Plyometrics and jump training, part 1: working back from the sport

Plyometric and jump training is a very popular topic in high performance sport, with many differing views on training and assessing different types of jumps. To tackle this topic, I will present a series of three articles, each addressing a critical consideration for sports performance practitioners: 1) working back from the sport, 2) assessing and diagnosing plyometric and jump ability, and 3) programming plyometric and jump training. These articles will attempt to give coaches and practitioners a clear and practical guide to picking the type of jumps and lower body plyometrics most suited for their sports and athletes.

First, a disclaimer. I am going to use the terms “plyometrics” and “jump training” interchangeably. A purist might define plyometrics as any type of fast stretch shortening cycle activity with a contraction time less than ~150-300ms, depending on if you listen to Komi, Schmidtbleicher or Verkoshanksy. However, most jumps you see in “plyometric” programs are likely not performed within these time frames. For example, a countermovement jump common in “plyometric” programs normally has a contraction time >500ms. But you could call it a slow stretch shortening cycle activity a la Schmidtbleicher ^[1], who places his cut-off at contraction times greater than 250ms.

Know the sport to know your plyometrics priorities

One of the best quotes I use (stolen, of course, from Dr. Jeremy Sheppard) is: “the preparation framework has to serve the performance model.” With any type of physical preparation system, one of the first considerations I always have is what an athlete needs to do in their respective sport. I will generally prioritize these sporting demands, and the positional demands within that sport, in my programming over any individual deficiencies, such as poor results on a movement screen (see Figure 1). The exception is when the individual deficiencies are extremely pertinent and need to be fixed before the athlete can compete in their sport, like in a post-surgery return to play process.

For instance, in terms of plyometrics, if an athlete does not need to land from high heights and rapidly jump or produce force again, as in gymnastics or snowboarding, depth jumps may not be the most relevant training exercise, even if the athlete is not very good at depth jumps compared to countermovement jumps. Likewise, if an athlete does not have to produce a high amount of force from a static position in their sport – for example, they do not start the event off starting blocks – I would rarely, if ever, use non-countermovement or squat jumps in their preparation. That would be true regardless of their eccentric utilisation ratio or the ratio between the countermovement and non-countermovement jump. More on that in the second article of this series.

Figure 1. Priorities in physical preparation systems

A sport relevance classification system

Different types of plyometric exercises are therefore relevant for different sports. Several factors can help determine how relevant any jumping exercise is for a given sport (see Figure 2).

Figure 2. Factors in determining the relevance of any plyometric/jumping exercise

Stance

The first factor I suggest coaches consider is what type of stance the athlete is in when he or she produces force or jumps. The fundamental question is between a bilateral or unilateral stance, which then should lead practitioners to another question: “If force is predominately produced from a bilateral/unilateral stance, are we improving force production from this stance in our training?”

Table 2 outlines some common sports and the type of stances athletes in those sports might jump from. For example, in sprinting, there is a bilateral (split) stance to start from the blocks, and then an athlete relies on unilateral force production from the first step. Meanwhile, in basketball, there is a range of different stances used for force production. Both bilateral and unilateral stance force production are common in variations of rebounding, shooting, accelerating and change of direction in basketball games.

It is also worthwhile considering whether bilateral stances are offset or split, and if this should influence what type of plyometric (and strength) training you do with athletes. My hunch from experience and preference is to account for this in programming, as jumping from a split stance can be very different practically than from a “true” bilateral stance. To improve the force production from a sprinter’s block start, bilateral split stance jump variations may be preferable to conventional bilateral jumps as you get closer to competition.

Table 2. Common type of jumps in different sports

Contact/Contraction time

The next factor to explore is the contact/contraction time the sport allows for producing the force needed for the activity, and comparing that with the contact/contraction time of the jumping exercises you are using. A good way to visualise this is by having a look at a force-velocity curve with common activities overlaid on the graph (Figure 3). Basically, the lower on the curve you get, the lower the contact/contraction times allowed to produce force in the activity.

Figure 3. Force-Velocity curve with common strength & conditioning activities overlaid

Although you will probably see the force-velocity curve in almost any strength & conditioning lecture you go to, I like to use it to remind myself where I need to be focusing my efforts for certain sports. For instance, if a sport involves activities like maximal velocity sprinting, which entail a relatively lower force and higher velocity (i.e., a low contraction time), the argument for doing any type of long contraction jump training may be limited. The same goes at the other end of the F-v curve. Relatively high force and low velocity (long contraction times) activities like weightlifting do not make a case for low contraction time jumping in training.

