I have a confession to make: Some of the things I've written about in years past could now stand to be updated, if not outright corrected. This article deals with one of those topics, plyometrics. In years past I've written quite about plyometrics from both a scientific and applied standpoint, but with new information, more up to date research, and more experience, viewpoints often change a bit. This article represents some of my current thoughts and recommendations on the topic. I will present my findings as a series of common myths I see. Some of these I've been guilty of promoting myself at one time or another.
Myth #1 - Plyometric ability (reactivity) is a distinct, separate quality
Pull a rubber band back, stretch it, and let it go. It has long been thought that muscles behave the same way. When you pre-stretch them force is stored in the tendon which allows you to exert more force. The pre-stretch is why you jump higher when you precede a jump with a short dip or you throw harder when you rear your arm back. This "plyometric action" exists in just about all movements and in most strength and conditioning texts has been though to be a separate, distinct quality. This might be partially true, however, more recent evidence indicates the reason we produce more force when we pre-stretch our muscles isn't due to a lot of magical stretch like plyometric action, it's largely due to the fact that preceding a movement with a countermovement allows us to position our limbs and muscles in a way to better exert force. (1, 2) It allows us to take up the slack in the muscle and gives us more room to build up force. The force is still voluntary and is still impacted by the same things that improve any other movement. Build powerful, strong, and efficient muscles and you improve plyometric action as well as everything else.
Myth #2 - Plyometric action is a highly trainable quality
How much additional force you get from a "plyometric" movement is mostly genetic and unique to you as an individual. True plyometric ability isn't something you can really impact through training to a large extent. In fact, it's likely to get less as you grow as an athlete even as you progress as an athlete. HUH!? Before everybody goes off the deep end with that statement let me explain:
Let's say your standing stationary vertical jump is currently 20 inches and your 3 step countermovement vert is 26 inches
That basically means you're getting 6 additional inches from plyometric action.
What I'm saying is you're unlikely to ever see that difference grow much. It can (and usually does) get smaller, but it rarely grows much, even as your overall performance gets better. The general trend in any developing athlete is to get more proficient at exerting force under smaller windows of opportunity so he finds over time he doesn't need as much wind-up to generate the same amount of power. This is even true for people like high jumpers, who seek to benefit as much as possible from plyometric action.
In sticking with this same hypothetical example, lets say you improve your stationary jump from 20 up to 35 inches. You're still unlikely to find more than a 6 inch difference in your running countermovement jump (41 inches), regardless of what type of training you did to get there. Generally speaking, the longer your limbs and legs (particularly lower legs), the greater you'll benefit from plyometric wind-up. The shorter your legs, the more likely you are to jump just as high or move just as well from a virtual standstill.
That brings us on to our next myth:
Myth # 3 Plyos work because they train "reactive" ability
If you've followed much of my writing the last few years you know I love to break all athletic movement down into 2 basic qualities:
A: Movement Efficiency
B: Horsepower
Movement efficiency is how efficiently you carry out your athletic movements and is impacted strongly by things like coordination, flexibility, posture, and practice. Horsepower is simply how much power you have behind your execution and is impacted strongly by things like muscular strength.
Plyos can effect both qualities. They directly enhance the movement efficiency aspect because they allow you specific practice and rehearsal carrying out a variety of jumps, bounds, and hops, which closely rival sporting movements.
With regard to the horsepower aspect, power in most sporting movements is a result of how much force you exert at the hips, knees, and ankles. The ankles are most important for absorbing forces allowing your quads and hips to drive your movements. Most plyos provide a low degree of overload to the muscles acting on the hip, a moderate degree to the muscles acting on the knee, and a HIGH degree of overload to the muscles acting on the ankles, due to the constant eccentric forces involved in landing.
