“Plyometric training” or “plyos” is a term that gets tossed around A LOT when in reality, the majority of people are NOT actually performing plyometrics. They are in fact doing jump training – which is very different. Let me quickly give some background information regarding plyometrics so you can understand.
Prof. Yuri Verkoshansky was the father of the “Shock Method”, or plyometric training. He was the one that developed the Depth Jump and utilized the exercise to develop explosive strength and reactivity. The method was designed to “shock” the system into producing as much force and tension as possible. A key characteristic of true plyometric training is an extremely short transition between the landing (eccentric) and propulsive (concentric) phases of the movement. If the transition phase is too long, the energy absorbed during the eccentric action isn’t fully utilized for the concentric action. In the book Supertraining, an action with a transition phase of greater than 150 milliseconds is NOT considered plyometric, but rather ordinary jump training. I’ve also heard of the cut-off being 250 milliseconds, but either way, THAT IS EXTREMELY QUICK and a speed at which very few people attain when they think they’re training plyometrics (except for elite or world-class athletes or when sprinting).
If we look at exercises people often refer to as plyometrics – squat jumps, lunge jumps, hurdle hops – the ground contact time is too long to be considered plyometric. Even if we took an exercise like a Depth Jump or Reactive Medicine Ball Throw, the vast majority of the athletes we (strength and conditioning coaches) work with are too slow to transition. This doesn’t come from a lack of effort, but rather from their training experience, current strength levels, and physical requirements of their sport.
Factor 1 - Training Experience
There has been an on-going debate for many years now in the strength and conditioning field regarding “young athletes and jump/plyometric training”. One side believes that an athlete should be able to squat twice their bodyweight before performing plyometrics, while the other side references the fact that young kids jump and land all the time just through play. Like anything, the answer is probably in the middle, and I think both sides are correct!
a) Young athletes should be performing some type of jump training, primarily in the form of landing drills and low intensity, extensive jump training such as jump rope or hop-scotch. This will build proper landing technique, increase eccentric/braking abilities, improve the athlete’s elasticity and rhythm, as well as have some form of speed carry-over from teaching the nervous system to be quick.
b) Young athletes lack a base of general strength and (in my opinion) should spend a much larger volume of training focused on building that. Structural balance training, hypertrophy training, relative strength, eccentric and isometric strength should be the primary focus of youth athletes to establish a solid foundation to build on.
Factor 2 – Strength Levels
A key training quality that an athlete needs to develop before starting to focus on plyometric training is their eccentric strength. (Link article about eccentrics). Eccentric strength refers to our ability to absorb forces. During a plyometric action, the muscle-tendon complex absorbs the kinetic energy as it is eccentrically stretched then transfers this energy into the propulsive phase (launch or concentric). The energy absorbed is used to ENHANCE our force production relative to had we not utilized that quick eccentric phase. However, if the force upon landing or during the stretch is too great, the Golgi Tendon Organ acts to inhibit the improved concentric phase (think of it as a governor on a car). Getting stronger, especially eccentrically, will act to “quiet” the Golgi Tendon Organ (which is why people advocate for having a certain level of strength established before jumping).
Let’s look at an example. I’m very fortunate to be able to work with the Hawkins Force Plates. With the technology, I am able to visually see an athlete’s strengths and weaknesses depending on certain metrics from their jump performance.
This is a picture depicts a force tracing (how much force is applied to the plates) during one of my Countermovement-Rebound Jump tests. Basically, with my hands on my hips, I do two consecutive squat jumps, both of which I try to jump the highest and be quick off the ground on the second jump. I want you to pay attention to the two white arrows. The one on the left points to the peak BRAKING (eccentric) force, while the one on the right points to the peak PROPULSIVE (concentric) force. As you can see, the propulsive force is GREATER than the braking force. This shows that I was able to utilize the absorbed energy from landing to produce more force, implying the Golgi Tendon Organ did not shut me down on the second jump. (Side note, my ground contact time was 247 milliseconds on the second jump).
For a younger, less developed athlete, what you would see on a force tracing is called an Impact Peak. An Impact Peak is when the force upon landing is the peak force experienced on a reactive jump (braking > propulsive) and signifies neural inhibition by the Golgi Tendon Organ. In this case, the athlete is not strong enough eccentrically to perform plyometrics and should stick with lower intensity, lower amplitude jump training while focusing on improving eccentric strength.
Factor 3 – Physical Requirements of the Sport
Finally, as a coach, you should wonder if plyometric training is necessary for your respective athletes’ sports.
When I started to train seriously for hockey, I did a good amount of plyometrics and jump training. Plyometrics are a very effective training tool for increasing explosive speed and reactivity. However, as I progressed as a coach, learned more about sport preparation, and became more critical of my coaching approach, I started to question the usefulness of plyometrics for improving hockey performance. The primary reason being that, unlike running sports, the length of time a skate is on the ice during a stride is much longer than the ground contact time when sprinting. Because of this prolonged transition time, the plyometric effect has, in most part, dissipated. So, is training the nervous system to fire at faster speeds than 150 milliseconds truly beneficial for ice hockey?
Another difference between running sports and ice hockey is where the primary forces are absorbed and produced from. In running, like 100m track-and-field events or football, the foot and ankle (lower leg) absorb ridiculous amounts of force upon ground contact, whereas in hockey, the principal force absorber and producer are the knees and hips (upper leg). Verkhoshansky developed and had much success with the Depth Jump and Plyometric/Shock Method for track and field and jumping sports (I believe) in part because of the mechanical similarities between the jumps and sprinting. They develop spring-like properties in the lower leg (especially Achilles tendon) that help improve running sports. For hockey though, with players’ feet locked in a hard boot, the lower leg is not the primary source for absorbing and produce explosive strength.
This does NOT mean plyometric-type training does not work for hockey players. It certainly does, if done properly (ex. Use of elastic bands for fast eccentric loading). What I am explaining is that classic plyometric exercises (ex. Depth jumps) are most likely not the best option for developing on-ice speed.
Before writing out an elaborate plyometric training plan for an athlete, make sure to think about the following first:
1) Am I doing plyometric training or jump training?
2) Does the athlete have an established base of eccentric strength and structural balance (GPP)?
3) What is the nature of the sport the athlete is training for?
Once you have answered those questions, then you will be able to develop a plan that better suits your athlete’s performance needs and set them up for long term athletic development.
Train hard folks.
Coach Max
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