Tip: How to Build a Professional Butt

Isometronics will turn your peach into a pumpkin, fast! Here's what to do.


If standard hip thrusts have lost their oomph, here's something you should try: isometronics.

Isometronics combine the principles of isometric and isotonic muscle contractions to reap the rewards of both. Performing hip thrusts using this technique would look like this:

  • Pick a weight you can barbell hip thrust for 12 reps (your 12RM).
  • Do 10 full reps.
  • On the tenth rep, pause at the top for 10 seconds.
  • Finish with as many partial reps as you can in the bottom position. If you've selected the right weight, this will be no more than 4-8 partial reps.
  • Tip: To get the most from it, initiate each rep with a tightening of your glutes and abs before each movement.

Now, there are no rules saying you need to use the rep ranges above. At their heart, isometronics are simply a form of drop set. Just work within a rep range that's in line with your training approach. If you want to go heavy, then drop down to 5-6 reps. If you're a volume junkie, go for 15-20. It'll all help build an impressive backside.

Isometronics are nothing new. You'll find evidence of them being used since the 1960s.

Classically, isometronics are performed using more of an "overcoming" isometric rather than "yielding" isometric. You'd set up in a squat rack and fire the bar against some pins, pressing as hard as you can. For hip thrusts, I'm sharing a more accessible version, and one that won't have the gym police bust your ass for being in the squat rack.

Isometronics can be done for any muscle you're looking to get bigger or stronger. Just do your full reps, follow that with an isometric hold in the muscle's shortened position (where you get the biggest squeeze), and finish with a few partials. These are particularly sadistic for any biceps or hamstring curl variation.

You shouldn't need to be convinced that drop sets are a useful tool for increasing training volume. They also allow you to do more of those "important" reps where you're able to fatigue the last remaining muscle fibers at the back end of each set.

Your glutes need some volume to grow. They also require you to tap into both fast and slow-twitch fibers. It varies depending on what you read, but your gluteus maximus has a 50/50 split in terms of fast versus slow-twitch muscle fibers.

As a form of mechanical drop set, isometronics begin with your weakest portion (full range of motion), drop to an isometric hold, then drop again to partial reps in your strongest position.

The reason why an isometric hold is stronger than when you're moving is because your muscles can find an extra 10-15% more force here. This isometric hold alone adds a big dose of intensity to any exercise. You'll get extra fast-twitch fiber engagement, lots of mechanical tension, and you'll stimulate hypertrophy.

You'd do well finishing each set with the isometric alone, but adding some partial reps will increase time under tension, fatigue even more motor units, and further stimulate muscle growth.

Use this technique sparingly. To shock your glutes into growth, do it at the very start of your workout as your key lift, then follow up with some basic sets of deep squats, deadlifts, and the like.

Gareth Sapstead is a leading strength and physique coach from the UK. He specializes in problem solving and breakthrough training techniques.

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