Last week, French tennis star Jo-Wilfred Tsonga posted a sneak peek video of his off-season training regimen...and almost every tennis fan on the web had a comment to share. Comments included “What’s Jo doing? He’s gonna hurt himself!” to “I would never lift weights during practice!”; while other comments were more encouraging, like “Wow look at his hard work, he’s gonna be ready to go for the 2017 season!”. Coaches had other things to say including a comment along the lines of...“This type of training just doesn’t work for tennis players, their skill will deteriorate due to fatigue of the lift”. In case you missed it, here's what the session looked like:
Is this true? Was Tsonga's training completely useless? Before drawing to a conclusion, we should define exactly what Tsonga and his team were doing. Here's an outline of this post
What is Post-Activation Potentiation (PAP)?
The technical term is what sport scientists refer to as post-activation potentiation (PAP). PAP is a sport science phenomenon (a phenomenon because the research on the subject is still relatively new). It’s generally used during a type of training called “complex training” whereby the athlete performs one movement (like a bench press) at maximum or near maximum effort (even supra-maximum effort at times) and follows that movement (either immediately or after a short delay) with a high-velocity type movement (like smacking high forehands). The basic premise being that the initial heavy movement increases the central nervous systems (CNS) excitability which therefore “potentiates” - or increases the power/velocity output - of the second movement.
Another more common example would be performing heavy back squats (high force) and following that up with a vertical jump (high velocity). In tennis, a common example we often see coaches employing is using a medicine ball (MB) to replicate a tennis movement - like a MB side throw (high force - compared to the tennis movement) and then performing the tennis movement (a groundstroke). These examples, along with Tsonga's, all have one thing in common, the goal is to somehow increase the power of the subsequent/desired movement.
But the question still remains, does PAP really work? Does Tsonga and his team know something the rest of us don't? In this article I’m hoping to shed some light on this topic by briefly explaining the underlying mechanisms of PAP, what parameters need to be considered when employing a PAP complex along with some of the research in favour and against it. I'll finish the article with a final note as to how you can test PAP either in your training, or your athletes training and a few recommendations to better optimize PAP and it's potential benefits.
PAP - How Does it Work?
The scientific literature defines PAP as being a phenomenon whereby muscular performance is acutely (key word here) enhanced as a result of prior contractile/movement history (Tillin & Bishop 2009). Within a laboratory setting, PAP can be induced either through involuntary or voluntary muscle contractions. Because of it’s predominant use in sports performance settings, we’ll only be looking at PAP through the lens of voluntary muscle contraction and in movements that occur in sport. There are several mechanisms that could play a part in PAP’s manifestation but two stand out above the rest - through an increase in myosin light chain phosphorylation and/or the potential increase in recruitment of higher order motor units (MU).
For now, you need to know two things. First, when myosin (one of 2 contractile proteins within the muscle) is phosphorylated, it has a stronger affinity to bind with actin (the other contractile protein). This myosin-actin binding is what enables are muscle fibres to contract and catalyze movement. So a stronger bond, which occurs when lifting a heavy load, temporarily increases muscle fibres' potential for greater power output. Second, high order (or high threshold) MUs predominantly innervate type II fast-twitch muscle fibres. These MUs are activated during movements that require large muscular efforts - like Tsonga's heavy bench. So, when you perform a high force movement, you’re recruiting high threshold MUs and they are “heightened” or "potentiated" for a short period after that initial movement. When a high velocity movement follows, this stronger binding along with an increased recruitment effect increases power output in the desired movement.
In theory, this sounds great doesn’t it? An easy, efficient way to increase power output. Well...not so fast. The research on this phenomenon is still mixed with some studies pointing in favour while many others pointing against. Why exactly? Mainly because there are so many parameters at play. How long should you rest between exercises? What intensity should you use? Will it work with novice and elite athletes? The list goes on. Let’s try to get to the bottom of it.
PAP Loading Parameters
This isn’t just a question of PAP but any training modality - sport scientists are constantly striving to gain more insight into what intensities athletes should train with, for how long, how far, how much rest, with what frequency and so on. When it comes to PAP, there seem to be 5 important loading variables. Here’s a look at each one in more detail.