This is also relevant for different types of jumps and performance. Recent research on volleyball showed greater improvements in volleyball-specific jumping following predominately countermovement jump training (similar contraction times to most volleyball-specific jumps) versus predominately depth jump training (shorter contraction times than most volleyball-specific jumps) over six weeks. ^[2] Relatedly, I found it very interesting that in my time with the Chinese Olympic Weightlifting National team the amount of actual jumping work they did in training was very limited, besides the occasional challenge to see how high a box jump they could do. Although you may argue that every time they perform an Olympic lift they “jump” with a barbell (and they were all very good at bilateral jumps, but more on this in the next article), it made me question how activities far removed from one another on the force-velocity curve and with very different contact/contraction times benefit each other in higher level athletes.

From this work in weightlifting and my experience with elite jumpers and sprinters, my first suggestion for any jump or plyometrics training would be doing most of your work just above, at or below where the activity you want to improve sits on the force-velocity curve. This does not mean never doing any work outside of that range, like some heavy strength training or Olympic lifting with an athlete concerned with improving their sprinting speed. But it does mean focusing on contact/contraction times slightly longer or slightly shorter than those of the activity you want to focus on with jumping/plyometrics training methods.

Besides different types of jumping exercises, this might also mean athletes jump with slightly heavier or lighter loads than bodyweight; or slightly faster or slower than normal. To provide some examples, here are contact time ranges in elite male athletics that we may be able to use to help us determine how relevant any training activity is for any sport-relevant activity we are trying to improve:

• Unilateral
  • Sprinting at maximal velocity: 90-100ms
  • Long jump take-off and triple jump hop: 120-135ms
  • High jump take-off, and triple jump step and jump: 150-190ms
• Bilateral
  • Discus and javelin transition and delivery: 300-400ms
  • Shot put transition and delivery: 380-440ms

From practical experience, a good rule of thumb is a bandwidth of up to ~100ms for bilateral and ~150-200ms for unilateral jumps (which take longer for athletes to generate enough force) above and below the activity you want to target. The closer the contraction time, the more relevant.

Of course, if you are targeting faster contraction times like in sprinting, the upper limits of these bandwidths only really apply above the targeted contact/contraction time. The only exception I have is when an athlete is coming off boxes higher than their vertical jump in a depth jump. Then I generally stick with a 350-400ms contact time limit for both bilateral and unilateral jumps. This would be different for a drop jump where contact time is prioritised.

As an example, my primary choices to augment maximal velocity sprinting performance will be jumps/plyometrics with contact times below ~200ms for bilateral jumps and ~300ms for unilateral jumps (e.g., bounds or pogo-type jumps).

Coaches in field/court sports should remember these contact/contraction times will normally be longer in lower level or less explosive athletes and on different surfaces. I also believe the high jump take-off contact times are probably more relevant than the long jump equivalents to any unilateral jumping exercises in field/court sports, due to the approach speed before take-off. Similarly, the contact times of the transition and delivery in the throws in athletics are probably most applicable to any bilateral jumping or force production (e.g., tackling in rugby league) in field and court sports.

Measuring these contact times yourself in competitive situations for whatever activity you want to improve is easy enough. All you need is a slow-motion camera and timing application (e.g., MyJump 2) on a smartphone.

None of this implies that you would never do jumps with contraction times outside of these bandwidths to improve certain aspects of performance if diagnosed/warranted. You may, for example, want the athlete to improve their impulse through time on the ground or “feel” the ground to generate force. There is a fine art in balancing “relevant” plyometric activity with what an athlete does regularly in their sport, so you are not overloading a particular stimulus and cause the athlete’s performance to regress.

Direction of jump

The direction of the plyometrics or jump is the next factor that should be considered in establishing how relevant it is to the athlete. The four directions that are pertinent are vertical, horizontal, lateral and rotational.

Again, the nature of the sport influences which directions to apply with any jumping /plyometric work. For track & field sprinters and jumpers, obviously, vertical and horizontal are the most relevant for their performance; whereas for field/court sports like basketball, all four directions would likely be relevant.

