Plyometrics training has been used for the past 50 years in athletic training and has been shown to increase jumping performance (Markovic, 2007) especially in dynamic power sports such as tennis, basketball, football and volleyball. For an exercise to be considered plyometric the use of the stretch shortening cycle by the active muscles must exist with a high intensity eccentric contraction followed immediately by a rapid and forceful concentric contraction (Markovic, 2007). Common forms of ‘plyometric’ exercises include various types of jumping, hoping, bounding and bouncing. Popularly jumping over objects and onto boxes features heavily on YouTube videos from around the world. However it is important to consider what makes an exercise plyometric and not just a dynamic movement done at speed. In this article I shall describe the importance of plyometrics, explain what, why and when you should include different levels of plyometric drills and discuss the volume of plyometrics used in an athletes’ programmed load.
Why should you include plyometrics in an athletes’ training program?
An increased power output is an important characteristic of successful sports players. Plyometrics should only be added to a training program after a good foundation of strength has been established via strength training (Cormie, McGuigan, and Newton, 2011). This has been a common view for several years, however if we examine the physiological effects of plyometric training, whereby significant – up to 10x bodyweight – load is place through the bodies’ muscles, ligaments and tendons, which all combine to create a stretch shortening reflex and a power output, it is possible to find simple everyday exercises than also create similar effects on the body. Everyday examples include running, jumping, hopping, bounding or quick changes of direction. Most of these movements are limited in adult daily life by choice of how we move – we don’t run everywhere or have to jump across gaps in our path like our primal ancestors, however one population group that do several of these movement patterns by choice are children.
Children love to play, it increases their learning via sensory feedback and children enjoy running, chasing, jumping, climbing, changing direction etc, especially if this is masked as a game or even sport. However most children will not have a formal ‘strength training’ background. So does that mean we shouldn’t let them do plyometric ‘training’? Ultimately a discussion on this topic will have to wait until a future time where it can be discussed. However my initial take is that ‘plyometric’ activities are a primal form of ‘exercise’ in which we would outrun, jump or throw objects at potential dangers. The fear of injury has led to us questioning this type of training and wanting to find ways of improving our young athletes. Whilst I believe it is important that young athletes complete strength training, they will already be doing plyometrics within their sport, for example; tennis players are taught to split step and be light and agile around the court, this involves many plyometric type movements and muscle contractions. Therefore I see the role of the S&C coach to improve the factors that could lead to injury – landing mechanics, deceleration drills and strengthening of the connective tissues around joints. Teaching young athletes how to perform jumping, quick ground force reactions and balanced landings correctly will also help, however I feel that large doses of plyometrics training is not necessary and should not be prioritised ahead of strength training and fundamentals.
Back from this tangent, adult and older or rather more developed adolescents that are involved in a competitive sporting environment should have plyometrics as part of their training. Once a good strength base has been established – values of up to 3.0 x body weight across compound lifts – more advanced plyometrics exercises can and should be used. However as stated at the beginning of this piece, these more advanced exercises are often utilised too early in the stages of development and without having completed the basics first. Overall the aim of the plyometrics is to increase power across a very short space of time – less than half a second. Therefore the speed of the exercise should be of paramount importance ahead of the loading, difficultly or volume. With younger children all the way through to adults simple starter exercises such as skipping (jump rope) and agility based games will encompass several of the outcomes desired.
Additional benefits of doing lower level plyometrics can mean an increased volume can be used, a lower risk of injury occurrence and a focus on ground reaction times and stiffness through the ankles can be coached. First step quickness and reactions to external stimuli also increase speed in games play. These skills can be worked on with low level plyometric exercises and will have a significant impact on performance, especially in younger athletes. As stated earlier, many quick feet and low level plyometrics will be used in a games situation, with younger athletes – under 12 – where they may not have chosen a sport they wish to focus on, small sided or 1v1 games such as mirroring, ball drop reactions, tag and agility races will engage the player greater than strict drills focusing on running technique or box jumping.
This video shows a few examples of quick feet, low level plyometrics and reaction games that can be encompassed into plyometrics sessions at any level.
Once an athlete has been involved in physical training for a period of time which enables them to be stronger, less susceptible to injury and have greater power outputs an increased level of plyometrics can and should be used to develop elite standard athletes. There are many flashy videos available to watch online, however most are impressive feats of jumping onto or over objects, few encompass the eccentric component of the stretch shortening cycle or rebound nature of quick ground reaction times. One must also look at the relativity of certain plyometric exercises to specific sport movements, for example box jumps are not a part of any sport but are a particular favourite of the S&C coach. Rarely do you see lateral plyometrics exercises being showcased on videos; however it is important that athletes can control stretch shortening cycles. Some of the best athletes that utilise plyometrics most effectively can be showcased in this video.
Free runners or Parkour athletes have fantastic spring in their movements (stretch-shortening cycle) and are also adept at landing. They train for their sport by doing their sport. This is not always the best approach, but as discussed above many of the training qualities a coach may wish to encompass can be integrated into games and sport specific movements. The key to increasing the difficulty of the plyometric exercise is to start small with the movements and maintain the speed of contraction and quick ground force reaction time.
When it comes to the amount of plyometrics you should include in a session there is a lot of differing arguments about how much is too much. Typically I would stick to around 60-100 foot contacts for most sessions. 60 ‘hits’ would be a low volume session, 100 medium and 120+ a high volume session. A ‘hit’ is counted as a single ground force reaction. An example of which is a two-footed jump or bounce and land, however single leg exercises would count as 2 ‘hits’ as the same amount of load is placed on half the ground reaction surface and therefore equates to twice the load as an equivalent. So 10 tuck jumps would equal 10 hits, whereas 10 single leg hops would equal 20 hits. This is important to consider when counting the number of repetitions in a session or over a period of time such as a training week. What is counted as a rep? An important question also. I would only count the reps where a maximal intention to produce force following a stretch-shortening cycle (load-unload) has occurred or an eccentrically controlled landing has occurred. Due to the forces involved in plyometric exercises, especially jumping, I would not recommend anything greater than low level plyometric exercises for beginners. The joints and structures particularly in the legs – knees, ankles – and in female exercisers (larger Q angle and common valgus knee alignment issues) are in a vulnerable state if not physically strengthened prior to engaging in this type of activity.
In conclusion, plyometric exercises are great for increasing power output from an athlete. An appropriate strength training program should precede dynamic explosive exercises but low level plyometrics can be encompassed concurrently alongside strength training. Care should be taken with the level of athlete, their past training history, age, gender and injury history being taken into consideration.