Intensity
It seems that when using resistance training to gain the PAP effect, you'll need to use at least 80% of your max in that lift (Tillin & Bishop 2009). Anything below this threshold won’t excite your CNS - or recruit the necessary MUs - and won’t provide the potentiation for the subsequent explosive movement. Looks like Tsonga used a pretty heavy load for his bench press (it was probably close to 90% of his 1RM). Taking this into consideration, could it also be possible to use a lighter load and still get the PAP effect? Research with weighted baseballs (Escamila et al 2000) seems to point in that direction. When using weighted balls and then throwing normal balls, pitchers increased their throwing velocity by up to 6%. Imagine getting that much extra heat on a 120mph serve? That would be a 7.2mph increase! Don’t you love this sport science stuff?!?
Contraction Type
Remember we mentioned earlier that you could potentially go above 100% of your 1RM (i.e. supra-maximal loading)? Generally this type of loading for PAP is called an isometric contraction - i.e. the load is too heavy to move but your intent to move that load is still at max effort. The other, and more common contraction type is dynamic (either eccentric or concentric). Tsonga obviously used a dynamic movement to gain the PAP effect. Why? Well, although isometric contractions seem to have a greater excitatory effect on the CNS, this type of contraction also produces more fatigue, which will inhibit the potentiation, unless you provide enough rest between the high force and high velocity movements. But Tsonga performed his high velocity movement almost immediately...likely less fatigue because the bench press was dynamic. This brings us to our next point.
Recovery Time
If fatigue is greater than the excitation of the CNS, you can pretty much throw PAP out the window - the research is clear on this, there will not be a positive effect So there seems to be this balance at play between exciting the CNS while not fatiguing the system AND/OR providing enough recovery time to dissipate fatigue. If your recovery time is too long however, you’ll also lose the PAP effect. Tsonga seemed to hit groundstrokes right after his PAP exercises, which may also be a personal bias (more on individual characteristics below). While this may work for some, most research suggests that providing some rest between movements will enhance the PAP effect - anywhere from 2min to 20min has been seen. But who can wait 20 minutes?
Volume of Work
Along the lines of fatigue, research suggests that too much volume - in other words, too many reps, too high of a load or a combination of the two - could provide too much fatigue and inhibit the PAP effect. That’s probably why Tsonga kept his reps in check - he only performed 4 reps per arm with the 1-arm rows and 2 reps with the bench press. And probably why he hit groundstrokes almost immediately after...very little, if any, fatigue present.
Type of Explosive Activity
Although not an exact science, most research steers towards matching the kinematics (i.e. similar movement patterns) of the explosive activity with the PAP enhancing activity. This will ensure that you’re activating the appropriate MUs - remember, the ones you’ll be using in the subsequent activity. Tsonga used a bench press exercise and followed it up with forehands. There are similarities between these exercises - especially if you look at the acceleration phase of each movement. In both movements, shoulder flexion (via deltoids, pectorals) and elbow extension (via triceps) occur - there is slight forearm pronation in the forehand, not the bench press however. Aside from forearm pronation, the other actions are quite similar. That said, perhaps a closer PAP enhancing movement would have been a MB side throw (look below). Although the forehand does utilize the upper-body, the stroke is initiated with your lower-body, transferred through the trunk through rotational power and then into the upper body. An exercise like the MB side throw would be more mechanically similar from a full stroke production perspective - as it employs leg drive, trunk rotation and an upper body push.
Subject Characteristics
It’s not just the loading parameters that are important when it comes to PAP. The athlete and his or her training history play a vital role as well. Let’s take a closer look.
Muscular Strength
Stronger athletes are more responsive than weaker athletes. For example, in one study, subjects that could squat 160kg or more had an increase of 4% on their subsequent countermovement jumps (CMJ) while all subjects who squatted less than 160kg, only had a 0.4% improvement in CMJ (Gourgoulis et al 2003). Tsonga seems like a pretty strong dude for a tennis player as his bench press was around 100kg. And according to the interwebs (not sure if this is accurate), he weighs about 90kg. I’m guessing his 1RM is about 110-115kg so his upper-body strength to bodyweight ratio is about 1.25-1.30...high enough to get a PAP effect.
