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Principles Over Methods: The Role and Importance of Plyometric Training

Plyometrics

Almost every athlete wants to be more explosive. They see themselves running faster, cutting with more intent, jumping higher, or in collision sports, being the dominant contact.

Plyometrics is a special form of strength training because it involves exercises where there is an important build up of kinetic energy as the body absorbs the contact which is then used to potentiate the concentric portion of the exercise.

Does that sound complex? If it does, I don’t blame you – Lachy and I did over four years of university to get our head around the concepts of joint stiffness and plyometrics.

In layman terms, it’s best to describe this phenomena using an elastic band.

Imagine pulling an elastic band back, and letting it go quickly. The stored energy in the band (kinetic energy) is released and facilitates (potentiates) the band to become a projectile as it rockets towards your target.

Now, imagine pulling an elastic band back, but instead of letting it go from that stretched position quickly, you slowly bring it back to the starting position and then let it go. Don’t be surprised if it flops on the floor at your feet.

Plyometrics is the training of the former scenario – the tissue is loaded and the kinetic energy that is stored is released to propel you forward.

This in essence, is explosiveness. It’s like a spark to dynamite.

This type of training has been referenced under a few different terminologies, including shock training, powermetrics, kinetic energy accumulation training, and in western coaching, plyometrics.

This type of training works so well because the kinetic energy that is produced during the yielding phase (aka the eccentric portion) is transferred and ‘added’ to the execution of the concentric portion, increasing your power, and force production. Better yet, it also improves your neural drive (brain-muscle connection), your reflex, and other muscular factors involved in the production of force.

There are a multitude of ways to complete plyometric drills.

However, the underlying premise is simple. Once you know to to decelerate the body (we’ll provide you with a video series where Lachy teaches safe and efficient landing mechanics), then you must move through the eccentric portion fast and make the coupling time as short as possible (the time it takes to transition from eccentric to concentric). .

The three forms we’ll cover are:

  1. Altitude Landings
  2. Low Intensity Jumps
  3. Depth Jumps

Altitude landings

It is the eccentric portion of the lift where the kinetic energy is accumulated and stored ready to be utilised during the concentric phase. It naturally follows that it is then the eccentric component of plyometrics that has the greatest effect on vertical jump and lower body power.

Lachy and I are firm believers that before you earn the right to produce power, you need to earn your stripes by learning to absorb force first. By learning how to break fall, you’ll become a more robust, resilient athlete.

If you want to think of it another way, don’t do advanced plyometrics before you learn how to maximise the eccentric portion of the exercise. It’s like wanting to max out on bench before you can even control yourself in a pushup.

You’ll be selling yourself short because the coupling time/amortisation that it takes to switch from eccentric to concentric will be high and as a result, your jump capacity will be low. To reduce this time during transition the only way is to increase eccentric strength and the capacity to absorb the kinetic energy that is produced during landing.

The best way Lachy and I coach this is using a depth jump (jumping off a box or from height), but only doing the eccentric portion of the exercise whereby you ‘stick the landing in an athletic position’. This allows you to use increasing drop heights to progress your capacity to do this.

It’s important to note that you need to land in an athletic position that reflects a position related to your sport – but as a general rule, hips slightly back, torso forward, knees bent at 90-110 degrees is a good starting point.

Understand though that depth jumps in this fashion are still highly taxing and should only be used for short periods of time at low volumes. As you’ll see below, we show a jump progression that will suit most athletes who are introducing the training into their routine.

Low Intensity Jumps

A great jump progression between altitude landings and higher intensity depth jumps are repeated contact jumps. We like this as a bridging exercise because it allows the athlete to get used to applying force, quickly. This effectively trains the coupling time, or the amortisation phase, which we know as that transition between eccentric and concentric.

We want to know our athletes can apply force quickly enough (and with control), before the intensity of the depth jump is implemented. Here is Lachy taking an athlete through repeated low intensity jumps, and some variations on the theme.

 

Plyometric Progression with Coach Wilmot | Part 2

 

Depth Jumps

Traditional depth jumping attained spotlight during the 1970’s through a Russian weightlifting coach called Yuri Verkoshansky. The principle behind this method was to increase power and force output by potentiating the muscles via the ‘shock stretching’  that is experienced during landing prior to the concentric movement.

This is typically accomplished through dropping from a low box (starting around 30cm, progressing to around 50-70cm), to produce a powerful stretch reflex, and immediately jumping up as high as possible, spending as little time in contact with the floor as possible.

The reasons for the dramatic increases in concentric power and strength whittle down to 3 primary factors:

Improvements to Neural Drive

During an intervention of depth jumps, athletes are able to activate more motor units during the movement (recruitment increases), they have better planning (EMG activity demonstrates more rapid pre-activity of the target muscles), and the quality and efficiency of the jump increases.

Improvements to Reactive Strength

Reactive strength is the capacity to rapidly switch between the eccentric and concentric phase of movement. This is commonly known as the amortisation or, coupling time. An athlete with lower levels of reactive strength will spend more time on the ground after landing, and will produce lower levels of force and power during the concentric phase. This is important for athletes, especially those who are required to change direction quickly, requiring a quick turn around from moving in one direction, to another.

Structural Changes

Depth jumps have been shown to increase muscular soreness, which makes sense considering there is a significant eccentric component to the exercise, even if it does end very quickly. However, this differs to time under tension training in the sense that this form of eccentric load doesn’t result in hypertrophy changes in the muscle. This suggests that the improvements in strength is a result of improvements to the contractile capacity of the muscle fibres, not as a result of increase in cross sectional area.

Here are some of our suggestions to help you improve your depth jump:

  1. The joint position of the ankle, knee and hip should be as close to your sporting action as possible upon initial landing.
  2. The coupling time should be kept below 1 second in all instances to avoid losing the elastic energy.
  3. The height of the jump should be regulated by the readiness, capacity and preparedness of the athlete. We recommend a range between 30-70cm in height, and seems to work for most of our athletes.
  4. Don’t do this all year around – periodise this into your training when you need significant increases in power. Here is one possible method to integrating this into your training program:

 

Weeks 1-4 : Altitude Landings

Weeks 5-8 : Low Intensity Jumps

Weeks 9-12: Depth Jumps

Weeks 13-16: Low Intensity Jumps

Repeat this 2-3x per year when suitable around periods of competition.

  1. Don’t over do the volume. Jumping should be performed at a high intensity, not a high volume.

Level of Athlete Height & Optimal Reps (per/week)

Beginner: 30cm – 24 reps

Intermediate: 50cm – 30 reps

Advanced: 70cm – 30-40 reps

 

Plyometric Progression with Coach Wilmot | Part 3