Arnold Schwarzenegger Relied on This Simple but Effective 21-Rep Method for Growing His Biceps

Whatever Arnold Schwarzenegger was doing in the gym 50 years ago is probably worth copying – and his 21-rep technique is no exception.

Popularised by Arnold in 1985 with the release of his book The New Encyclopaedia of Modern Bodybuilding, 21s is a method the Austrian used to regularly target his biceps and force them to grow. He adopted the high-intensity method, whereby you perform 21 total reps of bicep curls – though not all the same – as a way to achieve that intense muscle pump he loved so dearly.

And it clearly worked, with Arnold's biceps proving a defining feature of his peak physique.

Now, it's used in gyms around the world, with lifters attempting to emulate the bodybuilding GOAT.

But what do 21s actually entail, and why do they work?

A combination of partial and full length reps, 21s are broken up into three distinct parts: you perform seven reps in the bottom half of the movement, seven reps in the top half, and seven at full range. This design hits every part of the muscle, and needs to be performed with a lighter weight in order to ensure strong technique is maintained throughout.

21s are often reserved for bicep curls, but the method translates across many other exercises.

• Stand with your feet shoulder-width apart, holding two dumbbells or a barbell directly in front of you.
• Brace your core and keep your elbows in tight to your torso. Bending only at the elbows, curl the weight from the bottom position to a 90-degree angle, where the elbows are bent and halfway through the movement. Lower it back down and repeat seven times.
• After 7 of those reps, start from the 90-degree halfway point and curl the weight all the way to the top, lowering it back down to the halfway mark. Again, complete 7 reps.
• Finally, perform 7 standard bicep curls, using a full range of motion to finish the set.

Time Under Tension

Completing 21 reps takes time, thus increasing the amount of time your biceps are under tension. Time under tension is a key growth stimulus, placing more stress on the muscle and activating more fibres in the process. This also helps create higher metabolic stress.

Combination of Full and Partial Reps

Research has proven that lengthened partials are an effective way to build muscle by themselves, though a full range is also useful in working the entire muscle. Shortened partials, meanwhile, can help achieve a better peak contraction – something Arnold became synonymous for in his peak.

This combination of full range and partial reps adds extra mechanical tension, stimulating the muscle across its entire range.

Strengthens Sticking Points

Most people are strong towards the top of a bicep curl, but might struggle to initiate the movement when the muscle is fully lengthened. What 21s do is focus on each individual area, ensuring progress and helping you potentially break through a plateau in your training. The exercise's ability to attack the muscle from multiple angles ensures a full development as a result.

Versatility

Though bicep curls are preferred for 21s, the concept doesn't have to just stop there – your triceps, chest, shoulders, legs and back can all benefit from this type of training, provided you're challenging yourself hard enough and maintaining strong form.

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