despite looking similar. The preacher pad slopes, so resistance is heaviest near the bottom with the arm extended; the spider curl hangs the arm vertically, so it is heaviest at the top. If you already do preacher curls, this adds the other half of the range.

What bench angle should I use?

Around forty five degrees. The only requirement is that your arms hang vertically and your face is not buried in the pad, so adjust for your height.

Do I need this exercise at all?

No. It is a curl, and curls are the least interesting variable in an arm programme. If you enjoy it and it lets you work hard without cheating, keep it. If the benches are occupied, a low cable curl covers the same ground.