Post-Activation Potentiation (PAP) – What is it, and Who Can Benefit From Utilizing it?

Post-Activation Potentiation: Learn how you can increase your vertical jump height by squatting heavy!

Just Stopping in – The Takeaways

• PAP is the idea that the force a muscle may be able to exert can be increased based on a previous contraction.
• Typically PAP is utilized to improve power on a subsequent explosive activity to be performed.
• There are 4 types of ways to illicit a PAP-like stimulus: Overload, Ballistic, Overspeed and Whole Body Vibrations.
• Thus far, different PAP protocols have shown increases in subsequent explosive activity power (higher vertical jump), but most of these findings have not obtained significance in research yet.
• If you chose to incorporate PAP in your training, scroll down to the bottom for our recommendations on when to use it and a chart on how to use it, by the foremost expert in the field, Dr. Lee Brown.

I’m Here for the Long Haul……..

Post-Activation Potentiation (PAP) is a new training stimulus that, over the last few years, has taken the strength and conditioning scene by storm. The reason for this article is to bring attention to it in the rehabilitation world, make a determination if we should incorporate it into our training for athletes, and if we decide to, what is the best possible way to do that. In the rehabilitation world, principles of strength and conditioning are acknowledged far and few between and put into practice even less so. Perhaps an article directly outlining the benefits of applying strength and conditioning principles to the rehabilitation world is warranted, but I digress. The need to understand PAP is critical for the rehabilitation specialist particularly involved in return to sport rehabbing for the athlete, the strength and conditioning specialist, and for the athlete who does not have access to these resources, but still wants to base their training protocols around current research. For strength and conditioning experts and healthy athletes, this article should be enough to evaluate whether you would like to incorporate this type of training stimulus into your programming. For the rehabilitation specialist working with return to sport protocol, you must ensure that your athlete has absolutely no joint effusion, full AROM of the pathologic joint, proprioceptive awareness, and normal strength levels before subjecting them to this type of training stimulus. REMEMBER when you are in the rehab world, despite what a coach, athlete, or parent may want, injury prevention is always the most important factor when deciding on an exercise type or training parameter. For the strength and conditioning specialist and healthy athlete, although this is obviously also a concern, it is more so for the rehabilitation expert.

So, what exactly is PAP?

PAP is the idea that the contractile history of a muscle will influence future subsequent musculature contractures. So, the force that a muscle may be able to exert can be increased based on its previous contraction. The main use of PAP protocol is typically to improve power on subsequent explosive activity following a regular muscular contraction. Below are two proposed mechanisms by which this may take place, and a third mechanism which warrants further study, listed in that order.

1. Phosphorylation of myosin regulatory light chains, which are catalyzed by myosin light chain kinase, allow for an increase in sensitivity of the myosin-actin complex to sarcoplasmic Ca2+ potentiating subsequent contraction.
2. Increases in transmittance of excitation potentials (via increase in neurotransmitter production or neurotransmitter sensitivity) across the synaptic junction at the spinal cord, which will subsequently increase post-synaptic potentials. Thus with more action potentials and motor unit recruitment we have increased force production1.
3. Decreased pennation angles of the muscle fibers in relation to the connective tissue/tendon allow for higher force transmission to tendons. Mahlfield et al. found decreases in pennation angles 3 – 6 minutes following isometric maximal voluntary contractions. Although, a conditioning contraction or an isokinetic contraction will also typically increase connective tissue/tendon compliance to match the decrease in pennation. Further studies are warranted to determine which effect is greater or if they just cancel each other out2.

Small Side Note: PAP has the highest potential in Type II fibers or essentially the fibers with the shortest contraction times. People training for explosive sports such as jumping events, Olympic lifting, and sprinting will experience the greatest benefit from PAP protocols1.

Are there different types of protocol that may utilize PAP responses?

In fact, there are 4 different types of protocol that utilize one or more of the above principles:

1. Overload
2. Ballistic
3. Overspeed
4. Whole Body Vibration [there is research indicating its effectiveness, but WBV is not discussed in this article]3

For the sake of understanding, it is worth defining a few terms as they are utilized in this article:

• Strength: the exertion of force at a determined velocity
• Power: force multiplied by velocity (distance/time)
• Rate of Force Development (RFD): the rate at which we can produce force

 

Complex Training – Overload Principle

The most common way to utilize this principle is through something called complex training. Complex training is essentially the idea of combining high-load strength training with plyometric exercise within one set. It focuses primarily on the overload principle to elicit a PAP response. Though this seems like an easy principle, there is such a large range of variables that you can play around with. The jury was out on how best to apply it for years. More recently, the research has narrowed down the variables slightly and given us smaller ranges to work with, but there is still significant work to be done1.

