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How to Activate More Muscle

It's a technique many strength coaches use to give their athletes the edge before a big workout or competition. And it's even beginning to gain traction with elite rugby players before a game. What is it?

It's called isometric post-activation potentiation, or PAP for short. It simply involves performing a maximal isometric exercise, then waiting about 3-5 minutes before seeing an increased neural drive.


The competitive edge it'll give you can transfer to athletic speed and explosiveness and a more efficient nervous system when lifting. That means more strength, more power, and more muscle.

In hidden back-room gyms, sometimes even old janitorial closets in stadiums, there are strength coaches preparing their athletes before a game by simply having them press, pull, and squat against immoveable bars.

It doesn't look like a lot is happening... that is, until these athletes run out onto the playing field and smash their opposite number in the first play. But the benefits don't stop on the field or court. You can get an advantage in the weight room.

There have been studies showing an increase in various performance measures including, for example, a 5.5 percent increase in jump height (Berning et al. 2010), a 6.1 percent increase in knee extension torque (French et al. 2003), a 2.8 percent increase in ballistic bench press power (Esformes et al. 2011), and an 8.6 percent increase in peak power output after isometric preloading (Rixon et al. 2007).

Research is a little behind on isometric exercise though, and it's worth noting that using a heavy dynamic contraction for PAP has been better researched. However, using an isometric contraction instead has several advantages.

In the real-world there are many lifters successfully using this technique to increase their rep-maxes and reps to failure (like the 225-pound bench press test included in the NFL Combine), as well as those doing it as an extension of their warm-ups to potentiate their entire workout.

Try this and see how it feels for yourself:

Set-up to bench press as usual, do a few warm-up sets, gradually building up to your first working set for the day.

Now, before your first working set, put around 120 percent of your estimated 1RM on the bar. Grab a spotter just in case and start with a lower weight if you need to, but all you're going to do is set-up and hold the bar in the lockout position for 3-7 seconds, then re-rack it.

Then wait at least 4 minutes. Do your first working set as intended and note how much lighter the bar feels and how many more reps you could get if you wanted. What you're feeling is a PAP effect.

Isometrics refer to exercises where your muscles are producing force without any movement. This is best achieved by either pressing or pulling against an immoveable resistance (called an "overcoming" isometric), or by holding a resistance in a certain position preventing gravity from pulling it down (called a "yielding" isometric).



Back in 2004, Christian Thibaudeau wrote Isometrics for Mass and mentioned how it can be used as a potentiator. Before most of the research even existed, he was ahead of the game.

Isometrics can typically produce around a 5-6 percent higher level of motor unit activation versus both concentric and eccentric actions (Babault et al. 2001). This is partially why isometrics might be superior to concentric and eccentric exercises when trying to elicit a PAP effect.

Also, from a practical point of view, it's much easier and safer to pull, press, or squat against something immobile than it is to set a specific weight as required with some other PAP protocols. This is especially true when training athletes in groups.

To date, research has identified two primary mechanisms that may be involved. The first is related to an enhanced phosphorylation of myosin regulatory light-chains, leading to an enhanced calcium sensitivity within the muscle. The second is suggested to be an increase in type 1a afferent fiber and a-motoneuron excitability.

What we do know is that when it comes to an elevation in performance, we're seeing it happen with our own eyes and we're just now starting to see it in the research. You can see it first hand too, but there are a few important things you need to know first.

During repeated muscle actions an accumulation of both neurological and metabolic fatigue occurs, resulting in reduced performance. At the same time, for reasons not fully known, contractile properties are also enhanced.

So during exercise, fatigue and potentiation are considered to coexist. It's the careful balance of each that determines whether performance is reduced or increased. If fatigue is high following a PAP exercise, instead of an increase in performance you may see a reduction. This trade-off is important to understand, and why some protocols work while some don't.

There will also be some differences among different lifters. Someone might see a massive jump in performance, while another person might not see enough of a jump to reflect more weight on the bar or more reps.

More experienced lifters seem to show a bigger jump in performance than novices. There are some specific protocols which we'll get to, but personal experimentation will be required.

There seems to be a sweet spot when it comes to rest, and everyone is a little different. In 2013 one researcher showed a 9 percent increase in jump power 8 minutes after an isometric mid-thigh pull (overcoming isometric deadlift from a mid-thigh position). Whereas after 4 minutes, only a non-significant 2.8 percent increase was shown (Sapstead & Duncan 2013).