Many athletes are less than stellar because they lack "stiff ankles". By stiffness I'm referring to how much your muscles "give" when you move. You want to be like a racquetball and not a flat basketball. Practicing plyo drills on their feet allows them to improve their coordination and ability to quickly engage and generate force thru the ankles. This is an example of good ankle stiffness:
So, in a nutshell plyos work primarily because they improve your feet; They make the muscles acting on your ankle (plantar flexors/calves) stronger, more powerful, and help you become "stiffer." They also allow you specific practice performing jumps, hops, and bounds.
It's also worth noting that people with longer, slender legs often inherently tend to be more ankle dominant. People with thicker builds and shorter legs tend to inherently be more hip and knee dominant. Great athletes often put all 3 together very well.
In my opinion tests such as the consecutive bounce jump test (designed to measure elastic/plyometric ability) really measure how proficiently and powerful your plantar flexors are in relation to your hips and thighs, or simply, how good your feet are. Here is a video of Mike Boyle demonstrating the test and talking about the concept:
Myth #4 - The "shock" method gives supramaximal muscle recruitment
The shock method primarily refers to the use of depth jumps as a training strategy. Read any russian text on the shock method and you'll likely come away thinking all an athlete ever needs to become great is a couple of boxes to do jumps with. The magic of depth jumps is explained by the notion that they give involuntary muscle recruitment.
Muscle recruitment refers to how well you use or "turn-on" your existing muscles. The explanation is that great athletes are great becuase they can utilize, or turn-on, more of their existing muscles in a given task. However, because of the shock method all hope is not lost for the average Joe athlete. Most exercise variations are limited by the force we can voluntarily exert. However, imposing a high amplitude forceful stretch on a muscle, such as what happens when you drop off a box, hit the ground, and jump back up, (the shock method) causes the muscles to involuntarily stretch and in an effort to protect the joint it causes the involuntary recruitment of ALL existing muscle cells. Over time this allows the average Joe to become like a superstar. Sounds great eh?
Unfortunately, we now know this is partly a myth. It is true that great athletes get more out of their muscles but not because of muscle recruitment. Even beginners can recruit all their muscles. Anything equivalent to around 80-85% of max voluntary effort will do it. The reality is great athletes can really ramp up something called rate coding and this is largely due to the inherent excitability of their central nervous systems.
Rate coding refers to the frequency that your brain sends messages telling a muscle to contract. The faster the frequency the greater the intensity of any given muscular contraction. Rate coding is similar to beating the heck out of a drum with your hands. The faster and harder you move your hands the stronger the beat. Rate coding appears to be highly related to the excitability of the CNS. Activities that cause a great psychological arousal fit the bill here. This explains why we're capable of exerting more force in our movements when we're excited or slightly nervous. A highly excitable nervous system can produce greater force at a faster rate due to the positive impact on rate coding.
The Stimulation Method
In this regard the Russian "stimulation method" in my opinion is better at doing what the shock method/depth jumps are supposed to do. Here you perform one exercise to really activate or excite the CNS. You then follow it up with an exercise to take advantage of the CNS excitability, which temporarily boosts rate coding. Over time your body becomes more sensitive to the neural discharges from your CNS and learns to accept a new level of force as being normal for a particular movement. Think of a baseball player swinging a bat loaded up with weights before he steps in the batters box. The loaded bat allows him to swing a regular bat with more speed and power. The stimulation methods are also known as post-activation potentiation methods. Here are a few examples:
Squat x 2-3 with 90% load - rest 5 minutes jump squat- x 6-8 with 20% load
Depth jump x 5 from 24 inch box rest 3 minutes running jump x 3
Loaded sled sprints x 20 yards with 50 pounds rest 5 minutes bodyweight sprint x 10-40 yards
Jump with weighted vest x 3 rest 5 minutes regular jump x 3
Bench press unrack and hold 110% of 1rm at lockout x 5 seconds rest 3-5 minutes 1rm Bench press
Snatch grip partial deadlift from blocks with shrug - x 5 reps rest 5 minutes Hang Power snatch x 2-3
Squat 2 x 2 at 90-95 % - rest 4-6 min depth jump- 2 x 5 from 24-30 inch box.