So, what variables do I even consider when performing complex training?

The variables that affect us during complex training are essentially the same variables you would consider when creating any type of program:

• Training experience
• Volume
• Intensity
• Rest
• Frequency
• Exercise selection
• Etc.

Currently, the research has narrowed down the most effective way to use these conditions together to maximize the PAP protocol.

Let’s take a look at the research:

• Mitchell et al. tested whether a five-repetition maximum on the squat both induced a PAP response and increased the height of subsequently performed counter-movement jumps (CMJ). Subjects performed five sets of CMJ prior to and four minutes following one set of barbell back squats at the participants 5-RM. The researchers noted a 2.9% increase in CMJ four minutes following the squat. Unfortunately, the authors were unable to correlate the increase in CMJ height to the magnitude of the PAP, though they noted that it may be a primary contributor1.
• Chiu et al. reported 1 – 3 % vertical jump increases following 5 minutes of rest after participants performed 5 sets of 1 repetition of the back squat at 90% of their concentric max4.
• Gullich et al. found that immediately following a conditioning contraction, there was either a decrease or no change in isometric rate of force development. Though they did find that after adequate recovery period between 4.5 – 15 minutes isometric RFD increased by 10 – 24% (p < 0.05). This increase in RFD was also correlated with a similar pattern when assessing counter-movement jump peak power (7 – 8 %; p < 0.05) and 30-m sprint performance (2 – 3%; p < 0.05), both of which showed decreases/no change initially, but following an 8 – 12 minute and 5 minute rest respectively showed significant increases. These results show that although studies have shown the max PAP potential is directly following a contraction, peak fatigue numbers are also present early on. In fact, fatigue seemed to dominate early on following the contraction, though seems to deteriorate at a faster rate than PAP, thus warranting extended rest periods.
• Tillin & Bishop also cite four studies that demonstrate with relatively low volume conditioning contraction, PAP develops more quickly than fatigue, while with a high volume conditioning contraction, fatigue develops more quickly than PAP. Essentially these studies agree with the above study, noting the necessity for adequate rest time following a high volume contraction, but additionally providing us with new information regarding the PAP-fatigue relationship. What we can learn from these studies is that with a low volume contraction, we can perform our subsequent explosive exercise almost immediately or with significantly less rest periods.
• Gourgoulis et al. observed a 4% increase in CMJ height (p < 0.05) following five sets of back squats in those subjects that were able to squat a load of > 160 kg, while those subjects unable to squat at those loads only recorded a 0.4% increase in CMJ height. Thus informing us the importance of muscular strength and training experience on the benefits of PAP.
• French et al. analyzed CMJ, depth jumps, and 5-second cycle sprint performance before and immediately after three 3-second maximum voluntary contraction knee extensions. What they found were significant improvements in depth jump height and rate of force development, while the CMJ and 5-second spring cycle showed no significant increases. It was determined that knee extension loading was most closely related to muscular sequencing in the depth jump, while the CMJ and 5-second cycle sprint required contributions of more muscle groups that were not experiencing PAP. This shows us that PAP is also specific to the exercise we select and the subsequent explosive activity we choose following our contraction2.
• Two studies by Comyns et al. again helped to outline the necessity of specificity when choosing our subsequent explosive intervention. In one study, Comyn found significant improvement in depth jump performance following 3 repetitions of the back squat at 93% of 1 RM due to improvements in leg stiffness and ground contact time. These improvements resulted in a “stiffer, shorter, and more elastic leg-spring action.” In another study, in which he attempted over 4 post-test sessions to replicate these results on 20 and 30 m sprints, he found that there was no significant potentiation effect, though decreases in sprint times were noted on session 3 and 45.

