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#FlexFriday | How Iso-Tension Can Boost Muscle Definition

#FlexFriday | How Iso-Tension Can Boost Muscle Definition

You’ve gone through the gears in the gym, eaten ‘clean’ in the kitchen and didn’t have to count sheep to fall asleep each night. Sorted. Now that you’ve done everything possible to build muscle, it’s only natural that you want your hard-earned muscle to show. Whether you call it getting ‘ripped,’ ‘shredded’ or ‘cut,’ they all mean the same thing – muscle definition.

What is Iso-Tension?

‘Iso’ means “equal, same” and ‘tension’ means “tighten, stiffen or contract.” So, ‘iso-tension’ is basically bodybuilding lingo for contracting your muscles and holding them in the same place – with no movement. Maybe you think of muscle-flexing as something only bodybuilders (and, um, posers) do, especially in a crowded gym?

But we’re going to walk you through why you should consider making iso-tension a staple of your training regime.

What is the Science Behind Iso-Tension?

We don’t want to blind you with science but, according to the Mayo Clinic, flexing your muscles – iso-tension – is a type of ‘isometric’ exercise. Even though the targeted muscle doesn’t change length and the joint doesn’t move during isometric exercise, it can help you to:

  • maintain muscle strength
  • improve stabilisation
  • lower your blood pressure.

How Do You Perform Iso-Tension Exercise?

 Here’s how iso-tension exercise is done. You’ve just finished a grueling weights set and your muscles feel like they’re on fire. During your rest between sets, instead of sitting around watching your training partner doing their set, tense the muscle you’re training as hard as you can and hold the contraction for six to ten seconds.

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Take a breather for ten seconds and keep repeating for the length of your rest. In a 60-second rest period, you should be able to squeeze in three sets of contractions.

Let’s say you’re doing dumbbell triceps kickbacks. Immediately after each set, put the dumbbell(s) down. Straighten your arms, lock your elbows and flex your triceps hard. Perform this same tensing action regardless of the triceps exercise you’re doing.

What are the Training Effects of Iso-Tension?

Mind-muscle connection

When you flex a specific muscle between sets, it focuses your mind on the feeling you want to repeat during the set itself – like a dress rehearsal before a performance.

Training past failure

Iso-tension after a set keeps the tension on the target muscle, allowing you to safely push past the point of failure without using a training partner – or even a weight.

Who Uses Iso-Tension?

Seven-time Mr. Olympia-cum movie star-cum Governor of California-cum movie star (again), Arnold Schwarzenegger is a massive fan of iso-tension (and he was no slouch in the gym). Nicknamed the “Austrian Oak” in his heyday, Arnold swears by two other forms of iso-tension: ‘flushing’ and posing.


Flushing involves holding a weight steady at different points along the exercise path – forcing isometric muscle contraction. After Arnold maxed-out on reps of dumbbell laterals, for example, he would pick up a lighter set of dumbbells, hold his arms locked out by his sides and lift them about five inches from his thighs. He would hold this position for about ten seconds.

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Arnold thinks iso-tension applied at the tail-end of an exercise gives your body a noticeably chiselled look.

Flushing can be used with exercises across all muscle groups. Here’s a couple to get you started:

Chest: Cable crossovers – hold the cables across your chest with your pectorals fully contracted.

Back: Chin-ups – hang from the bar and lift your body up by only a few inches.

Flushing is a good substitute for those of you who find tensing your muscles without added weight resistance a little artificial.


Arnold says that one reason why posing (which is, after all, isometric contraction of the muscles) is so beneficial is that it works muscle areas that training often misses – creating definition and muscle separation that diet and training alone can’t.

You, too, can reap the rewards of “striking a pose,” such as a front double-biceps or rear lats spread (rather than the Madonna variety).

Take-Home Message

So, if you want to get ripped in record time, the next time you see a bodybuilder (or poser, for that matter) flexing their pecs in front of the gym mirrors, you might want to consider joining them…



Writer and expert

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