In today’s post, Dr. Natalia Verkhoshansky gives us a preview of one of her presentations at The 2013 Seminar “Drop Jump vs. Depth Jump.”

In sport training literature, the terms “Depth Jump” and “Drop Jump” are usually understood as synonyms and both of them are used to name the same exercise: a jump executed by droping from a height with vertical rebound.   It is well known that this exercise was invented by Verkhoshansky at the end of the 1950’s for Track & Field jumpers and sprinters, and was also successfully used in many other Olympic sports.  These coaches recognized it as the most powerful training means for increasing explosive strength.

Near the end of the 1960’s, this “secret weapon” of Soviet athletes became known in the United States under the name Depth Jump thanks to the English translation of some of Verkhoshansky’s articles (M.Yessis, 1968, 1969). In 1978, Fred Wilt, who was a pen friend of Verkhoshansky sense from the 60s, presented the Depth Jump as one of the exercises, which were termed as Plyometrics[1]:

“The way drop jumping has become popular is typical of how training methods evolve.  It is rumored that the Russian athlete who won the 100 and 200m  dash in the 1972 Olympics, Valery Borzov, utilized plyometric drills as part of his training (Wilt, 1978). Coaches of rival athletes became interested and began to search for more information. They found a description of drop jumping in a translated Russian paper by Verkhoshansky (1966), and adopted the idea and developed their own modifications. These modifications are now incorporated in widespread athletic programs” (Bobbert, 1990)[2]

Unfortunately, in these programs the rules proposed by Verkhoshansky in applying Depth Jumps in the training process were often not taken into consideration. The rules were associated with Verkhoshansky’s methodology of Special Strength Training and were not well known in the West because his books were not officially translated into English. Near the end of 1970, the ways to apply this exercise in training practice was strongly influenced by the researches of Paavo Komi and his collaborators.

Komi introduced a new understanding of Plyometrics as exercises which involve the Stretch-Shortening Cycle. The exercise, which was termed Drop Jump, was used as the model of the SSC and adapted to study its mechanics and energetics in standardized conditions. These studies analyzed how the changes in these conditions influence the activity of physiological mechanisms which were hypothesized to be responsible for the enhancement of performance during the final phase of reversing in landing-take-off movements. In the longitudinal experiments the training effect of this exercise was evaluated based on the level of the subject’s improvement. Subsequently, a certain technique of the Drop Jump was developed which allowed emphasizing these physiological mechanisms.  This technique was standardized in the Drop Jump test, which was proposed by Carmelo Bosco to be the control in evaluating the level of athlete’s jumping
abilities.

Since the terms “drop jump” and “depth jump” were considered to be synonyms, Drop Jump and Depth Jump were considered to be the same exercise. In consequence, coaches began to apply Bosco’s Drop Jump in the athletes training believing it was the same training means as the Depth Jump developed by Verkhoshansky.

However, for those who are familiar with the works of Verkhoshansky, the execution technique of Drop Jump may seem to be very different from the technique proposed earlier for the Depth Jump.  The first difference is in regards to the athlete using an arm swing. Even if the coach allows arm swings in training with the Drop Jump, the arm swing is not allowed in the Drop Jump Test, so in evaluating the SSC the evaluating movement would be different than the training exercise. The same characteristic appears in the early research on the Drop Jump. The exercise was always applied as the jump with the hands on hips. In regards to the Depth Jump, we don’t find such constraints. In fact, the athlete should use the arm to reach (touch) the overhead goal.

The second difference is in the technique of landing. Drop jumps should be executed with a hard landing keeping the leg muscles stiff, in attempt to minimize the leg’s flexion during the landing. This is a fundamental condition for the elastic energy recoil. On the contrary, in Depth Jump the athlete should not land with rigid, extended legs.  The landing should be resilient and elastic, with the optimal depth of knee flexion at the end of the amortization phase.

Also in the rules of applying these exercises we find differences as well.  The first difference regards the goal of the exercise. Drop Jumps should be performed trying to obtain the maximal height of rebound with minimal ground contact time. The short ground contact time is considered to be the fundamental condition for the elastic energy recoil. Whereas the Depth Jump should be performed trying to obtain the highest height of vertical rebound using the overhead goal. The ground contact time should be short, but it should be the optimal time to allow the athlete express the maximal explosive effort in take-off phase.

The third difference regards the drop height. Depth Jump should be performed from the drop height of  75 cm (or even 1.10 m when this exercise is used to increase maximum strength), while the Drop Jump should be from 20 to 60 cm. For the Drop jump, the distance of dropping higher than 60 cm is considered to be dangerous for the leg joints of athletes and inappropriate for reaching the goal.  Increasing the height above .6 M leads to an increase in ground contact time and to decreasing the height of rebound, which is the exact opposite of the goal of utilizing this exercise (decreasing ground contact time and increasing rebound height by increasing the ability to utilize the SCC).

How, with all these differences, could the confusion be explained through point of view of modern research?