This research only represents a fraction of the different studies that have been utilized in order to determine the effect of PAP and the exact variables at which it will work best. Thankfully for us, Ducan and Pedro conducted a meta-analysis of 32 studies utilizing the overload principle to determine the optimal conditions for potentiation. Their findings are as follows:

• Volume: multiple sets (vs. single), multiple reps (vs. single)
• Intensity: moderate (60 – 84%)
• Rest: moderate (7 – 10 minutes)
• Experience: athletic (the more training experience (> 3 years) the participants had the greater the PAP effect)Athletes benefited from multiple set stimulus prior to explosive exercise while novices performed better with single sets
• Athletes experienced similar PAP effects at 3 – 7 minutes as moderately trained individuals at 7 – 10 min
• Gender: No preference

The big take away from this meta-analysis was that experience played the biggest role in deciding variables mainly due to its impact on fatigue. The researchers found that individual experience and strength were related and there was a positive correlation (r = .63) between 1 RM and potentiation effect. As we saw in the studies above, the PAP-fatigue relationship is critical in determining our variables. We are always in a constant battle between experiencing potentiation or fatigue. More experienced trainees can usually be programmed to the higher end of intensity/volume variables while staying at the lower end of rest time variables, this was vice versa for less experiences trainees4.

The Ballistic Principle

Another type of stimulus less commonly used to elicit a PAP response is the ballistic principle, which essentially utilizes a ballistic movement rather than a high load weighted movement to garner the same response. Chattong et al. attempted to study the efficacy of this technique by having athletes perform body weight vest jumps prior to performing vertical jumps for height. In their study, they utilized the participants actual body weight followed by trials of 5%, 10%, 15%, and 20% body weight. They found that with as little as 5 repetitions onto a box of knee height followed by a 2 minute rest, significant difference was noted in vertical jump height at every bodyweight percentage. Important to note here was that though not significantly different from the loaded vest jumps, regular body weight box jumps with no external load had the greatest absolute improvement in vertical jump height performance6.

Criteria Utilized:

• 5 to 20% body weight vest jumps
• 1 set of 5 repetitions
• 2 minutes of post box jump rest
• Increases in vertical jump height

Findings on Ballistic based PAP:

• Volume: multiple sets (vs. single), multiple reps (vs. single)
• Intensity: maximum
• Rest: (1 – 4 minutes)
• Experience: athletic (the more training experience (> 3 years) the participants had the greater the PAP effect)
• Gender: No preference

The Overspeed Principle

The final type of stimulus that we will go over is the overspeed stimulus. The overspeed stimulus is the concept of gaining assist via training apparatus or other modulation that allows us to perform the movement at a greater speed than normal. Overspeed is commonly used to assist in sprinting speeds, but we decided to choose two studies that articulate other ways it can be utilized. The two studies here will help us understand the way overspeed is performed to help gain a PAP response:

1. Montoya et al. had participants randomly warm up by swinging either a light bat, normal bat, or heavy bat prior to performing post warm up swings with a normal bat. What they found was that participants that utilized the light bat had significantly higher bat speeds than participants that used the normal bat and even higher than the heavy bat (p > 0.05)7.This finding is actually very interesting because frequently baseball players, whether professional or recreational, often swing a donut which adds weight to a normal bat in the on-deck circle prior to taking an at-bat. In this study, the heavy bat actually decreased the bat speed rather than increase it as many people believe.
2. Criteria Utilized:Maximum velocity swings
3. 1 set of 5 repetitions
4. 30 seconds of rest prior to normal swings
5. Increases in bat speed with the light and normal bat
6. Brown et al. performed two assisted vertical jump studies where he used different levels (10, 20, 30, 40%) elastic cord assistance to determine if improvements in jump height (JH), takeoff velocity (TOV), relative ground reaction force (rGRF), relative impact force (RIF), and descent velocity (DV). What they found was increases at JH and rGRF increased linearly up to 40% body weight reduction from elastic cord system. However TOV, RIF, and DV all increased up to 30% body weight reduction, but showed no significant difference between 30 and 40%8,9.Criteria Utilized:BW assistance @ 10, 20, 30, 40%
7. 1 set of 3 counter jumps
8. 1 minute of rest
9. Increases in jump variables noted up to 30 and 40% depending on variable

The idea behind the overspeed concept is that velocity can be increased to supra-maximal levels, which can acutely enhance an activity such as the vertical jump by increasing motor neuron excitability and motor unit synchronization. A critical point when considering the use of overspeed training to elicit a PAP response or increased training response is to ensure that the mechanics of the movement are not being compromised by the reduction in body weight. This is an issue that is frequently a problem, not only in overspeed training, but in weighted training such as sled pushes as well. Remember, if the mechanics are compromised, not only will the training effect be negligible, but you risk injury as well.

Findings on Overspeed based PAP:

• Volume: 5 reps/20 meters
• Intensity: 30 – 40% body weight assistance
• Rest: 1 – 2 minutes
• Experience: athletic (the more training experience (> 3 years) the participants had the greater the PAP effect)
• Gender: No preference

Okay so now that we’ve overloaded with all this post-activation potentiation information, what the hell does it all mean? Should I even use PAP? I still have no idea how?