It's possible isometrics may work more through peripheral mechanisms than say a heavy dynamic contraction but that can also produce more central fatigue. Dynamic contractions on the other hand may initiate a PAP response through central mechanisms but accumulate more peripheral fatigue. This is something important to consider for your recovery because of the effects isometrics have on the CNS.

Bottom line? The use of isometrics for PAP is a powerful tool, but if you abuse it, it'll bite you in the ass. So here are some things to remember...

  • The potentiating movement must closely resemble the lift you're wanting to increase.
  • An overcoming isometric is best performed at the point of weakness in a lift. The isometric contraction should be as close to your sticking point as possible.
  • The weight should be immoveable, for example pressing against immoveable pins in a rack.
  • A yielding isometric is best performed at the top of lift where you're strongest, such as the top of a squat or bench press in the locked-out position. This is a supra-maximal lift with 120-150 percent of your 1RM.
  • The contraction must be maximal; merely holding a low-level isometric won't have a potentiating effect. A 5-minute long wall squat with your back against a stability ball won't cut it.
  • In both types of isometric (yielding and overcoming) each contraction should be held for 3-7 seconds.
  • Do just 1-3 cluster reps per set. The amount of sets you do will depend on the protocol you use, as described further down.
  • Rest anywhere from 3-8 minutes prior to your next set. The optimal time will differ for everyone.
  • Experiment and find out which protocol works best for you. Test it out. Remember, it's a fight between fatigue and potentiation, and you need to find your own balance.

You might need to give yourself a quick refresher on the isometric/CAT contrast method before diving into this.

Outcome: Continuously spike potentiation for an explosive lift (like a dynamic effort lift) or movement (like box jump).

Method: Isometric/CAT Contrast Method

  • Heavy isometric (rest 3-5 minutes)
  • Explosive lift/movement (rest 3-5 minutes)
  • Repeat for desired sets

Outcome: Continuously spike potentiation for a heavy lift.

Method: Isometric/Max Effort Contrast Method

  • Heavy isometric (rest 3-5 minutes)
  • Max effort lift (rest 3-5 minutes)
  • Repeat for desired sets

Outcome: Switch on the nervous system at the start of a workout.

Method: Pre-Workout Primer

  • Normal warm-up
  • Heavy isometric (rest 3-5 minutes)
  • Main lift (start a little heavier than normal)

Outcome: Potentiate a single big lift or reps to failure test, for purpose of testing or competition (e.g. 225 bench press test).

Method: Pre-Workout Primer

  • Normal warm-up
  • Main lift, build up in weight, but don't fatigue
  • Heavy isometric approximately 4-8 minutes before testing/competition
Movement Yielding PAP * Overcoming PAP – Immoveable/Maximal
Bench Press Lockout holds Isometric press against the pins 4-6 inches off the chest
Back Squat Lockout holds Isometric squat against the pins at 90-120 degree knee bend
Deadlift N/A Isometric mid-thigh pull
Snatches and Cleans N/A Isometric mid-thigh pull
Heavy shrug iso-holds
Vertical Jumps Back squat
lockout holds
Isometric mid-thigh pull
Squat against the pins at 90-120 degree knee bend
Sprints and Horizontal Jumps Back squat
lockout holds
Heavy glute bridge iso-hold

* Yielding PAP — 120-150% 1RM

Capitalize on the unique nature of isometric exercise. By adopting the protocols prescribed you can expect to see almost immediate results.

  1. Babault N et al. Activation of human quadriceps femoris during isometric, concentric, and eccentric contractions. J Appl Physiol (1985). 2001 Dec;91(6):2628-34. PubMed.
  2. French DN et al. Changes in dynamic exercise performance following a sequence of preconditioning isometric muscle actions. J Strength Cond Res. 2003 Nov;17(4):678-85. PubMed.
  3. Rixon KP et al. Influence of type of muscle contraction, gender, and lifting experience on postactivation potentiation performance. J Strength Cond Res. 2007 May;21(2):500-505. PubMed.
  4. Berning JM et al. Effect of functional isometric squats on vertical jump in trained and untrained men. J Strength Cond Res 2010 Sep;4(9):2285–2289.
  5. Esformes JI et al. Effect of different types of conditioning contraction on upper body postactivation potentiation. J Strength Cond Res. 2011 Jan;25(1):143-8. PubMed.
  6. Sapstead G et al. Acute effect of isometric mid-thigh pulls on stretch-shorteining cycle and non-stretch-shortening cycle vertical jumps. Medicina sportive. 2013 Mar;17(1):7-11.
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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