Fibre Type Distribution
When you’re an athlete who regularly lifts heavy, you probably have a higher proportion of type II fibres. That said, these fibres also fatigue at a faster rate - due to a greater utilization of anaerobic energy stores, and due to their limited supply. It’s a bit of a catch-22 but something you’ll likely need to monitor when incorporating PAP techniques into your training. Tsonga looks like he’s done his fair share of lifting, I mean, have you seen the guy move on the court? There’s no doubt that if we took his muscle biopsy, the proportion of type II fibres would be quite high.
Training Level
It’s no surprise here but the more trained you are, the better you’ll respond. If you’re strong, have the appropriate muscle fibre distribution, and your CNS is able to quickly recruit those type II fibres, PAP will likely work out for you. Tsonga is a well trained athlete so it’s not unlikely that he’ll experience the benefits of PAP, but what about a typical 12 year old junior? When it comes to the gym, young athletes should focus on improving their general strength and power abilities through general bodyweight and plyometric exercises. There’s plenty of time for them to employ PAP when the time is right. That’s not to say a 17 year old with 10 years of training experience won’t benefit from PAP, as I believe they would.
PAP Recommendations For Tennis and Final Thoughts
What Tsonga and his team failed to do, or at least failed to show us, was whether PAP worked for the French star? In other words, did they measure his groundstroke speeds before and after lifting? That would give a clear indication if the PAP effect in fact had the desired result. You may be able to use a radar gun with your athletes to determine if PAP works - or if certain variables need to be adjusted to get an increase in ball speed. I do believe there’s a time and a place to employ PAP into the training regime of a tennis player but before you start imitating Tsonga's training routine, read the following recommendations first:
Advanced Athletes
Athletes with a solid training history can incorporate PAP methods into their training program. It’s important to determine if they have the necessary background with weights, otherwise, get them strong and powerful first (with traditional methods) and then move on to more advanced methods. This could take several years however, but patience is important when it comes to an athlete's development.
Strong Athletes
Similar to above, strength levels need to be monitored. Generally speaking, if your athlete cannot squat at least 1.5x their bodyweight, or bench at least 1x their bodyweight, they’re not ready for PAP.
Powerful Athletes
There are many ways to get an athlete explosive without incorporating PAP techniques. Methods that are tried, tested and proven. Use those methods first, then move to PAP.
Appropriate Intensities
When using weight training methods to gain the PAP effect, intensity should be at least 80% of max, otherwise it won’t work. Check out this article to see how you can test your 1RM.
Non-Fatiguing Exercise Volumes
Like Tsonga, do not fatigue yourself with the pre-explosive exercise. With most exercises, less than 5 reps seems to be key (and never go to muscular failure...you DO NOT want to feel a burn).
Rest Intervals
Because the research is all over on this one (anywhere from immediate to 20min rest may work), a good rule of thumb is to perform the explosive exercise when you feel ready. In strength training, rest intervals are generally just average values taken from research, and many top athletes have better results on feel.
Mechanically Similar Exercises
This is critical. Both exercises need to be similar in terms of the kinematics/kinetics. For example, I actually prefer using a MB side throw (the ball must be heavy enough for optimal fibre recruitment) followed by groundstrokes. When performing this complex, athletes I’ve worked with have shared comments like “the racquet felt so light” and “I felt like I could swing faster”. Although I didn’t have a radar gun, those are good indications from your athletes that there may be a benefit.
Use PAP Only During Training
If you are incorporating PAP into your training, make sure it’s just in the training and not prior to a match or tournament. The research is scarce on this topic so for now, let’s play it safe.
Responder vs Non-Responder
Test to see if your athlete is a responder or not. There are various ways to do this. Let’s say you want to play around with an athlete’s serve speed. First, test the serve speed by hitting a bunch of flat ones (make sure to warm-up beforehand). After a suitable break, perform an exercise with a similar movement pattern to serving, like a split-jerk or MB push press throw. Again, after a break, re-test the serves. Was there a change? Did the serve speed increase or decrease? It’s an interesting test.
Whether you like it or not, we have a lot to learn from science yet - and in this particular case - we can’t rule out PAP's potential benefits just yet. Maybe you thought Tsonga’s routine was ridiculous or maybe it intrigued you. Whatever the case may be, it’s an interesting area not to overlook. I personally have tried various forms of PAP both in my own training and that of my athletes - with more traditional movements (i.e. back squat to jump squat). But perhaps what Tsonga did will open up some new avenues for us to explore...I mean the game is constantly evolving, why not stay ahead of the curve.
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