Do This for 30-Seconds Between Sets for Big Quads

Inter-Set Isometric Holds for Leg Size

Spend the first 30 seconds of your rest period doing this to gain some bonus muscle in your quads. Here’s the science and the training method.

Big Quads in 30 Seconds?

There probably isn’t an experienced lifter who hasn’t come up with the idea of doing some sort of iso-holds – contracting or flexing the muscles – between sets in the hopes of getting stronger or bigger.

Of course, any lifter who ever tried it probably didn’t do it for long because it’s hard to keep doing some new technique on faith alone. Too bad they didn’t keep it up because, according to one study, it looks like it works – at least for quads.

Granted, a single study does not always a new reality make, but the team that conducted the study included T Nation contributors Brad Schoenfeld and Bret Contreras.

Both of these guys are Ph.D. types, but almost more importantly, they’re also big-time lifters, which isn’t always the case with scientists who study these things. As such, the two have important perspectives based on experience and can devise legitimate training programs to test their hypotheses.

Anyway, they found that doing 30-second iso-kinetic holds in between sets of back squats and leg presses increased the muscle thickness of the quads. Unfortunately, the results weren’t the same for other body parts.

The Study

Schoenfeld and Contreras recruited 26 male lifters from a university population.

Each training session involved 3 sets of 8-12 reps of the following exercises, each performed with a 1-second concentric (lifting) movement and a 2-second eccentric (lowering) movement:

  • Flat barbell press
  • Barbell military press
  • Wide-grip lat pulldown
  • Seated cable row
  • Barbell back squat
  • Machine leg press

Each lifter did the programs 3 times a week for 8 weeks. The load was subjectively adjusted for each exercise as needed on successive sets and attempts were made to progressively increase the loads each week.

Now here’s the rub: The subjects were divided into two groups:

  1. The first group rested quietly for 2 minutes between each set of each exercise.
  2. The ISO group, however, performed a no-load isometric contraction for the first part of each rest period. They were prodded to squeeze the muscle as hard as possible for 30 seconds and then spend the remaining 90 seconds of the inter-set period resting.

For the biceps, they tucked their upper arms close to the body and flexed the elbows as far as comfortably possible.

For the triceps, they kept their upper arms pressed to their sides and extended the elbows as far as possible.

For the quads, they sat down and extended the legs out straight as if they were performing a leg extension.

Did All the Flexing Work?

The only muscle that seemed to benefit from the inter-set isometric holds was the mid-thigh area of the quadriceps (which was the only part of the thigh included in their measurements). The ISO group also showed a modest improvement in muscular endurance.

Disappointingly, though, the mid-thigh hypertrophy didn’t translate into greater strength increases, but that’s often the case – bigger doesn’t always mean stronger.

In their conclusion, the researchers wrote:

“Those interested in maximizing muscular hypertrophy can consider employing iso-holds in the inter-set period, as this strategy may help to enhance hypertrophy of the quadriceps without increasing total training duration.”

How to Use This Info

  1. After doing a set of squats or leg presses, sit down on a bench and extend your lower leg straight out as if you were just completing a concentric rep on a leg extension machine.
  2. Hold the lower leg out there and squeeze the bejesus out of the quad for 30 seconds.
  3. Relax and spend the next 90 seconds before doing the next set of squats or leg presses.

The scientists don’t mention whether this technique would work between rest periods of leg exercises other than leg presses and squats, but I think Ph.D. guys like Brad and Bret must swear some kind of oath, probably on the codpiece of Galileo – the father of the scientific method – that prevents them from any extrapolation of their results to include other exercises.

Yeah, yeah. Sure. Fine. But it only makes sense that it would work with any quad exercise.

This study aside, there may be some other benefits to flexing outside of the gym, and not just for awesome selfies. Check out: Flex Your Way to a Harder Body.

Make any workout work better. Fuel it.




  1. Schoenfeld BJ et al. To Flex or Rest: Does Adding No-Load Isometric Actions to the Inter-Set Rest Period in Resistance Training Enhance Muscular Adaptations? A Randomized-Controlled Trial. Front Physiol. 2020 Jan 15;10:1571. PubMed.

Everybody reading this whether at their desk, on their couch, on the train, or even in the gym is now doing their best impression of an L


So they got a null result for strength on all 6 exercises and a null result for hypertrophy on 5 of 6 exercises? Then are trumpeting their one and only positive result? This seems like an obvious case of p-hacking.

If the method were to really work, I would expect it to work in either all muscle groups or at least ones that are similar in say fiber composition, like triceps, or anatomical placement, like glutes/hamstrings.

I hear you. It could just be that it’s easier to get a hard contraction on the quads. I mean, try flexing your lats for 30 seconds.

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Lats are a great example. I get a cramp just wiping my ass after a big back session.

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I think that’s the story line of the next Charmin’ bears toilet paper commercial.


Quads are the distance runners muscle. Hams are the sprinters muscle. Seems obvious that the quads need more time under tension.

Man, that MUST be one helluva back session if you have to wipe after you’re done!


If I don’t get a hemorrhoid flare-up, I didn’t train hard enough.


Shee-it. If I don’t get a subarachnoid bleed and get read the last rites, I didn’t train hard enough.