In fact, Verkhoshansky’s Depth Jump could be seen as a Drop Jump executed wrong: with inappropriate drop height and with inappropriate technique (without the close control of the ground contact time and the level of leg flexion at the end of landing phase). With this confusion we could only wonder why Depth Jump was considered by several generations of Soviet coaches and athletes as the most effective jumping exercise.  The reason is because they are two different training means for two different purposes.  Many advanced coaches who tried to keep abreast of modern scientific research had noted these differences and had decided to modernize the execution technique of this exercise. Their thinking was that it’s effect would improve.

On the other hand, a great part of trainers/practitioners did not attach great importance to these differences in the execution of these exercises.  They only heard of this exercise that was a powerful training means discovered by Verkhoshansky, but they did not read his works. As consequence, they accepted the results of research on Drop Jumps as the rules for correct execution of technique of the Depth Jump. We often find such confusion in the popular texts about Plyometrics where Verkhoshansky’s Depth Jump is described as the Drop Jump.   All indications for this application is that the information was taken from the articles about Drop Jump and misinterpreted.  In both cases, the use of the Drop jump as the original exercise, or an advanced form of the Depth Jump, led to an misinterpretation of the methodical guidelines elaborated by Verkhoshansky.

Thus, the results of one Italian researcher showed disagreement with the opinion of Verkhoshansky, and that his famous exercise may be successfully used only by low level athletes. In this research, the experimental group of low-level athletes carried out this exercise during a certain period and obtained a greater increase in the maximal height of the countermovement vertical jump than a control group of same level athletes who used only ordinary jumping exercises. The problem is that the experimental group carried out not Depth Jumps, but Drop Jumps executed according to the technique proposed by C. Bosco.  In fact, Verkhoshansky considered Depth Jump as a Shock Method exercise.  These powerful training means for development of explosive strength should be used only by the high level athletes.  This is not because it is ineffective for the low-level athlete, but because the ordinary jumping exercises could give them the same results.  Nevertheless, we do not always find the same opinions about the training effect of the Drop Jump and we often find discussions about the ways of applying them in the training of low-level athletes, adolescents and even children.

May Depth Jumps and Drop Jumps be considered as the same exercise?

If the answer is “yes”, what technique of this exercise is more correct? In other words, who was wrong: Verkhoshansky of Bosco? If the answer is “no”, what exercise is more effective?

To answer these questions, Depth Jumps and Drop Jumps were analyzed beginning with their origins. To clarify the similarities and the differences between them, the results of the recent research was analyzed in which the physiological mechanisms involved in these exercises were investigated as were the results of applying these exercises in training practice.  The results of this analysis showed that Y. Verkhoshansky and C. Bosco were both correct.  They not only used different terms, but also different exercises which should be used for different purposes, and should be applied according different rules.

Coaches should be advised to distinguish between these two exercises that are so often confused.  The main purpose of using Drop Jumps in training process is, mostly, the improvement of the athlete’s capacity to utilize the elastic energy recoil during the reversal phase of SSC movements. Whereas, the main purpose of using Depth Jumps is, mostly, increasing the explosive strength and improvement of the athlete’s ability to express the highest explosive strength effort in specific take-off movements.  This could be performed not only in the reversal SSC regime, but also in isolated concentric regime.   Another feature of this training means is that it allows the athlete to increase maximal strength through the improvement of their neural mechanisms.  More exactly, the exercises increase the level of motor unit synchronization, the level of motor unit recruitment, and firing rate at the beginning of maximal strength effort. Depth Jumps performed with a high drop height (1.10 m) allows the stimulation of muscles in similar way as the Barbell Squat executed according to Maximal Effort Method, but not by the same means.  The depth jump does not use a high level of
opposition (barbell weight) to the bring about a maximal voluntary strength effort, but utilizes the forcible muscle activation brought on by the impact with the ground.

The recent research[3] indicates that this forcible activation of muscles starts not at the beginning of touchdown phase, but before ground contact and that it is provoked by the increased descending drive from the motor cortex. This pre-landing muscle activation serves to protect the athlete’s feet from the impact.  It is determined by the perceived distance of falling by the athlete when he/she stands on the raised platform before the drop down. As consequence, the stretch reflex mechanisms are likely to contribute to, but not control, the post-landing muscle activity during the downward movement after touchdown and mediated not by stretch receptors, but by higher order CNS structures. As a result, during the push off phase these structures work in concert with simple reflexes to reach a given goal; to achieve a maximal height of rebound or to achieve a maximal height with minimal ground contact time.  This explains why the obtaining a shortest ground contact time is not as important in the Depth Jump as in the Drop Jump, and therefore a higher height of dropping is allowed.

The muscle activity prior to foot contact is timed to the expected instant of touch down and is modulated as a function of drop height. More than this, the pre- and post-landing EMG activity amplitude, which determines the level of muscles activation before the active take-off movement, is scaled to drop height in an approximately linear fashion. So a high drop height used in Depth Jump, which is inappropriate for increasing of the elastic energy recoil, allows obtaining an extremely high level of muscles activation during the take-off movement. However, such a high level of training stimuli is needed only for  high-level athletes and its applying requires  careful considerations.

The rules of the preliminary preparation to the use of Depth Jump will be analyzed in the second presentation: “Progressing the Jumping Exercises: Practical Application for Coaches”.

[1] Fred Wilt. “Plyometrics – What is it and how it works”, Modern athlete and coach, 1978, n.16, pp.9-12.