Well, let me introduce Dr. Lee Brown. Dr. Brown is the current director of the Center for Sport Performance and the Human Performance Laboratory at Cal State Fullerton. He previously served as the president of the National Strength and Conditioning association. He is a pioneer in the world of human responses to high velocity training and is on the forefront of much of the PAP research that I presented above. At the National Strength and Conditioning Association’s National Conference & Exhibition in New Orleans in 2016, Dr. Brown had this to say at the end of his presentation on PAP:

“Training studies supporting the use of PAP complex training are lacking and therefore it remains to be determined whether performing PAP complexes over time leads to greater training adaptations than interventions where the plyometric or speed exercises are not performed in PAP format but rather in isolation”

– Lee Brown3

So one of the foremost experts in the field of post-activation potentiation readily admits that the evidence is not there yet to determine if there is any training benefit to introduce PAP to your training protocol.

In my experience as a health practitioner, I feel there are a few situations to implement PAP format training:

1. Rehabilitation: Within the rehabilitation setting, especially following an injury, there is a hesitance to weight bear over a previously injured extremity despite normalization of effusion, strength, and AROM. Now we probably cannot use a 1 RM formula due to safety concerns to determine what intensity to use, but there are several formulas that allow us to deduce a 1 RM from a 5 RM. Once we have a 1 RM, we can run our athlete through a single leg PAP protocol as a way to promote weight bearing over the previously injured leg and to perhaps gain that extra leg up in power to help equalize the two legs. As Mike Boyle, famous strength and conditioning expert, references in his book “New Functional Training for the Athlete,” unilateral training is the possibly the most sport-specific type of training that we can perform, so it serves a substantial purpose in the return to sport programming of an athlete.
2. Strength & Conditioning: If you are an athlete or strength and conditioning professional who is trying to develop power, these principles (though not always significant) have shown increases in explosive movement in almost all cases. You can implement these training protocols if you are looking for that extra edge in your power programming or perhaps if your programming is lacking and thus you are not developing the explosive power you are looking for.
3. Performance: If you are at an athletic event and have determined previously the variables that work best for you to elicit an increase in explosive subsequent movement, then this PAP format could be perfect to help boost your numbers for a combine-like event.

In any case, if you are looking to utilize the PAP formatting, here is a picture from Dr. Brown’s slide to help make the research as concise as possible:

References 

1. Lorenz D. (2011) Post-Activation Potentiation: An Introduction. The International Journal of Sports Physical Therapy. 6(3): 234 – 240.

2. Tillin N, Bishop D. (2009) Factors Modulating Post-Activation Potentiation and its Effect on Performance of Subsequent Explosive Activities. Sports Medicine. 39(2): 147 – 166.

3. Brown L. (2016) Post-Activation Potentiation. National Conference & Exhibition NSCA. July 6 – 9, 2016. Lecture

4. Wilson J, Duncan N, Marin P, et al. (2013) Meta-Analysis of Post-Activation Potentiation and Power: Effects of Conditioning Activity, Gender, Volume, Rest Periods, and Training Status. The Journal of Strength and Conditioning Research. 27(3) 854 – 859.

5. Comyns T, Harrison A, Hennessey L, etl al. (2010) Effects of Squatting on Sprinting Performance and Repeated Exposure to Complex Training in Male Rugby Players. The Journal of Strength and Conditioning Research. 24(3): 610 – 618.

6. Chattong C, Brown L, Coburn J, et al. (2010) Effect of a Dynamic Loaded Warm-Up on Vertical Jump Performance. The Journal of Strength and Conditioning Research. 24(7): 1751 – 1754.

7. Montoya B, Brown L, Coburn J, et al. (2009) Effect of Warm-Up with Different Weighted Bats on Normal Baseball Bat Velocity. The Journal of Strength and Conditioning Research. 23(5): 1566 – 1569.

8. Tran T, Brown L, Coburn J, et al. (2011) Effects of Different Elastic Cord Assistance Levels on Vertical Jump. The Journal of Strength and Conditioning Research. 25(12): 3472 – 3478.

9. Cazas V, Brown L, Coburn J, et al. (2013) Influence of Rest Intervals Following Assisted Jumping on Bodyweight Vertical Jump Performance. The Journal of Strength and Conditioning Research. 27(1): 64 – 6