Want to jump higher, sprint faster and improve reactive speed? These are valuable qualities for an athlete. Most people who train have heard of plyometrics and the fact that plyometric training can improve power output is fairly common knowledge. In our new book, Athletic Movement Skills author Clive Brewer dedicates a chapter to ‘Developing Jumping and Plyometric Skills’. In this chapter, he discusses ‘Shock Plyometrics’.
What is plyometrics?
Plyometrics is defined as a form of exercise that involves rapid and repeated stretching and contracting of the muscles, designed to increase strength. It first gained popularity in the 1960’s, Russian jumping specialist and track coach Yuri Verkhoshansky was the creator.
Shock plyometrics such as depth jumps and drop jumps are physically very demanding.
The depth jump is performed when an athlete drops from a height, usually off a box, lands briefly absorbing the shock and then immediately jumps as high as possible. The landing period (or amortisation phase) is short, usually less than 0.2 seconds.
Why shock plyometrics?
Because gravity accelerates the body mass to the floor from a vertical height, shock plyometrics are the highest intensity plyometrics that an athlete can perform. Within this category, progressions and regressions enable practitioners to differentiate between athletes. Key differentiating variables relate to the height from which the athlete drops and the required movement that follows the dropping action.
The higher the drop height is, the greater the acceleration to the floor is and the more eccentric strength the athlete will need to maintain the quality of the plyometric rebound through a minimised amortisation phase. The athlete can develop eccentric strength by practising landing and absorbing force eccentrically. The integrity of the plyometric movement must not be lost by having the athlete drop from too great a height. The longer the ground contact is, the longer the amortisation phase is and the less reactive the training response is. The objective of the shock action needs to be clearly understood; if minimal ground contact is the aim, then drop jumps from smaller heights should be used.
If vertical force is the required outcome, ground reaction times may be longer to enable the athlete to apply greater forces for longer. This concept may help distinguish between a depth jump to squat jump movement (longer absorption of eccentric forces, longer ground contact, reduced plyometric effect) and a normal depth jump for height, in which force absorption through the hip, knee and ankle joints is minimal and ground reaction times are reduced (although they will still be higher than in a drop jump from an appropriate height). An advanced technique and strength base is important.
Is shock plyometrics for everyone?
Brewer says shock exercises should be used only with advanced athletes who are competent in landing techniques. When complexity significantly exceeds the athlete’s capacity to execute a mechanically sound landing, the injury risk increases exponentially. The athlete also needs to have a well-developed sense of the countermovement to develop reactive forces into the floor. This action is important because the maximum height that an athlete can achieve in a countermovement jump plays a role in determining the appropriate height from which a shock plyometric should be undertaken.
What should you look out for?
Two variables are important for the practitioner to monitor in assessing both the quality of the depth jump and the appropriate height from which to perform a shock plyometric. The first is jump height; the second is ground contact time. If suitable equipment, such as a jump mat or force platform, is available, quantitative data relating to both variables should be instantly available. Without such technology, jump height can be measured either by a simple reaching test with the arms or by a jump onto or over a box or hurdle of known height. Although not an exact science, ground contact time can be observed with an experienced coaching eye and it can be heard as well.
The use of video aids this process enormously, particularly when the practitioner is developing a coaching eye and can benefit from the opportunity to review high-speed actions repeatedly. The athlete also can benefit from the visual feedback to support the proprioceptive feedback he or she experiences. The quality of the ground contact (length of time, stiffness in the joints, weight distribution through the foot and so on) plays an important part in whether the action looks and sounds to be of the desired quality. Sound is important, because a crisp, aggressive and active flat-foot contact sounds very different from one that occurs with technical errors.
Because of the influence that gravity-assisted movement has on the eccentric lengthening of the muscles, a rebound jump following a depth jump from a low height (for example, 10 centimetres) should always be higher than the athlete can achieve with a simple countermovement jump. Starting with low box heights, the practitioner can simply increase the drop height by small and known increments until the athlete either cannot maintain or match the jump height achieved in a maximal countermovement jump or until the ground contact time is observably increased or the quality is decreased.
Since shock methods increase plyometric capacity and the ability to use the stretch-shortening cycle they are beneficial for virtually any lower body explosive power movements including sprinting, jumping, agility, gymnastics etc. An experiment revealed that a group of track and field jumpers executing primarily depth jumps (all of them did 475 jumps) over a 12 week period showed greater improvement in reactive ability than a group which trained with traditional methods and executed 1472 general push offs.
If performed correctly shock plyometrics can be a very functional exercise, benefitting athletes in track and field, basketball, football, volleyball, tennis and any other sport that requires sprinting or jumping.
For shock progressions and much more information on plyometrics and depth jumps and drop jumps check out Athletic Movement Skills.
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