

Written by Greg Robins

Necessary information and concepts:

Strength can be displayed in many ways. In general we can classify methodologies for specializing strength training into these categories: absolute strength, speed-strength, explosive strength, reactive ability, and strength-endurance.

We can generalize further and say there are three ways to improve these qualities: repetitive efforts, maximal efforts, and dynamic efforts.

We are focusing on the improvement of Maximal Strength: “The maximal force that a person can develop voluntarily, as measured on dynamometer or in terms or in terms of the heaviest weight that can be lifted.” (Siff)

We are investigating how methods created to improve speed-strength, explosive strength, and reactive ability transfer to the improvement of maximal strength.

In particular, we are looking at how plyometrics can be used to improve maximal strength.

Plyometrics: “Stimulating muscles by means of a sudden stretch preceding any voluntary effort.” (Siff)

Plyometric Activities and Plyometric Training: Plyometric has become a blanket term for A TON of training methods. In reality, many of the things you consider plyometrics are not plyometric at all. In addition, many of the activities you would not consider plyometric, running and jump rope for example, are. Therefore, a distinction must be made between plyometric activities, and plyometric training used as a tool to improve explosive strength and reactive ability. As Siff points out, the Westernization of the term has led to its misuse. Many of the “plyometric training” means are based off of Yuri Verkhoshansky’s brilliant development of the “Shock Method,” and his (and others’) application of this method in Russia and other Eastern countries.

What is a Plyometric Activity (Adapted from Super Training)

A plyometric activity occurs in five phases:

The initial momentum: The phase where the body, or part of the body, is moving because of kinetic energy (KE) it has accumulated from a preceding action. The delay: This phase occurs as an event, such as ground contact, takes place and stops a limb from moving, causing muscle contraction. The delay is noted by the time it takes from the bodies sending of the electrical signal to the actual mechanical contraction of the muscle. In example, your feet hit the ground, and the split second it takes for the muscles to actually fire to help stabilize you / slow you down. The Amoritisation Phase: This is the VERY brief phase in which the stored KE produces a stretch reflex that leads to eccentric muscle contraction (phase 2) WITH explosive isometric contraction, and stretching of the tendons. This phase marks the time between slowing you down to a brief STOP, and the beginning of the concentric (re-moving) stage. It is also given called your “coupling” time. The Rebound: This phase involves the release of elastic energy, coupled with the involuntary contractions caused by the stretch reflex. It will also involve any voluntary concentric contractions you are able to produce in such as brief window opportunity. The Finish: This occurs after the concentric contractions are complete and the body continues to move via the aid of KE imparted by concentric contraction and the release of elastic energy.

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The “Coupling Time” could be considered your “turn around” time. In classical plyometric training the coupling time should last no more than .15 seconds. Although this number has been debated, arguments for a longer figure are still well under 1 second. Therefore, activities that involve longer “coupling times” would not be traditionally considered plyometric in nature.

Coupling times however, can’t be used as the only variable to distinguish something as either a plyometric activity or plyometric training mean. If coupling times were the only decider, activities such as jogging would be considered a plyometric training method.

Because of this, it is easier to categorize plyometric training within the context of intensity. Doing so not only makes them easier to apply within long term programming of athletes in general, but also easier to apply in the planning of an athlete looking to improve maximal strength. This is because they are categorized in a similar fashion to weight training, a percentage scale based off of a 1RM.

In the interest of time, and the very likely possibility that all you want to know is what plyometrics to use and when, I’m going to keep this next part brief.

If Force + Mass x Acceleration, then there are two ways to improve one’s force production. The same force could be trained through loading an individual, or unloading an individual, but the training effect is not the same. Mainly, one trains the involuntary muscle contraction, and the other train the voluntary.

Understanding whether or not you would benefit from one or the other is best decided by determining someone’s weaknesses, in particular by assessing their “strength deficit” (realized force potential subtracted from possible force potential). Doing so is a tough task. Even trying to evaluate someone as “slow” or “fast” is mostly guess work. A further point to be made is that grouping people into fast or slow, especially power lifters, is a misguided outlook. It leads to trying to make a “slow” person “fast” when their improvement in that sense is of little overall value to their goal.