*45 degree back extension Iso hold with toes pointed x 7 seconds - rest 3 minutes - jump variation
* This one is the brainchild of Coach Andrew Darqui who had excellent results with it.
Getting back to depth jumps, what they really are is:
A: A form of loaded jump training
B: Specific strength training for the plantar flexors and to a lesser extent the knee extensors (quadriceps).
Depth jumps enable you specific practice jumping while simultaneously providing a HIGH degree of eccentric overload to the plantar flexors (ankles/calves). Anytime you practice an activity you optimize qualities such as rate of force development in the task. As a lone training method depth jumps have a weakness in that they are quad and calf dominant and don't affect the glutes and hamstrings strongly, thus aren't effective for long in isolation. (4) You can still use them though, but just know what they're capable of and what they're not. You need good strength at the hips and knees (a.k.a.- a good squat) before you can really benefit much from them. Think about it - If shock methods were all they were cracked up to be all these guys doing this new age "parkour" would be jumping out of gyms.
Myth #5- Plyos/Depth jumps don't improve standing vert
This is one I hear a lot. The reality is anything you do to improve one form of vert will likely improve the others. Providing you can benefit from them, in my experience depth jumps do a good job of improving standing vert. Squats will also improve running vert. The reality is it's about impossible to improve your running vert without improving your standing and vice versa. The exception is increased strength in squats won't always impact your running single leg jump.
Myth #6- One MUST engage in specific plyometric activities
If you want to optimize your jumping efficiency you need to jump. If you want to optimize your sprinting efficiency you need to sprint. The best way to improve horsepower for most muscle groups is through strength training with weights. You can certainly jump high without ever performing a single plyometric drill you just need to optimize your jumping technique and get stronger. The same goes for sprinting. You can certainly add in some plyos for enhanced effectivness if you want, but don't think you NEED to.
In my observations more people screw up by doing too many plyos than those that don't do enough. Plyos are kinda like dating the Hooters chick. She might be better than what you have on your plate, but you better be careful or you're just setting yourself up for a fall! Many athletes border on overusing their ankles and knee extensors already and plyos surely don't do anything to help that. In the last few years I've had the privilege of working with 5 athletes who achieved a 37 inch vert or better while improving at least 8 inches. Most of them did very little plyo training. That's not to say they wouldn't have benefited more from plyos, but with practice, games, and other qualities being more important, plyos are the first thing I'd put on the backburner. If you're 100% structurally sound and you've determined you can benefit from them and you're in offseason mode and don't have practices, games, or frequent conditioning seassions to work around, you might be the type that can get away with more plyo work.
Myth #7- Plyo workouts should be fatiguing and exhausting
Most young guys think a plyometric workout should be as fatiguing as an Army Ranger obstacle course. The reality is completely opposite. In general you should finish any plyo workout just as fresh if not fresher than you were when you started, or you did too much. You should keep the reps low enough so that each rep is a quality rep. With regard to rest intervals, you should pretend that each set you're going to do is a test of some sorts and rest long enough to be at 100%. For depth jumps a workout of 20 foot contacts is usually plenty and for most athletes I would keep the box heights at no more than 18 inches. Personally I prefer to use plyos as sort of a warm-up to strength training. See my Ultimate Split article for some ideas on how to implement plyos to your strength training workouts.
Until next time!
-Kelly
References:
1. Why is countermovement jump height greater than squat jump height? Bobbert MF, Gerritsen KG, Litjens MC, Van Soest AJ.
2. Is the effect of a countermovement on jump height due to active state development. Bobbert MF, Casius LJ.
3. Contribution of the lower extremity joints to mechanical energy in running vertical jumps and running long jumps.Stefanyshyn DJ, Nigg BM.
4. Drop jumping. I. The influence of jumping technique on the biomechanics of jumping
5. Effects of plyometric training on passive stiffness of gastrocnemii and the musculo-articular complex of the ankle joint. Scand J Med Sci Sports. 2008 Aug 5.