That is not to say that any “less relevant” jumping work (i.e., in directions outside what is in the sport) is not of any benefit for an athlete. It’s likely that the inclusion of lateral and rotational jumps are beneficial for injury risk reduction in the more “linear” sports like track & field. ^[3] There is also some debate over whether vertical or horizontal is most relevant to sprinting performance. These choices at the elite level depend on the athlete. A technical appraisal of their running (e.g., how much does their centre of mass oscillate when sprinting) or a stride length:flight time ratio can help coaches determine which direction to prioritize or bias towards.

Approach into the jump

The approach into the jump is the next factor I use to evaluate the relevance of any jumping/plyometrics training.

The final stage of any approach in jumping normally involves three components: the penultimate step, the transition or “cut step,” and the ultimate, block or take-off step (Figure 4). The “cut step” is called a cut because of the recovery transition of the take-off leg ankle across the penultimate stance leg – it “cuts” the penultimate stance leg at the ankle or lower shin, ideally.

There are some differences between a unilateral or bilateral take-off. For example, in a bilateral jump the block step becomes the penultimate step. Bilateral jumps also have a common pivoting action and knee valgus that you normally will not see in a unilateral jump, with an extra step added to the three components in Figure 4 to turn it into a bilateral jump.

Although a lot of jumps in sport rely on an approach (it is somewhat rare that athletes will jump out of stationary positions in a sport other than during starts), most jump training you see in strength & conditioning seems to rely on jumps with no approaches. I feel there is a disconnect here in programming, and adding simple 1-, 2- and 3-step approaches into jump training in repeated jumping drills, where appropriate, should benefit athletes. This would be, at a minimum, from a coordination/sequencing aspect. I would also suggest training both linear and curvilinear approaches to account for how athletes will jump in competition.

Figure 4. Final stages of a jump approach

This category also considers whether the athlete is dropping off a box or has a static start, as in a squat or non-countermovement jump. As I touched on at the start of the article, some of these types of jumps need to be considered in light of what occurs in the athlete’s sport and if using them as interventions will impact the performance model of the sport.

Surface

The final consideration revolves around the surface they train on. Surfaces will generally range from closed (e.g., track, rubber floor, hardwood court) to quasi-closed (e.g., sand, trampoline).

For relevance, the surface an athlete jumps on should be as close as possible to what they compete on. However, and similar to incorporating other directions of plyometrics for athletes to decrease injury risk, there are benefits to jumping on other surfaces. These include reductions in lower muscle soreness and joint load with repeated jumping on softer “closed” surfaces like an acromat, track or grass; along with some potential “overspeed” benefits of jumping on surfaces that give athletes some extra bounce. This would be the case with a gymnastics floor or trampoline, which provides an increase in speed of any jump and, hypothetically, may help the athlete improve their contraction velocities in explosive lower body movements.

Jump training on sand (which I consider a “quasi-closed” surface) has somehow gained a bad reputation in the performance world, perhaps due to the lower amount of elastic energy potentiation in the stretch shortening cycle. Even so, I have found key benefits from it. These benefits range from increases in foot function with low amplitude jumps to a skill acquisition/contrast effect when returning to the surface they normally compete on. Athletes can feel “pushing the ground away” much better on a track after jumping work in a long jump pit. In line with this, there is also some research from soccer ^[4] showing non-countermovement jump performance improved from jump training on sand versus training on grass, perhaps due to a greater emphasis on the concentric phase from lower elastic energy potentiation. This should be of interest for any athlete who needs to emphasize the concentric portion of an explosive activity, e.g., a block start in sprinting.

Working back from the sport to decide the way forward with plyometrics

Hopefully this article has provided some food for thought on the relevance of different plyometric and jumping exercises for performance benefits in an athlete’s chosen sport, and the process of “working back from the sport.” It has been based on not just my experience with elite jumpers and sprinters but a range of different sports I have been lucky enough to work with.

There are many factors I have not mentioned (e.g., injury history) that will determine which plyometrics or jumping exercises to use with athletes, but I suggest coaches consider and manipulate the stance, contact time, direction, approach, and surface to augment an athlete’s response to training. The next article in this series will build on some of the concepts in this article, and focus on assessing jumping ability and diagnosing performance interventions; especially with regards to the adequacy of assessing certain jumps for performance.