Instead, I recommend evaluating the goal. In the context of this article it is maximal strength. Therefore, slow or fast, plyometrics should NOT be a focal point to your programming. They do however have value.

Improving the explosiveness and elasticity of your muscles will help you move heavier things, albeit at a much slower speed. Some would argue this of greater concern to the raw lifter, over the geared lifter. I have NO personal experience with geared lifting. I can see to the eye why this argument makes sense. However, the stretch reflex is still a component to geared lifting, and plyometrics will improve the return you get on your eccentric contraction when you change the bar’s direction.

I would be interested in seeing how much energy the suit stores as it stretches, and if the ability to put a greater load on the bar because of this causes the training of the body’s improvement in this category to really just be a futile effort, I have no clue.

Suffice to say, plyometrics can help you lift more weight. While they train muscle contraction types that play a smaller role in maximal weight lifting, they still play a role, and their improvement will help you.

Use the tables below as a guide for implementing plyometrics into your training for maximal strength:

Table 1: High Intensity Plyometrics

High Intensity Depth Jumps (Intensity denoted by high drop height, weight of athlete, or use of external load to add mass to athlete such as vest or DB’s.) Advanced: 1 – 4 Sets of 6 to 10 JumpsIntermediate: 1 – 3 sets of 5 – 8 Jumps Rest is maximal, with at least 2m between jumps and 8 to 10m between sets If you do these traditionally, I don’t see their place in most people’s programs. The time is too long, and most of us are not physically prepared for this intensity, in addition to the intensity of subsequent bar loading. A great option for high level athletes, not so much for the strength athlete.

Table 2 Sub Maximal Plyometrics, Moderate Intensity

Depth Jumps (Done from moderate to low heights, with varying levels of effort to contract in opposite direction. These can be loaded with vests or DB’s. Reactive loading, where the weight is dropped upon ground contact is a good option here) Advanced: 1-5 Sets of 3 – 5 JumpsIntermediate: 1 – 3 sets of 1 – 3 Jumps Rest is near maximal: 1 to 2 minutes between jumps, 3 – 5 minutes between sets This is what I would call the top intensity that yields a return for strength athletes. These are best placed on 1 to 2 days of your week. Most likely on lower body training days. These would be used in a low volume fashion, and during a very low volume block of training.

Table 3 Sub Maximal Plyometrics, Low Intensity

Seated reactive jumps, seated static jumps, drop jumps, some variations such as approach jumps, and vertical jumps could be used. (Intesity based on the fact that eccentric muscle contractions are minimized. Arguments against the drop jump in this category are warranted, although most people can’t do them effectively enough to be considered high intensity) Advanced: 1-4 Sets of 8 – 10 JumpsIntermediate: 1 – 4 sets of 5 – 8 Jumps Beginner: 1 – 4 sets of 1 – 5 Jumps Rest in moderate. 30s – 1.5m between jumps, and 2 – 3m between sets These have a solid place in the training of the weight lifter or strength athlete. These are best placed on 1 to 2 days of your week. Most likely on lower body training days. These would be used in a moderate volume fashion, and during a moderate volume block of training.

Table 4 Prepatory Plyomterics

Skips, bounds, short repeated jumps (in place, forward, backwards, laterally). Intensity based on low intensity of contractions, can be done on one or two legs. Set prescriptions and ground contacts vary. Overall you can go pretty high on both. Multiple sets of 15 – 25 ground contacts is ok.For a more restorative function these can be done as high as 30 – 50 contacts. Rest is more minimal with none between ground contacts and 30sec – 2m between sets. These are excellent during high volume training phases and for beginners. These can be placed on 3 – 4 workouts per week. They will not retract from loaded training recovery. Again, use these during higher volume training phases.

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Greg Robins is a Strength and Conditioning Specialist at Cressey Performance in Hudson, MA. Greg has worked with clientele ranging from general population to professional athletes. His unique experience in many different aspects of fitness, strength training, and athletic preparation have helped him become an unbiased authority on all things fitness and performance related. Outside of coaching Greg is a former collegiate baseball player, active member of the MA ARMY National Guard, and enjoys power lifting.